Geminiraptor – Part of a Record Breaking Year for Utah’s Dinosaurs

By |2023-03-06T15:12:48+00:00December 16th, 2010|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles|0 Comments

New Troodontid Dinosaur from Utah – Record Breaking Year for the American State

The announcement of the discovery of a new genus of dinosaur from Utah, makes it a record-breaking year for the State, as this is the eighth new genus of dinosaur announced in 2010.  More importantly, the discovery of a troodontid dinosaur from Lower Cretaceous strata is the first evidence of this dinosaur family living in North America in the Early Cretaceous.

Troodonts were a group of active, relatively small theropod dinosaurs, that from a phylogenetic perspective seem to fit somewhere between the Ornithomimidae (ostrich-like dinosaurs) and the fearsome dromaeosaurids (raptors) on the dinosaur family tree.  These animals were bipedal, fast running and all the genera described to date had large eyes and big skulls.  Scientists believe that these little dinosaurs were warm-blooded and most probably covered in feathers.

The brains of troodontids were the largest brain in comparison to body size of any known type of dinosaur.  A number of palaeontologists, perhaps most notably Canadian Dale Russell, have suggested that had these meat-eaters not died out; they would possibly have evolved into an intelligent humanoid form over the sixty-five million years from the end of the Cretaceous to the Quaternary Period.

An Illustration of a Typical Troodontid (Troodon formosus)

Picture credit: Everything Dinosaur

Troodontid Dinosaur

Not only does this discovery make it a record breaking year for Utah, in terms of new dinosaurs but it adds greatly to our understanding of the Troodontidae.  Troodonts are known from the Upper Cretaceous of Asia and from the Upper Jurassic and Upper Cretaceous of North America, however, this is the first evidence of troodonts living in what was to become North America in the Early Cretaceous.

Commenting on the new dinosaur, Scott Foss, a regional palaeontologist for the U.S. Bureau of Land Management stated:

“Its skull is six times larger than other dinosaurs.  One find a year is unusual but eight is outstanding.”

He went on to add that approximately one percent of all known dinosaurs described to date have had their fossils found in Utah.  We at Everything Dinosaur, think this claim is a little exaggerated, but the importance of the western United States as a location for Mesozoic vertebrate fossils should not be underestimated.

Seven of the new types of dinosaur found this year in the State of Utah have been found on Bureau of Land Management territory, whilst the other find was from the Dinosaur National Monument.

The dinosaur has been named Geminiraptor suarezrum.  The name is derived from the Latin geminae (twins), in honour of Doctors Celina and Marina Suarez, twin geologists who discovered the fossil bearing rock strata in which this dinosaur and other dinosaurs remains have been found.  The scientific name can be interpreted as “twin thief from the Suarez site”.

The Suarez site, has produced a number of dinosaur fossils, notably the fossils of the Early Cretaceous therizinosauroid Falcarius (scythe lizard).  The rocks have been dated to the Barremian faunal stage, approximately 125 million years old, the first fossils of this particular dinosaur were found in 2004 and the animal has been estimated to have measured about two metres in length.  The upper jaw bone (maxilla) is small enough to fit in the palm of the hand.

Co-author of the scientific paper, James Kirkland of the Utah Geological Survey commented that the maxilla was hollow and could be inflated “like a balloon”.  This strange characteristic has got the scientists speculating as to what purpose this anatomical adaptation may have served.

He stated:

“There is no clue what it was used for.  Maybe it was some kind of resonating chamber for vocalisation.”

Geminiraptor suarezrum

Some birds have resonance capabilities using air to assist vocalisation and provide them with more powerful calls, if these little dinosaurs lived in flocks then perhaps the jawbone provided extra resonance for their communication calls.

The Maxilla of Geminiraptor suarezrum

Geminiraptor fossil material.

Picture credit: PLoS ONE Journal

Key to the Illustration

(A) a side view of the maxilla (upper jawbone) – Lateral view

(B) a view of maxilla (upper jawbone) – Cranial view

(C) a view of the inside of the maxilla, from the inside of the face looking outwards – Medial view

(D) a view of the jawbone from the bottom looking up – Ventral view

The thick, black line is a scale bar of one centimetre in size and the abbreviations stand for:

alv = dental alveoli – the cavities or sockets in which the teeth were located

iof = internal antorbital fenestra – a bony opening in the skulls of archosaurs between the naris and the eye socket

mxf = maxillary fenestra – a bony opening in the maxilla bone

pf = pro-maxillary fenestra – an opening in the archosaur skull in front of the mxf (anterior to)

Only fragmentary remains of this little dinosaur have been recovered to date, but it is hoped that more troodontid material will be discovered a the Suarez location.

To view models of troodontids and other small theropod dinosaurs: Beasts of the Mesozoic Models.