Megalosaurus: 1st dinosaur was named 200 years ago – 02/15/2024 – Science

On February 20, 1824, English naturalist and theologian William Buckland addressed the Geological Society of London, describing a huge jaw and limb bones unearthed in a slate quarry in the village of Stonesfield, near Oxford.

He recognized that these fossils belonged to a huge extinct reptile and gave it a formal scientific name: Megalosaurus, which means big lizard. With this, the first dinosaur was officially recognized, although the word dinosaur itself was only coined in the 1840s.

“It was the beginning of our fascination with dinosaurs,” said paleontologist Steve Brusatte of the University of Edinburgh. The announcement, according to him, also started a race for fossils, not only in England but in other countries.

Over the next 200 years, research revealed how these creatures lived, evolved, and what doomed them. Dinosaurs roamed the planet from 231 million years ago to 66 million years ago, during the Mesozoic Era.

“Our understanding of dinosaurs has changed significantly since the 19th century,” said paleontologist Emma Nicholls of the University of Oxford’s Natural History Museum, home of the dinosaur fossils. Megalosaurus studied by Buckland.

“Buckland and other naturalists of the early 19th century would be shocked by how much we now know about dinosaurs,” she added.

O Megalosaurus is an example of that. Buckland thought it was a lizard about 20 meters long, walked on four legs and could live on land or in water. Today, scientists know that it was not quadrupedal and was not a lizard, but belonged to the theropod group, formed by carnivorous dinosaurs such as Tyrannosaurus and Spinosaurusand was approximately 9 meters long.

“It ran on its hind legs, chasing its prey,” Brusatte said.

Like others at the time, Buckland did not understand how long dinosaurs lived, believing the Earth was only a few thousand years old. It is known today that our planet is around 4.5 billion years old. O Megalosaurus lived about 165 million years ago.

English naturalist Richard Owen recognized that fossils found in southern England of Megalosaurus and two other large land reptiles, Iguanodon It is Hylaeosaurusformed a common group, calling them “Dinosauria” in an 1841 lecture and in a publication the following year.

The subsequent discovery of fossils of Hadrosaurus It is Dryptosaurus in New Jersey, in the United States, showed that at least some dinosaurs were bipedal. Beginning in the 1870s, the first complete skeletons of large species — first in the American West, then in Belgium and elsewhere — demonstrated the diversity of these animals.

In the 1960s, the identification of the carnivore Deinonychus shook science by showing that dinosaurs could be small and agile. Some were anatomically similar to primitive birds like the Archeopteryx, confirming how birds evolved from small, feathered dinosaurs. It also sparked a debate over whether dinosaurs were warm-blooded like birds, contradicting the long-held view that they were slow, heavy and cold-blooded.

“In the following decades, there was an increase in work on dinosaur growth, in the use of CT scans, in analytical methods for reconstructing evolutionary relationships and biomechanical function, all of which helped to create a more dynamic and biological view of dinosaurs as living beings,” said paleontologist Thomas Holtz of the University of Maryland.

Paleontologists place cranial fossils in computerized tomography scanners to build digital models of brains, gaining better knowledge of senses such as vision, hearing and smell. Researchers can also determine the color of dinosaurs if their skin or feathers are preserved to retain microscopic blobs of melanosomes that contain pigment in the cells.

Currently, more than 2,000 species of dinosaurs are known and paleontology is a vibrant and international science. Remarkable fossil discoveries are being made in places such as China, Argentina, Brazil, South Africa and Mongolia.

“As far as dinosaur discoveries in recent decades are concerned, the most important, in my opinion, is that at least the carnivorous dinosaurs, theropods, had feathers rather than scales and that some had very well-developed feathers on their arms. , even if they were unable to fly,” said paleontologist Hans-Dieter Sues of the Smithsonian Institution’s National Museum of Natural History in Washington.

“Possibly, these feathers, which were often colorful, provided insulation for the body and, in at least some species, were used for display,” Sues added.

End of the Age of Dinosaurs

The extinction of dinosaurs has long intrigued scientists, with several hypotheses offered, some plausible and others ridiculous. Some have even proposed that the shrew-sized mammals of the time devoured dinosaur eggs.

In 1980, researchers identified a layer of sediment dated precisely to the end of the Age of Dinosaurs containing high concentrations of iridium, an element common in meteorites, indicating that a huge asteroid had hit Earth. The Chicxulub crater on Mexico’s Yucatan Peninsula—180 km in diameter—was later identified as the site of the asteroid impact that wiped out three-quarters of Earth’s species, including dinosaurs.

If this asteroid had gone in another direction, would dinosaurs still dominate the Earth?

“Almost certainly yes,” Holtz said. “Mammals emerged shortly after the first dinosaurs, but spent many millions of years in their shadow. Mesozoic mammals were highly successful and diverse, but only at smaller body sizes.”

“Dinosaurs would have had to deal with the eventual drying out and cooling of the world, and with it the reduction of forests and their replacement by grasslands,” Holtz added. “But these changes appear to have been gradual enough that dinosaurs had a chance to evolve and adapt to new conditions, just as large mammals did.”

Scientists evaluated dinosaur metabolism using a formula based on body mass, revealed by the volume of their thigh bones, and growth rates, demonstrated by growth rings on tree-like fossil bones. Research has suggested that dinosaurs were intermediate between today’s warm-blooded and cold-blooded animals.

Scientists have also refined their assessment of the size of several dinosaurs, including the sauropod group. A 2023 study, based on the dimensions of the paw bones, crowned the Argentinosauruswhich was about 35 meters long, like the heavyweight champion weighing about 76 tons.

Even after two centuries, the research is far from over.

“Outside the field of new technology, there are still many wastelands in various corners of the world that are largely unexplored paleontologically,” Holtz said. “These regions will reveal new species from the Age of Dinosaurs. It is virtually certain that there are entire groups still unknown.”