Haikouella lanceolata Chordate Fossil

Haikouella is conjectured by some scientists (i.e., Chen et al., Nature 402) to be the oldest member of the craniata in the fossil record. Their studies purport a phenotype having many vertebrata-like traits, including brain putative circulatory system, gills, heart, notochord, musculature, heart with dorsal and ventral aorta, a posterior projection that might be a proto tail fin, possibly a pair of lateral eyes and probable pharyngeal teeth, and some evidence of dorsal and ventral fins.

Haikouella fossils are found in association with Haikouichthys and Myllokunmingia that by consensus are considered to be the oldest known true craniates and probably the oldest fishes.

Craniata (meaning animals with a hard bone or cartilage skull, or more simply, chordates with heads) is a huge animal clade containing lampreys and armored jawless fishes, armored fish, sharks, skates, and rays, spiny sharks, bony fish, reptiles, birds and mammals. The earliest craniates are thus of obvious importance to our understanding of evolution, with Haikouella a prime candidate to be an ancestor to all vertebrates that have followed, including you.

This fossil has three Haikouella measuring some 16 to 22 mm.

Reference: Chen, J.-Y.; Huang, D.-Y.; Li, C.-W. (1999). "An early Cambrian craniate-like chordate". Nature 402 (6761): 518–522.

Also see: Chengjiang Biota, Chengjiang Fossils, Cambrian Explosion