St. George Dinosaur Discovery Site (Split Tracklayer) (Jurassic of the United States)

Also known as Johnson farm, SGDS, STL, SPL

Where: Washington County, Utah (37.1° N, 113.6° W: paleocoordinates 17.3° N, 52.8° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Whitmore Point Member (Moenave Formation), Hettangian (201.3 - 199.3 Ma)

• among the lowest of the 25 regional track-bearing layers, 4-15 cm above MTL layer

•Most of the Moenave Formation is the Dinosaur Canyon Member. In the Moenave type section, near Tuba City, Arizona, all of the Moenave section is Dinosaur Canyon Member, as it is throughout the Moenave outcrop belt along the Echo Cliffs and Ward's Terrace of northern Arizona. However, north of the Grand Canyon in Arizona and in southwestern Utah, the upper part of the Moenave Formation is lacustrine strata. These strata are the Whitmore Point Member.

•Lucas et al. (2011: Palaeo3 302: 194-205) proposed, on the basis of multiple lines of biostratigraphic evidence, that the Triassic–Jurassic boundary is placed within the middle part of the Whitmore Point Member of the Moenave Formation where this member is present, and high in the Dinosaur Canyon Member elsewhere. The "Whitmore Point assemblage" of vertebrate taxa, earliest Jurassic (Hettangian) in age. The underlying "Dinosaur Canyon assemblage", is latest Triassic (Rhaetian) in age.

•Lucas et al. (2011) noted that the St George tracksite is of latest Triassic age, rather than earliest Jurassic as initially reported

• bed-level stratigraphic resolution

Environment/lithology: lacustrine; fine-grained sandstone and mudstone

• mudflats and beaches surrounding ancient lake, forming an oasis during deposition of the Wingate erg to the NE

Size class: macrofossils

Preservation: cast, mold/impression, trace

Collected by S. Johnson, A. Milner in 2000-

Collection methods: quarrying, surface (in situ),

• discovered by Sheldon Johnson

Primary reference: A. R. C. Milner, M. G. Lockley, and S. B. Johnson. 2006. The story of the St. George Dinosaur Discovery Site at Johnson Farm: an important new Lower Jurassic dinosaur tracksite from the Moenave Formation of southwestern Utah. In J. D. Harris, S. G. Lucas, J. A. Spielmann, M. G. Lockley, A. R. C. Milner, & J. I. Kirkland (eds.), The Triassic-Jurassic Terrestrial Transition. New Mexico Museum of Natural History and Science Bulletin 37:329-345 [M. Carrano/M. Carrano/M. Carrano]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 121311: authorized by Matthew Carrano, entered by Matthew Carrano on 02.12.2011

Creative Commons license: CC BY (attribution)

Taxonomic list

Insecta
 Insecta -
Insecta indet.3 insect
trackways
 Dicondylia -
Coleoptera indet.3 Linnaeus 1758 beetle
trackways
Reptilia
 Theropoda - Grallatoridae
Eubrontes giganteus1 Hitchcock 1836 theropod
Grallator cursorius1 Hitchcock 1858 theropod
 Ichnofossils -
Bifurculapes sp.2 Hitchcock 1858
SGDS.197
Kouphichnium sp.3 Nopcsa 1923