Some 200 to 250 million years ago, Earth’s terra firma was nowhere near the way we know it today.
Continents had merged together to form one huge landmass called Pangea – a supercontinent.
It was around this time that dinosaurs came into existence but they were not the only ones to roam the Pangea, because with them came the ancestors of modern-day crocodiles, pterosaurs, turtles, amphibians, lizards and mammals.
Also co-existing with them was a species of “mammal-like” reptiles called therapsids that has recently piqued the curiosity of scientists, who believe that they were the ancestors of modern-day mammals, including humans.
A sub-species group of therapsids called dicynodonts – believed to have become extinct before the dinosaurs became the dominant species on land – had actually survived until 10 million years later, contrary to what earlier discoveries had suggested, say scientists based on the latest findings.
There were different species of these dicynodonts, ranging from small burrowers to large browsers, but they were all herbivores and a majority of them were toothless.
As part of a research program called Evolution and Development, scientists at the Uppsala University in Sweden, along with researchers at the Polish Academy of Sciences in Warsaw, have discovered the fossilized remains of a new dicynodont species near the Polish village of Lisowice.
The species has been Christened Lisowicia bojani in recognition of the place where it was unearthed and in honor of the German comparative anatomist Ludwig Heinrich Bojanus, known for his anatomical discoveries.
The findings, published in the journal ‘Science’ on Nov 22, have revealed that the dicynodont Lisowicia bojani was roughly the size of a modern-day elephant, some 4.5 meters long and 2.6 meters tall, with a body mass of around 9 tons.
All of this puts paid to the established theory that only dinosaurs could grow as big as they did; we now know that “stem-group mammals” had also grown to similar proportions – something that never happened again until the Eocene Epoch, also known as the “dawn” of modern-day animals.
The Lisowicia discovery is the first evidence that dinosaurs were not the only biggies roaming the earth at the time.
Our huge mammal cousins were also breathing the same Triassic air that the familiar long-necked sauropodomorph and other dinosaur species did.
“The discovery of Lisowicia overturns the established picture of the Triassic megaherbivore radiation as a phenomenon restricted to dinosaurs and shows that stem-group mammals were capable of reaching body sizes that were not attained again in mammalian evolution until the latest Eocene,” say the research authors.
“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,” said the paper’s lead author Dr. Grzegorz Niedzwiedzki from the Department of Organismal Biology at Uppsala University says
“It’s natural to want to know how dicynodonts became so large,” he said and added that “Lisowicia is hugely exciting because it blows holes in many of our classic ideas of Triassic ‘mammal-like reptiles’.”
“Dicynodonts are so-called a sister line to mammal line, but they are not their ancestors,” Niedzwiedzki also said.
“We are distant cousins, but they are not our immediate ancestors.”
Polish researchers Robert Borzecki and Piotr Menducki were the first to discover fossilized remains of prehistoric animals near Lisowice, as far back as 2005.
Since then, more than 1.000 bones and bone fragments have been recovered from Lisowice and the surrounding areas, which scientists believe had been a river deposit during the Late Triassic period.
“The discovery of Lisowicia changes our ideas about the latest history of dicynodonts, mammal Triassic relatives,” said study co-author Dr. Tomasz Sulej from the Institute of Paleobiology, Polish Academy of Sciences (PAS).
“It also raises far more questions about what really make them and dinosaurs so large, he said, adding that “such an important new species is a once in a lifetime discovery.”
“Lisowicia is the largest synapsid from the Triassic and is even larger than some synapsids from Permian,” says Niedzwiedzki,
“This discovery falsifies the established picture of the Late Triassic megaherbivore radiation as a phenomenon restricted to dinosaurs.”