Also known as Main Dinosaur Ridge Tracksite, Stop 12

Where: Jefferson County, Colorado (39.7° N, 105.2° W: paleocoordinates 39.6° N, 67.2° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Muddy Sandstone Formation (Dakota Group), Early/Lower Cenomanian (99.6 - 93.5 Ma)

• originally considered upper part of South Platte Fm., now "the middle to upper part" of the Muddy Formation, within Sequence 3; 6 track-bearing levels in total

• group of beds-level stratigraphic resolution

Environment/lithology: estuary or bay; sandstone and shale

Size class: macrofossils

Preservation: cast, mold/impression, trace

Collected by Markman, Lockley in 1938-1990

Collection methods: surface (in situ), peel or thin section,

• Original discovery in 1938 followed by renewed excavation in 1990s by Lockley et al.

Primary reference: M. G. Lockley. 1987. Dinosaur footprints from the Dakota Group of eastern Colorado. The Mountain Geologist 24(4):107-122 [M. Carrano/M. Carrano] more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 66900: authorized by Matt Carrano, entered by Matt Carrano on 23.10.2006, edited by Steven Miller