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Tacuarembemys, new turtle from Uruguay + Eurysternum revised



Ben Creisler
bcreisler@gmail.com

In the new JVP:

Daniel Perea, Matías Soto, Juliana Sterli, Valeria Mesa, Pablo Toriño,
Guillermo Roland & Jorge Da Silva (2014)
Tacuarembemys kusterae, gen. et sp. nov., a new Late
Jurassic–?earliest Cretaceous continental turtle from western
Gondwana.
Journal of Vertebrate Paleontology 34(6): 1329-1341
DOI:10.1080/02724634.2014.859620
http://www.tandfonline.com/doi/full/10.1080/02724634.2014.859620#.VFkL2PnF_To

A new continental turtle, Tacuarembemys kusterae, gen. et sp. nov., is
described on the basis of a partial external mold of the carapace and
associated shell bone fragments recovered from the Batoví Member (Late
Jurassic–?earliest Cretaceous) of the Tacuarembó Formation, Paraná
Basin, Uruguay. The estimated length of the carapace is 18 cm. This
new genus and species shows a unique combination of characters: a
large nuchal notch, a pair of anterior supernumerary scales, the
absence of a cervical scale, and an external surface ornamentation
that is macroscopically smooth with some thin linear ridges
perpendicular to the margins of the plates and microscopically
composed of small, randomly distributed pits. The first two characters
resemble those seen in the solemydid Naomichelys speciosa from the
Cretaceous of North America, although the ornamentation is markedly
different. Although this combination of characters—some shared with
other taxa (including cryptodires and pleurodires) and some others
that are autapomorphic—allows the recognition of a new genus and
species, additional remains are yet needed in order to clarify its
phylogenetic relationships. Tacuarembemys kusterae is part of the
Priohybodus arambourgi Assemblage Zone, which is of Late
Jurassic–?earliest Cretaceous age. This is the first turtle to be
discovered in South American continental deposits of that age and thus
increases the knowledge on the regional evolution of Mesozoic turtles.
The paleoenvironment for this species includes lakes and permanent and
ephemeral rivers in arid-to-semiarid climatic conditions.

*****


Jeérémy Anquetin & Walter G. Joyce (2014)
A reassessment of the Late Jurassic turtle Eurysternum wagleri
(Eucryptodira, Eurysternidae).
Journal of Vertebrate Paleontology 34(6): 1317-1328
DOI:10.1080/02724634.2014.880449
http://www.tandfonline.com/doi/full/10.1080/02724634.2014.880449#.VFkLgfnF_To

Eurysternum wagleri is one of the first named, yet most poorly
understood turtles from the Late Jurassic of Europe. Over the years,
many specimens have been referred to and many species synonymized with
E. wagleri, but little consensus is apparent, and the taxonomy is
therefore highly confusing. Based on the rare, only known illustration
of the lost holotype and on the reassessment of select individuals,
the species E. wagleri is recharacterized herein. Eurysternum wagleri
is diagnosed by a deep pygal notch, a carapace with a pentagonal
outline, a contribution of vertebral 5 to the posterior carapace
margin, three cervical scales, very wide vertebral scales with a
well-developed radiating pattern, well-developed costoperipheral
fontanelles in medium-sized individuals, a plastron connected to the
carapace by ligaments, gracile, peg-like bony projections of the hyo-
and hypoplastra, and large, oval-to-quadrangular lateral plastral
fontanelles. A lectotype is designated for Acichelys redenbacheri, and
this taxon is interpreted as the junior subjective synonym of
Eurysternum wagleri. All other, previously proposed synonymies are
rejected, because they lack characters that would allow diagnosing
them as E. wagleri.