Enigmatic Typhloesus Conodont Animal from Bear Gulch

Description: The Bear Gulch Limestone is a deposit of some 70 square km in extent and 30 m in depth that has been a source of one of the most diverse assemblages of fossil fish with some 110 species having been described over the past 30 years. Most were new to science, and provided a unique view of the marine environment of Mississippian times. Fine preservation of both fish and invertebrates is a hallmark of these deposits, presumably due to an anoxic depositional environment. First discovered in the early 1970s, this enigmatic creature was found to contain conodonts within, and was such termed the first conodont animal. Some 20 years later it was determined that the conodonts were not native to the specimen, but a result of predation, resulting in conodont within the interior. It is still an open question as to the affinities of this enigmatic metazoan. The genus derives its name from the belief that it has a blind gut, much like some coelenterates. What is a mystery is that most animals having blind guts are either sessile or at most slow-moving while this one has the streamlined body and fin of an actively-swimming predator. Note the darkened circular structure, known as a ferrodiscus. This circular structure has a high concentration of iron, hence the name. It is not know for sure what its function was, but some researchers think it had something to do with the circulatory system. The most striking feature of this one is the possession of conodonts within the interior seen as darkened spots which show up best on the more lightly-colored counterpart. Whether the animal contains them as a result of ingestion of another organism or because they were native to the taxon is still a topic of debate.

References:
Melton, W and Scott, Geological Society of America, Special Paper 141, pp 32-65, 1973
Morris, S. Phil. Trans. R. Soc. Lond. B, 327, pp 595-624, 1990