STL Science Center

STL Science Center

13 January 2018

Welcome Back to Crazy Animals

©Dinoguy2 CC BY-SA 3.0
Coming back from a short hiatus and a very long Twitter feed at a scientific conference, this blog is ready to talk fossils and extinct animals again. We are going to go back pretty far into the fossil record for this first week back too. As I stated in the name change post, we are expanding our view beyond dinosaurs alone and even further than we ever have in the past (such as mammals and amphibians). To start looking at how massive the fossil record truly is, we will relaunch this week looking at one of the earliest known large sea creatures, an arthropod genus known as the "Abnormal Shrimp"; Anomalocaris. Some may recognize the name from the documentary series Walking with Prehistoric Monsters, the final series in the Walking with series of documentaries. Known largely from deposits of the Burgess Shale and other shales such as the Ogygopsis Shale (a subseries of the Burgess Shale), Anomalocaris consists of two accepted species and a third more contentious species. The original fossils, dating from 1892, consisted of a deceptively separated "arm", now known to be an individual portion of the feeding appendages encased in Middle Cambrian (508 MA) shales. The fragmentary nature of many specimens of Anomalocaris have, in the past, led to this single type of animal being labeled as many different animals and different types of animals. The body consists of many lobes and, as with all arthropods, these lobes are covered in a mineralized shell. The frightening look of this multi-lobed, shelled animal may be more a remnant of its alien (to us) body plan than it was an actually frightening carnivorous animal. One of the three species appears to have possessed robust feeding appendages capable of piercing the shells of other animals of the Cambrian sea; however, the other two species do not possess these and the diet of these other two species has been hypothesized to have been filter feeding rather than carnivory. Multiple dietary preferences in this genus point to a much more diverse group than has been portrayed in common accounts and means that the animal we are going to discuss this week is much more complex than originally thought as well.

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