Describer

Xu & Wang, 2004

Time

Cretaceous Early

Classification

Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Troodontidae

Diet

Carnivore

Fossilsite

Yixian Formation, Western Liaoning, China

Info

Genus - Typespecies - Skull

Sinusonasus magnodens (Xu & Wang, 2004) > Sinucerasaurus (Xu & Wang, 2004 vide Xu & Norell, 2006)

Sinusonasus magnodens represents a new genus and species of troodontid theropod. The new taxon is named and described on the basis of the holotype and the only known specimen, which comprises an articulated skelton with the presacral vertebral, shoulder girdle and forelimbs missing as preserved.

Diagnosis

Diagnostic features of the new species include nasals that are sinusoid in lateral view, absence of a passage connecting the antorbital and maxillary fenestrae, relatively large teeth, plate-like chevrons forming a band along most of the length of the tail, and a long neck between the femoral head and shaft.

The temporal constraints of the three paravian groups (Troodontidae, Dromaeosauridae and [Aves] Avialae) combined with the character distributions among the earliest known troodontids indicate a rapid evolution at the base of the Troodontidae.