Osmakasaurus

Osmakasaurus was a basal iguanodontian dinosaur that lived in what is now South Dakota during the Early Cretaceous period. First discovered in the late nineteenth century in the Lakota Formation, it was initially described as an unusual species of Camptosaurus due to similarities in pelvic anatomy. Subsequent re-evaluations placed it as a more advanced iguanodontian, leading to its own genus name derived from the Lakota word for canyon. It reached roughly five to six metres in length and weighed roughly several hundred kilograms. Like other early styracosternans, it possessed robust hindquarters and flexible forelimbs capable of switching between two-legged walking and four-legged browsing. Because the known remains consist mostly of pelvic fragments, vertebrae, and parts of the limbs, much about its exact skull morphology remains to be resolved.

Originally named as a species of Camptosaurus by Charles Gilmore in 1909.

Where and when

Osmakasaurus lived in the Early Cretaceous, from 139.8 to 132.9 million years ago (Valanginian age). Its remains come from United States, in the Lakota Formation.

The numbers

Length 5.3 m (estimates run from 4.5 to 6 m). Mass about 670 kg. Hip height about 1.7 m. That is 3.1 human-lengths, or 0.47 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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