Bothremydids are an extinct group of Side-necked Turtles (i.e. Turtles that could not withdraw their heads back into their shells, bt had to fold it sideways instead) that arose in the Early
Cretaceous and persisted till the Eocene. The earliest
members of the group are thought to have been Freshwater Turtles
living in the Gondwanan interior, but members of the group evolved to
colonize first brackish and then fully saline waters, enabling them
to spread around the margins of the Atlantic. Bothremydids were an
ecologically diverse group, producing a variety of forms, including
species interpreted as adapted to specializing in feeding on
Molluscs, others with a piscavorous (Fish-eating) diet, and more
generalist forms.
In a
paper published in the journal PeerJ on 26 September 2016, WalterJoyce of the Departement für Geowissenschaften at the Universität Freiburg, Tyler Lyson of the Department of Earth Sciences at the
Denver Museum of Nature and Science and James Kirkland of the UtahGeological Survey describe a new species of Bothremydid Turtle from
the Late Cretaceous Naturita Formation of MacFarlane Mine in
southwest Utah.
The
specimen was excavate in the early 1960s and has since resided
unprepared in the collection of Zion National Park, prior to being
rediscovered by James Kirkland and Don DeBlieux of the Utah
Geological Survey and moved to the Natural History Museum of Utah.
Since the time of its discovery the MacFarlane Mine site has been
buried by a major landslide, and is no longer accessible, however the
specimen was preserved in a block that also contained numerous
Molluscs and other invertebrates, enabling a detailed diagnosis of
both its stratigraphic and palaeoenvironmental context. These suggest
that the Turtle was buried in a brackish water environment, such as
an estuary or lagoon with freshwater input, and that it lived in the
latest Cenomanian, i.e. about 94 million years ago.
The
specimen is described as Paiutemys tibert,
where 'Paiutemys'
refers to the Southern Paiute people who inhabit the area where the
specimen was found (-mys
is a commonly used suffix for Turtles), and 'tibert'
honours Neil Tibert, who established the stratigraphy (rock dating
sequence) for the area where the specimen was found. The specimen is
largely complete and undistorted, being s shell 16.5 cm in length,
estimated to have been about 18 cm long in life.
Paiutemys
tibert, Late Cretaceous
(Cenomanian) of Utah, USA. Photographs and illustrations of shell in
(A) dorsal and (B) ventral view. Abbreviations: Ab, abdominal scute;
An, anal scute; co, costal; EG, extragular scute; ent, entoplastron;
epi, epiplastron; Fe, femoral scute; Gu, gular scute; Hu, humeral
scute; hyo, hyoplastron; hypo, hypoplastron; Ma, marginal scute; mes,
mesoplastron; ne, neural; nu, nuchal; Pe, pectoral scute; per,
peripheral; Pl, pleural scute; SP, supernumerary pleural scute; SN,
supernumerary nuchal scute; spy, suprapygal; Ve, vertebral scute; xi,
xiphiplastron. Joyce et al.
(2016).
See also...
Xiaochelys ningchengensis: A Sinemydid Turtle from the Jehol Biota. Sinemydid Turtles are a group of extinct Turtles known from the Middle
Jurassic to the Early Cretaceous of Asia. They have traditionally been
thought to be stem-group Cryptodires (i.e. more closely related to...
Turtle remains from the Late Miocene to Early Pliocene Black Rock Sandstone of Victoria, Australia. Australia has a diverse
assemblage of Sea Turtles today, with six of the seven living Sea
Turtle species found in Australian waters and one found nowhere else.
The continent also has an extensive...
Turtle eggs from the Late Cretaceous of Madagascar. Turtles are
unique among living Amniotes (Vertebrates that can lay...
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