Long-held beliefs about dinosaurs before an asteroid strike are called into question by new research.

According to recent studies, North American dinosaur populations were flourishing just prior to the asteroid collision that caused their global extinction 66 million years ago.

This discovery provides a new angle on the long-running scientific controversy of whether or not their numbers were already declining. Experts warn that this is just one aspect of the global ecological challenge, though.

Before they were suddenly exterminated, dinosaurs roamed around in "distinct communities," according to research co-author Daniel Peppe, a palaeontologist at Baylor University.

The most recent proof comes from an analysis of a section of northern New Mexico's Kirtland Formation, which has been recognised for almost a century to contain a number of intriguing dinosaur fossils.

According to scientists, those fossils and the rocks around them are from a brief period of geologic time—roughly 400,000 years before the asteroid crashed. By examining tiny volcanic glass fragments found in sandstone and examining the orientation of magnetic minerals in the rock formation's mudstone, the age was ascertained.

According to Mr. Peppe, the findings indicate that "the animals deposited here must have been living close to the end of the Cretaceous," the final period of dinosaurs.

"The idea that dinosaurs were in decline is contradicted by the differences between the dinosaur species found in New Mexico and those found at a site in Montana previously dated to the same time frame," he said.

The massive, long-necked dinosaur Tyrannosaurus Rex and a horned herbivore resembling Triceratops are among the remains previously discovered at the New Mexico location.

Evidence from a single site may not indicate a larger trend, according to scientists who were not involved in the study.

Mike Benton, a palaeontologist from the University of Bristol who was not involved in the work, described the new data on these very late-surviving dinosaurs in New Mexico as "very exciting."

However, he clarified that this was "just one location." The intricacy of dinosaur faunas during the time, whether in North America or elsewhere, was "not a representation of the time."

According to Andrew Flynn, a palaeontologist and research co-author from New Mexico State University, scientists have discovered dinosaur remains on every continent, but precisely dating them has been difficult.

Researchers must hunt for nearby rocks with specific features that can be used to calculate dates because easily datable material, like carbon, does not remain in fossils.

According to Mr. Flynn, more investigation could help palaeontologists finish determining the variety of dinosaur species that were living on the eve of the asteroid disaster.

According to Dr. Lockwood's research, which was published in the scientific journal Papers in Palaeontology, the animal most likely had a noticeable sail-like feature over its back.

"Evolution seems to favour the extravagant over the practical at times," he remarked. Although the precise function of these features has long been disputed, with theories ranging from fat storage to body heat regulation, researchers think that visual signaling—possibly as part of a sexual display—is the most likely explanation in this instance, which is typically due to sexual selection.

Sail structures are frequently more noticeable in males of modern reptiles, indicating that these features developed to frighten off potential mates or rivals. We believe that Istiorachis might have been acting similarly.

In order to determine how these sail-like formations had formed, the researchers compared the fossilised bones with a database of comparable dinosaur back bones.

"We demonstrated that Istiorachis's spines weren't just tall, but more pronounced than is typical of dinosaurs resembling Iguanodons, which is precisely the kind of characteristic you'd expect to evolve through sexual selection," Dr. Lockwood stated.

The iguandontian dinosaurs of the Isle of Wight have been brought to life by Jeremy's meticulous examination of fossils that have been in museum collections for a number of years, according to Natural History Museum Professor Susannah Maidment.

His research emphasises the value of collections such as Dinosaur Isle's, where fossil specimens are kept forever and may be examined and updated in light of fresh information and evolving theories.

"Istiorachis shows that we still have a lot to learn about Early Cretaceous ecosystems in the UK, and Jeremy alone has quadrupled the known diversity of the smaller iguanodontians on the Isle of Wight over the last five years."