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Aniksosaurus (Theropoda) bonebed found in Upper Cretaceous Bajo Barreal Formation, Argentina

From: Ben Creisler

New in open-access PLoS ONE:

Lucio M. Ibiricu, Rubén D. Martínez,  Gabriel A. Casal & Ignacio A. Cerda (2013)
The Behavioral Implications of a Multi-Individual Bonebed of a Small
Theropod Dinosaur.
PLoS ONE 8(5): e64253


Central Patagonia, Argentina, preserves an abundant and rich fossil
record. Among vertebrate fossils from the Upper Cretaceous Bajo
Barreal Formation of Patagonia, five individuals of the small,
non-avian theropod dinosaur Aniksosaurus darwini were recovered. Group
behavior is an important aspect of dinosaur paleoecology, but it is
not well-documented and is poorly understood among non-avian

Methods/Principal Findings

The taphonomic association of individuals from the Bajo Barreal
Formation and aspects of their bone histology suggest gregarious
behavior for Aniksosaurus, during at least a portion of the life
history of this species. Histology indicates that the specimens were
juvenile to sub-adult individuals. In addition, morphological
differences between individuals, particularly proportions of the
appendicular bones, are probably related to body-size dimorphism
rather than ontogenetic stage.


Gregarious behaviour may have conferred a selective advantage on
Aniksosaurus individuals, contributing to their successful
exploitation of the Cretaceous paleoenvironment preserved in the Bajo
Barreal Formation. The monospecific assemblage of Aniksosaurus
specimens constitutes only the second body fossil association of
small, coelurosaurian theropods in South America and adds valuable
information about the paleoecologies of non-avian theropod dinosaurs,
particularly in the early Late Cretaceous of Patagonia.