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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.


Related in: MedlinePlus

Inference for salt glands in Stereogenyina turtles.(A) cross section of a generalized Stereogenyina skull, indicating (red arrow) the position of the “posterior pocket on septum orbitotemporale”; (B) distribution of character 19 “fossa orbitalis caudal pocket” (left tree) and inferred paleoenvironment (right tree) in the phylogenetic hypothesis presented here. The coding of the character 19 is based on personal observations and on Gaffney et al. (2011) coding. Abbreviations: ane, apertura narium externa; cc, cavum cranii; ju, jugal; msp, midline cleft of the secondary palate; mx, maxilla; pa, parietal; pal, palatine; pm, premaxilla; po, postorbital; pt, pterygoid; ptp, processus trochlearis pterygoidei; sot, septum orbitotemporale.
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fig-9: Inference for salt glands in Stereogenyina turtles.(A) cross section of a generalized Stereogenyina skull, indicating (red arrow) the position of the “posterior pocket on septum orbitotemporale”; (B) distribution of character 19 “fossa orbitalis caudal pocket” (left tree) and inferred paleoenvironment (right tree) in the phylogenetic hypothesis presented here. The coding of the character 19 is based on personal observations and on Gaffney et al. (2011) coding. Abbreviations: ane, apertura narium externa; cc, cavum cranii; ju, jugal; msp, midline cleft of the secondary palate; mx, maxilla; pa, parietal; pal, palatine; pm, premaxilla; po, postorbital; pt, pterygoid; ptp, processus trochlearis pterygoidei; sot, septum orbitotemporale.

Mentions: Given the compelling evidence that stereogenyin turtles were adapted to life on sea, they might bear osteological correlates of salt glands. A very good candidate is an excavation, identified by Gaffney, Tong & Meylan (2006) (character 27) as synapomorphic for Bothremydidae, and by Gaffney et al. (2011; character 27) as the “fossa orbitalis posterior pocket in septum orbitotemporale”, seen in all Stereogenyina in which that area is exposed (Fig. 9A). In fact, the authors speculate that it could contain “eyeball attachments or orbital glands”. Indeed, its location is comparable to that of salt glands in extant turtles (Baccari, Matteo & Minucci, 1992; Babonis & Brischoux, 2012), and the prevalence of such an organ in extant marine reptiles suggests the “fossa orbitalis posterior pocket in septum orbitotemporale” as a possible osteological correlate of salt glands in Stereogenyina turtles.


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)

Inference for salt glands in Stereogenyina turtles.(A) cross section of a generalized Stereogenyina skull, indicating (red arrow) the position of the “posterior pocket on septum orbitotemporale”; (B) distribution of character 19 “fossa orbitalis caudal pocket” (left tree) and inferred paleoenvironment (right tree) in the phylogenetic hypothesis presented here. The coding of the character 19 is based on personal observations and on Gaffney et al. (2011) coding. Abbreviations: ane, apertura narium externa; cc, cavum cranii; ju, jugal; msp, midline cleft of the secondary palate; mx, maxilla; pa, parietal; pal, palatine; pm, premaxilla; po, postorbital; pt, pterygoid; ptp, processus trochlearis pterygoidei; sot, septum orbitotemporale.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig-9: Inference for salt glands in Stereogenyina turtles.(A) cross section of a generalized Stereogenyina skull, indicating (red arrow) the position of the “posterior pocket on septum orbitotemporale”; (B) distribution of character 19 “fossa orbitalis caudal pocket” (left tree) and inferred paleoenvironment (right tree) in the phylogenetic hypothesis presented here. The coding of the character 19 is based on personal observations and on Gaffney et al. (2011) coding. Abbreviations: ane, apertura narium externa; cc, cavum cranii; ju, jugal; msp, midline cleft of the secondary palate; mx, maxilla; pa, parietal; pal, palatine; pm, premaxilla; po, postorbital; pt, pterygoid; ptp, processus trochlearis pterygoidei; sot, septum orbitotemporale.
Mentions: Given the compelling evidence that stereogenyin turtles were adapted to life on sea, they might bear osteological correlates of salt glands. A very good candidate is an excavation, identified by Gaffney, Tong & Meylan (2006) (character 27) as synapomorphic for Bothremydidae, and by Gaffney et al. (2011; character 27) as the “fossa orbitalis posterior pocket in septum orbitotemporale”, seen in all Stereogenyina in which that area is exposed (Fig. 9A). In fact, the authors speculate that it could contain “eyeball attachments or orbital glands”. Indeed, its location is comparable to that of salt glands in extant turtles (Baccari, Matteo & Minucci, 1992; Babonis & Brischoux, 2012), and the prevalence of such an organ in extant marine reptiles suggests the “fossa orbitalis posterior pocket in septum orbitotemporale” as a possible osteological correlate of salt glands in Stereogenyina turtles.

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.


Related in: MedlinePlus