Fossil egg shell from the Hell Creek Formation

FOSSIL EGG SHELLS FROM THE HELL CREEK FORMATION

Excerpts from Jepsen's (1931) paper:

"Mr. E.J. Moles, Jr., a senior in the Princeton department of geology, and the writer spent the latter part of last summer in the vicinity of Red Lodge, at the invitation of Dr. J.C.F. Siegfriedt, in a search for vertebrate fossils which might aid in determining the stratigraphic elements and boundaries of the local Fort Union Formation......"

"The Lance strata [Jepsen calls the Hell Creek Formation the "Lance Formation" throughout his paper]....are poorly exposed in most of the area due to the vegetation and soil mantle, but limited bare rock escarpments ....yielded fragments of dinosaur bones and teeth...."

"Several pieces of egg shell, none over an inch in length, were picked from the surface of the shale close to the [mammal] tooth and also down the slope below it. That these fragments were at one time parts of the case about a potential or actual dinosaur embryo is considered probable, though no one has reported a whole egg of this type from America, and our evidence is appearance, structure and size as judged from the curvature of the preserved pieces. If they were not flattened by crushing, the whole eggs were very likely larger than the Mongolian eggs, for even the most curved portion of the Montana shell is a segment of a circle greater than the circumference of the complete Mongolian eggs. No thorough comparison has been made with those fragments in the American Museum which are labeled as being from the largest dinosaur eggs discovered in Asia, and are known only from pieces. In external appearance as well as internal structure, the Montana shell scraps resemble some of the Mongolian dinosaur egg shells and share with them common differences from most egg shells of Chelonians, crocodilians and birds......Deep brown, almost black, the Red Lodge shell pieces are perforated by numerous pores and are characterized externally by hillocks and valleys similar to those on some of the Asiatic dinosaur eggs. In section the mamillar zone appears thin and the pyriform zone thick."

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Since Jepsen's paper, not much has been written on fossil eggs from the Hell Creek Formation. Horner and Gorman make a short note of Jepsen's discovery in their book Digging Dinosaurs (p. 195).

References:

Horner, J. and Gorman. p. 195. Digging Dinosaurs. Workman Press.
Jepsen G.L. 1931. Dinosaur egg shell fragments from Montana. Science 73(1879): 12-13.