The first dinosaur was named 200 years ago. We know so much more now
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[February 13, 2024]
By Will Dunham
(Reuters) - On Feb. 20, 1824, English naturalist and theologian William
Buckland addressed the Geological Society of London, describing an
enormous jaw and limb bones unearthed in a slate quarry in the village
of Stonesfield near Oxford.
Buckland recognized that these fossils belonged to a huge bygone
reptile, and gave it a formal scientific name: Megalosaurus, meaning
"great lizard." With that, the first dinosaur was officially recognized,
though the actual word dinosaur would not be coined until the 1840s.
"It was the beginning of our fascination with dinosaurs," University of
Edinburgh paleontologist Steve Brusatte said. "His announcement opened
the flood gates and started a fossil rush, and people went out looking
for other giant bones in England and beyond."
In the intervening 200 years, dinosaur science has flourished, providing
insight into what these creatures looked like, how they lived, how they
evolved and what doomed them. Dinosaurs trod the planet from about 231
million years ago to 66 million years ago during the Mesozoic Era. Their
bird descendants remain with us today.
"Our understanding of dinosaurs has changed significantly since the 19th
century," said paleontologist Emma Nicholls of the Oxford University
Museum of Natural History, home to the Megalosaurus fossils Buckland
studied.
"Buckland and other gentlemen naturalists of the early 19th century
would be stunned at how much we now know about dinosaurs," Brusatte
added.
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 the water. Scientists now know it was not quadrupedal and not a
lizard, but belonged to the theropod group comprising meat-eating
dinosaurs such as Tyrannosaurus and Spinosaurus and was about 30 feet (9
meters) long.
"It scampered around on its hind legs, chasing down its prey, using its
clawed hands and toothy jaws to subdue its victims," Brusatte said.
Buckland, like others at the time, did not grasp how long ago dinosaurs
lived, believing Earth to be only a few thousand years old. Scientists
now know Earth is about 4.5 billion years old. Megalosaurus lived about
165 million years ago.
"It took several decades for geologists to understand that the Earth was
truly old, and that life has evolved over vast stretches of time.
Dinosaurs and the other fossils being discovered were a huge impetus in
this bombshell change in people's understanding of their place in the
world," Brusatte said.
'DINOSAURIA'
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 common group, calling
them "Dinosauria" in an 1841 lecture and a publication the following
year.
The subsequent discovery of Hadrosaurus and Dryptosaurus fossils in the
U.S. state of New Jersey showed that at least some dinosaurs were
bipedal, changing the perception that they had resembled reptilian
rhinoceroses. Beginning around the 1870s, the first complete large
dinosaur skeletons - first in the American West, then in Belgium and
elsewhere - demonstrated the distinctive anatomy and diversity of
dinosaurs.
In the 1960s, the identification of the smallish meat-eating dinosaur
Deinonychus shook up dinosaur science, helping inaugurate a research
period called the "Dinosaur Renaissance." It showed that dinosaurs could
be small and agile. Some were remarkably similar anatomically to early
birds like Archaeopteryx, confirming how birds evolved from small,
feathered dinosaurs. It also prompted a debate over whether dinosaurs
were warm-blooded like birds, contradicting the long-standing conception
of them as slow, lumbering and cold-blooded.
"In the decades following that, there was increasing work on dinosaur
growth, on the use of CT scans, on analytical methods for reconstruction
of evolutionary relationships and of biomechanical function, all helping
to create a more dynamic and biological view of dinosaurs as living
things," said University of Maryland paleontologist Thomas Holtz.
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The skeleton of a Triceratops named "Big John" is seen on display
before its auction by Binoche et Giquello at Drouot auction house in
Paris, France, October 20, 2021. Picture taken with a slow shutter
speed. REUTERS/Sarah Meyssonnier
Paleontologists put cranial fossils into CT scanners to build
digital models of dinosaur brains and ears, gaining better knowledge
of dino senses like sight, hearing and smelling. Researchers also
now can tell the color of dinosaurs if their skin or feathers are
sufficiently well preserved to retain microscopic melanosome bubbles
holding pigment in cells.
More than 2,000 dinosaur species are now known and paleontology is a
vibrant, international science. Remarkable fossil finds are being
made in places such as China, Argentina, Brazil, South Africa and
Mongolia.
"Regarding discoveries about dinosaurs in recent decades, the most
important one to my mind is the discovery that at least meat-eating
dinosaurs, theropods, had feathers rather than scales and that some
had really well-developed feathers on their arms even though they
were, for a variety of reasons, incapable of flight," said
paleontologist Hans-Dieter Sues of the Smithsonian Institution's
National Museum of Natural History in Washington.
"Presumably these feathers, which were often colorful, provided
insulation for the body and, in at least some species, were used for
display," Sues added.
THE KILLER ASTEROID
The extinction of the dinosaurs had long puzzled scientists, with
various hypotheses offered, from the plausible to the ridiculous.
Some even proposed that the shrew-sized mammals of the time ate up
the dinosaur eggs.
In 1980, researchers identified a layer of sediment dating precisely
to the end of the dinosaur age containing high concentrations of
iridium, an element common in meteorites, indicating a huge space
rock had struck Earth. The Chicxulub crater at Mexico's Yucatan
Peninsula - 112 miles (180 km) wide - subsequently was identified as
the impact site of the asteroid that wiped out three-quarters of
Earth's species, including the dinosaurs.
Had that asteroid missed Earth, would dinosaurs still rule, instead
of the mammals - eventually including humans - that inherited a
shattered world?
"Almost certainly yes," Holtz said. "Mammals arose not long after
the first dinosaurs, but spent many tens of millions of years in
their shadows. Mesozoic mammals were highly successful and diverse,
but only at smaller body sizes."
"The dinosaurs would have had to deal with the eventual drying and
cooling of the world, and with it the reduction of the forests and
their replacement with grasslands," Holtz added. "But these changes
seem to have been gradual enough that the dinosaurs would have had a
chance to evolve adaptations to the new conditions, just as large
mammals did."
Scientists have evaluated the metabolism of dinosaurs using a
formula based on body mass, as revealed by the bulk of their thigh
bones, and growth rates, as shown by growth rings in fossil bones
akin to those in trees. The research suggested dinosaurs were
intermediate to today's warm-blooded and cold-blooded animals.
Scientists have also refined their assessment of the size of various
dinosaurs, including the sauropod group that numbered among them the
largest land animals in Earth's history. One 2023 study based on
limb bone dimensions crowned Argentinosaurus, which was around 115
feet (35 meters) long, as the heavyweight champion at about 76
metric tons.
Even after two centuries, the research is far from done.
"Outside the realm of new technology, there are still many badlands
in various corners of the world which are largely unexplored
paleontologically," Holtz said. "These regions will reveal new
species from the age of dinosaurs. There are almost assuredly entire
groups of dinosaurs which we currently know nothing about waiting to
be discovered."
(Reporting by Will Dunham in Washington, Editing by Rosalba O'Brien)
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