Canadian abnormal shrimp
Cambrian to Ordovician Periods, 515-472 MYA
3 feet long, 20 pounds
- It is believed that Anomalocaris was a predator. Trilobite fossils have been found with unusual W-shaped bite marks that seem to match up with its mouthparts, as have fecal pellets containing bits of trilobite armor that are so large as to only have come from Anomalocaris. However, Anomalocaris mouths do not show the wear that would be expected if they were regularly biting hard shells and some biomechanics research suggests they could not generate the forces needed to crush such armor. Some scientists believe that it may have used its spined arms to dismember trilobites or that it perhaps it fed on soft-bodied prey via suction feeding.
- Anomalocaris had a series of paired, flexible lobes running along either side of its body. These lobes overlapped each other and functioned like a single giant fin to propel the animal through the water. It probably swam much like the modern cuttlefish. Such an arrangement is inherently stable in the water and it is believed that Anomalocaris would have been able to maintain balance in the water column without the need of a complex brain. The tops of the lobs contain strictures believe to be gills.
Anomalocaris is believed to be a distant cousin of modern arthropods. Like their extant relatives, it had a tough cuticle of armor, a body divided into segments, and complex compound eyes, although their exact relationship with living animals is still a matter of scientific debate. The discovery of Anomalocaris is one of the more unusual stories in all of paleontology. Different pieces were found at different times separate from each other and believed to be from different animals. The first parts discovered were the grasping arms, which were mistaken for the tail of a shrimp and gave rise to the animal’s name. The mouth, shaped somewhat like a barbed pineapple slice, was initially taken for a jellyfish fossil and the body was thought to be a sponge. It was not until a later specimen was uncovered that it was shown that all these odd bits were parts of a single, very strange animal.
Kingdom - Animalia Phylum - Ecdysozoa Class - Dinocaridida Order - Radiodonta Family - Anomalocarididae Genus - Anomalocaris Species - A. canadensis