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Early Cretaceous metriorhynchid from France + Eudes-Deslongchamps fossil crocodyliform MS

From: Ben Creisler

New online papers:

I haven't seen this paper yet so it's not clear if a new taxon is named.

Mark T. Young, Marco Brandalise de Andrade, Jean-Jacques Cornée, Lorna
Steel & Davide Foffa (2014)
Re-description of a putative Early Cretaceous "teleosaurid" from
France, with implications for the survival of metriorhynchids and
teleosaurids across the Jurassic-Cretaceous Boundary.
Annales de Paléontologie (advance online publication)

Thalattosuchia was a diverse clade of marine crocodylomorphs known
from the Early Jurassic to the Early Cretaceous. Recent studies have
hypothesized that their extinction was two-phased: (1) habitat loss
near/at the Jurassic-Cretaceous boundary heavily reduced their
morphofunctional diversity, particularly in Europe, while (2) climate
change and a shift in marine fauna during the Early Cretaceous (either
at the Valanginian-Hauterivian boundary or during the early
Hauterivian) finished off the already stressed clade. Unfortunately,
the Cretaceous fossil record of thalattosuchians is poor, with only
one putative "teleosaurid" specimen and approximately ten
metriorhynchid specimens. Here we re-describe the youngest known
teleosaurid from the Cretaceous (Valanginian of south-eastern France).
Originally considered to be a teleosaurid (possibly Steneosaurus), we
demonstrate that it belongs to Metriorhynchidae, and a newly
discovered subclade, Plesiosuchina. It differs from Plesiosuchus in
the pattern of tooth enamel ornamentation and the variation in dentary
alveoli size. Referring this specimen to Metriorhynchidae means there
are no definitive Cretaceous teleosaurid specimens. Furthermore, it
suggests that both durophagous and piscivorous teleosaurids became
extinct at the end of the Jurassic. Interestingly, this is the fourth
metriorhynchid lineage known to cross the Jurassic-Cretaceous
boundary. As such, it would appear that the two thalattosuchian
families responded very differently to the lowering sea levels at the
end of the Jurassic: teleosaurids possibly became extinct, while
metriorhynchids were seemingly unaffected.


Arnaud Brignon (2014)
Un travail inédit de Jacques-Amand Eudes-Deslongchamps sur les
crocodyliformes marins du Jurassique de Normandie. [A Jacques-Amand
Eudes-Deslongchamps' unpublished work on marine crocodyliforms from
the Jurassic of Normandy (France).]
Geodiversitas 36(1): 5-33
doi: http://dx.doi.org/10.5252/g2014n1a1

An unpublished manuscript by Jacques-Amand Eudes-Deslongchamps
describes the remains of two species of fossil crocodyliforms
attributed to the genus Steneosaurus Geoffroy Saint-Hilaire, 1825. It
is demonstrated that these notes give detailed explanations of three
engravings that were executed under the direction of Étienne Geoffroy
Saint-Hilaire in 1831. These plates represent remains of Steneosaurus
megistorhynchus Geoffroy Saint-Hilaire, in J.-A. Eudes-Deslongchamps,
1866 and Teleidosaurus calvadosii (J.-A. Eudes-Deslongchamps, 1866).
Written before 1837 and likely between June 1831 and June 1832, this
work would be the oldest study on thalattosuchians from Normandy,
known to date, by Jacques-Amand Eudes-Deslongchamps. This document
prefigures the quality of his future works on fossil crocodyliforms
that he published more than thirty years later. An extensive excerpt
from this document has been used by his son, Eugène
Eudes-Deslongchamps, in his Prodrome des Téléosauriens du Calvados
published in 1869. An unrecorded drawing found in the archives of
Georges Cuvier housed in the central library of the Muséum national
d'Histoire naturelle, Paris is also presented. This drawing represents
the mandible and the anterior extremity of the upper jaw of the first
specimen of Teleosaurus cadomensis (Lamouroux, 1820). These remains,
discovered in 1817, were prepared by Jacques Amand Eudes-Deslongchamps
between 1826 and 1830. All of these documents shed light on the first
studies of one of the major players in vertebrate paleontology at a
time when this science was still in its early stages.