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Paleontology Index:ABCs of Paleontology |
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A Aalenian: The first stage in the Middle Jurassic period, dating from 173-170 mya. Abrahamskraal
Formation: A
Late Permian
formation in the Beaufort Group, on the western side of the Karoo Basin
in
South Africa. It contains part of the Tapinocephalus Faunal Assemblage
Zon Acanthostega gunnari: (“spiny jaw”) An early tetrapod from the Late Devonian period, found in East Greenland. It was classed by Romer (1966) as an amphibian in the subclass Labyrinthodontia and the order Ichthyostegalia. Acanthostega is now placed in the "grade" Ichthyostegalia also including the primarily aquatic primitive labyrinthodonts Ichthyostega and Tulerpeton (Coates et al. 2008). The species name gunnari is for the Danish paleontologist Gunnar Save-Soderburgh, who with Eric Jarvik first discovered Acanthostega in the early 1930s. A more complete skull was found by Jennifer Clack in 1987 (Clack 2012). Acrodus anniangiae: An Early Jurassic shark dating from 200-195 mya, discovered in the Lower Blue Lisa Formation at Lyme Regis, Devonshire, England in 1834 by Mary Anning, Elizabeth Philpot, and Louis Agassiz. The species is named for Mary Anning. Adelobasileus cromptoni: A small stem mammal found in Crosby County, Texas in strata from the Dockum Formation, dating from the Late Carnian stage of the Triassic (225 mya). Fossils of a partial skull about 1.7 cm long, and teeth were discovered by Lucas and Hunt (1990). While the lower, rear part of the skull (basicranium) shares numerous traits with early Jurassic mammals, other cranial features such as the petrosal region, which has only a small or incipient promontorium housing the ear cochlea, indicate only an intermediate stage of the character transformation from non-mammalian cynodonts to mammals. If they are mammalian, the Adelobasileus fossils would be at least ten million years older than than those of any previously described mammal (Lucas and Luo 1993). Aegyptopithecus zeuxis: The well-preserved skull of a small female of this early anthropoid species from the Egyptian Fayum, dating from the Early Oligocene period at 30-29 mya. Aelurognathus: ("cat jaw") A
genus of gorgonopsian (carnivorous) therapsids from the Late Permian of
South Africa. Its temporal range was the Wuchiapingian phase, extending
from 260.9–254 Mya. Aeronian: The second stage of the Early Silurian period, lasting from 441-438 mya. Afropithecus turkensis skull : A Miocene hominoid dated 16 - 18 mya, found in 1986 near Lake Turkana in northern Kenya by Richard and Meave Leakey. Agassiz, Louis: (1807-1873) A pioneer Swiss researcher on fossil fish and a geologist. His five volume work Recherches sur les poissons fossiles ("Research on Fossil Fish") published from 1833 to 1843 is a major landmark in paleontology. Albian: The sixth and last stage of the Early Cretaceous period, dating from 112-99 mya. Amalitsky, Vladimir Prokhorovich: (1860 -1917) A Russian paleontologist who, together with his wife Anna, excavated at Kotlas on the Northern Dvina River. Between 1899 and 1914 they discovered a wealth of Late Permian vertebrate and plant fossils, defining the Solkolki Assemblage. Amnion: The innermost layer of the amniotic egg found in reptiles and synapsids. It retains a fluid which surrounds the embryo. Amphibians: ("two life types") A class of tetrapods whose name stems from the fact that at least the first part of the life cycle must be spent as tadpoles in open water. The earliest amphibians evolved in the Mississippian period at ca. 340 mya. Extant amphibians include frogs and newts or salamanders, who descended from Lissamphibia, first appearing in the Early Triassic period at 250 mya.. Amphioxus (lancelets): ("two sharp ends") Lancelets are slender, eel-like filter feeders which appear pointed at both ends. They are chordates in the subphylum Cephalochordata ("head-chordates"), which also includes the Cambrian fossil chordates Pikaia from the Burgess Shale in British Columbia and Yunnanozoan from Yunnan province, China. Anabaena: A present-day, filamentous cyanobacteria which performs photosynthesis, and grows in freshwater lakes and ponds. Its cells divide by forming crosswalls within an outer sheath. The joined cells form a filament-like colony. Photosynthetic membranes called thylakoids line its inner cell walls. Anning, Mary: (1799-1847) An expert fossil collector who lived at At Lyme Regis in coastal Devonshire, England. She discovered several new species of large marine reptiles from the Early Jurassic, including Ichthyosaurus platydon and Plesiosaurus dolichodeirus. She worked with leading geologists including Roderick Murchison and Louis Agassiz, with whom she co-discovered various taxa of fossil fish. Anteosaurus magnificus: A genus of large carnivorous synapsids from South Africa, dating from the Middle Permian period,
which lived in rivers and hunted like crocodiles. It body length
was 5-6 m (16-20 feet), making it one of the largest known therapsid
carnivores. Antiarchi: A widespread order of Devonian armored fish within the placoderm class. Antiarchs inhabited both freshwater and marine environments, including lagoons, rivers, deltas, and coastal environments, and probably fed on invertebrates such as crustaceans and molluscs. The most diverse family of antiarchs was the Astrolepidae, with several dozen genera known in the Middle to Late Devonian (380-359 mya) Anticline: In structural
geology, a fold which slopes away from a common center or peak. Younger
layers
are outside of older layers. It is thus the opposite of a
syncline. Aptian: The fifth stage of the Early Cretaceous period, dating from 125-112 mya. Arandaspida: One of three suborders of the jawless fish order Pteraspidomorphi. Archosaurus rossicus: A proterosuchid reptile from the Late Permian, Upper Tatarian phase, dating from 258-252 mya. It was found at Vyazniki, a town 50 km south of the Volga River in Russia. Ardipithecus: ("basal ape") A Late Miocene and Early Pliocene hominin from the the Afar Depression of Ethiopia. Two fossil species include A. ramidus (4.4 mya) and A. kadabba (5.6 mya). Artinskian: The third stage of the Early Permian period, dating from 290.1 - 283.5 mya. Asaphus: A genus of trilobites dating from the Lower Silurian period, first described by Sir Roderick Murchison in the Llandeilo formation in Carmarthenshire,Wales. Several species are used as index fossils, including Asaphus buchii, A. kowaleski, A. Playurus, and A. tyrannus. Asselian: The first Stage of the Early Permian period, dating from 298.9 – 295.0 mya. Astraspida:
(“star-shields”): One of three suborders of the jawless
fish order
Pteraspidomorphi. Astrapida include the armored species Astraspis desiderata
from the Ordovician period at ca. 450 mya. Astroceras obtusam: A Jurassic ammonite commonly found in the Lower Blue Lias formation at Lyme Regis and other sites on the south coast of England. Ateles geoffroyi skull and brain : Geoffroy’s spider monkey. also known as the black-handed spider monkey, is a New World Monkey living in southern Mexico, Central America, and Colombia. Spider monkeys are regarded as among the most intelligent primates. Ateles distribution map in Amazonia: Spider monkeys are New World Monkeys living in southern Mexico, Central America, and South America. This map shows their distribution along the rivers of Amazonia. Ateles geoffroyi in Costa Rica: The black-handed spider monkey is one of the largest New World monkeys, weighing up to 9 kg. It has a prehensile tail, and ranges over large forest areas in search of fruit, its principal diet. Australopithecus africanus Mrs. Ples skull: A nearly complete female A. africanus skull found in 1947 by Robert Broom and John T. Robinson in a cave near Sterkfontein, South Africa. A. africanus Mrs. Ples skull & brain endocast: This female A. africanus skull has a cranial capacity of about 485 cubic centimetres, slightly larger than that of a chimpanzee, and a foramen magnum showing upright (bipedal) posture. A. africanus Taung skull & brain endocast: This skull and endocast of a juvenile early hominin was found in South Africa by Raymond Dart in 1924, which he named Australopithecus africanus (“southern ape of Africa”). Autapomorphy: a
cladistic term for an anatomical trait or
character which is unique to a particular taxon. B Bajocian: The second stage in the Middle Jurassic period, dating from 171-169 mya. Balfour Formation: An Early Triassic formation of the Beaufort Group in the Karoo Basin of South Africa, exposed in the lowest part of the Lystrosaurus Assemblage Zone, representing low-sinuosity rivers flowing through a semi-arid region. Sidor & Smith (2004) Bambiraptor skull and brain:
This 1-meter tall juvenile dinosaur from the Late Cretaceous
period (72 mya) had the largest brain per body size of any
dinosaur, and is probably related to birds. Bashikirian: The first stage of the Pennsylvanian period, dating from 323.2 to 315.2 mya. Bathonian: The third stage of the Middle Jurassic period, dating from 169 - 164 mya. Beaufort Group: A geological region in the Karoo Basin of South Africa, comprising a group of terrestial formations, largely river-deposited shales and sandstones, dating from the Middle Permian through Early Triassic periods. The Beaufort Group includes an important series of Faunal Assemblage Zones containing vertebrate and plant fossils. It overlies a series of Early Permian marine formations called the Ecca Group. Belemnites:
Extinct, squid-like cephalopods, who belong to the subclass Coleoidea
and the order Belemnitida, common in the Jurassic and Cretaceous periods. Their pointed, rodlike "guards," which were once attached to a
many-chambered midsection, are the most frequently
found fossil part. Bitter Springs Formation: A Precambrian fossil zone in Australia where fossilized bacteria dating from 850 mya have been discovered. These include Oscillatoriopsis, Cephalophytarion, and Filiconstrictosus, resembling the extant filamentous bacteria Oscillatoria amena. Boccone, Paolo: (1633 - 1704) A major 17th century Italian naturalist whose works describe marine fossils as well as many plant genera. Boccone's drawing of Miocene echinoids: These drawings, including "sand dollar" fossils, were published in 1674 in Boccone's Recherches et observations naturelles. Boccone's drawings of Miocene marine fossils: These drawings published by Boccone in 1674 include sea urchin fosslis from Malta and Sicily. Bonobo female skull: Pan Paniscus, also called the pygmy chimpanzee, is one of two species making up the genus Pan, and lives south of the Congo River. Bothriolepis
canadensis:
("pitted scale from Canada") A small placoderm in the family
astrolepidae dating from the Middle and Late Devonian
period (387-360 mya), abundantly found in Bradysaurus bainii: An herbaceous therapsid from the Late Permian in South Africa, with heavily armored scales for protection against carnivores. Branchiostoma:
