About 66 million years ago, a giant asteroid struck Earth, marking the beginning of a mass extinction event, during which three quarters of plant and animal species on our planet were wiped out.
Among the animals that disappeared during the extinction were non-avian dinosaurs, pterosaurs, ammonites, as well as many birds and mammals.
But what were some of the last dinosaurs to live around the time the asteroid struck?
The last era of dinosaurs, known as the Maastrichtian, spanned about eight million years and ended with a devastating impact. This era was the last part of the Cretaceous period and the wider Mesozoic era.
Scientists know little about the Maastrichtian as a whole, but only a few sites around the world preserve the end of this period on land, reducing our knowledge of the dinosaurs that lived at this time.
“That’s why we mostly hear about the last dinosaurs that survived in North America, because some of the best and only rocks we’ve discovered to date are in Montana and the Dakota,” said Ashley Post, of San Diego Natural History Museum, a paleontologist told newsweek,
“This is only a very small part of the possibility of a vast, unknown diversity of ‘last dinosaurs’ worldwide,” he said. “Dinosaurs in some places have now been stressed by giant volcanic eruptions in India, but we have every reason to believe that dinosaurs and their ecosystems were functioning until the end, so we would expect many good dinosaurs around the world.” . Live in all kinds of dwellings.”
The time just before the mass extinction was a time when many of the best-known dinosaur species roamed the Earth. When it comes to dinosaurs that lived at the end of the Maastrichtian, the ones we know best from rocks in North America include the iconic Triceratops and Tyrannosaurus Rex,
Triceratops was a heavy, three-horned, herbivorous dinosaur that walked on four legs with a parrot-like beak and a large frill that could measure about three feet across.
“Triceratops was one of the first of the horned dinosaurs, which was similar in size to a modern elephant, and could be recognized by its distinctive three horns and the broad bony frill forming the back of its skull,” said Thomas Cullen, a postdoctoral fellow in Canada. K research associate at Carleton University and the Field Museum of Natural History newsweek,
“While Triceratops was not the largest herbivorous to walk the earth—that honor would go to the long-necked sauropod dinosaurs—it was an enormous animal and would no doubt pose a formidable challenge to potential predators.”
Tyrannosaurus RexWhich coexists with Triceratops, meanwhile one of the largest predators known to science.
,Tyrannosaurus Rex Was one of the largest bipedal animals to walk the earth, measuring over 12 meters [40 feet] in length as an adult, with a large, heavy skull, short forelimb, and relatively long counterweight to the tail,” Cullen said. “It would have been the apex predator of its time, and is estimated to have been one of the The strongest bite forces known among any terrestrial carnivore.”
Triceratops and t rex According to Matthew Lamanna, a Carnegie paleontologist, they are among the many other dinosaurs found in the Hell Creek Formation—a rock unit spread across the Montana and Dakota samples—the best evidence of an age just before the asteroid hit. preserves. Museum of Natural History.
Other dinosaurs documented in the Hell Creek Formation include the “duck-billed” herbivorous Edmontosaurus, the heavily armored plant-eating Ankylosaurus, the thick-skulled plant-eating Pachycephalosaurus, the “raptor” Echeroraptor, and the bizarre, bird. Chicken from Hell” Anju, which was described by Lamanna and colleagues in 2014.
“These must have been some of the last non-avian dinosaurs on Earth; most or all probably existed when that giant asteroid fell from the sky 66 million years ago and caused massive environmental disturbances,” Lamanna said.
“The ancient environment of the Hell Creek Formation must have been a coastal lowland adjacent to a gently flowing inland sea. In terms of modern analogies, it is often compared to places such as the Louisiana Bayou—hot, humid, and chock-full of succulents. , diverse flora.”
The above dinosaurs were very typical of western North America and do not appear to have lived anywhere else.
“Dinosaur fossil-bearing rocks from the very end of the Mesozoic are very rare on other continents, but it is clear that various dinosaur creatures were living on other lands when the asteroid hit,” Lamanna said.
“For example, fragmented fossils have been found in sea rocks that date to the latest Mesozoic in Morocco that indicate the presence of a small-faced, short-armed, sometimes horny meat-eating dino group called abelisaurids. which were probably not found in the North. Americas or Asia at that time.”
Some species of giant, long-necked sauropod dinosaurs known as titanosaurs were also alive at the time of the mass extinction event.
“One of the last people is the Jainosaurus that trampled the red rocks of India before it was even associated with the rest of Asia,” Post said.
Roughly speaking, at roughly the same time as the mass extinction event and geologically speaking it was also shortly before (so many million years ago) when large bizarre theropod species such as Deinocheurus and Therizinosaurus were found in Mongolia. could, and the long-necked herbivorous Rapetosaurus, according to Cullen. The predatory theropod Majungasaurus can be found in Madagascar, and the relatively small and likely aquatic Vegavis can be found in Antarctica.
“Vegavis is particularly interesting in being representative of the only group of dinosaurs to actually survive a mass extinction—birds,” Cullen said. “It has been thought to be quite similar in appearance to modern waterfowl such as ducks and geese, and lived in a relatively cool climate along the coastlines in the southern polar region, which, although cooler by Cretaceous standards, was still significantly warmer than Antarctica today. . “
Therefore, it is probably not really correct to talk about “last” dinosaurs when birds (i.e. avian dinosaurs) are essentially living dinosaurs, with more than 10,000 species present on Earth today.