Anomalocaris (abnormal shrimp,) is an extinct genus of anomalocaridids, which, are thought to be closely related to arthropods. It was originally thought to be three separate creatures, as three separate parts, the mouth, the feeding appendages, and the tail. This was corrected in a 1985 journal article by Harry B. Whittington and Derek Briggs.
It is thought that Anomalocaris was a predator, and that it swam by undulating the lobes on the side of the body, where each lobe sloped below the one closest behind it. Anomalocaris had a large head with a pair of large compound eyes on stalks, each with ~16,000 individual lenses. It had a mouth that I can best describe as a pineapple-ring-shape, as I’ve picked that up from my paleontology professor. This mouth consisted of 32 overlapping plates, four large ones and twenty-eight smaller ones. There were two large, for lack of a better term, arms in front of the mouth, which were covered in barb-like spikes, could reach up to seven inches when extended, and were likely used to capture prey. It was truly a huge creature for the Cambrian, reaching up to two meters in length.
Here’s a video to describe it, it’s in Japanese, but there’s a translation under the video.
For the Model:
By Photnart (Own work) [CC0 (creativecommons.org/publicdomain/zero/1.0/deed.en)], via Wikimedia Commons
For the Fossil:
By Keith Schengili-Roberts (Own Work (photo)) [GFDL (www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (www.creativecommons.org/licenses/by-sa/3.0/) or CC-BY-SA-2.5-2.0-1.0 (www.creativecommons.org/licenses/by-sa/2.5-2.0-1.0)], via Wikimedia Commons