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Haikouella lanceolata
Haikouella lanceolata (after Chen et al. 1999, and Palaois 2014)
Haikouella lanceolata
was a lower Cambrian chordate found in Yunnan Province of Southern
China, dating from about 535-525 mya. The name means "lancelet-like
from Haikou," referring to the similarities between extant lancelets
and these very early fossil chordates. A large sample of 300 specimens
of H. Lanceolata was reported by Chen, Huang, and Li in 1999, found in the Lower Cambrian Maotianshan shales of Chengjiang
County of Yunnan Province.
Haikouella lanceolata belongs to the phylum Chordata and the subphylum Cephelacordata A second species, Haikouella jianshanensis, is also described by Shu et al. 2003 from the same beds.
H. lanceolata was a cephalochordate with a notochord, and tentacles near its mouth somewhat analogous to those of the lancelet. Haikouella does not have bones or a movable jaw, but it otherwise resembles vertebrates. Compared to another early chordate, Yunnazoon, the anatomical differences include a larger stomach and smaller (0.1 mm) pharyngeal teeth for H. Lanceolata, the latter evidenced by tiny structures present in the body cavity.
Its body length was normally 20-30 mm, with the largest at 40 mm. H. lanceolata has a head, gills, brain, notochord,
well developed musculature, heart and circulatory system. It has a bent
caudal projection of the notochord, perhaps a primitive tail fin,
dorsal and ventral fins, and possibly a pair of lateral
eyes.
References:
Chen, Huang, and Li 1999
Palaios website, 2013-2014
Shu et al. 2003e
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