ammonites
Purgatoire River tracksite, Unit B2 (Jurassic to of the United States)

Where: Colorado (37.5° N, 103.7° W: paleocoordinates 32.8° N, 51.0° W)

• coordinate based on nearby landmark

• small collection-level geographic resolution

When: Unit B Member (Morrison Formation), Kimmeridgian to Kimmeridgian (155.7 - 145.5 Ma)

• bed-level stratigraphic resolution

Environment/lithology: coastal; ooidal, shelly/skeletal, sandy lime mudstone

• Tracks are at the top of the shoreline facies beds.
• "imbricate lithoclasts at the base with minor quartz grains, ooids and transported biota including chara, ostracods, fish debris and transported unionid shells in a sparry micritic matrix, and fine upward to micrites with ripple marks and mudcracks, representing higher energy shoreline conditions indicative of flood/storm events."

Size class: macrofossils

Preservation: mold/impression, trace

Collected by Bird, Lockley in 1935, 1938, 1985

• site discovered by Ridennoure and R. Owens

Primary reference: J. S. MacClary. 1938. Dinosaur trails of Purgatory. Scientific American 158(1):72 [M. Carrano/M. Carrano] more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 52919: authorized by Matt Carrano, entered by Kaitlin Maguire on 26.08.2005, edited by Matt Carrano