[New species arrow worms with a big bite discovered in Burgess Shale]
Decades of Royal Ontario Museum discoveries and research has culminated in the naming of a new fossil species that belongs in a mysterious group of predatory marine invertebrates that are still alive today, called arrow worms. Capinatator praetermissus, which literally means, “a swimming and grasping animal which remained overlooked for a long time,” comes from the famous 508 million year old Burgess Shale site in British Columbia.
Its description, published in August 3, 2017 in the scientific journal Current Biology, is significant because it shows that primitive arrow worms were much larger and had evolved greater number of spines around their mouths, compared to modern species, which are miniaturized and mostly planktonic. The study is based on the largest and best-preserved collection of fossils of this tiny phylum anywhere, and the new fossil species is one of the oldest examples of fossilized arrow worms known to scientists.
The arrow worms are a rather enigmatic phylum of marine invertebrates. Formally known as chaetognaths, which means “bristle jaws,” because of the conspicuous claws around their mouths, these arrow-shaped animals have translucent bodies that make them difficult to spot even under the best of circumstances. Their sharp claws are almost as long as their heads, and can splay apart astoundingly fast, projecting forward and closing in on anything unlucky enough to be within striking distance. It is very fortunate for us that chaetognaths are so tiny. These animals grow to only a few millimeters in length, so they cannot do us, or other larger animals, any harm.
http://www.sciencedirect.com/sci ... i/S0960982217308606
Illustration of Capinatator praetermissus. Drawing by Marianne Collins. © Royal Ontario Museum
Capinatator praetermissus fossil . Specimen from the Walcott Quarry, Burgess Shale (Yoho National Park, BC). Photo by JB Caron © Royal Ontario Museum