Nectocaris pteryx Reinterpreted as a Cephalopod

26 05 2010

The middle Cambrian species Nectocaris pteryx has long puzzled paleontologists.  Originally described as “a shrimp with a chordate tail,” two Canadian scientists have reexamined the organism and come to the conclusion that it is a cephalopod.

The findings are published as a letter in the May 27 issue of the journal Nature.

Based on new material from the Burgess Shale, Martin R. Smith and Jean Bernard Caron of the University of Toronto have grouped N. pteryx along with Nectocaris, Petalilium, and (probably) Vetustovermis to form the clade Nectocaridae.

Smith and Caron describe the new clade as “characterized by an open axial cavity with paired gills, wide lateral fins, a single pair of long, prehensile tentacles, a pair of non-faceted eyes on short stalks, and a large, flexible anterior funnel.”  It pushes back the presence of cephalopods in the fossil record by more than 30 million years.  It also indicates that “[t]he explosive diversification of mineralized cephalopods in the Ordovician may have an understated Cambrian ‘fuse’.”

In addition, Smith and Caron conclude that “primitive cephalopods lacked a mineralized shell, were hyperbenthic, and were presumably carnivorous.”

They also conclude that “[t]he presence of a funnel suggests that jet propulsion evolved in cephalopods before the acquisition of a shell.”

To read an abstract of the article or to purchase the entire article, please use the following link:
http://www.nature.com/nature/journal/v465/n7297/full/nature09068.html.

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