Mouthparts of Cambrian Wiwaxia and Odontogriphus Creatures Revealed

Posted on August 24, 2012

The mouthparts of the Cambrian animals Odontogriphus and Wiwaxia have been revealed. Researchers have found that the mouthparts of these 500-million-year-old creatures were somewhat similar to the radula found in modern molluscs.

The Odontogriphus was an ancient type of slug and the Wiwaxia was a sea bottom dweller covered in spines and scales. A Wiwaxia fossil with mouthparts toward the front is pictured above. University of Toronto graduate student Martin Smith used a new, non-destructive type of Electron Microscopy to examine hundreds of fossil specimens.

Smith says, "I put the fossils in the microscope, and the mouth parts just leaped out. You could see details you'd never guess were there if you just had a normal microscope."

The new observations demonstrated that the mouthparts consisted of two to three rows of 17 similarly-shaped teeth, with a symmetrical central tooth and smaller teeth on the edges. The teeth would have moved round the end of a tongue in the conveyor-belt fashion seen in molluscs today, scooping food, algae or detritus from the muddy sea floor. Smith was able to demonstrate that the mouthparts formed a shorter and squatter forerunner to the modern radula. A reconstruction of the Odontogriphus mouthparts is pictured below.

Smith says, "When I set out, I just hoped to be a bit closer to knowing what these mysterious fossils were. Now, with this picture of the earliest radula, we are one step closer to understanding where the molluscs came from and how they became so successful today."

The findings are reported this week in the paper, "Mouthparts of the Burgess Shale fossils Odontogriphus and Wiwaxia: implications for the ancestral molluscan radula," published in Proceedings of the Royal Society B.

ANIMALS
EXTINCT SPECIES