By Will Dunham
(Reuters) – On February 20, 1824, English naturalist and theologian William Buckland addressed the Geological Society of London, describing a giant jaw and limb bones found in a slate quarry in the village of Stonesfield near Oxford.
Buckland identified these fossils as belonging to a giant, extinct reptile, and gave it a formal scientific name: Megalosaurus, meaning “big lizard.” With that, the first dinosaur was officially recognized, although the actual word dinosaur wouldn’t be coined until the 1840s.
“It was the beginning of our interest in dinosaurs,” said University of Edinburgh paleontologist Steve Brusatte. “His announcement opened the floodgates and started a fossil rush, and people went out looking for other giant bones in England and further afield.”
In the intervening 200 years, dinosaur science has boomed, providing insights into what these creatures looked like, how they lived, how they developed and what happened to them. Dinosaurs roamed the planet from about 231 million years ago to 66 million years ago during the Mesozoic Era. Their bird offspring remain with us today.
“Our understanding of dinosaurs has changed dramatically since the 19th century,” said paleontologist Emma Nicholls of Oxford University’s Natural History Museum, home of the Megalosaurus fossils studied by Buckland.
“Buckland and other noble naturalists in the early 19th century would be stunned by what we now know about dinosaurs,” said Brusatte.
Megalosaurus is a case in point. Buckland thought it was a lizard about 66 feet (20 meters) long, walked on four legs and could live on land or in water. Scientists now know that it was not a tetrapod and not a lizard, but belonged to the theropod group made up of meat-eating dinosaurs such as the Tyrannosaurus and Spinosaurus and was about 30 feet (9 meters) long.
“It circles around on its hind legs, chasing its prey, using its clawed hands and its toothy jaws to control its victims,” said Brusatte.
Buckland, like others at the time, did not realize how long ago dinosaurs lived, believing that the Earth was only a few thousand years old. Scientists now know that the Earth is about 4.5 billion years old. Megalosaurus lived about 165 million years ago.
“It took geologists many years to realize that the Earth was really old, and that life has evolved over vast periods of time. The dinosaurs and other fossils that were being discovered were a huge impetus in the change These bombs in people’s understanding of their place in the country. world,” said Brusatte.
The English naturalist Richard Owen recognized that fossils found in southern England of Megalosaurus and two other large land-dwelling reptiles, Iguanodon and Hylaeosaurus, formed a group, called “Dinosauria” in an 1841 lecture and publication of the following year.
The subsequent discovery of Hadrosaurus and Dryptosaurus fossils in the US state of New Jersey revealed that at least some dinosaurs were bipedal, changing the view that they were similar to reptilian rhinoceroses. Beginning around the 1870s, the first complete large dinosaur skeletons—first in the American West, then in Belgium and elsewhere—revealed the distinctive anatomy and diversity of dinosaurs.
In the 1960s, the identification of the small meat-eating dinosaur Deinonychus shook up dinosaur science, helping to inaugurate a period of research called the “Dinosaur Renaissance.” He showed that dinosaurs could be small and agile. Some bore a striking anatomical resemblance to early birds such as Archaeopteryx, confirming how birds evolved from small feathered dinosaurs. It also sparked a debate about whether the dinosaurs were hot birds, contradicting the long-held perception that they were slow, lumbering and cold-blooded.
“In the years that followed, there was increasing work on dinosaur growth, the use of CT scans, analytical methods to reconstruct evolutionary relationships and biomechanical function, all helping to create a more dynamic and biological view of dinosaurs as living things. ,” said University of Maryland paleontologist Thomas Holtz.
Paleontologists put cranial fossils into CT scanners to build digital models of dinosaur brains and ears, gaining better insight into dino senses such as sight, hearing and smell. Researchers can also now tell the color of dinosaurs if their skin or feathers are well preserved to retain microscopic bubbles of pigment in the cells.
There are now more than 2,000 known species of dinosaur and palaeontology is a vibrant international science. Amazing fossil discoveries are being made in places like China, Argentina, Brazil, South Africa and Mongolia.
“In terms of dinosaur discoveries in recent years, the most important in my mind is the discovery that at least meat-eating dinosaurs had feathers rather than scales, and that their arms had highly developed feathers some though they were. , for various reasons, are unable to fly,” said paleontologist Hans-Dieter Sues of the Smithsonian Institution’s National Museum of Natural History in Washington.
“These feathers, which were often colorful, probably provided insulation for the body and, in at least some species, were used for display,” Sues said.
THE KILLING ASTEROID
Scientists have long been puzzled by the extinction of the dinosaurs, with various hypotheses being offered, from the plausible to the ridiculous. Some have even suggested that prehistoric shale mammals ate the dinosaur eggs.
In 1980, researchers identified a series of sediments dating precisely to the end of the dinosaur age that contained high concentrations of iridium, an element common in meteorites, indicating that a giant space rock had hit Earth. The Chicxulub crater on Mexico’s Yucatan Peninsula – 112 miles (180 km) wide – was later identified as the impact site of the asteroid that wiped out three-quarters of Earth’s species, including the dinosaurs.
If that asteroid had missed Earth, would dinosaurs still rule, instead of the mammals – eventually including humans – who inherited a broken world?
“Almost certainly,” said Holtz. “Mammals arose not long after the first dinosaurs, but spent thousands of years in their shadows. Mesozoic mammals were extremely successful and diverse, but only at smaller body sizes.”
“The dinosaurs would eventually have to deal with the drying and cooling of the earth, and with the reduction of the forests and the replacement of grasslands,” said Holtz. “But these changes seem to have been gradual enough to allow the dinosaurs to adapt to the new conditions, just as large mammals did.”
Scientists evaluated dinosaur metabolism using a formula based on body mass, as indicated by most of their femur bones, and growth rates, as indicated by growth rings in fossil bones similar to those in trees. The research indicated that dinosaurs were intermediate between today’s warm-blooded and cold-blooded animals.
Scientists also refined their assessment of the size of various dinosaurs, including the sauropod group that was the largest land animals in Earth’s history. One 2023 study based on limb bone dimensions of the Argentinosaurus, which was about 115 feet (35 meters) long, ranked the heavyweight champion at about 76 metric tons.
Even after two hundred years, the research is far from done.
“Outside the realm of new technology, there are still many badlands in different corners of the world that are largely unexplored paleontologically,” said Holtz. “These regions will reveal new species from the age of dinosaurs. There are definitely whole groups of dinosaurs that we don’t know about right now waiting to be discovered.”
(Reporting by Will Dunham in Washington, editing by Rosalba O’Brien)