Imagine if you crossed a rhinoceros with a giant turtle and then translated the result: You might get something like Lisowicia bojani, a newly discovered cousin of a Triza mammal, who had a rhinoceros-like beak like a turtle and weighed as much as an African elephant – about 9 tons. Paleontologists say this amazing creature offers a new look at the dawn of the dinosaur era. "Who would think there are giant mammalian cousins who live with some of the first dinosaurs?" Steven Brutte, a vertebrate pathologist at the University of Edinburgh, wonders.
Researchers have thought that during the late trias of about 240 million to 201 million years, early mammals and their relatives "retreated in the shade, while dinosaurs rose and reached huge proportions," says Brucete. "This is the story I tell my students in my lectures, but it throws the key to this simple story," which suggests the same evolutionary forces that prefer giant dinosaurs to work on other beings as well.
The new fossil, a partial skeleton, described online this week science, is an ancient plant dish called dicynodont; the name means "two dog tooth" referring to the characteristic tusks of the upper jaw, which resemble too large dogs. Apart from the tusks, the dycylonones were mostly toothless, with a horn beak like modern turtles. They are part of the great evolutionary group called synapsids, which includes our mammals predecessors, and they were one of the richest and most diverse Earth animals from the Middle Ages to the Middle Trias from 270 million to 240 million years ago,
Dicynodonts "are the first group of vertebrates that have been able to eat plants," says Tomasz Sullay, a paleontologist at the Institute of Palaebiology at the Polish Academy of Sciences in Warsaw.
Dicinondones develop a striking range of forms: one is veiled as modern moles, the other is the first known spine to live in the trees. Some of them were as big as today's hippos, weighing about 1.5 tons. However, fossils indicate that the group was in decline at that time L. bojani hunched. And even in the bloom of dicinonites, they do not come close to the early dinosaurs in size.
Suele, a paleontologist at the University of Uppsala, Sweden, discovered a new fossil in a clay pit that had acquired bricks in the village of Lysowice, about 100 kilometers northwest of Krakow in southern Poland. In 2006 the team received advice that someone was found bone fragments on the site. During their first visit, they found fossils within 15 minutes; for 11 years of field work, they dug more than 1,000 bones.
They did not immediately recognize the new dyskinonon as such – partly because he is so big, says Sulle. "Our first idea was that it was a sauropod," which were the largest known herbivores during this period, reaching 11 meters. But parts of the skull and bones of the limbs identify the animal as the largest and most recent cylinder he has ever found. The team called it after the village and the comparative anatomist of the 18th century, Ludwig Heinrich Boyanus; they estimate it is more than 4.5 meters long and 2.6 meters high.
Most painkillers had a posture that seemed uncomfortable to the modern eye: their hind limbs were straight, like those of today's mammals, but their forelegs were stretched, with a lizard-like style, with a bend of the elbow. The team assumes that because of the road L. bojanion the upper arm attached to the shoulder, his forelegs should be vertically oriented, giving him a more upright position than in modern reptiles. This posture, similar to that of sauropod dinosaurs and modern mammals, may have helped maintain its enormous weight. Others, however, warn that restoring posture without soft tissue can be difficult.
L. bojanithe bones also lacked the lines that, in most fossils of dicinone, marked periods when bone growth slowed down. The animal may have grown unusually fast or has not grown when it dies. Given the "really unbelievable" size of the creature, "it has probably grown rapidly," says paleontologist Jennifer Botta-Brink of the Bloomfontein Paleospatial Center and the National Museum in South Africa. But he adds that the lines that signal slower growth could be wiped out when the bone was remodeled during adulthood, which is happening today in the elephants.
Researchers have suggested that sauropods have increased to avoid eating. This may be true L. bojanialso says Sulay. Louswice's bone bed also contains the remains of a thousand feet predator – probably a dinosaur – and coprolites (fossilized feces) containing bones of dicinonite.
Researchers will search for more specimens to the east in Russia and Ukraine. "There is definitely something else to be found," said Nijuwaji. "How many surprises still waiting for us in the rocks?"