CNN About 100 million years ago in what is now the state of Utah, its 10-foot-long (3 meters) duck-billed dinosaur cousin crushed the stems and leaves of tough plants with its powerful teeth and jaws.
Chewing may be too busy to notice that the once-familiar world around him is shifting. But for the scientists who recently described this newly discovered species, its fossils provide clues to life during the middle Cretaceous period (145 million to 66 million years ago), when rising temperatures and sea levels reshaped Earth’s fertile habitat.
One of the first ornithopods were plant eaters – a group of herbivorous dinosaurs, mostly bipedal. By the end of the Cretaceous, Ornithopods had become the most successful vegetarians of the age, including the duck-billed hadrosaurs, sometimes called “Cretaceous cows” and the crested Parasaurolophus, among others.
Ornithopods first appeared during the Jurassic period (201.3 million to 145 million years ago) and although early species were common throughout North America, populations dwindled and died out as the Earth warmed. These new fossils provide evidence that some of these early lineages survived despite climate change, the researchers report June 7 in the journal PLOS One.
The analysis of the bones surprised them — the animal appears to be a close relative of rhabdodontomorphs, a species of ornithopod previously known almost entirely from European fossils.
Investigate new species
The newly discovered species, named Iani (YAH-nee) Smithy, is the first early ornithopod from the Cretaceous period to be discovered in North America. This is an important discovery because it offers a glimpse into a time in North America that very little was known about the continent’s dinosaurs, said Darla Zelenitsky, professor in the Department of Earth Sciences at the University of Calgary in Canada.
“These new fossils show that rhabdodon-like ornithopods were more diverse and persisted in North America longer than previously thought,” Zelenitsky, who was not involved in the study, told CNN by email.
The dinosaur’s genus name – ianni – refers to its changing world. The study’s authors state that it refers to the two-faced Janus, the Roman god of transformation.
Lead study author Lindsay Zanno, chair of paleontology at the North Carolina Museum of Natural Science and research professor of biological sciences at North Carolina State University in Raleigh, said paleontologists unearthed the fossils in 2015 at a site called the Mussentuchit Member in southern Utah. .
The bones include the skull, several ribs, vertebrae, leg bones, and parts of the pelvis. This well-preserved Cretaceous skull from this part of North America is extremely rare; The area once bordered a vast inland sea, Zano told CNN in an email, and bones fossilize badly in the coastal humidity.
“Most of the specimens we found in the mossentoshet were very fragmentary or in a jagged shape,” said Zano. In comparison, these fossils were in such good condition that researchers could identify the specimens as juveniles.
“The spines don’t fuse together, which leaves room for them to grow,” explains Zano.
Because rhabdodontomorphs are known almost exclusively from Europe (with a few species possibly identified in Australia), scientists did not expect to find them in late Cretaceous sediments in North America.
However, a number of features in this animal are similar to those of the rhabdodontomorph, including its unique cheekbones; Large, deeply recessed teeth and openings in the skull for arteries. Other features, such as the shape of the brain and palate, as well as the position of the teeth on the front of the face, suggest it is a new species.
Successful pedigree
Because I. smithi was a primitive ornithopod, it may provide clues as to how the group fared during the late Cretaceous period, Zelenitsky said in an email.
Hadrosaurs, which evolved tens of millions of years after I. smithi, adapted to share ecosystems with dinosaurs, and were among the most ferocious predators of all. They were able to do this without using the horns or shields that protected other herbivorous dinosaurs, says Zelenitsky.
“Ornithopod species may have evolved in a certain way or adopted certain behaviors to succeed,” he said. “Primitive forms, like Iani, are close to the roots of the ornithopod evolutionary tree and will certainly provide some answers.”
I. Smithy’s fossils also provide an important puzzle piece from Earth’s past as climate change altered the planet, wiping out many species of North American dinosaurs. Zano adds that preserved remains from such times can provide valuable insights for navigating today’s increasingly heated world.
“The more we can understand how these changes affected ancient animals, the better prepared we will be for what the future holds for us.”
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2023-06-09 17:52:52
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