AGr-4 (Cretaceous to of the United States)

Where: Greene County, Alabama (32.9° N, 88.2° W: paleocoordinates 35.7° N, 60.2° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Mooreville Chalk Formation (Selma Group), Early/Lower Campanian to Early/Lower Campanian (83.5 - 70.6 Ma)

• "lower member of the Mooreville Chalk Formation [which] ranges from latest Santonian to middle Campanian in age... AGr-4... lies in approximately the middle of the Mooreville Chalk Formation... Thus [it is] late-early to early-middle Campanian in age" Chiappe et al. 2002.

•Per Gentry 2016 "Isotopic analysis (Liu 2009) and nanofossils (Raymond et al. 1988) from the Mooreville Chalk of Greene County indicate a Campanian age for these deposits of between 82 and 83.5 Ma."

• formation-level stratigraphic resolution

Environment/lithology: deep subtidal shelf; concretionary, pyritic carbonate

• "a near-shore depositional environment... [with] fairly clean, shallow waters of normal marine salinity within a warm climatic regime... AGr-4 is estimated to have been about 50 km offshore"
• vertebrate fossils are from dark "dysoxic layers" that "contain abundant pyrite concretions"

Size class: macrofossils

Collected by S. L. Olson in 1992

Collection methods: quarrying, surface (float)

• many "elements were found as a fan-shapeed scatter on a slightly sloping surface" and "a few" others were found during "subsequent excavation"

Primary reference: L. M. Chiappe, J. P. Lamb, and P. G. P. Ericson. 2002. New enantiornithine bird from the marine upper Cretaceous of Alabama. Journal of Vertebrate Paleontology 22(1):170-174 [M. Uhen/M. Uhen]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 80890: authorized by Mark Uhen, entered by Mark Uhen on 19.05.2008, edited by Patricia Holroyd

Creative Commons license: CC BY (attribution)

Taxonomic list

Reptilia
 Testudines - Pancheloniidae
Ctenochelys acris Zangerl 1953 turtle
Aves
 Enantiornithes - Avisauridae
Halimornis thompsoni n. gen. n. sp.
Halimornis thompsoni n. gen. n. sp. Chiappe et al. 2002 bird