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The so-called giant Miocene dolphin Megalodelphis magnidens Kellogg (Mammalia: Cetacea) is actually a crocodile (Reptilia: Crocodilia)

Published online by Cambridge University Press:  19 May 2016

Gary S. Morgan
Gary S. Morgan*
Affiliation:
Florida State Museum, University of Florida, Gainesville, 32611
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Abstract

The type specimen of Megalodelphis magnidens Kellogg, 1944, from the Late Tertiary of Florida, is not a long-beaked dolphin of the mammalian order Cetacea as it was originally described. The presence of splenial and angular bones in the holotype mandible, along with a suture for the surangular bone and an external mandibular fenestra, are reptilian characters unknown in the Mammalia. Details of the morphology and placement of the teeth and the conformation of the mandible reveal that this specimen belongs to a crocodilian, and should be referred to the long-snouted estuarine crocodile, Gavialosuchus americanus. Therefore, Megalodelphis magnidens Kellogg, 1944, becomes a junior synonym of Gavialosuchus americanus (Sellards, 1915). The edentulous “rostral” (actually mandibular) fragment referred by Kellogg to M. magnidens does represent a large, long-beaked odontocete cetacean; however, its fragmentary condition does not permit a positive allocation to genus. Pending a revision of the long-beaked odontocetes, this specimen is regarded as Odontoceti incertae sedis.

Type
Research Article
Information
Journal of Paleontology , Volume 60 , Issue 2 , March 1986 , pp. 411 - 417
Copyright
Copyright © The Paleontological Society 

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