Lisowicia Bojani: Colossal Lizard Mammal That Walked With Dinosaurs Discovered

Artistic reconstruction of Lisowicia bojani, front view. Karolina Suchan-Okulska

A humongous lizard mammal that lived alongside the dinosaurs over 200 million years ago has been discovered in Poland. The herbivorous creature, named Lisowicia bojani, was about 40 percent bigger than any other species of its kind, measuring 4.5 meters in length, 2.6 meters in height and weighing approximately nine tons. This is roughly equivalent to a the size of an elephant.

Tomasz Sulej, from the Polish Academy of Sciences, and Grzegorz Niedźwiedzki, from Sweden's Uppsala University, say the discovery overturns the belief that the only giant herbivores to exist during the Triassic period were dinosaurs. The findings are reported in the journal Science.

Lisowicia is a dicynodonts—a group of animals belonging to the therapsid order. Therapsids were mammal-like reptiles that lived alongside the first mammals, crocodiles and dinosaurs.They became a dominant species during the Middle and Late Triassic period. Until now, dicynodonts were thought to walk in a sprawling manner—similar to modern reptiles—and could grow to sizes anywhere between a rat and an ox.

Lisowicia Bojani
Artistic reconstruction of Lisowicia bojani, front view. Karolina Suchan-Okulska

However, fossils uncovered in the Polish village of Lisowice have now obliterated both these assumptions. Since 2005, over 1,000 bones have been collected from the region.

Analysis of the bones allowed scientists to build up a picture of Lisowicia—revealing its immense size and how it would have walked in an upright manner, similar to large mammals like rhinos and hippos. It lived between 210 and 205 million years ago—roughly ten million years later than previous dicynodont findings.

Lisowicia is the first evidence that giant dicynodonts were alive at the same time as large herbivorous dinosaurs like sauropodomorphs. It shows features thought to characterize large mammals had also evolved separately in dicynodonts. Lisowicia was also found to have fast growth, similar to dinosaurs and mammals.

dicynodont bone
Lisowice, Poland. Limb bones of dicynodont. Grzegorz Niedzwiedzki

Researchers believe selection pressures—potentially to protect themselves from larger predators—may have been the driver behind their giant size, but more research will be needed to understand Lisowicia and its place in the evolutionary tree.

"Dicynodonts were amazingly successful animals in the Middle and Late Triassic. Lisowicia is the youngest dicynodont and the largest non-dinosaurian terrestrial tetrapod from the Triassic," Niedzwiedzki said in a statement. "It's natural to want to know how dicynodonts became so large. Lisowicia is hugely exciting because it blows holes in many of our classic ideas of Triassic 'mammal-like reptiles'."

Sulej said the find completely changes our ideas about the history of the dicynodonts and is a "once in a lifetime discovery."

Nick Fraser, head of the Department of Natural Sciences at National Museums Scotland, who was not involved in the study, said Lisowicia was a "remarkable discovery" that was "completely unexpected."

Lisowicia bojani
Skeleton of Lisowicia bojani. Tomasz Sulej

"Previously it was widely thought that only sauropodomorph dinosaurs attained such gigantic proportions on land at this time," he told Newsweek. "We now know there was a completely separate group of huge terrestrial vertebrates muscling in on the scene."

Fraser also said the discovery also upturns current thinking about the fall of the dicynodonts: "It demonstrates that, contra the current widely held view that dicynodonts were on the decline in the later stages of the Triassic period, there was at least one lineage of dicynodonts diversifying very late on in the Triassic.

He continued: "The Triassic is already known for its remarkable diversity of weird land-living vertebrates living alongside the earliest dinosaurs, mammals and crocodiles. Lisowicia adds one more twist to this fascinating and critical period in the history of life on Earth."