A Fossil Amniote Egg from an Upper Cretaceous Deposit (Mooreville Chalk of the Selma Group) in Alabama

Abstract

The first fossil amniote egg reported from the southeastern part of the United States, Auburn University Museum of Paleontology (AUMP) 1235, was found in a Mooreville Chalk deposit of Late Cretaceous age near Harrell Station in Dallas County, Alabama. The egg is elliptical, about 76 by 64 mm in original dimensions, has a major break traversing almost its entire length, has one broken end and resembles an egg from which a hatchling emerged. The outer surface of the egg is randomly covered with papillae and interspersed between papillae are pores, external openings of canals which pierce the shell's outer (tuberculate) and inner (mammillary) layers. Characteristics of the Harrell Station egg are not such that it can be identified with certainty even to amniote class. Comparisons of the structure of the egg from Harrell Station with those of eggs of dinosaurs, alligator, hen and ratites, revealed the unlikelihood that any of those was the depositor of AUMP 1235. All of the recent turtle eggs that have been examined lacked a mammillary layer; thus, it is unlikely that a turtle laid the egg. Mosasaurs and plesiosaurs may have been oviparous and are thus candidates. However, the absence of any eggshell material from either mosasaurs or plesiosaurs makes such a determination impossible.