A fossilized turtle egg clutch with embryos from the upper cretaceous Oldman formation, southeastern Alberta: description, taxonomic identity, and embryonic staging

Date
2012
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Abstract
Fossilized turtle clutches containing embryos are heretofore undescribed. Here the description of such a specimen from the Upper Cretaceous of Alberta sheds light on the taxonomic identity and paleobiology of the turtle that laid the clutch. Examination of the clutch reveals 33 rigid-shelled, spherical eggs arranged in a layered cluster. Clutch size and the paleoenvironment of the nest site suggest that the fossil clutch belongs to a large, freshwater turtle. Numerous embryonic bones described from virtual reconstructions of computed tomographic data reveal that the embryonic bones are well-ossified. Comparisons with modem turtles indicate the fossil embryos were at a late stage of development, near batching, at the time of death. Morphology of the maxillae, dentary, and plastron suggests affinities with Adocidae, an extinct freshwater turtle clade. Additional lines of evidence, including egg and eggshell morphology, the predicted size of the female, and geographic and stratigraphic location, also suggest that the fossil clutch belongs to adocids.
Description
Bibliography: p. 91-103
Some pages are in colour.
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Citation
McGee, A. R. (2012). A fossilized turtle egg clutch with embryos from the upper cretaceous Oldman formation, southeastern Alberta: description, taxonomic identity, and embryonic staging (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/4558
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