The extant lancelet genus. Broom, Robert: (1866-1951) A South African doctor and vertebrate paleontologist who found many Therapsid fossils in the Karoo Basin, some now in the American Museum of Natural History; and who also discovered various Australopithecine fossils including the Taung child and the early robust hominid named Paranthropus. Buccal: In skull anatomy, buccal refers to the cheek (Latin bucca = cheek). In dentition, bucccal refers to the "outside" of the teeth, toward the cheeks. Same as labial and opposite of lingual. Buffon, Georges-Louis Leclerck: (1707-1788) Comte de Buffon was a French naturalist whose encyclopedic writings entitled Histoire Naturelle influenced Lamarck and Cuvier, among many other 18th and 19th century scientists Burroughs shale: A Middle Cambrian formation In British Columbia dating from 520-505 mya, with exceptional fossil preservation of an ancient shallow water setting, first revealing a highly complex Paleozoic marine fauna when excavated in 1909-1911. Calcareous: In geology, a type of sedimentary rock made up of biogenic calcium carbonate (i.e., derived from shells and related materials). Thus calcareous limestone is limestone of biogenic origin, made up of crushed fragments of shells that have solidified into rock over time and under pressure. Callovian: The fourth stage in the Middle Jurassic period, dating from 163-166 mya. Camarasaurus lentus skeleton: A juvenile plant-eating sauropod dinosaur from the Late Jurassic period (150 mya), now in the Yale Peabody Museum. Camarasaurus skull: The cranium of this Late Jurassic dinosaur from the Morrison Formation in Utah is relatively short, with large openings or foramen, and long, chisel-shaped teeth for eating tough plants. Cambrian period timeline: The geological period from 543 - 486 mya, the first period in the Paleozoic era. The Cambrian is preceded by the Edicarian stage at the end of the Pre-Cambrian period, and followed by the Ordovician period. Camelid skull: A Miocene camelid from the Agate Basin of Nebraska, now in the Yale Peabody Museum. Canidae ancestry: This cladogram by Tedford (2008) shows the three major groupings of canid ancestors from 42 mya onwards, including the extinct Hesperocyonines and Borophagines, and the extant Canines (wolves, dogs, coyotes, and jackals). Canis latrans skull with auditory bulla: The underside of a coyote skull, showing the large auditory bullas which housed its middle ear ossicles. Cantius frugivorus: A small, New World adapiform primate from the early Eocene period, related to Notharctus. Capitanian: The third and last Stage of the Middle Permian period, dating from 265.1 – 259.8 mya. Captorhinidae cladogram: ("Nose-capturer") An early reptile family from the subclass Anapsida and the order Cotylosauria, dating from the Late Pennsylvanian and Early Permian periods (ca. 310-290 mya), found in Oklahoma, Texas, Brazil, India, and Zambia. Their relations are shown in a branching diagram or cladogram. Captorhinus laticeps skeleton: A member of the Captorhinidae family with a body lenth of 30 cm and a broad, well-armored skull. Captorhinus magnus skull: A larger and earlier species of Captorhinidae, found in Oklahoma in Late Pennsylvanian levels.Carboniferous timeline: The fifth geological period
in the Paleozoic era, dating between 359 – 298.9 mya. The Early
Carboniferous (359-323 mya) is known as the
Mississippian in North America, divided into the
Tournasian,
Viséan and Serpukhovian Ages. The North American Late
Carboniferous (323- 298.9
mya) is the Pennsylvanian, which includes the Bashkirian,
Moscovian,
Kasimovian and Gzhelian Ages. Carpus: In skeletal anatomy, the assemblage of wrist bones which connect the radius and ulna with the finger bones. Humans have eight carpal bones placed in two rows. The basic features of the reptilian carpus show differences with those of mammals. Casineria kiddi:
The earliest known fossil taxa classified as an amniote or early
reptile. Dating from the Late Mississippian period at about 335 mya, it
was discovered in 1992 at Cheese Bay, Scotland. Catfish Pseudopimelodus bufonius : The bumblebee catfish from South American rivers shows a striking camouflage design on its body. Catfish skull and brain: The brain of Pseudopimelodus, the bumblebee catfish was examined by Abrahão and Shibatta (2015), who found the cerebellum and visual lobe to be the largest structures, probably related to hunting activities. Cenomanian: The first stage of the Late Cretaceous period, dating from 99.0 - 93.5 mya. Cenozoic Era: ("recent life") In the geological timescale, the Cenozoic is the recent era of life, dated 65 – 0 mya. The Cenozoic is comprised of seven periods: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene and Holocene . These are organized into two groups, the Paleogene (Paleocene, Eocene and Oligocene); and the Neogene (Miocene, Pliocene, Pleistocene and Holocene). Cephalerpeton ventriarmatum: An early reptile (eureptile) in the subclass Anapsida and the order Cotylosauria, dating from the Late Pennsylvanian period (307-305 mya), discovered in Illinois. Cephalochordata:
(“head-chordates”) are a subphyllum of chordates which
includes present day
lancelets, and the Cambrian fossils Pikaia from the
Burroughs Shale in Changhsingian: The second and last stage of the Late Permian period, dating from 254.1 – 252.2 mya. Charassognathus gracilis: ("notched jaw") The earliest known of the cynodonts ("dog-teeth"), a therapsid sub-order occuring widely during the Late Permian in South Africa and elsewhere, and considered ancestral to early mammals.Cheek teeth: Any teeth located behind the canine teeth, within the area of the cheeks. In mammals, this generic term includes both premolars and molars, which are specializing grinding teeth. In other tetrapods such as reptiles and early synapsids, cheek teeth may have different forms and functions, not being specialized as molars. Chlamydomonas: A genus of present-day green algae (Chlorophyta) found in both stagnant and fresh water, with the form of a one-celled flagellate. Chlorophyta: A division of green algae which was the ancestor of land plants and remains widely extant today. Chloroplast: An organelle in plants, algae, and cyanobacteria, containing folded membranes or thyllakoids which are lined with chlorophyll pigments. These absorb photons of sunlight, which are converted by photosynthesis into metabolic energy in the form of ATP (adenotriphosphate) molecules. Chondrichthyes: The class of cartilagenous fish, including sharks and rays. Chroniosaurus dongusensis: A reptiliomorph from upper Permian deposits in western Russia in the Novgorod region, dating from 258-252 mya. Chroniosuchus paradoxus: A reptiliomorph ca. 1.5 m long from the Late Permian period, found in the Arkhangelsk region and elsewhere in northern Russia. Cistecephalus augusticeps: A small, burrowing, mole-like therapsid from the Late Permian period, found in the Karoo Valley of South Africa as well as in Zambia and India. It is classified as a dicynodont. Clade: In cladistic terminology, the term
for a specific branch
of an organism, showing the shared inheritance of physical traits; ie.,
an organism and all of its descendants. From Greek clados =
“branch”, the source of the term “cladistics” . Cladistics: A system of classification
initiated by Willi Hennig, a
Swiss entomologist or specialist in insect biology. The goal of the method is to
create
phylogenies by arranging taxa by shared traits or characters into
clades or branches.
Clamorosaurus borealis:
An Early Permian amphibian found in western Russia from ca. 272.5
mya. It is in the order Temnospondyli and the family Eryopidae, related
to Eryops in South Africa. Clear Fork Group: A geological formation from the Early Permian in northwest and central Texas and Oklahoma. It mainly consists of thin layers of sandstone, mudstone, and shale, representing flood plains and point bars deposited by rivers with high sinuosity. It also contains thin beds of limestone and dolomite. The Clear Fork exposures have yielded abundant fossil remains of reptiles, lepospondyl amphibians, and pelycosaur synapsids. Taxa include Tetraceratops, Varanops, sphenacodonts, and large “sailback” reptiles including both carnivorous (Dimetrodon) and herbivoran (Edaphosaurus) genera. Coal Measures: In geology, coal-bearing formations in which seams of coal, derived from the vegetation of lowland swamps, are separated by sedimentary rock (limestone or shale) resulting from periodic marine incursions. In North America, most coal measures date from the Mississippian and Pennsylvanian periods when such swampy environments were common. In Great Britain, the Lower, Middle and Upper Coal Measures refer to the Late Carboniferous, Westphalian stages A, B and C. The Lower and Middle Coal Measures correspond with the second half of the Bashkirian Stage ( 316 - 311 mya), and the Upper Coal Measures correspond to the first half of the Moscovian Stage (311 - 306 mya). Cod (Gadus Morhua): The Atlantic cod, found throughout the north Atlantic to the North sea, has been commerically overfished in many areas. It dates from the Paleoccene period. Cod skull and brain: The brain of the Atlantic cod has been studied as an example of a high degree of plasticity in teleost brains caused by changes in environment and feeding habits. Concinella concinna: Non-marine, riverine bivalves or pelecypods found in western Russia, dating from the Late Permian period at about 260-255 mya. Condyle: In anatomy, a
protruding element (from Greek kondylos
= “knuckle”). This forns the protruding element of a hinge,
or ball-and-socket
joint. Examples are in the knee joint of the femur, or the elbow joint
of the
humerus; or the occipital condyle, where the base of the skull attaches
to the
atlas bone. Coniacian: The third stage of the Late Cretaceous period, dating from 89.0 - 85.8 mya. Conodonts: ("cone teeth") Small, worm-shaped marine chordates found in Paleozoic deposits around the world, whose tooth-like elements long remained a mystery until well-preserved whole specimens were discovered in the 1980s. They are now used as accurate chrono-markers for Ordovician through Devonian strata. Conservation of Energy, Principle of: This law, as formulated by the 19th century German physicist Ferdinand Von Helmholtz, states that energy cannot be created or destroyed, and the sum total of energy in the universe always remains the same. All living organisms are thus constrained by the Principle of the Conservation of Energy; there can be no “perpetual motion” machines which create energy. Photosynthesis, for example, the most widespread activity of life, requires sunlight and water to be converted into energy by plants or algae. Continental Drift: The theory that the continents were slowly moving around on the surface of the Earth was first accurately formulated in 1912 by Alfred Wegener, a German meterologist, polar researcher, and geophysicist. Craton: Bedrock of ancient crystalline basement rock, that forms an old, stable part of the continental lithosphere, in contrast to more unstable, geologically active regions on a continent.Cretaceous period timeline: The third and last period of
the Mesozoic Era, dating from 144 - 65 mya. It follows the Jurassic period,
and precedes the
Paleocene. The symbol for Cretaceous on
geological maps
is K. Cuvier, Georges: (1769-1832) A French naturalist who was a major figure in comparative anatomy and paleontology, and whose work is considered the foundation of vertebrate paleontology. Cuvier & Brogniart's geologic maps of Paris Basin: In 1808, Cuvier and Brogniart published a series of sections of the Paris Basin showing various fossil-bearing layers, totalling 300 m in depth. Cyanobacteria: ("blue-green bacteria") Photosynthetic microbes or bacteria who constitute some of the most primitive forms of life. A present-day example is Anabaena, a filamentous cyanobacteria in freshwater lakes. Cyanobacteria first appear in the fossil record 2.1 billion years ago. Cynodont chronology: Cynodonts lasted from the Late Permian to the Middle Triassic period, being among the few synapsid groups to survive the massive extinctions occurring ca. 252 mya at the Permian-Triassic boundary. Cynodont phylogeny: Cynodonts ("dog-tooth") were therapsids or "mammal-like reptiles" who, by the Middle Triassic period, constitute direct ancestors of early mammaliforms. Cynognathus crateronotus: ("dog
jaw") A eucynodont ("true cynodont"), a branch which lived from the
