Fossil Enigmas
"Square objects" (left), which are really barrel-shaped with an opening at one end, are enigmatic animals that occur by the hundreds in some layers. Their surface texture is distinctive.
The most enigmatic and challenging of the Bear Gulch "invertebrates" is Typhloessus (right). You are free to position this animal in any orientation you wish, with the one constraint that the tail (which is obvious) is at the anatomical rear. In any other matter, your guess is as good as anyone else's. This animal is either a very primitive chordate or a stem group relative of the echinoderms and chordates. There is an extensive, if inconclusive, bibliography on this form. The majority of specimens of Typhloessus have conodonts in their gut cavities, an interesting observation considering their abundance and the absolute lack of any other conodont-bearing animals or plants in the Bear Gulch Limestone. If indeed Typhloessus preyed upon conodont animals, as claimed by Simon Morris, they violated one of nature's most basic laws, namely that the prey should outnumber the predators, or at the very least, occur where the predators occur. They do not; there are over 50 Typhloessus specimens know from the Bear Gulch member, and no other conodont-bearing animals.
References
- Melton, W. G. jr., and H. Scott, 1973. "Conodont bearing animals from the Bear Gulch Limestone, Montana." Geol. Soc. America Special Paper 141:31-65.
- Morris, S. C. 1985. "Conodontophorids or conodontophages? A review of the evidence on the "conodontochordates" of the Bear Gulch Limestone (Namurian) of Montana." Compte Rendu, Neuvième Congrès International de Stratigraphie et de Géologie du Carbonifère, 5:473-480.
- Morris, S. C. 1990. "Typhloesus wellsi (Melton and Scott, 1973), a bizarre metazoan from the Carboniferous of Montana, USA." Phil. Trans. Royal Soc. London B, 327: 595-624.