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| Globidens simplex
Leblanc, Mohr & Caldwell, 2019
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Abstract
Durophagous mosasaurs are rare members of Late Cretaceous marine faunal assemblages and new fossil discoveries can shed light on their anatomy, functional morphology and evolutionary history. Here we describe a new species in the durophagous genus Globidens from the Maastrichtian phosphate deposits of Morocco, based on a partial disarticulated skull and cervical vertebral series. This new species shares many anatomical similarities with the only other described Maastrichtian species, G. phosphaticus, but differs in several key features, including the absence of pronounced swellings and sulci on the crushing teeth and the absence of cervical zygosphenes and zygantra. Histological thin sections of a rib from the holotype show that this was not a juvenile individual and reveal osteosclerotic-like bone compactness for the first time in a paddle-bearing mosasaurine. We interpret the highly compact ribs, as well as several peculiarities of the temporal arcade and lower jaws, as adaptations to a diet of benthic, hard-bodied prey.
Keywords: Cretaceous, fossil, Globidensini, histology, Mosasaurinae
Systematic palaeontology
Reptilia Linnaeus, 1758
Squamata Oppel, 1811
Mosasauridae Gervais, 1853
Mosasaurinae Gervais, 1853
Globidens Gilmore, 1912
Globidens simplex Leblanc, Mohr & Caldwell, sp. nov.
Etymology: The epithet simplex is Latin for ‘simple’ or ‘plain’, referring to the simple shapes of the large crushing tooth crowns relative to other species of Globidens, as well as the absence of accessory vertebral articulations (zygosphenes and zygantra) on the cervical vertebrae.
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| Globidens simplex sp. nov. MHNM.KHG.221, holotype dental series |
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| Partial skull reconstruction of Globidens simplex sp. nov. Grey outline represents hypothetical soft tissue and life reconstruction, in addition to the maxilla and upper tooth row. |
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| Globidens simplex sp. nov. MHNM.KHG.221, holotype rib, general histology. |
Aaron R. H. Leblanc, Sydney R. Mohr and Michael W. Caldwell. 2019. Insights Into the Anatomy and Functional Morphology of Durophagous Mosasaurines (Squamata: Mosasauridae) from A New Species of Globidens from Morocco. Zoological Journal of the Linnean Society. zlz008. DOI: 10.1093/zoolinnean/zlz008
the inside of a rib of the newly discovered species of shell-crushing mosasaur, Globidens simplex. The ribs are almost completely filled with bone, making them very dense. This may have helped this animal sink to the seafloor and forage for food!
