A gravid fossil turtle from the Upper Cretaceous (Campanian) Kaiparowits Formation, southern Utah

Abstract

An Adocus turtle collected from the Upper Cretaceous (late Campanian) Kaiparowits Formation in southern Utah contains partial eggs and numerous well-preserved bones beneath the carapace. The bones include the closely associated–articulated elements of the right pectoral girdle, skull and cervical vertebrae. The eggs are about 35 mm in diameter, and the rigid 250–280-μm thick eggshell exhibits needle-like aragonitic crystals that form the narrow, straight shell units. The eggs appear smaller than those within a gravid Adocus from Alberta, and the eggshell is thinner and lacks the feathered structure reported in the Alberta eggs. Differences in the Utah and Alberta Adocus eggs may result from differences in the stage of egg formation or the specimens may represent different Adocus species.

Keywords:

• gravid turtle
• Adocus
• eggs
• Testudoolithus
• Kaiparowits Formation

Acknowledgements

We thank S. Richardson for fossil preparation; D. Majerus and T. Spence at Bozeman Deaconess Hospital, Department of Radiology for the CT scans. R. Jackson, D. Zelenitsky and D. Brinkman provided helpful editorial comments and suggestions that improved the manuscript. We thank E. Roberts for providing stratigraphic location of the specimen relative to ash layers. Finally, we thank the staff at the Utah Bureau of Land Management and Grand Staircase-Escalante Partners for support and access to the Monument for this research.

Notes

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Additional information

Notes on contributors

Frankie D. Jackson

† † Email: [email protected]

Alan L. Titus

‡ ‡ Email: [email protected]

L. Barry Albright

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