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. This is a rare example of the lamprey Hardistella montanensis. The genus derives its name from Professor M. W. Hardisty, a well-known autghority on lampreys. Only a half dozen specimens of this species are known to science. It most closely resembles the roughly contemporay Mayomyzon pieckoensis from Mazon Creek, whose specimens have far better preservation. Nevertheless the branchial pouches, eye, intestinal tract, and oral hood are all preserved, rendering its identity apparent. Due to the scientific value of such a specimen I am prepared to offer a 30% discount to any recognized institution that may wish to secure this specimen.

References:

• Journal of Vertebrate Paleontology, 2 (4) February 1983, pp. 407-413.
• Geobios No19(5) 1986 pp. 647-652
• Journal of Vertebrate Paleontology, 24(3) September 2004, pp. 742-743.