FIELD, D.J., LEBLANC, A., GAU, A., BEHLKE, A.D. 2015. Pelagic neonatal fossils support viviparity and precocial life history of Cretaceous mosasaurs. Palaeontology, 58, 3, 401–407.
Daniel J. Field, Aaron LeBlanc, Adrienne Gau and Adam D. Behlke- Daniel J. Field - Department of Geology & Geophysics, Yale University, New Haven, CT, USA (email: daniel.field@yale.edu)
- Daniel J. Field - Department of Vertebrate Zoology, Smithsonian National Museum of Natural History, Washington, DC, USA
- Aaron LeBlanc - Department of Ecology and Evolutionary Biology, University of Toronto Mississauga, Mississauga, ON, Canada (email: aaron.leblanc@mail.utoronto.ca)
- Adrienne Gau - Department of Geology & Geophysics, Yale University, New Haven, CT, USA (email: adrien.gau@yale.edu)
- Adam D. Behlke - Department of Geology & Geophysics, Yale University, New Haven, CT, USA (email: adam.behlke@yale.edu)
- Issue published online: 21 APR 2015
- Article first published online: 10 APR 2015
- Manuscript Accepted: 9 MAR 2015
- Manuscript Received: 12 JAN 2015
Mosasaurs were large marine squamates that inhabited all of the world's oceans during the Late Cretaceous. Their success as apex predators has been attributed to their rapid acquisition of aquatic adaptations, which allowed them to become fully pelagic. However, little is known about the breeding biology of derived, flipper-bearing mosasaurs, as the record of neonatal mosasaur fossils is extremely sparse. Here, we report on the fragmentary cranial remains of two neonatal mosasaurs from the Niobrara Formation, referred to Clidastes sp. Comparison with other preliminary reports of neonatal mosasaurs reveals that these specimens are among the smallest individuals ever found and certainly represent the smallest known Clidastes specimens. The recovery of these extremely young specimens from a pelagic setting indicates that even neonatal mosasaurs occupied open oceanic habitats and were likely born in this setting. These data shed new light on the ecology of neonatal mosasaurs and illustrate the degree to which size-related taphonomic and collection biases have influenced our understanding of the early life history of these iconic marine reptiles.
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