Hardistella montanensis Lamprey from Bear Gulch Limestone

A supremely rare museum paleozoic fish fossil

Allenypterus montanus

Class Petromyzontida, Order Petromyzontiformes

Geological Time: Mississippian (~320 m.y.a.)

Size (25.4 mm = 1 inch): Fish fossil is 30 mm Matrix: 125 mm by 125 mm

Fossil Site: Heath Shale Formation, Bear Gulch Limestone, Fergus County, Montana

Fossil Code: BGF422

Price: Sold

Hardistella montanensis Lamprey Fish FossilDescription: 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 Lampreydeposits, 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.


  • 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.

Fish Fossil Purchase

click to enlarge fossil pictures

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