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The last marine pelomedusoids (Testudines: Pleurodira): a new species of Bairdemys and the paleoecology of Stereogenyina.

Ferreira GS, Rincón AD, Solórzano A, Langer MC - PeerJ (2015)

Bottom Line: Here, we describe a new Stereogenyina species, based on an almost complete skull from the middle Miocene Capadare Formation, of Venezuela.Based on geometric morphometrics analyses, we related the development of the stereogenyin secondary palate with the acquisition of a durophagous diet.These two inferences allowed us to hypothesize that stereogenyins occupied an ecological niche similar to that of the extant Carettini sea turtles, and that the rise of the latter group may be related to the Stereogenyina diversity fall in the end of the Miocene.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratório de Paleontologia de Ribeirão Preto, FFCLRP, Universidade de São Paulo , Ribeirão Preto, SP , Brazil.

ABSTRACT
The extinct Stereogenyina turtles form a relatively diverse Podocnemididae lineage, with twelve described and phylogenetically positioned species. They are characterized by a wide geographic and temporal range, from the Eocene of Africa to the Pleistocene of Southeast Asia, and a peculiar palate morphology, with a secondary palate that is unique among side-necked turtles. Here, we describe a new Stereogenyina species, based on an almost complete skull from the middle Miocene Capadare Formation, of Venezuela. A new phylogenetic analysis supports the assignment of the new species to the genus Bairdemys. Based on geometric morphometrics analyses, we related the development of the stereogenyin secondary palate with the acquisition of a durophagous diet. Based on a review of the sedimentary environments where their fossils are found, we also propose that stereogenyins were a marine radiation of podocnemidid turtles, as corroborated by previous studies of fossil eggs and limb morphology. These two inferences allowed us to hypothesize that stereogenyins occupied an ecological niche similar to that of the extant Carettini sea turtles, and that the rise of the latter group may be related to the Stereogenyina diversity fall in the end of the Miocene.

No MeSH data available.


Bairdemys thalassica sp. nov.Holotype skull IVIC-P-2908 in (A) dorsal, (B) ventral, (C) rostral, (D) caudal, (E) left, and (F) right lateral views.
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fig-2: Bairdemys thalassica sp. nov.Holotype skull IVIC-P-2908 in (A) dorsal, (B) ventral, (C) rostral, (D) caudal, (E) left, and (F) right lateral views.

Mentions: Skull—The holotype and only specimen assigned to Bairdemys thalassica, IVIC-P-2908 (Figs. 2 and 3), is very well preserved, with almost no taphonomic distortion. It is nearly complete, lacking only the rostral and the right dorsal regions. Only the vomeri, the premaxillae, and the prefrontals are completely absent. The frontal, jugal, quadratojugal, parietal, squamosal, maxilla, and palatine have one of the elements of the pair entirely or partially missing, but the other is complete, allowing a detailed description.


The last marine pelomedusoids (Testudines: Pleurodira): a new species of Bairdemys and the paleoecology of Stereogenyina.

Ferreira GS, Rincón AD, Solórzano A, Langer MC - PeerJ (2015)

Bairdemys thalassica sp. nov.Holotype skull IVIC-P-2908 in (A) dorsal, (B) ventral, (C) rostral, (D) caudal, (E) left, and (F) right lateral views.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493680&req=5

fig-2: Bairdemys thalassica sp. nov.Holotype skull IVIC-P-2908 in (A) dorsal, (B) ventral, (C) rostral, (D) caudal, (E) left, and (F) right lateral views.
Mentions: Skull—The holotype and only specimen assigned to Bairdemys thalassica, IVIC-P-2908 (Figs. 2 and 3), is very well preserved, with almost no taphonomic distortion. It is nearly complete, lacking only the rostral and the right dorsal regions. Only the vomeri, the premaxillae, and the prefrontals are completely absent. The frontal, jugal, quadratojugal, parietal, squamosal, maxilla, and palatine have one of the elements of the pair entirely or partially missing, but the other is complete, allowing a detailed description.

Bottom Line: Here, we describe a new Stereogenyina species, based on an almost complete skull from the middle Miocene Capadare Formation, of Venezuela.Based on geometric morphometrics analyses, we related the development of the stereogenyin secondary palate with the acquisition of a durophagous diet.These two inferences allowed us to hypothesize that stereogenyins occupied an ecological niche similar to that of the extant Carettini sea turtles, and that the rise of the latter group may be related to the Stereogenyina diversity fall in the end of the Miocene.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratório de Paleontologia de Ribeirão Preto, FFCLRP, Universidade de São Paulo , Ribeirão Preto, SP , Brazil.

ABSTRACT
The extinct Stereogenyina turtles form a relatively diverse Podocnemididae lineage, with twelve described and phylogenetically positioned species. They are characterized by a wide geographic and temporal range, from the Eocene of Africa to the Pleistocene of Southeast Asia, and a peculiar palate morphology, with a secondary palate that is unique among side-necked turtles. Here, we describe a new Stereogenyina species, based on an almost complete skull from the middle Miocene Capadare Formation, of Venezuela. A new phylogenetic analysis supports the assignment of the new species to the genus Bairdemys. Based on geometric morphometrics analyses, we related the development of the stereogenyin secondary palate with the acquisition of a durophagous diet. Based on a review of the sedimentary environments where their fossils are found, we also propose that stereogenyins were a marine radiation of podocnemidid turtles, as corroborated by previous studies of fossil eggs and limb morphology. These two inferences allowed us to hypothesize that stereogenyins occupied an ecological niche similar to that of the extant Carettini sea turtles, and that the rise of the latter group may be related to the Stereogenyina diversity fall in the end of the Miocene.

No MeSH data available.