Lurdusaurus

Lurdusaurus was an exceptionally robust iguanodontian dinosaur that inhabited the rivers and wetlands of Early Cretaceous Niger. Unlike the agile, mostly bipedal forms typical of many ornithopods, Lurdusaurus was heavily built with unusually thick limb bones, a wide ribcage, and a barrel-like body. These proportions led its describers to coin the name heavy lizard. Reaching up to nine metres in length and weighing several tonnes, its forelimbs were strong and carried enlarged thumb spikes for defense. Because of its dense skeleton, low centre of gravity, and paddle-like spread of its feet, palaeontologists have hypothesised that Lurdusaurus lived a semi-aquatic life analogous to a modern hippopotamus. It shared lush river systems with the giant crocodilian Sarcosuchus and the sail-backed herbivore Ouranosaurus, feeding on thick aquatic vegetation and riparian plants along water margins.

Unusually broad, massive bones and a low-slung body have led researchers to propose a semi-aquatic lifestyle.

Where and when

Lurdusaurus lived in the Early Cretaceous, from 115 to 112 million years ago (Aptian age). Its remains come from Niger, in the Elrhaz Formation.

The numbers

Length 8 m (estimates run from 7 to 9 m). Mass about 3.2 t. Hip height about 2.2 m. That is 4.7 human-lengths, or 0.71 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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