Gilmoreosaurus

Gilmoreosaurus was an early hadrosauroid dinosaur that inhabited the ancient floodplains of what is now Inner Mongolia, China. Discovered during the famous Central Asiatic Expeditions led by the American Museum of Natural History, it was originally assigned to the genus Mandschurosaurus before receiving its own name in 1979. Gilmoreosaurus was a moderately large herbivore, reaching six to eight metres in length, possessing sturdy limbs that enabled it to alternate between bipedal running and quadrupedal walking. Its jaw contained complex batteries of ridged teeth, tailored for grinding tough Cretaceous vegetation, though it lacked some of the most specialised dental modifications seen in later duck-billed dinosaurs. Because it bridges the morphological gap between non-hadrosaurian iguanodontians and the true Hadrosauridae, palaeontologists study Gilmoreosaurus extensively to reconstruct the early evolution and biogeographical dispersal of duck-billed dinosaurs across eastern Asia.

It represents an evolutionary intermediate displaying features of both iguanodontians and true duck-billed dinosaurs.

Where and when

Gilmoreosaurus lived in the Late Cretaceous, from 96 to 89 million years ago (Cenomanian-Turonian age). Its remains come from China, in the Iren Dabasu Formation.

The numbers

Length 7 m (estimates run from 6 to 8 m). Mass about 2.1 t. Hip height about 2.2 m. That is 4.1 human-lengths, or 0.63 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, first ma, last ma, hip height.

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