Early through Middle Triassic period (247-237 mya). Cynognathus distribution map: Shows the widespread distribution of Cynognathus in the Early and Middle Triassic period across southern Africa, South America, and northwest Antarctica, in the context of the merged continents known as Pangaea. Dapingian: Darriwilian: Dart, Raymond:
(1893–1988) An Australian-born anatomist and
paleoanthropologist who worked in South Africa, where in 1924 he
discovered the skull fossil of the Taung child, about 1.8 million years old, which he named Australopithecus africanus ("southern ape from Africa"). Darwinius masillae skeleton: An Eocene adapiform primate represented by the fossil skeleton of a juvenile preserved in Middle Eocene sediments at Messel, Germany, dated at 47 mya. Da Vinci, Leonardo: (1452-1519) A portrait drawn in 1513 of da Vinci, the artist and investigator of many subjects, ranging from human anatomy to the origin of fossil marine deposts in central Italy. Da Vinci drawing of human skull interior: This drawing by Leonardo da Vinci, dating from about 1480, portrays the basicranial area of a human skull, showing numerous holes or foramen for nerves and blood vessels. Da Vinci anatomy of human & dog legs: This ca. 1480 comparative anatomy drawing by da Vinci contrasts the bipedal vs. quadrapedal lower leg configurations of humans and dogs. Deltavjatia rossicus: A Late Permian herbivore reptile found in Upper Tatarian layers at Kotel'nich on the Vyatka River in western Russia.Deltavjatia vjatkensis: A pareisaur reptile from the Late Permian period, found along the Vyatka River in western Russia.Dendrerpeton arcadiatum skull: A land-based amphibian in the Temnospondyl order and the superfamily Edopoidea, found in Late Carboniferous (Pennsylvanian) deposits in Nova Scotia, and dating from 314-311 mya. Devonian period timeline:
The fourth geological
period of the Paleozoic Era, between the Silurian and Carboniferous periods, dating from 417 - 354 mya, and named for exposures in Devonshire Devonian globe: Map of the position of the continents in the Early Devonian period at ca. 400 mya, showing areas of major orogenies or mountain-building episodes caused by shifting continental plates. Diadectes sideropelicus: ("Crosswise biter, from iron clay") A terrestial, herbivorous, reptilomorph amphibian from the Early Permian period (ca. 280 mya), found in northern Texas. Diapsids: Dickinsonia costata: A marine organism resembling a sea pen from the Ediacaran phase of the Late Precambrian period, dating from 558-555 mya; one of numerous enigmatic organisms found in Australia and elsewhere from the Late Proterozoic. Dicynodon: ("Two dog teeth") A medium-sized, herbivorous therapsid from the end of the Late Permian period (257-252 mya), abundantly found in South Africa and Russia. Dimetrodon limbatus: Dinocephalian: A sub-order of large, early therapsids from the Middle Permian period (270-260 mya) found in South Africa, Russia, China and Brazil. which included herbivorous, carnivorous, and omnivorous forms, many having thickened skulls with bony projections. Drepanaspis gemuendenensis: A jawless, armored fish in the subclass Diplorhina and the family Drepanaspidae, from the Early Devonian period (419-380 mya), found at a Rhine River site in Germany. Dryopithecus skull: A Late Miocene ape that spread from East Africa into Europe, first discovered at Saint-Gaudens, France by Lartet in 1856, and dated at about 11.5 mya. Dubois, Eugene: (1858-1940) A Dutch doctor and anatomist who discovered the first fossils of Homo erectus in Trinil, Java in 1891, including a skullcap and femur, which he named Pithecanthropus erectus ("erect ape man"). Dvinia suschkini: A Late Permian cynodont ("dog-tooth") therapsid named for the Dvinia River near Arkhangelsk, Russia, found in Upper Tatarian deposits (258-255 mya)
Eastern water dragon (Physignathus leseurii): A present-day sauropsid reptile from eastern Australia. Edaphasaurus boanergi: An early Permian synapsid of the cotylosaur grouping, contemporary with Dimetrodon and also having a sailback of elongated neural spines, but an herbivore; commonly found in the Permian Basin redbeds of Texas. Edentulous: Ediacaran:
the last stage of the Precambrian period, dated 635-542 mya, and named for the
Ediacara Hills in Eifelian: Emeroleter levis: ("Day thief") A small, carnivorous, and at times insectivorous parareptilian dating from the Middle to Late Permian period (265-252 mya), found on the Vyatka River in western Russia, and in North America. . Emsian: The third and last stage of the Early Devonian period, from 400 - 391 mya. Encellius, Christoph: (1517-1586) A German priest and geologist, whose 1557 book De Re Metallaci (On Metals) included the first printed drawings of fossil mollusks. Endothiodon: A Late Permian dicynodont dated ca. 255 mya, first discovered in South Africa, and later found throught the southern hemisphere in ancient Gondwanaland. Endothiodon augusticeps: A Late Permian dicynodont therapsid, whose skull was first described by Owen (1879) and whose skeleton was first recovered by Broom (1915) at Beaufort West in South Africa. Entelognathus primordialis: ("complete jaw") A placoderm found in south China dating from the Late Silurian period (419 mya), the first fish to show osteichthyan (bony fish-like) jaw bones. Entropy: A concept in physics for how energy runs down or is dispelled. As defined in 1865 by Rudolf Clausius, Entropy is a thermodynamic property related to work performed by engines, machines, or energy conversion devices like refrigerators. During such work, entropy accumulates in the system, then dissipates in the form of waste heat. This is known as the Second Law of Thermodynamics.Eocasea martinis skeleton: ("dawn caseid") The earliest known synapsid, an amphibian in the order Pelycosauria, the Suborder Edaphosauria, and the family Caseidae, found in Kansas from the Pennsylvanian period, dated 315 mya. Eocene period timeline: Eosphaera tyleri: An early Precambrian prokaryote from the Gunflint chert Formation in Canada, dating from about 1.9 billion years ago, the first well-preserved example found of a bacteria-like organism from that early period. Eryops megacephalus skeleton: ("large head with extended face") A large, Early Permian temnospondl amphibian dating from 295-280 mya, considered ancestral to large reptiles from the Early Permian period; found in northern Texas. Eukaryote: ("true cell") Organisms with complex cells, which include a nucleus containing the cell's DNA, and organelles such as mitochrondria, ribosomes, and chloropolasts, each of which also has its own DNA. Eukaryotes first appeared at or before 2 billion years ago, when oxygen in the atmosphere had gradually built up. Eusthenopteron
fordii skeleton: a
lobe-finned fish
from the Late Devonian period (380-360 mya) in the order
Crossopterygii, the suborder Rhipidistia, and the family Rhizondotidae,
showing a close relationship to
early tetrapods, and abundantly found in F Famennian: T Femur: Fenestra: ("window") In skull
anatomy, the term used for an opening in a structure, usually a
paired opening in complemenary (right and left side) bones. The term is
used
for the skull openings providing jaw muscle attatchments in synapsids
and
diapsids, as well as in the anatomy of the ear region. Fish and Tetrapod evolution chart:
Beginning with jawless fish (agnathans), showing the main fish
groupings, and the link of lobe-finned fish to early land vertebrates. Floian: Francis Creek Formation: A shale formation in northeastern Illinois, dating from the Pennsylvanian Period (324-298.9 mya). The shale contains both fish and notochord fossils, some with excellent preservation, including a fossil hagfish named Myxinikela siroka. Frasnian: Green frog: Rana clamitans, the green frog, is well camouflaged to lie within the greenery at the edge of a wooded pond. Frog skeleton: The oversized legs and toes of frogs are specialized for jumping. Frog skull and brain: The cranium and brain of a green frog, as a representative present-day amphibian who lives on the ground. Frontal bones: Ganoid: In
fish anatomy, a heavy form of enamel characteristic of the scales of
various
early fish and extant Polypteriformes, such as the gar (Lepisosteus). Gauja
Formation: Geissner, Conrad: (1516-1565) A Swiss physician and naturalist, best known for his systematic and encyclopedic writings on animals and plants in his four volume Historiae animalium. Geissner's drawing of belemnites: In his 1565 book On Fossil Objects, Geissner shows tubular-shaped guards of fossil belemnites, as well as crinoid peduncles, both of which which he considered to be natural crystal forms. Geologic timescale: A graph of all geological periods from Pre-Cambrian to Holocene, showing the major life forms associated with each period. Gephyrostegus bohemicus: A small reptiliomorph amphibian in the order Anthracosauria and the suborder Emblomeri, dating from the Late Carboniferous (Pennsylvanian) period at about 310 mya, discovered in Nıřany in the Czech Republic. Ghorstian: The first stage of the Late Silurian Period, lasting from 427-425 mya. Gibbon female skull & brain : Gibbons are apes in the family Hylobatidae, and are smaller than the other hominoid apes (chimpanzees, gorillas, and orangutans) although their skulls and teeth are similar, with a dental formula of 2.1.2.3. Gibbon painting from China: Two gibbons in an oak tree painted by the Song dynasty painter Yì Yuánjí (ca. AD 1000-1064), representing a species of gibbons living in China. Givetian: Glossopteris: Fossil leaves and stem of the Permian plant, considered a large seed fern, which grew throughout the southern megacontinent of Gondwanaland. Gondwanaland: The southern landmass which existed between the Cambrian and Triassic periods, made up of South America, Africa, Madagascar, India, Australia, and Antartica, named by Suess for the Gondwana area in India that contained Glossopteris fossils Gorgonopsians: An expansive order of carnivorous therapsids, comprising a total of 25 genera and 41 species, from South Africa, Tanzania, Zambia, and Malawi, as well as from Russia. Gorgonops torvus: A medium-size therapsid carnivore from the Middle and Late Permian period of the Karoo Basin in South Africa (ca. 265-252 mya), one of the gorgonopsidae family who were highly successful predators. Gorilla (Western Lowlands) female skull & brain: Gorillas, the largest living primates, have DNA from 95 to 98% similar to that of both chimpanzees and humans. their facial structure is highly prognathic, and there is significant sexual dimorphism. Gorilla gorilla in Central West Africa: Western lowland gorillas (Gorilla gorilla) are ground-dwelling, herbivorous hominoid apes that live in dense forests and lowland swamps and marshes as low as sea level. Gracile: Guadalupian Series: In the geological timescale, equivalent to the Middle Permian period (272.3 – 259.8 mya), comprising three Stages: Roadian, Wordian, and Capitanian. Guiyu oneiros: ("ghost fish"). The earliest known bony fish, with fossils from Chinese deposits dating from the Late Silurian, 419 million years ago About 33 cm in length, Guiyu had a combination of both ray-finned and lobe-finned features, although overall analysis has placed it closer to lobe-finned fish (Zhu et al 2009). Gunflint Formation: A
formation of chert deposits
around
Hadrocodium wui: ("full head") A small, Early Jurassic mammaliaform dating from ca. 195 mya, found in Yunnan, China, named for its large brain capacity, and for the discoverer, Dr. X.-C. Wui. Haeckl, Ernst: (1834-1918) A German anatomist and embryologist who significantly advanced the synthesis of traditional Linnean taxonomy with the Darwinian view of evolution.
