Geminiraptor

Geminiraptor (meaning "twin seizer") is a genus of troodontid theropod dinosaur that lived in North America during the Early Cretaceous period.

[1] The holotype and only known specimen of Geminiraptor is CEUM 7319, a maxilla recovered from the Lower Yellow Cat Member of the Cedar Mountain Formation, in Utah, dating from the early to late Valanginian stage (about 139 to 134 million years ago).

The maxilla is long and low, with the process above the antorbital fenestra being horizontal, similar to other advanced troodontids.

[1] Geminiraptor is uniquely characterized by the presence of a large pneumatic chamber which expands the maxilla into a triangular shape in cross section, with the base formed by a bony shelf lingual to the teeth.

The phylogenetic analysis conducted by its describers placed it in a clade with derived troodontids due to the oblong shape of its maxillary fenestra.

It lived in the Lower Yellow Cat Member of the Cedar Mountain Formation[1] about 139-134 million years ago.

Possible size estimated by Holtz 2012
Comparison of the maxilla of Geminiraptor to those of other paravians
Geminiraptor compared to the fauna of the Yellow Cat Member from the Cedar Mountain Formation ( Geminiraptor in purple, next to Martharaptor )