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Sulcusuchus (polycotylid plesiosaur) revised and elasmosaur material from Argentina
From: Ben Creisler
Two new plesiosaur papers in Alcheringa:
José P. O’gorman & Zulma Gasparini (2013)
Revision of Sulcusuchus erraini (Sauropterygia, Polycotylidae) from
the Upper Cretaceous of Patagonia, Argentina.
Alcheringa 37: 161–174
Sulcusuchus erraini, from the upper Campanian–lower Maastrichtian of
Patagonia, Argentina, is the only polycotylid from the Southern
Hemisphere for which the skull and mandible are known. The diagnosis
of the species and genus is emended based on new observations.
Sulcusuchus is characterized by the following autapomorphies: (1) deep
and broad rostral and mandibular grooves and (2) a wide notch on the
posterior margin of the pterygoids that are combined with a part of
the body of the basioccipital, forming a wide plate. Several
hypotheses about the identity of the structures that could have been
housed in the rostral and mandibular grooves are evaluated. Only two
of several hypotheses were not discarded. The first is that the
grooves may have accommodated oral glands (supralabial and sublabial),
but the biological role of such glands could not be inferred. The
second hypothesis is the presence of special structures of an
electrosensitive and/or mechanosensitive nature, which might allow the
detection of infaunal or semi-infaunal food in soft substrates, as is
represented in modern analogues, such as dolphins.
José P. O’Gorman, Leonardo Salgado, Julio Varela & Ana Parras (2013)
Elasmosaurs (Sauropterygia, Plesiosauria) from the La Colonia
Formation (Campanian–Maastrichtian), Argentina.
Alcheringa 37: 257–265
Elasmosaur postcranial remains from the La Colonia Formation
(Campanian–Maastrichtian), Chubut Province, Patagonia, Argentina, are
described. The new material has small dimensions and caudal vertebrae
with parapophyses strongly projected laterally—characters shared with
some Elasmosauridae indet. from the coeval Allen Formation, Río Negro
Province, Argentina. These features reinforce the similarities between
the plesiosaur faunas to the north and south of the Somún Curá
Plateau. The small size of these elasmosaurs may be palaeoecologically
related to the marginal marine depositional environment of the
sedimentary host rocks.