Hagfish:
(class Myxini). Hagfish are primitive, eel-shaped marine creatures who
live in
the continental shelf waters off Haikouella lanceolata: ("lancelet from Haikou") A lower Cambrian chordate found in Yunnan Province of Southern China, dating from about 535-525 mya, showing similarities with extant lancelets. Haikouichthys ercaicunensis (head): ("fish from Haikou"). An early Cambrian notochord fish genus from the Maotianshan shales at Ercaicun inHaikouichthys ercaicunensis (overall form): The Cambrian notochord H. ercaicunensis had a distinct head and tail, with the head showing at least six and perhaps nine probable gills. There are a number of muscle segments (myomeres) with rear directed chevrons in the tail. Hauterivian: The third stage of the Early Cretaceous period, dating from 131-128 mya. Hesperocyon gregarius: An early canid from the Eocene period (42-31 mya), whose descendents split into three main canid groups, including the canidae leading to today's wolves, dogs, foxes, coyotes, and jackals. Heterostraci: "other shields" A sub-order of early jawless fishes in the order Pteraspidomorphi. Heterostraci: ("Different scales"): One of three subclasses of Pteraspids, the others being Arandospida and Astraspida. They are a long-lived group who arose in the Ordovician, between 488 and 443 mya, and lived through the Silurian and into the Late Devonian (380-370 mya), primarily in marine and estuary environments. Heterostraca is divided into two orders, Pteraspidiformes ("Wing Shields"), and Cyathaspidiformes (“Cup Shields”). Members of the larger, “wing-shield” order occur first in the Late Silurian, but become much more diverse during the Early Devonian As with many agnathan groups, heterostracans had no fins besides the tail or caudal fin. Hettangian: The first stage in the Early Jurassic period, dating from 202-199 mya. Hirnantian: Homerian: The second and final stage of the Middle Silurian period, lasting from 430-427 mya. Homo erectus Peking ZKD V skull & brain: The ZKD V "Peking Man" cranium from Zhoukoudian near Peking, dated ca. 415,000 years ago by Wu et al. (2010), has yielded a well-preserved endocast. Homo erectus Sangiran 17 skull: Discovered at Sangiran in the Solo River valley of central Java , this nearly complete skull has both the prominent brow ridges and thick skull bones typical of Homo erectus, and a relatively large brain size. Homo erectus Sangiran 17 skull & brain: Sangiran 17 is the most complete Homo erectus skull found in East Asia, dating from 700,000 years a go, with a cranial capacity estimated at 1004 cc. by Holloway (1981). Homo erectus Trinil skullcap: This upper skull fragment, found in Trinil, Java by Eugene Dubois in 1891, dated about 700,000 years ago, was the first definite find of a Homo erectus fossil, at first called Pithecanthropus erectus ("erect ape-man"), since Dubois also found a femur indicating upright posture. Homo habilis skull: An early hominin from East Africa, first discovered at Olduvai Gorge in Tanzania and dating from the Early Pleistocene at about 2.0 mya,considered a transitional form between australopithecines and later species of Homo. Homo rudolfensis skull: An early hominin from Kenya dating from the Early Pleistocene at 1.90-1.88 mya, named for Lake Rudolf (now Lake Turkana). The type skull (KNM-ER-1470) was found in 1972 by Bernard Ngenyeu Kanyenze, working with Richard Leakey. Hooke's drawing of a flea: This drawing though a microscope of a flea (Ctenocephalides), magnified about 100 times, was drawn by the English scientist Robert Hooke and published in a 1705 letter. Hoplophoneus mentalis: An Oligocene saber tooth carnivore related to modern felids. This fossil skeleton, about the same size as that of a large leopard, was found in the Brule Formation in the Badlands of South Dakota. Human and chimp skulls and brains: Comparison of the cranium and brain of an anatomically modern human (Homo sapiens), and a male chimpanzee (Pan troglodytes). Huxley, Julian: (1887-1975) A geneticist and biologist who was a grandson of T.H. Huxley, and formed part of an influential group of scientists in the early 20th century who synthesized Darwinian evolutionary theory with genetics. Huxley, Thomas Henry: (1825-1895) A preeminent British anatomist, educator, and friend of Darwin, who strongly supported Darwinian evolutionary theory, and synthesized it with accurate interpretations of many fossil types. Hyaenadon cayluxi: An early carnivore in the creodont order. Hylaeosaurus armatus: ("forest lizard with armor") A plant-eating, armored Early Cretaceous dinosaur about 5 m long and dating from 136-137 mya, discovered by Gideon Mantell in Sussex, England in 1832. Icthys: Greek for “fish”, as in the two fish orders Chondricthyes, “cartilagenous fish,” or Osteichthyes, “bony fish.” Ichthyosaurus platydon: ("fish-lizard with flat teeth") The skull of a large Early Jurassic marine reptile, dating from 200-195 mya, and found in 1811 by Joseph Anning at Lyme Regis, England. Ichthyostega: ("fish roof"). An early tetrapod genus from the Upper Devonian period (374 – 359 mya), up to 1 m. in length, and one of the earliest tetrapods known in the fossil record; discovered in 1931 in East Greenland by the Danish paleontologist Gunnar Save-Soderbergh. Ichthyostegalia: An order of early tetraforms including the genera Ichthyostega, Acanthostega, Tulerpeton, and Elginerpeton. Ichthyostegalia contains the most basal of tetrapods which have toes rather than fins, including all taxa more advanced than Tiktaalik, the closest relative of tetrapods. Ichthysaurus platydon skull: A large Early Jurassic marine reptile dating from 200-195 mya, whose skull was found by Joseph Anning, brother of Mary Anning, in 1811 at Lyme Regis on the south coast of England. Iguana Iguana: The green iguana, a sauropsid New world reptile, first described by Linnaeus in 1758, with the Spanish name taken from the Taino iwana. Iguanodon bernissartensis skeleton: ("iguana tooth") A large plant-eating dinosaur, widespread in Asia, North America, and Europe during a two million-year interval in the Early Cretaceous period (126-124 mya) Iguanodon bernissartensis skull: This Cretaceous dinosaur had a long, narrow skull, with a projecting keratin beak, and up to 29 chisel-like teeth per side, which were continually replaced, allowing the Iguanodon to eat tough plant material such as tree leaves and grasses. Iguanodon teeth portrayed by Mantell: An 1825 drawing by Gideon Mantell, establishing the reptilian type of teeth in the Iguanodon fossils he discovered in Early Cretaceous deposits in England. Incus: In
ear anatomy, the incus (from Latin incus , “anvil”)
is an auditory
ossicle derived from the quadrate bone, which was part of the lower jaw
in
fishes, early tetrapods, reptiles, and non-mammalian synapsids. Induan: The first Stage of the Early Triassic period, dating from 252.2 – 251.0 mya, contemporary with the end-of-Permian extinction event, shown in a global map of the Pangaea magacontinent. Inostrancevia alexandri: A large, carnivorous Late Permian theriodont ("beast tooth") of the gorgonopsidae ("gorgon face") family, found in the Dvina Valley in western Russia, and dating from ca. 265-252 mya. Jeholodens jenkensi: An early triconodont mammal from the Early Cretaceous period (ca. 125 mya), found in Liaoning Province, China. Jugal: In skull anatomy, the
jugal bone forms the lateral margin of the orbit. It occurs
in most reptiles, amphibians, and birds as well as mammals. In mammals,
the jugal is often called
the malar or Zygomatic.The jugal bone is the only bone that lies
entirely in
the zygomatic arch. At its anterior margin the
jugal articulates with the maxillary bone. Jurassic period timeline: The second geological period of the Mesozoic era, coming after the Triassic and before the Cretaceous and dating from 201-144 mya. By the Early Jurassic, the first mammals had evolved from cynodonts.
Kakabekia barghoorniana: An
extant anaerobic bacteria discovered in 1964 by S.M. Siegal,
named for Kakabeka Falls in Ontario, and for
Elso Barghoorn who discovered similar Early Precambrian bacteria in
the Gunflint Chert of Canada. Karoo Basin: A 1500 km-wide succession of five geological formations in South Africa dating from the Late Carboniferous through Jurassic periods, including the Beaufort Group, with a continuous fossil record from the Middle Permian through Middle Triassic periods (270-220 mya), divided into eight faunal assemblage zones. Kasimovian: The third stage of the Pennsylvanian period, lasting from 307.0 to 303.7 mya. Kelp (Laminaria sp.): The seaweed called kelp (Laminaria sp.) is a widespread brown algae with roots called holdfasts, a main stem or stipes, and long fronds called blades. A common seaweed today attached to rocks or pilings, kelp first appeared in the Miocene period between 15 and 5 mya. Kerpia macroloba: A fossil taxa of the Ginkgo tree found in the Ural region of western Russia, dating from the Kungurian stage of the Early Permian Period (272 mya). Kimmendjian: The second stage in the Late Jurassic period, dating from 157.3-152,1 mya. Kotlassia prima: A late Permian reptiliomorph, or amphibian with some reptilian traits, discovered by Amalitsky in 1898 at Sokolki on the North Dvina River in Russia. Kuanti Formation: Shale and limestone deposits from the Late Silurian period in Quijing, Yunnan, China, producing early fish fossils including Entelognathus primordialis, a placoderm (armored fish) with osteichthyan- like marginal jaw bones, and Guiyu oneiros, the first known Osteichthyan or bony fish, both dating from 419 mya. Kungurian: The fourth and last stage of the Early Permian period, dating from 283.5- 272.3 mya. Kunming, Maotianshan shales: A town located near the find sites of several early chordate fossils, discovered in Lower Cambrian deposits (525-520 mya) in the Maotianshan shales of Yunnan Province in southern China.. Labyrinthodont: ("maze teeth") A type of complex folded enamel and dentin tooth structure often found in amphibians, early tetrapods, and lobe-finned fish.This tooth structure, easily seen in microscopic cross-section, is the basis for identifying many early amphibians as Labyrinthodonts Labyrinthodontia: A subclass of Amphibians originally named by Owen (1860), on the basis of possession of labyrinthodont teeth. Originally intended to signify early amphibians ancestral to reptiles, the labyrinthodont trait does not always occur in the reptile-like amphibians called Reptilomorphs.Lagerstätten:
(lager-, “storage” and -stätte,
“place”) Shale deposits with
exceptional fossil preservation of soft tissues, including the Burroughs shale in Lanarkia: A flat-bodied, jawless fish in the Thelodont order, covered with protective spine-like scales, dating from the Late Silurian period at about 443-428 mya. The genus Lanarkia is named for Lanarkshire, Scotland where it was discovered in 1898. Lancelets (amphioxus): These slender, eel-like filter feeders, classified as Cephalochordates, appear pointed at both ends, giving rise to the name amphioxus ("both sharp).Late Permian Tetrapod Zones in Russia: Geological formations linked with numerous index fossils, which can be directly correlated with the fossil-rich Beaufort Group biozones in South Africa, and Permian sequences defined in the Americas, India, China, and elsewhere, Leakey, Louis: (1903-1972) A British paleoanthropologist and archaeologist who, together with his wife Mary, made a series of discoveries at Olduvai Gorge providing crucial evidence of the early evolution of hominins in East Africa.Leakey, Mary: (1913 – 1996) A British paleoanthropologist who discovered the first fossilised skull of the Miocene ape Proconsul in 1948, and the first evidence of the robust Australopithecine named Zinjanthropus at Olduvai Gorge in 1959. Lemur catta brain and skull: The ring-tailed lemur is diurnal, but like all strepsirhine primates, it has a reflective layer behind the retina that enhances night vision. It has small upper incisors and long upper canines which exhibit sexual dimorphism. Lemur catta (ring-tailed lemur): A strepsirrhine primate or prosimian living in southern Madagascar, Lemur catta is the most recognized lemur, due to its long, black and white ringed tail. It lives in gallery forests and is omnivorous, eating mainly fruit and leaves. Leptadapis magnus skull: An adapid Old World primate dating from the late Eocene to Early Oligocene period (40-25 mya) and found in France. The species, related to Adapis, was first described in 1874 by Filho. Limnoscelis paludis skeleton: ("marsh-footed swamp dweller") A large reptilomorph amphibian dating from the Late Pennsylvanian and Early Permian periods at 310-280 mya, first found by Williston in New Mexico in 1911. Limnoscelis paludis skull and hand: The arms and hands of Limnoscelis showed the primitive tetrapod traits of humerus, radius, ulna, and five digits, which lacked claws. Linnaeus, Carolus: (1707-1778) The Swedish naturalist, and author of Systema Naturae (1748-1758), which contained a comprehensive classification system for all known organisms, which became universally adopted for biology. Lithornis skull and brain: A long-beaked Eocene bird, who lived along lakes and whose large olfactory bulb and cerebrum indicates enhanced sensory abilities, has been found in North America and Europe, dating from 50-45 mya. Lithosphere: The outermost shell of the Earth and other rocky planets (from Greek lithos, "rock", and spheros, "sphere"). The lithosphere includes the crust and the uppermost mantle. Llandovery: The epoch equivalent to the Early Silurian Period, dating from 443-433 mya. Lobe-finned fish: (Sarcopterygii, or "fleshy fin") One of two subclasses of bony fish, today much reduced in number and diversity. The lobe-finned fish were the ancestors of all land vertebrates. Lochkovian: The first stage of the Early Devonian period, dating from 418 to 411 mya. Loganellia scotica:
