<em>Amiskwia sagittiformis</em> (IMAGE) University of Bristol Caption The fossil, Amiskwia sagittiformis from the Burgess Shale (508 million years old), preserving bilateral jaw elements inside its head. These jaw elements resemble those seen in rotifers and gnathostomulids, while the body resemble arrow worms. Credit Photo credit Luke Alexander Parry/University of Bristol--Yale University Usage Restrictions Single use only - please do not archive License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.