Dinosaurs were a successful group of animals that formed 240 to 230 million years ago and ruled the world until about 66 million years ago when a giant asteroid crashed onto Earth. During this time, dinosaurs evolved from a group of mostly dogs. and creatures the size of a horse to the largest animals that ever existed on earth.
Some carnivorous dinosaurs got smaller and evolved into birds over time. In that sense, only non-avian dinosaurs died out.
During the roughly 174 million years that dinosaurs existed, the world changed tremendously. When dinosaurs first appeared in the Triassic (252 million to 201 million years ago), they roamed the supercontinent of Pangea. When the asteroid collided at the end of the Cretaceous Period (145 million to 66 million years ago), the continents were roughly where they are today.
What Are Dinosaurs?
The most unmistakable dinosaur fossils date back to around 231 million years ago and originate from the Ischigualasto Provincial Park in northwest Argentina and include the genera Herrerasaurus, Eoraptor, and Eodromaeus. Scientists are still debating whether Nyasasaurus, a genus found in Tanzania that is about 240 million years old, is also an early dinosaur or a dinosaur, a group that includes dinosaurs and their close relatives, said Steve Brusatte, a paleontologist the University of Edinburgh in Scotland.
Whenever they first appeared, the unique anatomy of dinosaurs sets them apart from other groups of animals; dinosaurs are archosaurs, a clade (different groups of animals that have a common ancestor) that includes crocodiles, pterosaurs, dinosaurs, and birds. Archosaurs emerged after the last Permian extinction about 252 million years ago. Over time, some archosaurs, including dinosaurs, adapted to an upright posture, which meant they had legs under their bodies rather than on their sides.
Creatures that don’t have to move very quickly. But tucking the limbs under the body opens up a whole new world of possibilities, ”wrote Brusatte in“ The Rise and Fall of the Dinosaurs: A New History of a Lost World ”(William Morrow, 2018). Archosaurs, dinosaurs were given long tails, large leg muscles, and extra hip bones that allowed them to move quickly and efficiently, Brusatte wrote.
Some dinosaurs evolved into dinosaurs. The differences between the two are small, but the dinosaur anatomy offered greater benefits, including arms that could move in and out, vertebrae in the neck that could support stronger muscles than before, and a joint on which the thigh bone could be attached hits the pelvis, wrote Brusatte.
This unique anatomy helped the dinosaurs to succeed. An upright posture also freed the hands so dinosaurs like iguanodons could grab branches and carnivorous dinosaurs could scratch and kill prey, said Gregory Erickson, a paleobiologist at Florida State University. “They allowed the glide and then the birds to fly in,” he said. Also, according to research into their growth rates, the dinosaurs were likely warm-blooded. “When you become a warm-blooded animal, you can work 24 hours a day, 7 days a week,” Erickson told Live Science. “You are not exposed to the whims of the environment when it comes to being active.
Initially, dinosaurs weren’t as diverse as the crocodile-like archosaurs they lived with, noted Brusatte. In fact, dinosaurs “weren’t immediately very successful; Crocodiles ruled the Triassic, then the end of the Triassic was critically endangered and the dinosaurs survived and took over.
The clade Dinosauria (which means “terrible lizard” in Greek) was coined in 1842 by the English paleontologist Richard Owen, who included the theropod Megalosaurus, the long-necked sauropodomorph Cetiosaurus and the Ornithiscian Iguanodon as the first known species in the clade. based on the book “Dinosaurs Rediscovered” (Thames and Hudson, 2019).
It turns out that each of these dinosaurs represents one of the three main groups of dinosaurs.
Types of Dinosaurs
In 2021, there were 1,545 scientifically described types of dinosaurs, according to the paleobiological database. About 50 previously unknown species are described each year, which means roughly one new species is described every week, Brusatte said.
All of these dinosaurs fit into one. from three groups: Ornithischia, Sauropodomorpha, and Theropoda.
Ornithischian dinosaurs include beaked dinosaurs like Stegosaurus, duckbill dinosaurs (also called hadrosaurs), as well as horned dinosaurs like Triceratops and armored dinosaurs like Ankylosaurus. Some Ornithischians went on all fours, others on two.
Dinosaurs with tiny heads and columnar limbs. This group includes sauropods (like Diplodocus), their smaller ancestors (including Chromogisaurus), and extra-large sauropods known as titanosaurs (like Dreadnoughtus and Argentinosaurus), which are some of the greatest land animals of all time.
Theropods are a group of dinosaurs that eat meat, although some (like Chilesaurus diegosuarezi) have changed their diets to herbivores or omnivores, including Tyrannosaurus rex and Velociraptor, as well as birds that evolved from small theropods.
Ornithischian dinosaurs have a backward-pointing pubic bone. on the hip, which earned them the name avian dinosaurs (they are not, however, the ancestors of birds; theropods are. Meanwhile theropods and sauropodomorphs have Saurischians or “reptile hips”, which according to the book “Dinosaurs Rediscovered” can also be seen in modern crocodiles and lizards.
However, a 2017 study in the journal Nature uprooted the dinosaur family tree by suggesting that ornithischians and theropods were more closely related, based on analyzes of 74 species of dinosaurs, Live Science reported. The journal Nature found that none of the family trees, as well as a rarely viewed third family tree, are statistically significant over the other, meaning that all proposed family trees are equally plausible until further evidence emerges.
When Did They Live?
The Mesozoic Era, a geological age that lasted 252 million to 66 million years ago. Dinosaurs emerged from small dinosauromorphic ancestors in the Triassic when the climate was harsh and arid.
They “faced competition from croclin archosaurs for tens of millions of years, [but] they finally prevailed when Pangea began to split,” Brusatte told Live Science. At that time, volcanoes erupted along the supercontinent’s fissures, causing global warming and mass extinction, he said.
