Tue Feb 08 2005 at 3:40:12
Tullimonstrum gregarium - Illinois' "state fossil", as well as being one of the weirdest, most perplexing creatures known to paleontology.
In 1958, a Mr. Francis Tully brought a siderite (ironstone) nodule into Chicago's Field Museum of Natural History. He had found the nodule in a pile of coal mine tailings in the Mazon Creek area of central
Illinois. Since the mid-1800's, these tailings piles have been a treasure trove of fossils from the Late Carboniferous (Pennsylvanian) Period, about 300 million years ago.
The ironstone had preserved the impression of a soft-bodied invertebrate marine creature, previously unknown to paleontologists. This creature lived in the shallow seas that covered the American Midwest at the time, and was preserved because of a unique combination of quick burial in mud and chemical reactions. Its body is approximately 19 cm (8 in) long, and appears to have been round in cross section. Some specimens exhibit a Michelin Man-type segmentation. At the rear are two triangular fins which, one would assume, helped propel it through the water. At the front end was a flexible proboscis tipped with an eight-part "claw". Towards the foward end of the creature are two long stalks with sensory organs, probably eyes, on the end.