Revolution of understanding of dinosaurs over the last two centuries
Washington – William Buckland, an English naturalist and theologian, 200 years ago – on February 20, 1824, addressed the Geological Society in London regarding the discovery of giant bones in the quarry of the village of Stonesfield near Oxford.
He concluded that they were the remains of a huge reptile from the past – giving it the name Megalosaurus, which meant giant lizard. This officially recognized the existence of the first dinosaur – although the word itself wouldn’t be coined until the 1840s, according to the Rojters agency.
„It was the beginning of the fascination with dinosaurs. Buckland’s announcement initiated the discovery of numerous fossils. A massive search for dinosaur remains began in England and beyond,“ said paleontologist Steve Brusat from the University of Edinburgh.
Over the past two centuries, the study of dinosaurs has created a perception of the appearance of these creatures, their life, evolution, and the reasons for their extinction. They lived on Earth from about 231 million years ago to 66 million years ago – during the Mesozoic era. They left behind avian descendants.
„Our perception of dinosaurs has changed significantly since the 19th century. Buckland and other scientists of his time would be surprised by our knowledge of dinosaurs,“ said paleontologist Emma Nichols from the Oxford University Museum of Natural History, where the fossils of Megalosaurus studied by William Buckland are kept.
Megalosaurus is a true example of this. Buckland believed it was a twenty-meter long lizard that used four legs to move and lived on land or in the water, according to Rojters.
Swinging and chasing for prey
Modern scientists have determined that Megalosaurus was not a four-legged lizard – but was part of a group of theropods that included meat-eating dinosaurs such as Tyrannosaurus and Spinosaurus, which were about nine meters tall.
„It would swing on its hind legs, chasing prey, using its clawed forelimbs and sharp teeth to overpower its victims,“ Brusat describes.
Buckland, like his contemporaries, was not aware of how long ago the dinosaurs lived. They believed that the Earth at their time was only a few thousand years old. It is now clear that the Earth was formed about 4.5 billion years ago, and Megalosaurus 165 million years ago.
„It took geologists several decades to understand the facts about when the Earth was formed and how life on it evolved over very long periods of time. Dinosaurs and other fossils provided a huge boost in changing the understanding of the place, role, and position of humans on Earth,“ Brusat emphasized.
English naturalist Richard Owen realized, based on the study of Megalosaurus fossils found in southern England, as well as two large terrestrial reptiles, Iguanodon and Hyaleosaurus, that they lived in a group he called Dinosauria – his 1841 lecture and publication the following year.
Subsequent discovery of the fossils of Hadrosaurus and Driptosaurus in the U.S. state of New Jersey showed that some dinosaurs were bipeds. This changed the perception that dinosaurs resembled rhinoceros-reptiles. Beginning in the 1870s, the first complete large dinosaur skeletons – found first in the American West, then in Belgium and elsewhere – pointed to the recognizable anatomy and diversity of dinosaurs.
Birds and feathered dinosaurs
In the 1960s, the identification of a small carnivorous dinosaur – Deinonychus – shook up established scientific knowledge, directing research in a direction known as the Dinosaur Renaissance. It turned out that dinosaurs could be small and agile. Some of them were anatomically very similar to early bird species, such as Archaeopteryx, confirming that birds evolved from feathered dinosaurs. This also sparked debates about whether dinosaurs were warm-blooded like birds, which is contrary to the long-held belief that they were slow, cumbersome, and cold-blooded creatures.
„In the decades that followed, much more was done to study the growth of dinosaurs, the use of modern technology, the reconstruction of evolutionary relationships, and biomechanical function. This helped to create a more dynamic biological view of dinosaurs,“ explained paleontologist Thomas Holt from the University of Maryland.
Today, paleontologists use scanners to create digital models of dinosaur brains and ears, and to learn more about their senses of sight, hearing, and smell. It is possible to determine their color, or whether their feathers or skin are well enough preserved to retain pigment in the cells.
There are more than 2,000 species of dinosaurs known, and paleontology has become an international science. Dinosaur fossil sites are scattered around the world – in China, Argentina, Brazil, South Africa, and Mongolia.
„When it comes to discoveries related to dinosaurs in recent decades, one of the most important is that theropods – meat-eating dinosaurs – had feathers instead of scales. Some of them had very lavish feathers, although they were not able to fly,“ explained paleontologist Hans-Dieter Sues from the Smithsonian National Museum of Natural History in Washington.
Dinosaur extinction: Who ate their eggs?
The extinction of dinosaurs has long puzzled scientists. It was explained by various hypotheses – from credible to naive. According to some of them, mammals the size of raccoons ate dinosaur eggs, which led to their extinction.
However, in 1980, researchers identified a layer of sediments that coincided with the end of the dinosaur era. They contained a high concentration of iridium, an element common in meteorites, indicating the impact of a giant rock on Earth.
The Chicxulub crater on Mexico’s Yucatan Peninsula, 180 kilometers wide, was later identified as the site of the asteroid impact that wiped out three-quarters of Earth’s species, including dinosaurs.
If the asteroid had missed Earth, would dinosaurs still rule it instead of mammals – and even humans, who are said to have inherited the devastated world?
„Almost certainly. Mammals emerged shortly after the first dinosaurs, but spent tens of millions of years in their shadow. Dinosaurs would have had to cope with possible drying and cooling of the world, and thus a reduction in forested areas. It seems that these changes happened gradually enough for dinosaurs to have had the opportunity to adapt, just like mammals,“ explained paleontologist Holt.
Over the years, much more precise estimates of the sizes of different dinosaur species have been made, including the Sauropoda group – considered the largest land animal to walk the Earth. A 2023 study based on the dimensions of limb bones marked Argentinosaurus, around 35 meters tall, as the heavyweight champion with about 76 tons of weight.
However, despite two centuries of research, the work is far from finished.
„Apart from new technology, there are still many deserts in different parts of the world that are mostly unexplored. These regions will reveal new dinosaur species from the age of dinosaurs. There are almost certainly entire groups about which we know nothing and we look forward to their discovery,“ concluded Thomas Holt from the University of Maryland.
