Riojasaurus ‭(‬Rioja lizard‭)‬

Short Info

Riojasaurus ‭(‬Rioja lizard‭)‬

Phonetic : Re-o-jah-sore-us.

Named By : Jose Fernando Bonaparte‭ ‬-‭ ‬1967

Diet : Herbivore

Size : Estimated 10 meters long

Type of Dinosaur : Sauropod

Type Species : R.‭ ‬incertus‭ (‬type‭)‬e

Found in : Argentina,‭ ‬La Rioja Province‭ ‬-‭ ‬Los Colorados Formation

When it Lived : Late Triassic, 221-210 million years ago

Riojasaurus (meaning “Rioja lizard”) was a sauropodomorph herbivore dinosaur named in honor of La Rioja Province in Argentina which was discovered inside the Los Colorados Formation in the Ischigualasto-Villa Union Basin discovered by Jose Bonaparte. It lived through its Late Triassic (Norian stage) and was about 10 meters (33 feet) in length. Riojasaurus is known as the only riojasaurid species to reside throughout South America.

Riojasaurus was known for its large body, large legs and a lengthy length of neck as well as a tail. The leg bones of the animal were incredibly huge and dense for a early sauropodomorph. In 2010, Gregory S. Paul estimated its length to be 6.6 meters (22 feet) as well as its mass at around 800 kg (1,800 lbs). In contrast, its vertebrae were slender due to hollow cavities. And unlike earlier sauropodomorphs Riojasaurus included four sacral vertebrae, instead of three. It is believed that it was likely that it moved slowly on all fours, and could not rear up on its hind legs. The almost identical length of hind and forelimbs has been thought to suggest an unavoidably quadrupedal gait. In 2016 Scott Hartman found the hand anatomy, a fairly straight back, and almost immobile shoulder girdle Riojasaurus was bipedal.


Riojasaurus skullFunkMonk, CC BY 3.0, via Wikimedia Commons


The skull of the animal was not found with the first skeleton from Riojasaurus but a preserved skull believed to be that of Riojasaurus was discovered later. Its teeth Riojasaurus were leaf-shaped and serrated. The upper jaw was comprised of five teeth on the front, and 24 to their rear in rows that stopped in the eye area.

The rings of sclerals from Riojasaurus as well as modern birds and reptiles suggest it might be cathemeral and that was active throughout the day in shorter intervals.

Source: Wikipedia