Argentinosaurus

Argentinosaurus (meaning "lizard from Argentina") is a genus of giant sauropod dinosaur that lived during the Early Cretaceous period in what is now Argentina. Although it is only known from fragmentary remains, Argentinosaurus was one of the largest known land animals of all time, measuring 30–35 m (98–115 ft) long and weighing 65–80 t (72–88 short tons). It was a member of Titanosauria, the dominant group of sauropods during the Cretaceous. The first Argentinosaurus bone was discovered in 1987 by a farmer on his farm near the city of Plaza Huincul. A scientific excavation of the site led by the Argentine palaeontologist José Bonaparte was conducted in 1989, yielding several back vertebrae and parts of a sacrum—fused vertebrae between the back and tail vertebrae. Additional specimens include a complete femur (thigh bone) and the shaft of another. Argentinosaurus was named by Bonaparte and the Argentine palaeontologist Rodolfo Coria in 1993; the genus contains a single species, A. huinculensis, after its place of discovery, Plaza Huincul. The fragmentary nature of Argentinosaurus remains makes their interpretation difficult. Arguments revolve around the position of the recovered vertebrae within the vertebral column and the presence of accessory articulations between the vertebrae that would have strengthened the spine. A computer model of the skeleton and muscles estimated this dinosaur had a maximum speed of 7.2 km/h (5 mph) with a pace, a gait where the fore and hind limb of the same side of the body move simultaneously. The fossils of Argentinosaurus were recovered from the Huincul Formation, which was deposited in the Albian stage and contains a diverse dinosaur fauna, including the giant theropod Mapusaurus.