Arcola tracksite (Triassic of the United States)

Where: Montgomery County, Pennsylvania (40.2° N, 75.5° W: paleocoordinates 14.7° N, 20.4° W)

• coordinate based on nearby landmark

• small collection-level geographic resolution

When: Weehawken Member (Lockatong Formation), Norian (228.0 - 208.5 Ma)

• Approx. 100-200 m below the Gwynedd horizon and 1100 m belw members E-F of the Passaic Formation

• bed-level stratigraphic resolution

Environment/lithology: lacustrine - small; bioturbated, calcareous siliciclastic sediments

• The track-bearing surface was covered in shallow water and still supported living trees. It already had several centimeters of lacustrine mud deposited by a recent transgression of what was to become a perennial lake.
• "The bed is finely laminated at the base and ripple laminated at the top...there are small calcareous nodules within the oscillation-ripple bedded portion of the bed. This unit is borken by narrow but deep mud cracks...the track-bearing surface is covered by irregular patches of very fine, short wavy lines, which we suggest could be the impression of a filamentous algal scum. Large cylindrical siltstone tubes puncture the surface at irregular intervals."

Size class: macrofossils

Preservation: mold/impression, trace

Collected by Olsen & Banach in 1983; reposited in the YPM

Collection methods: quarrying, surface (in situ),

Primary reference: P. E. Olsen and D. Baird. 1986. The ichnogenus Atreipus and its significance for Triassic biostratigraphy. In: K. Padian (ed.), The Beginning of the Age of Dinosaurs: Faunal Changes Across the Triassic-Jurassic Boundary. Cambridge University Press, Cambridge 61-87 [M. Carrano/K. Maguire/M. Carrano]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 55415: authorized by Matthew Carrano, entered by Kaitlin Maguire on 20.10.2005

Creative Commons license: CC BY (attribution)

Taxonomic list

  - Rhynchosauroidae
Rhynchosauroides hyperbates Baird 1957 reptile
 Saurischia - Eubrontidae
"Atreipus milfordensis" = Anchisauripus milfordensis
"Atreipus milfordensis" = Anchisauripus milfordensis Bock 1952 theropod
YPM 9961
 Pseudosuchia - Chirotheriidae
"Brachychirotherium eyermani" = Chirotherium eyermani
"Brachychirotherium eyermani" = Chirotherium eyermani Baird 1957 archosaur
YPM 9963