Scientists have long accepted that ancient gigantism — that is, being the biggest animal around — during the Late Triassic was a dinosaur’s game. Huge, herbivorous dinosaurs, like the long-necked sauropods, first emerged during this period. Mammal-like reptiles called dicynodonts were around too, competing for the same salad, but they were always believed to be substantially smaller than the dinos. Recently unearthed bones in Poland, however, have overhauled this idea by revealing a never-before-seen colossus

The four-legged creature represented by the bones is named Lisowicia bojani, and it is the first substantial dicynodont discovery in Europe. In a study released Thursday in Science, researchers from Uppsala University and the Polish Academy of Sciences report discovering huge limb bones and an immense scapula in a clay pit that had previously revealed other Triassic-era remains. The video above reconstructs how these bodily pieces worked together to fuel forward a massive beast.

“In my opinion, this is one of the most unexpected fossil discoveries from the Triassic in Europe,” study co-author Grzegorz Niedzwidzki, Ph.D. tells Inverse. “Who would have ever thought that there, in the fossil record, were giant, elephant-sized mammal cousins in this part of the world.”

The bones indicate that the Lisowicia bojani had limbs that were 14 feet long and a body mass of 9 tons — giving it a heft comparable to that of an African elephant. By the Early Jurassic, no mammal-like reptiles (also known as stem-group mammals) like the dicynodonts were larger than about 1.6 feet in length, and most were much smaller. At the same time, herbivorous dinosaurs were clocking in at about 49 feet in length. Now, it’s clear that something happened to hyper-jump the dicynodont’s increase in size — at least when it comes to the Lisowicia bojani, which is 40 percent larger than any previously identified dicynodont.

skeleton
Skeleton of the *Lisowicia bojani*.

The discovery of Lisowicia suggests that “general ecological factors may have been driving the process” of gigantism witnessed during the Late Triassic, rather than “clade-specific attributes of dinosaurs,” the scientists write. Previously, gigantism during this time was thought to be entirely an adaptation of dinosaurs. Now, it seems that the environmental pressures of this era pushed animals to become large.

“Increase in the body size of dicynodonts across the Late Triassic may have been driven by selection pressure to reach a size refuge from large predators,” the scientists write. “It is possible also that the gigantism of the latest dicynodonts was a metabolic adaption that allowed these animals to maximize food retention time and consequently the energy gain.”

Environmental pressures also pushed the Lisowicia to have a body shaped unlike that of other dicynodonts as well. This creature had erect-gait forelimbs, suggesting that it had an upright limb posture similar to that of rhinoceroses and hippos. Other dicynodonts have sprawled out forelimbs, like lizards. Having an upright posture, the scientists reason, allowed the Lisowicia to experience decreased joint stress and use less energy while it moved.

“This animal is an interesting mosaic of characters,” says Niedzwiedzki.

Its body, meanwhile, was the result of 20 million years of evolution. Dicynodonts survived the Permian mass extinction and became dominant terrestrial herbivores in the Middle and Late Triassic. Scientists have long known about their existence — but this study, the authors write, is evidence that their evolutionary history in the Late Triassic has been poorly documented.

The Lisowicia bojani, meanwhile, likely represents one of the last dicynodont species on Earth. At the end of the Triassic, dicynodonts died out, while small, mouse-sized true mammals survived. During the Jurassic and Cretaceous, Niedzwiedzki explains, small mammals “lived in the shadow of the majestic dinosaurs” and by the Eocene epoch they finally reached the size of their Triassic cousin, the Lisowica bojani.

Photos via Tomasz Sulej, Video: Marek Dec Sound: Bensound.com, Karolina Suchan-Okulska