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Linhevenator, new troodontid from Inner Mongolia

From: Ben Creisler

New in PLoS ONE:

Xu X., Tan Q., Sullivan, C., Han F., Xiao D. (2011)
A Short-Armed Troodontid Dinosaur from the Upper 
Cretaceous of Inner Mongolia and Its Implications for 
Troodontid Evolution.
PLoS ONE 6(9): e22916. 

The Troodontidae represents one of the most bird-like 
theropod groups and plays an important role in our 
understanding of avian origins. Although troodontids have 
been known for over 150 years, few known derived 
troodontid specimens preserve significant portions of 
both the forelimb and the hindlimb.

Methodology/Principal Findings
Here, we report a new troodontid taxon, Linhevenator tani 
gen. et sp. nov., based on a partial, semi-articulated 
skeleton recovered from the Upper Cretaceous Wulansuhai 
Formation of Wulatehouqi, Inner Mongolia, China. L. tani 
has an unusual combination of primitive and derived 
character states, though our phylogenetic analysis places 
it in a derived clade within the Troodontidae. As a 
derived taxon, L. tani has a dromaeosaurid-like pedal 
digit II, and this species also possesses a humerus that 
is proportionally much shorter and more robust than those 
of most other troodontids.

The combination of features present in Linhevenator 
indicates a complex pattern of character evolution within 
the Troodontidae. In particular, the discovery of 
Linhevenator suggests that derived troodontids have 
independently evolved a highly specialized pedal digit II 
and have significantly shortened the forelimb over the 
course of their evolution.