A jawless fish in the Theolodont order, covered with armored scales, and found in several northern regions, dating
from the Late Ordovician period to the Late Silurian period (457-419
mya). Ludfordian: The second stage in the Late Silurian period (Ludlow epoch), lasting from 425-423 mya. Ludlow: The first epoch of the Late Silurian period, dating from 427-423 mya. Lufengpithecus lufengensis skull: A juvenile cranium of this Late Miocene ape found at the site of Shuitangba in Yunnan Province, China, dating 6.1 mya. Lycaenops ornatus skeleton: ("wolf face") A medium-sized gorgonopsian carnivore from the Late Permian period in South Africa, one of the top predators of its time.Lycaenops ornatus and L. angusticeps skulls: Both of these Late Permian gorgonopsian species have enlarged canines, analagous to those of the much later saber-toothed cats (Smilodon fatalis) from the Pleistocene period. Lyell, Charles: (1797-1865) A British geologist whose work was highly influential in influencing Darwin's theory of natural selcction. In a series of textbooks on historical geology written from 1833 onwards, Lyell demonstrated the vast time scale of the earth's geological past. Lystrosaurus: ("Shovel lizard") An herbivorous therapsid with only two upper canines (hence classified as a dicynodont, or "two dog teeth"), and a horny beak that was used for biting off pieces of vegetation. Lystrosaurus was the most common land animal in the Early Triassic period (252-247 mya). Maastrichtian: The sixth and final stage of the Late Cretaceous period, dating from 72-65 mya. Macropetalichthys Placoderm brain: Diagram of the brain and cranial nerves of Macropetalichthys, a Devonian placoderm. While the brain is relatively primitive, the cranial nerve organization is basically the same as in all later vertebrates (including humans). Magdalenian carvings of animals: Two ivory carvings of animals including an auroch or wild ox, and a possible lion, made by Magdalenian artists in France about 15,000-12,000 years ago, at the end of the Pleistocene or most recent glacial era. Mandelstamia maculata: A Late Jurassic ostracod (a tiny, shrimp-like animal) found in the North Sea off the coasts of England, Scandanavia, and Russia, used as an index fossil dating from the Kimmendgian stage at 157.3-152.1 mya. Mantell, Gideon: (1790-1852) An British doctor, geologist, and paleontologist who, between 1822-1832, discovered and named two dinosaur genera in southern England, Iguanodon and Hylaeosaurus. Map of Maotianshan
shales in China: A Lower Cambrian formation with diverse shallow
water
fauna preserved in extensive, well preserved (Lagerstätten) fossil deposits at Ercaicun in Map of Permian and Mesozoic zones in Russia: This geologic map shows the surface locations of Permian and Mesozoic zones in western Russia. Outcrops of all three periods of the Mesozoic era (Triassic, Jurassic, and Cretaceous) are specifically identified by period, as are Permian outcrops. Map of Permian sites in western Russia: Numerous Middle and Late Permian fossil sites are located along three major river drainages in west Russia, the Northern Dvina, Volga, and Ural Rivers. Map of Late Permian sites on the Dvina River: Detailed locations of a dozen Late Permian sites along the Northern Dvina and Sukhona Rivers in western Russia, dating from 259-252 mya. Map of Permian sites at Kotel'nich, Russia: Major Middle Permian fossil deposits are exposed along the Vyatka River, a Volga tributary, near the town of Kotel`nich in western Russia, Map of Triassic sites in China: Three zones of exposed Triassic formations in China include the southern area around the boundary of Yunnan and Gouzhou provinces, and two regions the north, in the Ordos and Jungghar Basins.. Meckel's groove: a feature of the dentary or lower jaw bone in reptiles related to Meckel's cartilage, which is retained in early placental stages of current marsupials such as short-tailed opossums (Monodelphis), and in Early Jurassic stem mammals such as Sinoconodon and Morganucodon. Mesocyon coryphaeus: ("middle dog) An early North American canid from the Oligocene and Miocene periods (30-20 mya), about the size of a coyote. The skull shows its enlarged auditory bulla, indicating enhanced hearing capabilities. Mesopithecus pentelicus skulls: ("middle monkey") A Late Miocene Old World monkey (Cercopithecoid) living in Europe and western Asia 7-5 mya, with considerable sexual dimorphism beween males and females in body and skull sizes. Mississippian period timeline: The fifth period in the Paleozoic era, following the Devonian and preceding the Pennyslvanian period, and corrsponding to the Early Carboniferous in the European system, dating from 359 – 324 mya. Mississippian period globe: (ca. 353 mya).The Mississippian saw the development of both land vertebrates (amphibians) and plants, and fishes and other marine life. Land vegetation in humid and tropical conditions led to coal deposits, and shallow seas were the origins of extensive limestone formations. Mississippi River channels in Holocene: The multitude of abandoned and active channels in the lower Mississippi valley in the past 10,000 years during the Holocene (recent) period, as mapped by Fisk (1944). Morganucodonts:
Small, early stem mammals named
for a site in Glanmorgan, Morganucodon watsoni:
An early stem mammal discovered in 1948 at Duchy
Quarry in Glanmorgan, Wales. Mosasaurs ("Meuse lizards") A term comprising several genera and dozens of species of large diapsid marine reptiles in the family Mosasaurinae, dating from the Late Cretaceous period. Their fossils are found worldwide in shallow water, estuarine settings such as along the Atlantic coastline, or in inland seas, such as existed in Kansas during the last two stages of the Late Cretaceous (85-65 mya), when they were a dominant marine predator. Murchison, Roderick: (1792-1871) A Scottish geologist who, on the basis of comparative stratigraphy and fossil content, defined the Silurian, Devonian, and Permian periods, working with Adam Sedgewick, Charles Lyell, and many other geologists. Muscovian: The second stage of the Pennsylvanian period, dating from 315.2 to 307.0 mya. mya: Abbreviation for “million years ago." Myllokunmingia: An early Cambrian notochord proto-fish genus from the Lower Cambrian Maotianshan shales at Ercaicun in Myxineidus gononorum: Necrolemur antiquus skull: ("dead lemur") An Omomyid primate from the Middle to Late Eocene period (50-35 mya), found in western Europe, first defined in 1873 by Filhol, and considered ancestral to modern tarsiers. Notharctus tenebrosus skeleton: An early, adapiform, tree-dwelling primate from the Eocene period, dating from 54-38 mya. With long and slender forelimbs and long fingers and toes, it was able to spring from branch to branch across great gaps and cling safely to branches, much like a living lemur. Notharctus tenebrosus skull: Adapids are considered to have been lemur-like, as contrasted with tarsier-like omomyids.The eyes of the adapiform Notharctus were smaller than those of tarsier-like omomyids such as Tetonius, and were higher on the skull. Northarctus tenebrosus skull & dentition: The skull of the Eocene adapiform Notharctus had a complete postorbital ring and a cranial crest. Both eyes were directed forwards for binocular vision. Orangutan skulls of male, female, and juvenile: There is considerable sexual dimorphism in the orangutan (Pongo pygmaeus). Males, weighing about 120 kg, are about twice as large as females, whose adult skull retains more of the gracile form of juveniles. Orangutan male skull: The adult male Pongo (orangutan) has a robust skull with a long, jutting upper jaw, massive teeth, and a sagital crest not seen in the more gracile female. Ouranopithecus skull: A Late Miocene great ape (hominoid) with two species dating 9.6-7.4 mya, O. macedoniensis from Greece and Bulgaria, and O. turkae from Turkey. Ossicle: In ear anatomy, any
of the small bones in the middle ear used to conduct sound vibrations
to the
fluid-filled inner ear. The term is normally used to refer to the three
ossicles
in the mammalian inner ear, the stapes,
malleus (articular), and incus (quadrate). It also applies to
the
columella (hyomandibula) used as a sound amplifier by other tetrapods;
and the
bones in the Weberian organs of various fishes. Osteichthyes: ("bony fish") The class of fish with bony skeletons, as opposed to fish with cartilagenous skeletons (Chondrichthyes). The class Osteichthyes, frist defined in 1880 by Thomas Henry Huxley and made up of lobe-finned and ray-finned fishes, is the largest class of vertebrates in existence today, with about 28,000 species. Osteolepis macrolepidotis:
("bone scale"). A lobe-finned fish in the order Crossopterygii and the suborder Rhipidistia, dating from the Late Devonian period, covered with large, square scales, and found in Osteostracci: (“bone shields”) An widespread order of jawless fish including at least seven families and about 200 species, which lived from the Early Silurian to the Late Devonian period (ca. 430-370 mya). Oudenodon bainii skull: A dicynodont therapsid common throughout South Africa in the Late Permian period (265-252 mya), and also found in Madagascar, Zambia, and India. Owen, Richard: (1804-1892) A British paleontologist who was curator at the British Museum and published many works on fossil vertebrates and invertebrates. Among other accomplishments, he was the first to define dinosaurs ("terrible lizards")
Paleomutela: A clam-like bivalve genus from the Late Permian period (258-252 mya) in western Russia, with three species: P. wohrmani, P. amalitzky, and P. attenuata. Paleontology: The study of ancient life, based on
the discovery and interpretation
of fossil evidence. This is closely linked to stratigraphy, or the
geological
study of successive rock layers, and interpretation of the past
environments
