Makoviky, P.J., Apesteguía, S. and Gianechini, F.A.
A new coelurosaurian theropod, Alnashetri
cerropoliciensis, is reported here based on articulated hind
limbs of a single individual discovered at the locality of La Buitrera (Candeleros Formation, Cenomanian–Turonian),
Río Negro Province, Argentina. The new taxon differs from other
coelurosaurs in the possession of a low ridge that separates the rostral tibial
surface from the outer face of the lateral malleolus, and which extends
proximally beyond the tip of the ascending process of the astragalus, and in
the possession of ventral notches on the hemicondyles of the distal
articulations on pedal phalanges III-1 and III-2. Alnashetri
is easily distinguished from the dromaeosaurid Buitreraptor, the only other known small theropod from La
Buitrera. Phylogenetic analysis supports alvarezsauroid affinities. The
evidence supporting this relationship comes from the detailed anatomy of the
ankle, however, and this concentration of character support within a single
anatomical region may bias our results. If our proposed phylogenetic placement
is accurate, Alnashetri antedates all
other Argentinian alvarezsaurids and indicates that alvarezsaurids were present
in the Neuquén Basin
Makoviky, P.J., Apesteguía, S. and Gianechini, F.A., 2012. Chapter 7: A
New Coelurosaurian Theropod from the La Buitrera Fossil Locality of Río
Negro , Argentina
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