Sorry Tony, thanks for asking though!
That was a bit obscure; I should have called the animal 'anomalocaris' in the poll. Then you certainly would have had some hits. I have banged on about this bizarre animal before; probably too many times in a cephalopod web-site.
was one of the animals that belong to the anomalocaridids, a diverse group of top predators that inhabited the Cambrian seas. This group were the world's first large predators, at this date the molluscs were confined to small shells and were barely significant in the fossil record. The arthropods dominated the seas in the Cambrian, and Anomalocaris
was the most fearsome of the whole group.
from the 525mya Burgess Shale is the best known animal from the group and is usually reconstructed as a gliding manta-like animal with a circular crushing mouth and two large grasping claws on the head. Fragments of these animals have been found in Australia that imply this arthropod could have reached a length of 2 metres or more; the animal was clearly a very impressive animal. Elrathia
trilobites have been found in Utah that display semi-circular bite marks that were probably wounds inflicted by this animal.
had been assumed to be three separate animals until the early eighties as it was thought that the mouth parts were remains of shrimp-type animals, the mouth being a peculiar form of jellyfish and the body some form of sponge. The chance discovery of a complete specimen at the Burgess site led to a reappraisal of all the old specimens that have been collected and a much more interesting animal was the result.
Since the eighties, members of the anomalocaridids have been found in the earlier Sirius Passet fauna at Greenland and in the Chenjiang fauna from China, both of which display creatures that were quite diverse; some of the Greenland examples display lobopod-style legs. It is interesting to note that the earliest nautiloids that rose to the position of top predator and diversified massively in the subsequent Ordovician period appeared after the extinction of the anomalocarids. One could almost argue that the molluscs had been held in check by the arthropods in the Cambrian, and it was only after a mass extinction that the molluscs were able to exploit the niches largely vacated by the arthropod predators.
Interesting stuff, and a fascinating animal! This is the ultimate place to go for details on the anomalocaridids, and it is a truly brilliant website:
And (hope you don't mind) are a few clay models of a few of the anomalocaridids I made a couple of years ago. Don't be too harsh, I only made them to keep myself amused, normally they would not see the light of day!