they represent. Paleozoic: ("ancient life"). In the geological timescale, the era from the start of the Cambrian period to the end of the Permian period (543-252 mya). It spans from the first evidence of notochords and primitive vertebrates through the rise of large reptiles and synapsids, lasting until the end-of-Permian extinction. Pander, Heinz Christian: (1794 - 1865) A Baltic German biologist from Riga who discovered the three germ layers of the embryo, and is considered a founder of embryology. Pangaea globe in Early Triassic: In the Early Triassic period (252-247 mya), all continental plates were joined into the mega-continent named Pangaea except China, Indonesia, and Thailand. Pangaea with island location of south China: During the Permian period (298-252 mya), southern China including Yunnan provice was separated from the mega-continent named Pangaea. Panthalassic Ocean: ("whole sea") The large body of water, roughly comparable to the Pacific Ocean, which existed on the western side of the northern landmass Laurasia, and the southern landmass Gondwanaland, during part of the Paleozoic era, and most of the Triassic period. Paracalamitina striata: A relatively small, fern-like plant resembling a horsetail, which grew along lagoon banks and lake shores in the Ural region of Russia during the end of the Early Permian period (258-252 mya).Paracolobus chemeroni skull: ("near colobus") A Cercopithecoid (Old World Monkey) from Africa, dating from the Pliocene period (5-2 mya), is considered an ancestor of today`s Colobus monkey. The skull was discovered by Richard Leakey and his co-workers at Lake Turkana, Kenya in 1969. Paranthropus robustus male skull (SK-48): The most complete of several skulls and jaw fragments of Paranthropus robustus found by Robert Broom and John Robinson in 1948 at Swartkraans cave in South Africa. Paranthropus robustus female skull (DNH-7): A nearly complete female skull found in 2000 at Drimolen Main Quarry in Guateng Province, South Africa. Parakannemeyeria dolichocephala: a dicynodon ("two dog tooth") therapsid from the Early to Middle Triassic period in northern China, dating from 247-242 mya.Patranomodon: An anomodont ("toothless") therapsid found in the lowest biozone of the Beaufort Group, in the Karoo Basin of South Africa, dating from the Middle Permian at about 265 mya. Pederpes: ("Peter's foot"). An early tetrapod from Scotland dating from the Early Carboniferous (Mississippian) period (345 mya), originally considered a lobe-finned fish but reclassified by Clack et al. in 2002 as a tetrapod somewhat close in form to Whatcheeria from Iowa. Pelycosaurs: (“pelvis lizards”) Synapsids who emerged during the Late Pennsylvanian period (330-310 mya), with early versions of differentiated teeth which featured larger canines, and a developing hard palate. Pennsylvanian period timeline: A geological period in the Paleozoic era, preceded by the Mississippian and followed by the Permian. It is the second period in the Carboniferous system, equivalant to the Late Carboniferous, dating from 324 – 298.9 mya. Named for extensive coal deposits from the period in Pennsylvania. Permian time chart: The final geological period in the Paleozoic era, preceded by the Late Carboniferous (Pennsylvanian) and followed by the Triassic. Named by Murchison in the 1840s for the ancient kingdom of Perm in Russia. Petromyzontiformes (lampreys)
In the order Cyclostomata, an extant suborder of jawless fishes, usually considered the most basal
group of the Vertebrata. The earliest known fossil taxa of lampreys date from the
Late Ordovician period (ca. 450 mya). Phanerozoic Era: ("visible life") In the geologic timescale, the era of larger, more complex life forms begins at the end of the Late Precambrian period at about 600-550 mya, when the earliest evidence of macroscopic (i.e., non-microscopic) life appears. Pharyngolepis: ("scaly throat") A jawless fish in the order Anaspida and the family Birkeniidae, from the Late Silurian period (470-455 mya), found in the Baltic region of Norway. Pholidogaster pisciformes: ("scaly stomach with fish form") An early Tetrapod in the order Anthracosauria and the suborder Schizomeri, discovered in coal deposits in Scotland, dating from the Early Carboniferous (Mississippian) period, 338-320 mya.Photosynthesis: a complex
biochemical procedure which transforms sunlight and water into
metabolic energy for plants and algae via the molecular exchange
of ions. There are two phases of photosynthesis, a light phase which
captures light ions from sunlight via pigments in chloroplasts, and
converts them into free hydrogen ions, and a dark phase which combines
the hydrogen with water. The overall process creates energy-storing
molecules called ATP for the plant, and releases oxygen into the
atmosphere as a secondary byproduct. This process began in simple
microbes called cyanobacteria by or before 3.5 million years ago,
during the Archean era, and continues to be the mainstay of life on
Earth. Pikaia gracilens: A cephalacordate from the Burroughs shale of western Canada, dating from the Middle Cambrian period (520-505 mya). In various ways it resembles the lancelet Branchiostoma, the hagfish, and the Early Cambrian Chinese notochords Haikouichthys and Myllokunmingia. Placoderms: ("plate skin") A class of armored, jawed fish, dating from the Late Silurian period, whose expansion peaked in the Middle and late Devonian period (400-360 mya). Their groupings are shown in a timechart. Placoderm brain: Diagram of the brain and cranial nerves of Macropetalichthys, a Devonian placoderm. While the brain is relatively primitive, the cranial nerve organization is basically the same as in all later vertebrates (including humans). Plesiadapis cookei skeleton: ("near adapis") A late Paleocene proprimate found in Wyoming, P. cookei was an arboreal mammal with long, slender limbs used for climbing and leaping among branches. Plesiadapis cookei skull & brain: The small brain of this P. cookei from Wyoming with relatively large olfactory bulbs indicates Plesiadapis was more primitive than either a primate or a dermoptera (arboreal gliding mammals from southeast Asia). Plesiosaurus: ("near lizard") Plesiosaurs were large diapsid sea reptiles which first appeared in the Late Triassic Period (205 mya) and flourished through the Jurassic and Cretaceous periods until about 65 mya. Their fossils have been found worldwide. Plesiosaurus dolichodeirus drawn by Mary Anning: This large Early Jurassic marine vertebrate (200-195 mya) was discovered as a full skeleton by Mary Anning in 1823 in the Blue Lias formation at Lyme Regis in Devon, England. Pliensbachian: The third stage in the Early Jurassic period, dating from 191-183 mya. Pliopithecus :
A gibbon-sized Miocene ape found in Europe. It was discovered in
France in 1837 by Édouard Lartet, with fossils later found in
Switzerland, Slovakia and Spain. Six species have been identified. Pragian: the second stage of the Lower Devonian period, dating from 411 to 408 mya. Precambrian period time chart: The longest geological period by far, lasting from the Earth's formation 4.5 billion years ago until the Cambrian period at 545 mya. Pridoli: the final stage in the Late Silurian period, dating from 423-417 mya. Primate chart 1: The relations between Proprimates and early Primates, which in the Paleocene and Eocene periods split into two groups, lemur-like Adapoids and tarsier-like Tarsoids or Omomyids. Primate chart 2: Relations between developing Anthropoidea taxa from the Early Oligocene period onward, which include New World Monkeys, Old World Monkeys, and Hominoidea (Apes and Humans). Primate skull comparisons: Skulls of five recent anthropoids, including Australopithecus africanus, Homo sapiens, baboon, gelada, and chimpanzee. Pristerodon skull and lower jaw: Small dicynodonts ("two dog teeth"), a common group of therapsids or mammal-like reptiles from the Late Permian period, found in South Africa,Tanzania, and India. Pristerodon chewing muscles: This Late Permian dicynodont lived on vegetation which it snipped off with its horny beak, then chewed with a jaw built as a flexible unit, able to slide back and forth while eating. Pristerognathus bainii skull: Medium size therapsids from the late Middle Permian period. Classified as Therocephalians ("beast heads"), they represent index fossils for one of the Faunal Assemblage Zones in the Karoo Basin of South Africa, dating from 265-260 mya. Probainognathus jenseni skull: ("progressive jaw") A Late Triassic cynodont ("dog tooth") that lived 235 to 221.5 million years ago in what is now Argentina, named for its for its advanced jaw articulation. Procolophon skeleton: A small, anapsid reptile, widely distributed in Late Permian and Early Triassic times in North America, Europe, China, Russia, Africa, and Antarctica, dating from about 252-248 mya.Proconsul hesoloni skull: A Miocene ape dating from 23-14 mya, considered an ancestor of modern apes. The first nearly complete skull was found by Mary Leakey in 1948 on Rusina Island, Kenya. Procynosuchus delaharpae skeleton: A semi-aquatic cynodont from the Late Permian period, found in South Africa, Zambia, and Russia, and dating from 260-253 mya. Procynosuchus delaharpae skull: ("before dog crocodile") One of the earliest and most basal cynodonts ("dog teeth"), widespread in the Late Permian. Prokaryote: ("proto cell") The simplest forms of life, composed of a single cell lacking a nucleus, with the DNA used for reproduction simply floating about within the cell. Prokaryotes were the only life forms on Earth until about 2 billion years ago, when organisms called Eukaryotes with complex cells first appear, in conjunction with increased oxygen in Earth's atmosphere. Examples of prokaryotes are bacteria, while algae are eukaryotes Prosimian vs. simian skulls: One difference between skulls of prosimians (such as the lemur) and simians (ie., monkeys) is whether the adult frontal bone is fused or not. Proterogyrinus: ("early tadpole"). A medium-sized amphibian dating from the Late Mississippian period (330-320 mya), whose fossils have been found in Novia Scotia. It had partly reptilian anatomy but retained an amphibian skull and labyrinthodont teeth. Proterosuchus fergosi skull: ("early crocodile") An Early Triassic archosaur, a large crocodilian-like reptile, one of three species of Proterosuchus known in South Africa, with another in China, all dating from 252-247 mya. . Proterozoic: In the geological timescale, the era of “proto-life" or "preliminary life”. This began about 2 billion years ago during the Precambrian, when Eukaryotic organisms such as algae appear, probably related to an increased oxygen supply The oxygen in Earth's atmosphere had been gradually created by photosynthetic microbes called cyanobacteria during the preceding Archaan era. The Proterozoic era lasts until about 700-650 mya, when the Phanerozoic or era of "visible life" began. By then, multi-celled forms of marine life had appeared, ranging from photosynthetic seaweed (algae) to various multi-celled animals resembling sponges, whose fossils have been found in coastal sites in Australia and Nova Scotia. Pteraspidomorphi:
(“wing-shield forms”): An order of early jawless fishes who
lived from the
Ordovician through Devonian periods (495-359 mya). They are
characterized by
massive dermal head armour composed of median, ventral, and dorsal
plates. Many had hypocercal tails to
facilitate
swimming. The taxon contains the suborders Arandaspida, Astraspida,
and
Heterostraci. Some species may have lived in fresh water (Janvier 1997). Pteraspidiformes ("wing shields") one of the two orders of Heterostraci, the other being Cyathaspidiformes. They occured first in the Late Silurian, but became much more diverse during the Early Devonian. The Pteraspidiformes are divided into five families, Anchipteraspididae, Protopteraspididae, Pteraspididae, Protaspididae, and the Psammosteidae. Four of the five heterostraci families became extinct during the late Devonian (ca. 380-370 mya). The fifth, Psammosteidae, lived until the major Devonian extinction at 359 mya. Pter- : The Greek root for “wing”. Used in various descriptive terms such as the pteroid bone, or in taxa names such as Pterydactylus ("winged finger"), the first flying reptile to be discovered. Pterydactylus antiquus: (“winged
finger”) A Late Jurassic flying reptile (151-148 mya), first discovererd in Purgatorius: A small placental mammal found in eastern Montana from Late Cretaceous/ Early Paleocene deposits dating 66-63 mya, considered as the earliest known primate or a proto-primate, and a precursor to the Plesiadapiformes. Qingmenodus: A Devonian lobe-finned fish recently discovered in China.. Qingmenodus skull and brain: A Devonian lobe-finned fish, whose skull has provided a clear endocast critical for understanding bony fish evolution. Quaternary: In the geological timescale, referring to the Glacial era of the Pleistocene, combined with the Recent or Holocene period, from about 2-0 mya. In an early 19th century formation, The Quaternary was preeded by the Tertiary, which includes the first five periods of the Cenezoic (Paleocene, Eocene, Oligocene, Miocene, and Pliocene). While the original system using “Tertiary” and “Quaternary” is largely defunct, these two terms have remained in familar use . Ray-finned fish: (Actinopterygii, or "ray fins") One of two subclasses of bony fish, whose fins are composed of spines rather than limb bones. Today ray-finned fish make up over 95% of extant fishes, comprising about 28,000 species. Rechnisaurus cristarhynchus skull: A dicynodont ("two dog teeth") herbivore from the Middle Triassic period, found in the Pranhita-Godvari Valley of central India, dating from 247-242 mya. Red Bed: In geology,
red beds are sedimentary layers which are predominantly oxidized or red
in color,
but also
may contain reduced layers which are grey, grey-green, brown or black
layers.
