More than 200 million years ago, a mammal weighing more than a modern-day ambulance and measuring some 4.5 meters long (15 feet) and 2.6 meters tall (8.5 feet) once roamed the Earth. Lisowicia bojani walked like the hippos or rhinos of today and, despite their gargantuan size, survived off of plants during the Triassic Period.
Previously, paleontologists thought these massive creatures "retreated to the shadows while dinosaurs rose up and grew to huge sizes," study author Grzegorz Niedzwiedzki told IFLScience. They were believed to be scuttling along the ground in places like Africa, Asia, and North and South America. However, a new discovery of the most complete fossilized specimen discovered in Europe overturns this “established picture” of life at this time.
"We think it's one of the most unexpected fossil discoveries from Triassic of Europe. Who would have ever thought that there is a fossil record of such giant, elephant-sized mammal cousins in this part of the world," said Niedzwiedzki.
“Until now, gigantisms in the Triassic appeared to be entirely a dinosaur adaptation, and previously known Triassic dicynodonts were substantially smaller,” wrote the authors in Science. “The discovery of Lisowicia suggests that general ecological factors may have been the driving process rather than clade-specific attributes of the dinosaurs.”
The researchers believe that Lisowicia became specialized herbivores that adapted to the needs of their environment. For starters, several features in their limbs (such as a “massive scapula”) suggest they were postural animals, roaming upright on four legs to harvest food. Nearly the size of an elephant and weighing an estimated 9,000 kilograms (10 tons), the researchers say this increase in body size could also have been driven by a need to protect itself against large predators or as a way to maximize food retention and energy gain.
"Basically, the anatomy of Lisowicia does not diverge so far from the other dicynodonts but it shows some unique anatomical features (e.g. anatomy of forelimbs, cervical vertebra, sternum) unknown in other dicynodonts. Lisowicia is the youngest (geologically) and largest member of the dicynodont-line," said Niedzwiedzki, adding Lisowicia are mammalian relatives of the family dicynodonts, a group of synapsids that includes mammals and their ancestors.
But this evolution didn’t happen overnight. The team believes it took around 20 million years for Lisowicia to come into their giant forms at a gradual size increase similar in pace to dinosaurs and later mammalian lineages.
As the authors note, the research suggests the history of these giant animals is probably more “poorly documented” than previously believed and that the excavation in Europe calls into question certain beliefs about the animal and their geographic range, opening the potential for new research and a greater understanding of these gigantic animals and the world they once lived in.