Stewart-Walker Tracksites, St. George (Jurassic of the United States)

Also known as BBDC, DS, DS-W, WCSD, SGDS, Darcy Stewart sites, Washington County School District

Where: Washington County, Utah (37.1° N, 113.5° 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)

• about 2 m above the MTL and TS layers, in the upper shale interval

•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.

•Because the stratigraphic position of this site within the Whitmore Point is unclear, a Rhaetian–Hettangian age is given.

• group of beds-level stratigraphic resolution

Environment/lithology: lacustrine; paleosol/pedogenic sandstone

• "offshore" lacustrine faces
• ripple-marked sandstone with mud carcks and root casts, rhizoliths

Size class: macrofossils

Preservation: cast, mold/impression, trace

Collected by A. Milner in 2001-

Collection methods: quarrying, surface (in situ),

Primary reference: A. R. C. Milner, M. G. Lockley, and J. I. Kirkland. 2006. A large collection of well-preserved theropod dinosaur swim tracks from the Lower Jurassic Moenave Formation, St. George, 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 37:315-328 [M. Carrano/M. Carrano/M. Carrano]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 121320: authorized by Matthew Carrano, entered by Matthew Carrano on 02.12.2011

Creative Commons license: CC BY (attribution)

Taxonomic list

unclassified
  -
Reptilia
 Ornithischia - Moyenisauropodidae
Anomoepus sp.1 Hitchcock 1848 ornithopod
 Theropoda - Grallatoridae
Eubrontes sp.1 Hitchcock 1845 theropod
Grallator sp.1 Hitchcock 1858 theropod
Chondrichthyes
 Hybodontiformes -
Lissodus sp.3 Brough 1935 elasmobranch
teeth; "new species"
Helminthoidichnites
  -
Helminthoidichnites tenuis2
SGDS.375, 741–743, 747