Red Beds represent non-marine depositional environments which were
originally
exposed to the air at least periodically. These derive primarily from
riverine
deposition in deltas, alluvial fans, floodplains,
channels, and points bars, as well as lake strata. The
oldest known red beds date from the early Proterozoic era, about 2.1
billion years ago, representing rivers from that period.
Regression: In geology, a period
of low sea level when previous marine sediments are exposed. It is
the opposite
of transgression, when the sea level rises and the coastal areas are
flooded. Reptile: The term reptilia was originally used as as a class of vertebrates in Linnean taxonomy. Reptiles are now divided into two main groups, sauropsid and synapsid, with the former leading to dinosaurs and lizard-like reptiles, and the latter leading to therapsids and early mammals. Reptilian (amniotic) egg:
An egg with an outer protective shell and inner protective sac or layer
called an amnion, distinctive of reptiles and mammals, and contrastive
with the unprotected eggs of amphibians and fish, which are laid in
open water. Rhinoceros skeleton drawn by Cuvier: Drawing by Georges Cuvier from his 1812 Researches into the Fossil Skeletons of Quadrupeds, showing a relatively high standard of anatomical accuracy. Rhinoceros drawn by Albrect Durer: A 1515 drawing by Durer published in Conrad Gessner's History of Animals (1551-1558), showing the Rhinoceros as if it were armor-plated. Rhinoceros (Ceratotherium simum): The white rhinoceros, the largest extant species of rhinoceros. is mostly found today in South Africa. Rhuddanian: the first stage in the Early Silurian period, dating from 443-441 mya. Roadian: The first stage of the Middle Permian period, dating from 268.8 – 265.1 mya. Romer, Alfred Sherwood: (1894-1973) An American paleontologist and professor who through his textbook Vertebrate Paleontology became a widely-followed authority on vertebrate evolution. Among other basic concepts, he first clearly defined the essential groupings of synapsids, diapsids, and anapsids.Romer's Gap: A discontinuity in the fossil record described by Romer (1956) between vertebrates at the end of the Devonian period, with its high diversity of fishes, and the low density of both fish and tetrapods in the early Carboniferous, corresponding to the early Mississippian Tournaisian stage (360-345 mya).Romeria prima: An Early Permian captorhinid ("nose-catcher") reptile found in the Permian Basin of northern Texas, dating from the Cisuralian epoch, about 299–294.6 mya. Rondalet, Guillaume: (1507-1566) A French professor of medicine at the University of Montpellier, and a naturalist who wrote an illustrated treatise on fish and other aquatic animals, entitiled Libri de piscibus marinis. Rondalet drawing of a Dory: This 1556 drawing of the Dory fish (Zeus faber) by Rondalet was published in his Book of Marine Fishes. The popular name of this ray-finned fish comes from doree, "gilded," for its golden color. Rooneyia viejas skull: An enigmatic primate from the Early Oligocene in Texas. It was discovered by Wilson (1966) in the Sierra Vieja of Trans-Pecos Texas, and dated at about 35 mya. Sacabambaspis: A
genus of jawless fish of the
order Pteraspidomorphi (“wing-shield forms”)
from Sacral: In skeletal anatomy,
pertaining to the sacrum, the lower region of the vertebral column
involved
with the pelvic girdle. The sacral vertebrae lie between the dorsal
(or, in
mammals, the lumbar) and the caudal (tail) vertebrae. They are usually
fused to
each other and to the ilium. Saimiri sciureus (squirrel monkey) skull & brain: Squirrel monkeys are among the smaller platyrrhines, with males and females each weighing less than 1 kg. The eyes are closely spaced, and in adults are separated by only membrane.. Saimiri (squirrel monkey) species in Amazonia: The main species, Saimiri sciureus,
has four varieties, which live in widespread wooded zones of river
valleys throughout the Amazon basin, mainly in Venezuela and northern
Brazil. Sandbian: The first stage of
the Late Ordovician period, dating from 461-456 mya.
Santonian: The fourth stage of the Late Cretaceous period, dating from 85.8 - 83.5 mya. Sauroctonus parringtoni skeleton: A Late Permian gorgonopsian carnivore, strikingly similar to the Pleistocene saber-toothed cat Smilodon fatalis, from the Northern Dvina region in Russia and the Ruhuhu Valley in Tanzania, dating from 260-252 mya. Sauroctonus parringtoni skull: Detail of front half of body with skull. Sauropsid:
Scheinwoodian: The first stage in the Middle Silurian period, dating from 433-430 mya.Scilla, Agostino: 1629-1700) A late Renaissance Italian artist and naturalist, whose findings on fossils were published with accurate drawings in his 1670 book La vana speculazione disingannata dal senso ("Vain speculation disillusioned by the senses").Scilla, drawings of fossil fish vertebrae: Marine fossils collected by Agostino Scilla from Messina, Calabria, and Malta. Scilla, drawing of fossil fish jaws: Fish dentaries and maxillae with teeth, found by Scilla in Messina and Malta. Scilla, drawing of marine invertebrate fossils: Miocene fossils of echinoderms found by Scilla in Messina and Malta. and published in 1670. Scutosaurus: ("shield lizard") A Late Permian anapsid reptile named for the large armor plates covering its body beneath the skin, from Russia, dating from 259-252 mya. Sedgewick, Adam:
A British cleric and geologist who, working with Roderick Murchison,
defined the Cambrian Period, based on geologic formations and
associated fossils in England and Wales. He was also a professor of
geology at Cambridge University and taught Charles Darwin the elements
of stratigraphy. sensu latu: A Latin term meaning “in the broadest sense”. The opposite is sensu strictu , meaning “in the narrowest sense,” or “strictly speaking.” Serpukhovian: The third and last stage of the Mississippian period, dating from 330.0 - 323.2 mya. Shale: In geology, a sedimentary rock primarily composed of clay and other fine-grained and organic particles, normally deposited by water in relatively calm conditions. Given its fine-grained structure, shale is often an ideal medium for fossil preservation. Shankouclava: An Early Cambrian tunicate from the fine-grained Maotianshan Shale at Shankou village, Kunming, in South China, dating from 530 mya. Shansiodon wangi skull:
An Early to Middle Triassic dicynodont with well-preserved stapes
or middle ear ossicles, found in Shanxi province in northern China. Shansiodon wuhsiangensis skull: An Early to Middle Triassic plant-eating dicynodont ("two dog teeth") with large paired tusks, found in Shanxi province in northern China, dating from 252-245 mya. Siberian Traps: A region of volcanic hills in Siberia between the Ural Mountains and Lake Baikal, whose basalt and tuff formations were caused by lava and ash expelled at ca. 252-251 mya, with related atmospheric changes thought to be a cause of end-of-Permian mass extinctions. Silurian period timeline: The third geological period of the Paleozoic Era, from 443-417 mya, between the Ordovician and Devonian Periods. The Early Silurian (443-423 mya) is usually referred to as the Llandovery. The Middle Silurian is the Wenlock (428-423 mya). The Late Silurian (423-417 mya) includes both the Ludlow and Pridoli stages. Most of the major groups of fishes had probably originated by the Early Silurian. Sinemurian: The second stage in the Early Jurassic period, dating from 199-191 mya. Sinoconodon ("Chinese tooth") A proto-mammal from Lower Lufeng Series in Yunnan province, China, dating from the Sinemurian stage of the Early Jurassic period (208-191 Mya). Sinognathus gracilis skull: A cynodont from the Upper Ermaying deposits in Shanxi Province in northern China, which date to the Early Triassic period at 249-245 mya.Sinopa rapax: A small Eocene carnivore of the creodont order, who lived in North America and Asia from 50-46 mya. This example was found in the Bridger Formation in Wyoming. Sister group: In cladistic terminology, a sister group is a clade thought to be the closest genealogical relative of a second taxon, with which it shares a common ancestor. Sivapithecus and orangutan skulls: Sivapithecus, a Miocene ape who lived in the Siwalik area of northern Pakistan between 13-8 mya, is considered to be the ancestor of the Southeast Asian ape Pongo pygmaeus, the orangutan,. Smilodectes gracilis skeleton: An adapid primate from the Early and Middle Eocene in Wyoming. It is related to Notharctus, and is grouped with the Nothacidae family of adapids, or lemur-like early primates. Smilodon fatalis skeleton: The saber-toothed cat (Smilodon) was an advanced mammalian carnivore, one of the top predators during the Pleistocene period. It first appears in the fossil record ca. 2.5 mya, and became extinct at the end of the Wisconsin glaciation at about 10,000 BP. Smith, William: (1769-1839) William "Strata" Smith was an English mining engineer and geologist who first accurately mapped the geological strata throughout Britain, and first described many index fossils which define the strata. Smith's geologic map of UK: Working as a canal surveyor, William Smith made the first accurate geologic maps of England and Wales, which he published at his own expense in 1815. Smith's index fossils in UK:
In 1816, a year after he published his geological maps, Smith published
a guide to the index fossils of each geological stratum in the maps.
