Beartooth Butte Formation

The Beartooth Butte Formation is a geologic formation in Wyoming. It preserves fossils dating back to the Devonian period.^[1]

Beartooth Butte Formation
Stratigraphic range: Lochkovian-Emsian ~419–394 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Fossil fish from the Beartooth Butte Formation
Type	Formation
Sub-units	Cottonwood Canyon Member
Lithology
Primary	Mudstone, sandstone
Other	Shale, limestone
Location
Coordinates	44°57′N 109°37′W
Approximate paleocoordinates	28.2°S 47.1°W / -28.2; -47.1
Region	Wyoming
Country	United States
Type section
Named for	Beartooth Butte
Beartooth Butte Formation (the United States) Show map of the United States Beartooth Butte Formation (Wyoming) Show map of Wyoming

Description

The formation contains a basal limestone conglomerate overlain by evenly bedded red or gray limestones (more accurately, limy mudstones) and calcareous shales. It is a lenticular, channel-fill deposit which is some 2,500 feet (760 m) wide and 250 feet (76 m) thick at maximum. Most collections are from the talus slope. Stable oxygen and isotope data (Poulson in Fiorillo, 2000) indicate that the Beartooth Butte Formation was deposited in an estuarine environment, with the Cottonwood Canyon section being slightly less saline than the type section.

Fossil content

The following fossils have been reported from the formation:^[1]

Fish

• Allocryptaspis ellipticus
• A. flabelliformis
• Anarthraspis chamberlini
• A. montanus
• Bryantolepis brachycephalus
• B. cristatus
• Bryantolepis major
• B. obscurus
• Bulbocanthus rugosus
• Cardipeltis bryanti
• C. richardoni
• Cosmaspis transversa
• Lampraspis tuberculata
• Machaeracanthus minor
• Onchus penetrans
• O. peracutus
• Protaspis brevispina
• P. mcgrewi
• Uranolophus wyomingensis
• Aethaspis sp.
• Cephalaspis sp.
• Simblaspis sp.

Arthropods

• Acanthoscorpio mucronatus
• Branchioscorpio richardsoni
• Hydroscorpius denisoni
• Praearcturus sp.

Flora

• Psilophyton wyomingense
• Drepanophycus devonicus
• Euphyllophytina sp.
• Gosslingia sp.

Invertebrates

• Brachiopoda indet.

See also

• List of fossiliferous stratigraphic units in Wyoming
• Paleontology in Wyoming