1 November 2012 Reappraisal of the Morphology and Phylogenetic Relationships of the Middle Eocene Alligatoroid Diplocynodon deponiae (Frey, Laemmert, and Riess, 1987) Based on a Three-Dimensional Specimen
Massimo Delfino, Thierry Smith
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Abstract

We describe a three-dimensionally prepared specimen of Baryphracta deponiae from the middle Eocene of Messel (Darmstadt, Germany). Based on a phylogenetic analysis that included the addition of 20 novel scorings for characters previously unavailable for this taxon and the recoding of four additional characters, we found B. deponiae to be nested within Diplocynodon. We propose the new combination Diplocynodon deponiae. The name Baryphracta is thus a junior synonym of Diplocynodon. The small species D. deponiae (∼1 m in total length) shares several features with other species of Diplocynodon, including the presence of two subequal alveoli in the maxilla and dentary, exclusion of the splenial from the symphysis, and the shape of the iliac blade. However, it also differs in a few characters, including the presence of molariform teeth and the extension of osteoderms along the limbs and tail. Such osteodermal cover, which developed very early in ontogeny, easily distinguishes even small-sized specimens of D. deponiae from the co-occurring Diplocynodon darwini. The crocodylian fauna of Messel shows an astonishing diversity including at least seven taxa, with two belonging to the same genus. The two congeners exhibit differences in dentition and size that likely allowed for niche partitioning that minimized competition, thereby allowing them to be syntopic.

© 2012 by the Society of Vertebrate Paleontology
Massimo Delfino and Thierry Smith "Reappraisal of the Morphology and Phylogenetic Relationships of the Middle Eocene Alligatoroid Diplocynodon deponiae (Frey, Laemmert, and Riess, 1987) Based on a Three-Dimensional Specimen," Journal of Vertebrate Paleontology 32(6), 1358-1369, (1 November 2012). https://doi.org/10.1080/02724634.2012.699484
Received: 9 September 2011; Accepted: 29 May 2012; Published: 1 November 2012
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