3 miles (5 km) northeast of Freeland Junction (Triassic of the United States)

Where: Natrona County County, Wyoming (42.7° N, 106.4° W: paleocoordinates 10.3° N, 31.8° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Alcova Limestone Member (Crow Mountain Formation), Spathian (251.3 - 247.2 Ma)

• Alcova (Limestone) Member, Crow Mountain Formation, Chugwater Group

•The stratigraphic correlation and hence determination of the relative geological age of the Alcova Limestone is rendered difficult by the general paucity of fossils, vertebrates (Corosaurus) and invertebrates alike (for a review see Storrs, 1991). The presence of the nothosauriform reptile Corosaurus has led some workers (Colbert, 1957; Zangerl, 1963) to assign the Alcova to the Upper Triassic. Storrs (1 99 1 : 10 1) accepted a late Lower Triassic (Scythian, Spathian) or, perhaps, an early Middle Triassic (Anisian) age for the Alcova Limestone

Environment/lithology: shallow subtidal; lithified, dolomitic, stromatolitic, shelly/skeletal, gray, silty, carbonaceous limestone

Size class: macrofossils

Collected by FIeld Museum in 1948; reposited in the FMNH

Collection methods: surface (in situ),

Primary reference: O. Rieppel. 1998. Corosaurus alcovensis Case and the phylogenetic interrelationships of Triassic stem-group Sauropterygia. Zoological Journal of the Linnean Society 124:1-41 [S. Peters/D. Lovelace]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 138080: authorized by Roger Benson, entered by Roger Benson on 04.01.2013

Creative Commons license: CC BY (attribution)

Taxonomic list

Reptilia
 Sauropterygia -
Corosaurus alcovensis Case 1936 diapsid
First reported by Zangerl (1963)