Riojasuchus Facts
Note: Although historically classified as a dinosaur, Riojasuchus is no longer considered one based on current scientific understanding. It remains a fascinating prehistoric creature.
Pronunciation: REE-oh-hah-SOOK-us
Name meaning: Rioja Crocodile
| Diet | Carnivore |
| Height | 1m |
| Length | 3m |
| Weight | 45 kg |
| Environment | Land |
| Era | Triassic |
| Period | Triassic |
| Type | Other |
| Location | Argentina |
Although once grouped with early dinosaur relatives, Riojasuchus is now known to be an ornithosuchid archosaur—a fascinating group of crocodile-line reptiles that lived alongside the earliest dinosaurs during the Late Triassic period, approximately 227 million years ago. This remarkable creature inhabited the ancient landscapes of what is now northwestern Argentina, representing one of the most complete examples of its family ever discovered.
Riojasuchus was a relatively small predator, measuring about 3 metres in length and standing roughly 1 metre tall at the hip. What made this archosaur truly special was its ability to switch between walking on four legs and running on two legs when needed—a rare adaptation that it shared with other members of its family. Its long, narrow skull housed sharp teeth perfectly designed for its carnivorous lifestyle, likely feeding on smaller reptiles, early mammals, and possibly scavenging from larger carcasses.
The single known species, Riojasuchus tenuisceps, was first described by renowned Argentine palaeontologist José Bonaparte in 1967. The remarkably well-preserved holotype specimen provided scientists with invaluable insights into the anatomy and lifestyle of these ancient archosaurs. Its discovery marked one of the early successes in Argentina's rich fossil-hunting endeavours, paving the way for numerous other important Triassic discoveries in the region.
What made Riojasuchus distinctive?
Riojasuchus had a notably long and narrow skull with sharp, pointed teeth adapted for carnivory. Its body was built for both quadrupedal walking and bipedal running, with relatively long hind legs and a long tail for balance.
Behaviour
Riojasuchus was likely an opportunistic predator and scavenger, using its sharp teeth to tackle smaller prey or feed on carrion. It could move efficiently on both two and four legs, probably running bipedally when chasing prey or fleeing from larger predators.
Discovery
Riojasuchus was first described by José Bonaparte in 1967. The original fossils were discovered at Los Colorados Formation, Ischigualasto-Villa Unión Basin, Argentina.
Riojasuchus FAQ
What did Riojasuchus eat?
Riojasuchus was a carnivore that likely hunted smaller reptiles and early mammals, whilst also scavenging from larger carcasses when the opportunity arose. Its sharp, pointed teeth were well-suited for gripping and tearing flesh.
How big was Riojasuchus?
Riojasuchus measured approximately 3 metres in length and stood about 1 metre tall at the hip. It weighed roughly 45 kilograms, making it a relatively small predator compared to many dinosaurs of later periods.
When did Riojasuchus live?
Riojasuchus lived during the Late
Triassic period, specifically around 227.3 million years ago. This was during the Norian stage, a time when dinosaurs were just beginning to diversify and spread across the world.
Where was Riojasuchus found?
Riojasuchus fossils were discovered in the Los Colorados Formation within the Ischigualasto-Villa Unión Basin of northwestern Argentina. This region has proven to be exceptionally rich in Late
Triassic fossils.
How do you pronounce Riojasuchus?
Riojasuchus is pronounced 'REE-oh-hah-SOOK-us'. The name comes from La Rioja province in Argentina where it was found, combined with 'suchus' meaning crocodile.
What does Riojasuchus mean?
Riojasuchus means 'Rioja crocodile', named after La Rioja province in Argentina where the fossils were discovered. The species name 'tenuisceps' means 'slender head', referring to its narrow skull.
How fast could Riojasuchus run?
The running speed of Riojasuchus is unknown, but its ability to move on two legs suggests it could achieve reasonable speeds when necessary, likely for hunting or escaping from larger predators.
What type of dinosaur was Riojasuchus?
Riojasuchus was not actually a dinosaur at all, but rather an ornithosuchid archosaur. These were crocodile-line reptiles that lived alongside early dinosaurs during the
Triassic period, representing a different branch of the archosaur family tree.
Was Riojasuchus related to birds?
Riojasuchus was not directly related to birds. As an ornithosuchid archosaur, it belonged to the crocodile line of archosaur evolution, whilst birds evolved from theropod dinosaurs on a completely different branch of the family tree.
How many Riojasuchus fossils have been found?
Only one specimen of Riojasuchus is currently known to science—the holotype specimen PVL 3827 discovered in 1967. However, this specimen is remarkably complete, providing excellent insight into the anatomy of this ancient archosaur.
