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Ocepechelon, giant suction-feeding marine turtle from Late Cretaceous of Morocco



From: Ben Creisler
bcreisler@gmail.com

New in PLoS ONE:

Nathalie Bardet, Nour-Eddine Jalil, France de Lapparent de Broin,
Damien Germain, Olivier Lambert & Mbarek Amaghzaz (2013)
A Giant Chelonioid Turtle from the Late Cretaceous of Morocco with a
Suction Feeding Apparatus Unique among Tetrapods.
PLoS ONE 8(7): e63586.
doi:10.1371/journal.pone.0063586
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0063586


Background

Secondary adaptation to aquatic life occurred independently in several
amniote lineages, including reptiles during the Mesozoic and mammals
during the Cenozoic. These evolutionary shifts to aquatic environments
imply major morphological modifications, especially of the feeding
apparatus. Mesozoic (250–65 Myr) marine reptiles, such as
ichthyosaurs, plesiosaurs, mosasaurid squamates, crocodiles, and
turtles, exhibit a wide range of adaptations to aquatic feeding and a
broad overlap of their tooth morphospaces with those of Cenozoic
marine mammals. However, despite these multiple feeding behavior
convergences, suction feeding, though being a common feeding strategy
in aquatic vertebrates and in marine mammals in particular, has been
extremely rarely reported for Mesozoic marine reptiles.

Principal Findings

A relative of fossil protostegid and dermochelyoid sea turtles,
Ocepechelon bouyai gen. et sp. nov. is a new giant chelonioid from the
Late Maastrichtian (67 Myr) of Morocco exhibiting remarkable
adaptations to marine life (among others, very dorsally and
posteriorly located nostrils). The 70-cm-long skull of Ocepechelon not
only makes it one of the largest marine turtles ever described, but
also deviates significantly from typical turtle cranial morphology. It
shares unique convergences with both syngnathid fishes (unique long
tubular bony snout ending in a rounded and anteriorly directed mouth)
and beaked whales (large size and elongated edentulous jaws). This
striking anatomy suggests extreme adaptation for suction feeding
unmatched among known turtles.

Conclusion/Significance

The feeding apparatus of Ocepechelon, a bony pipette-like snout, is
unique among tetrapods. This new taxon exemplifies the successful
systematic and ecological diversification of chelonioid turtles during
the Late Cretaceous. This new evidence for a unique trophic
specialization in turtles, along with the abundant marine vertebrate
faunas associated to Ocepechelon in the Late Maastrichtian phosphatic
beds of Morocco, further supports the hypothesis that marine life was,
at least locally, very diversified just prior to the
Cretaceous/Palaeogene (K/Pg) biotic crisis.