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Bonapartenykus, new alvarezsaurid from Argentina found with eggs
From: Ben Creisler
A new online advance paper in Cretaceous Research:
Federico L. Agnolin, Jaime E. Powell, Fernando E. Novas & Martin Kundrát (2011
New alvarezsaurid (Dinosauria, Theropoda) from uppermost Cretaceous of
north-western Patagonia with associated eggs.
Cretaceous Research (advance online publication)
The Alvarezsauridae represents a branch of peculiar basal coelurosaurs with an
increasing representation of their Cretaceous radiation distributed worldwide.
Here we describe a new member of the group, Bonapartenykus ultimus gen. et sp.
nov. from Campanian-Maastrichtian strata of Northern Patagonia, Argentina.
Bonapartenykus is represented by a single, incomplete postcranial skeleton. The
morphology of the known skeletal elements suggests close affinities with the
previously described taxon from Patagonia, Patagonykus, and both conform to a
new clade, here termed Patagonykinae nov. Two incomplete eggs have been
discovered in association with the skeletal remains of Bonapartenykus, and
several clusters of broken eggshells of the same identity were also found in a
close proximity. These belong to the new ooparataxon Arraigadoolithus
patagoniensis of the new oofamily Arraigadoolithidae, which provides first
insights into unique shell microstructure and
fungal contamination of eggs laid by alvarezsaurid theropods. The detailed
study of the eggs sheds new light on the phylogenetic position of
alvarezsaurids within the Theropoda, and the evolution of eggs among
Coelurosauria. We suggest that plesiomorphic alvarezsaurids survived in
Patagonia until the latest Cretaceous, whereas these basal forms became extinct