This figure shows fish and marine invertebrate fossils from a Mesozoic
chalk layer. Spriggina floudersi: A multi-celled marine invertebrate resembling a sea pen or cnidarian, found at Ediacara in Australia, and dating from the end of the Late Precambrian period at 600-542 mya. Stanton Formation: A limestone formation in Kansas, dating from the Late Pennsylvanian and earliest Permian periods. Primarily a marine and deltaic component noted for crinoids, it also has an important terrestrial or lacustrine component with a Permian-like biota, including fossil conifers, insects, and the edaphosaurid Ianthasaurus. (Formerly called the Admiral Formation or Stanton Limestone). Stapedius muscle: In ear anatomy, a
small muscle of the middle ear which acts to damp excessively loud
sounds by
restricting the movement of the stapes. Stapes: In ear anatomy, the stapes (Latin for “stirrup”) is a small bone used as an ossicle or sound amplifier. It evolved from the hyomandibular bone of fish. Originally this may have been the main upper element of a gill arch in jawless fish. It later (by the Late Devonian) appeared in lobe-finned fish as the hyomandibular bone, an accessory jaw element. In early tetrapods from the Late Devonian and early Carboniferous, it became a stout bone bracing the braincase against the quadrate. As the paroccipital process took over this function, the stapes was reduced, eventually (by the Triassic period) becoming specialized for hearing as the columella in reptiles and amphibians, or the stapes in mammaliforms. The stirrup-shaped stapes in mammals has a footplate which fits over the foramen ovale. Stegocephalians:
("roof-heads") A late 19th century grouping of amphibians and early
tetrapods based on their thick, heavily armored skull roofs, a trait
observed by researchers including Owen and Cope to often correlate with labyrinthodont teeth. Stem group: In cladistic terminology, the term “stem group” or simply "stem" as an adjective, is often used as a mixed, paraphyletic, or otherwise loosely defined grouping. An example is stem tetrapod, which includes Baphetidae, Colosteidae, and other difficult-to-classify amphibian taxa outside the probable crown group of Tetrapods. Steno, Nicholas: (1638-1686) A Danish Catholic bishop who also worked as an anatomist, who is recognized as a pioneer in the study of layered sedimentary rock formations and fossil interpretation. Steno's drawing of shark jaw with teeth: To explain how shark's teeth turned to stone or became fossilized, Steno proposed that the corpuscles in sharks teeth were replaced individually by mineral corpuscles. Steno's Law: The rule of superposition, namely that in undisturbed locations, the deeper the stratum, the older it is; and conversely, that the topmost strata are the youngest. It is named for Nicholas Steno, a 17th century Danish anatomist who first formally defined the rule of superposition with regards to understanding context of fossils within geological strata. Strata: In geology, a term for layers or
levels (from Latin strata for "spread layers"; stratum
for "single layer"), The
term (now used for any kind of layers or levels) was originally
used in ancient Roman road construction for the spread layers of
paving stones, with paved roads called strata via. Stromatolites: Layers of fossiled cyanobacteria in a chert formation in Pilbara Craton, Australia, dating from 3.6-3.2 billion years ago. Suess, Eduard: (1831–1914)
An Austrian geologist who specialized in the formations and
glaciations of the
Alps, and was a pioneer in the subject of continental drift, based on
his study of the southern megacontinent which he named Gondwanland Syncline: In structural
geology, a syncline is a fold with younger layers closer to the center
of the
structure. On a geologic map, synclines are recognized by a sequence of
rock
layers that grow progressively younger, followed by the youngest layer
at the
fold's center or hinge. For example, in the
Moscow Syncline in western Russia, the sequence of exposures in a group
of concentric
formations is 1) Permian 2)
Triassic 3) Jurassic., with the oldest
formation, the Permian, on the outside,
containing both the Triassic and Jurassic, and the youngest formation,
the Jurassic,
nested within the Triassic. Systematics:
T Tapinocaninus pamelae: ("humble canine of Pam") A large therapsid from the Middle Permian, Eodicynodon Zone in the Karoo Valley in South Africa, dating from 268.8-265.9 mya. Tapinocephalus atherstonei: ("humble head") A therapsid from the Middle to Late Permian period, and the type genus for the Tapinocephalus Zone in the Beaufort Group of the Karoo Basin of South Africa, dating from 265.8 -261.2 mya. Telychian: the third and final stage in the Early Silurian period, dating from 438-433 mya.Temnospondyl: ("cut vertebra") An order of amphibians ancestral to synapsid reptiles. Tethys Sea: The ancient area of ocean between China and the southern landmass called Gondwanaland, as named by Austrian geologist Eduard Suess in the 1860s. Combined with the larger Panthalassic Ocean in today's Pacific area, the Tethys Sea was one of the two main bodies of water surrounding the mega-continent Pangaea, during the Permian and Triassic periods. Tetonius homunculus skull: A very small omomyid primate, dating from the early Eocene period and found in Wyoming. As a member of the family Omomyidae it is considered ancestral to Tarsiers. Tetonius homunculus skull with brain endocast: The cranial capacity of the tiny T. homunculus was 1.5 cc., with a small cerebrum and olfactory bulbs, but relatively large visual cortexes, corresponding to its large eyes. Tetrapods: ("four feet") The earliest land vertebrates, who evolved from lobe-finned fish in the Late Devonian period. Thallophyca corrugata: A marine algae or seaweed from the Duoshantuo Formation in China dating from the Late Precambrian. Vendian stage (590-565 mya). Thallophyca corrugata, detail of algae cells: Preserved thallus tissue of Late Precambrian algae including nuclei and chloroplasts, similar to those in today's seaweed. Thelodonts: ("nipple teeth") Thelodonti were an order of jawless fish from the Late Ordovician through Devonian periods (450-359 mya) whose bodies were armored with tooth-like or spiny scales, identifiably distinct by genus, as illustrated from Paralogonia, Shielia, and Lanarkia. Therapsid: ("beast face"). The large group of mammal-like reptiles from the Middle and Late Permian periods, extensively known in South Africa, Russia, and elsewhere. These include the cynodonts, which survived the Permian-Triassic extinction event and led in the Middle Triassic to the first mammaliforms. Thrinaxodon liorhinus skull & brain endocast: Thrinaxodon was a medium-sized cynodont who lived in South Africa, India, and Antarctica during the Early Triassic period (252-247 mya), during and after the Permian–Triassic mass extinction event. Tibia: In skeletal anatomy, one of the two lower leg bones, along with the fibula. The tibia is the thicker of the two, and constitutes the shin bone, extending from the knee to the ankle. Tiktaalik roseae: A lobe-finned fish and tetrapodomorph (transitional form between fish and tetrapods) from the Late Devonian period at 356-374 mya, found at southern Ellesmere Island; the closest relative of tetrapods known to have retained paired fins rather than feet. Tilapia Oreochormis mossambicus: A small Perciform fish found in Madagascar, one of over 3000 species of cichlidae found worldwide. Tilapia skull and brain: The brain of the Madagascar tilapia Oreochromis mossambicus was studied by Simoes et al. (2012) through a series of MRI scans.The revealed structures may correlate with behavioral differences between cichlid species.Titanophoneus potens: ("titanic murderer") A carnivorous dinocephalian therapsid from the Middle to Late Permian period (270-260 mya), found at Isheevo in the East European Platform in Russia. Tithonian: The third and final stage in the Late Jurassic period, dating from 152-145 mya.Titi monkey (Callicebus) distribution in Amazonia: The Titi Monkey (genus Callicebus, family Cebidae) is a diurnal New World Monkey found throughout the Amazonian rain forest. It is one of the most widespread of the Platyrrhini, with some 24 species recognized. Titi Monkey in Brazil: The red bellied Titi Monkey (Callicebus moloch or Plectocebus moloch) is a diurnal New World Monkey (Platyrrhini) who inhabits the forests of Brazil.Titi Monkey (Callicebus moloch) skull & brain: The red bellied Titi Monkey (Callicebus moloch) has a rounded head with a short premaxilla, giving the appearance of a small, not especially prognathic face relative to other platyrrhines. Tournaisian: The first stage of the Mississippian period, dated at 356.9 - 346.7 mya. Tremadocian: The first stage of the Early Ordovician period, dated at 486-476 mya. Triassic period timeline: The first of three geological periods of the Mesozoic era (known as the Age of Reptiles), dating from 252.2 – 201.3 mya, following the Permian period, and preceding the Jurassic period. Trilobite: ("three lobes") Marine arthropods, mainly small, who were extremely common and diverse in the Paleozoic era. Trinucleus concentricus: A trilobite from the Caradoc epoch (Sandbian and Katin stages) of the Ordovician period (457-450 mya), found in Britain, and one of a group called trinucleids with protruding head shield segments and a much-shortened lower body serving as protection against predators. Tristichopterus alatus: A lobe-finned fish from the Givetian stage of the Middle Devonian period (387-382 mya), in the order Crossopterygii, the suborder Rhipidistia, and the family Rhizondotidae, one of a group of tetrapodomorph fishes first found in the Orkney Islands of Scotland in 1861. Tunicates: Present-day marine organisms named for their tough outer tunic or skin. They are basal chordates whose juveniles are free swimmers, but whose adult forms attach themselves to a substrate and live as stationary filter-feeders. Turkanapithecus kalkolensis skull: An Early Miocene hominoid found by Richard and Meave Leakey in 1986 at West Turkana, Kenya, dated at 20-16 mya,
Ulemosaurus svijagensis: A large herbivorous dinocephalian therapsid living in the Middle Permian period in the East European Platform of Russia. Ulna: In skeletal anatomy, one of the two lower arm bones, along with the radius. The ulna is the thicker of the two, and is on the outside, whereas the radius rotates with the interior wrist. The other end of the ulna forms part of the elbow, where it joins with the humerus or upper arm bone. Ulva (Sea lettuce): Sea lettuce is a present-day, edible green algae (Chlorophyta) eaten by many sea creatures, including sea slugs and manatees, and by humans in Japan and elsewhere. Ungulate: mammalian herbivores with hoofs, usually of
relatively large size. The grouping contains two main orders, odd-toed
ungulates (Perissodactyla) and even-toed ungulates (Artiodactyla). The
odd-toed ungulates include three families: equidae (horses, zebras, and
asses), tapiridae (tapirs), and rhinoceratidae (rhinoceroses). The
even-toed ungulates include camelidae(camels and llamas), suina (pigs
and peccaries), cervoidea (pronghorn, giraffes, okapi, deer, musk deer,
oxen, cows, and antelopes), hippopotamidae (hippopotamuses), and
Cetacea (whales and dolphins).
Valanginian: The second stage of the Early Cretaceous period, dating from 140-132 mya. Velociraptor: ("speedy plunderer") A Chinese fossil of this small, agile, bipedal dinosaur from the Late Cretaceous period (75-71 mya). Vendian: The last stage of the Precambrian, used for Old World fossil-producing sites such as found along the White Sea in Russia near Archalesk, dating from about 625-540 mya. It is a synonym for, and contemporary with, the Ediacaran stage, named for a fossil site in Australia. Ventral: In anatomy, this refers to the front side, as opposed to the dorsal which refers to the back. Vertebrate: Animals with backbones. In the Linnean system of classification, vertebrates are a sub-phyllum of the phyllum notochord, which is the more primitive condition. Vesalius, Andreas: (1514-1564) A 16th century professor of anatomy who, based on direct study of humans, provided the first truly accurate study of human anatomy from his 1543 textbook, De humani corporis fabrica (On the fabric of the human body), replacing the inaccurate ancient work of Galen based on study of apes and pigs. Victoriapithecus macinnesi skull: A Middle Miocene Old World Monkey (Cercopithecoid) found near Lake Victoria in Kenya by Brenda Benefit, the earliest Old World Monkey fossil so far known. Visean: The second stage of the Mississippian period, dated at 346.7 - 330.9 mya. von Leeuwenhoek, Antonie: (1632-1723) A Dutch researcher who revolutionized the science of biology through use of the microscope, and published a series of his many discoveries in drawings in letters to colleagues. von Leeuwenhoek's drawing of cow spinal cord:
This figure, drawn through a microscope by van Leewenhoek in 1717,
shows a much magnified cross section of a cow spinal cord, and a
plan drawing of a branching nerve. Wallace, Alfred Russell: (1823-1913)
A British naturalist and explorer who in 1858 independently
conceived the theory of evolution through natural selection, almost at
the same time as Charles Darwin. Wegener, Alfred Lothar: (1880–1930) A German geophysicist and polar researcher, who is best known for almost single-handedly conceiving and establishing the (now verified) theory of continental drift. Wenlock: The epoch equivalent to the Middle Silurian period, dating from 433-427 mya. Whatcheeria deltae: An Early Mississippian tetrapod found in Delta quarry, Iowa, dating from about 340 mya, grouped as as a stegocephalian ("roof-head").
Yonghesuchus sangiensis skull: A crocodilian-like diapsid reptile from the Upper Triassic period, discovered in 1992 in Shanxi Province, China. Yunnanozoon
lividum: ("life form from Yunnan") A
primitive chordate from the Lower
Cambrian Chenjiang fauna, found in the Maotianshan Shale deposits of
Yunnan province, southern China. Zhongjianichthys rostratus:
An early Cambrian notochord, proto-fish genus from the Lower Cambrian
Maotianshan
shales at Ercaicun in Zinjanthropus boesei skull: ("nutcracker man from the woods") An early hominin from East Africa, first discovered at Olduvai Gorge in Tanzania in 1959 by Mary Leakey, dating from the Early Pleistocene at about 2.0 mya. The name Zinjanthropus was coined due to the massive jawbones and teeth of this individual. Zygomatic arch: In skull anatomy, the cheekbone is composed of the zygomatic process of the temporal bone, which extends forward over the side of the skull, and over the ear opening, and attaches to the jugal bone which forms the lateral margin of the orbit. The term zygomatic derives from the Greek word zygoma for "bar" or "yoke"; the same meaning as in Latin juga. |
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