Bandringa rayi Zangerl, 1969 fossil shark from the Pennsylvanian of Illinois, USA (public display, FMNH PF 5686, Field Museum of Natural History, Chicago, Illinois, USA) (~10.7 cm across).

One of the most remarkable soft-bodied fossil deposits (lagerstätten) on Earth is the Pennsylvanian-aged Mazon Creek Lagerstätte near Chicago, Illinois. In the Mazon Creek area, the Francis Creek Shale consists of concretionary gray shales. The Francis Creek concretions are composed of argillaceous ironstone, and can be fossiliferous or nonfossiliferous. The fossiliferous concretions contain land plants and terrestrial & marine animals, including nonmineralizing organisms.

This bizarre-looking fossil shark is the holotype specimen of Bandringa rayi. Its size and lack of developed cartilaginous skeletal structures indicate that this is a juvenile shark. It has an extremely elongated snout, well-preserved eyespots, and a set of very small teeth arranged in a V-pattern (discernible as two light-grayish lines extending in the 2-o’clock and 3:30 directions from the lower eyespot). This rare species has been reported from the Mazon Creek deposit of Illinois and from Cannelton, Pennsylvania, USA.

Classification: Animalia, Chordata, Vertebrata, Chondrichthyes, Elasmobranchii, Eusealchii, Ctenacanthiformes, Ctenacanthoidea, Bandringidae

Stratigraphy: Mazon Creek Lagerstätte, Francis Creek Shale Member, Carbondale Formation, Desmoinesian Stage (= Westphalian D), upper Middle Pennsylvanian