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Plesiochelys (Jurassic marine turtle) neuroanatomy



From: Ben Creisler
bcreisler@gmail.com

A new paper in PLoS ONE:

Ariana Paulina Carabajal, Juliana Sterli, Johannes Müller & André Hilger (2013)
Neuroanatomy of the Marine Jurassic Turtle Plesiochelys etalloni
(Testudinata, Plesiochelyidae).
PLoS ONE 8(7): e69264.
doi:10.1371/journal.pone.0069264
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0069264



Turtles are one of the least explored clades regarding endocranial
anatomy with few available descriptions of the brain and inner ear of
extant representatives. In addition, the paleoneurology of extinct
turtles is poorly known and based on only a few natural cranial
endocasts. The main goal of this study is to provide for the first
time a detailed description of the neuroanatomy of an extinct turtle,
the Late Jurassic Plesiochelys etalloni, including internal carotid
circulation, cranial endocast and inner ear, based on the first
digital 3D reconstruction using micro CT scans. The general shape of
the cranial endocast of P. etalloni is tubular, with poorly marked
cephalic and pontine flexures. Anteriorly, the olfactory bulbs are
clearly differentiated suggesting larger bulbs than in any other
described extinct or extant turtle, and indicating a higher capacity
of olfaction in this taxon. The morphology of the inner ear of P.
etalloni is comparable to that of extant turtles and resembles those
of slow-moving terrestrial vertebrates, with markedly low, short and
robust semicircular canals, and a reduced lagena. In P. etalloni the
arterial pattern is similar to that found in extant cryptodires, where
all the internal carotid branches are protected by bone. As the
knowledge of paleoneurology in turtles is scarce and the application
of modern techniques such as 3D reconstructions based on CT scans is
almost unexplored in this clade, we hope this paper will trigger
similar investigations of this type in other turtle taxa.