Sundance Formation

The Sundance Formation is a western North American sequence of Middle Jurassic to Upper Jurassic age[1] marine shale, sandy shale, sandstone, and limestone deposited in the Sundance Sea.

Sundance Formation
Stratigraphic range: Middle Jurassic, Late Jurassic
TypeGeological formation
UnderliesMorrison Formation
OverliesGypsum Springs Formation
Otherlimestone, sandstone
RegionWestern North America
Country United States


The Sundance Formation underlies the western North American Morrison Formation, the most fertile source of dinosaur fossils in the Americas, and is separated by a disconformity from the underlying Middle Jurassic Gypsum Springs Formation.


The Sundance Formation is known for fossils of an extinct species of marine cephalopod, the belemnite Pachyteuthis densus, as well as several extinct species of oyster, including Deltoideum, Liostrea, and Gryphaea nebrascensis.

Fossil dinosaur 'footprints' on an ancient ocean shoreline are preserved in the formation and protected at the Red Gulch Dinosaur Tracksite, located in the Bureau of Land Management Red Gulch/Alkali National Back Country Byway, near Shell in Big Horn County, Wyoming.[2]

Vertebrate paleofaunaEdit


Pterosaurs of the Sundance Formation
Taxa Presence Description Images


  1. P. stokesi[3]
  • Found in Wyoming at the Alcova/Grey Reef Reservoir, Seminoe Reservoir, and Bighorn Canyon National Recreation area.[3]
  1. Found in Wyoming, at the ichnospecies' type locality.[3]
  • Alcova/Grey Reef Reservoir and Seminoe Reservoir housed at University of Wyoming, Laramie.[3] Alcova/Grey Reef Reservoir specimens are also housed at Tate Museum, Casper College.[3]
  1. Specimens housed at University of Wyoming, Laramie.[3]

Invertebrate paleofaunaEdit


Belemnoids of the Sundance Formation
Taxa Presence Description Images


  1. P. densus


  1. ^ Jennings, Debra S.; Stephen T. Hasiotis (2006). "Taphonomic analysis of a dinosaur feeding site using Geographic Information Systems (GIS), Morrison Formation, Southern Bighorn Basin, Wyoming, USA". PALAIOS. SEPM Society for Sedimentary Geology. 21 (5): 480–492. doi:10.2110/palo.2005.P05-062R.
  2. ^ BLM−Bureau of Land Management, Wyoming Office: "Red Gulch Dinosaur Tracksite" website, info, maps, photo gallery, accessed 8.21.2015
  3. ^ a b c d e f g Lockley, M.; Harris, J.D.; and Mitchell, L. 2008. "A global overview of pterosaur ichnology: tracksite distribution in space and time." Zitteliana. B28. p. 187-198. ISSN 1612-4138.