During the Jurassic Period (201 million to 145 million years ago) dinosaurs gained dominance and some grew to enormous sizes. For example, Vouivria damarisensis, the oldest titanosaur, is 160 million years old and weighed about 33,000 pounds (15,000 pounds). Kilograms) and over 15 meters long. Iconic dinosaurs from this period include Brontosaurus, Brachiosaurus, Diplodocus, and Stegosaurus. Flowering plants developed during the Jurassic and birds, including Archeopteryx, first appeared. There was “a small extinction at the end of the Jurassic that we still know little about,” said Brusatte.
In the Cretaceous Period, the dominance of dinosaurs continued as the continents diverged further. Famous dinosaurs of this time are the T. rex, Triceratops, Spinosaurus and Velociraptor.The largest known dinosaurs, including Argentinosaurus, date from the Cretaceous Period. The Cretaceous Period ended with the extinction of the Tertiary Cretaceous (KPg) when an asteroid 10 kilometers wide collided with the earth, leaving an impact crater more than 180 kilometers long. ) in diameter on the Yucatan Peninsula in what is now Mexico.
The impact area, known as Chicxulub Crater (CHEEKshehloob), shows evidence of “shocked quartz” and small glass-like spheres called tektites that form when rock evaporates and cools quickly – geological evidence that a space rock is incredibly powerful There Betsy Kruk, an associate paleontologist at Paleo Solutions, a California-based paleontology consulting firm, told Live Science. Chemical analyzes of the sedimentary rocks of Chicxulub melted and mixed at temperatures equivalent to an asteroid impact 66 million years ago, he added.
Why are the biggest dinosaurs? The smallest dinosaurs?
Some dinosaurs were huge.The smallest known dinosaur is a bird dinosaur living today: the Cuban bee hummingbird (Mellisuga helenae), which is just over 5 inches long and weighs less than 0.07 ounces (2 grams). ). As for dinosaurs not extinct by birds, there are a few candidates for the smallest animal, including a bat-like dinosaur from China called Ambopteryx longibrachium that was 32 cm long and weighed about 306 g, according to a 2019 study in the journal Nature.
Titanosaurs, however, were the largest dinosaurs because paleontologists rarely find a complete skeleton and because soft tissues such as organs and muscles rarely petrify, which determines the mass of the dinosaur, which weighed up to 110 tons (100 tons), an unnamed 98 million year old Argentine titanosaur, who weighed over 69 tons (63 tons), and Patagotitan who also weighed 69 tons.
The longest dinosaur is likely to be Diplodocus or Mamenchisaurus – long, slender sauropod dinosaurs that were approximately 35 feet (35 m) long. The largest dinosaur is likely Giraffatitan, a 12 m long sauropod dinosaur from the late Jurassic about 150 million years ago that lived in what is now Tanzania.
Pterosaurs are not dinosaurs
Many amazing animals lived in the age of the dinosaurs and some are mistaken for dinosaurs. Pterosaurs are winged reptiles and archosaurs, which means that they are relatives of dinosaurs but are not dinosaurs.
The order Crocodilia includes extinct and living crocodiles and their close relatives. Crocodiles are archosaurs, but not dinosaurs. Live crocodiles and birds (which are dinosaurs) are the only surviving members of the Archosauria group.
The Mesozoic oceans were teeming with marine life, including predatory reptiles known as Mosasaurus (like Mosasaurus), plesiosaurs, and ichthyosaurs. However, none of these reptiles are dinosaurs.
Did They have feathers?
Yes, some dinosaurs displayed feathers, as did their bird offspring. The feathers do not petrify well, but some notable fossils, particularly those from Liaoning Province in China that were buried after a volcanic eruption, have preserved the feathers. Here are some examples: Zhenyuanlong suni, Yutyrannus huali, and Jianianhualong tengi.
It’s not clear why dinosaurs first developed feathers, but they could be used to: as insulation to keep dinosaurs and their hatching eggs warm; for displays for use in dinosaur communication, such as courtship displays; and for gliding or powered flying, Michael Habib, a research fellow at the Dinosaur Institute at the Los Angeles County Museum of Natural History, previously told Live Science.
Originally only theropods and their offspring were thought to carry feathers, but researchers have also found soft feathers in the planter ornithischian dinosaur Kulindadromeus zabaikalicus, suggesting that the feathers were more common than previously thought, a 2014 study in the journal Science.
According to a 2018 study in the journal Nature Ecology and Evolution, pterosaurs may have feathers, but more feathered specimens need to be found and analyzed to be certain.
Noteworthy, even the T. rex had feathers. They rarely have feathers in popular culture, including the Jurassic Park films. Paleontologist Jack Horner, who served as a scientific advisor on some of the Jurassic Park films, recalls telling director Steven Spielberg that dinosaurs should have feathers.
“Even when Jurassic Park came out [in 1993] we knew velociraptors should have feathers, but at the time it would have been technically difficult to do that just from a CG (computer generated) point of view. Really too excited about that when I told him they should be brightly colored and have feathers and he said, ‘Feathered Technicolor dinosaurs aren’t scary enough,’ “Horner previously told Live Science.
Could They Fly?
Some could fly, including the oldest known bird, Archeopteryx, which was discovered in Germany and dated about 150 million years ago, in the late Jurassic.
However, unlike most birds today, extinct dinosaurs likely flew short distances. Research shows that ancient birds and bird-like dinosaurs required strong leg muscles, large wings, and a relatively small height for takeoff and flight, Habib previously told Live Science. Research suggests that the bird-like dinosaurs Microraptor, Rahonavis, and five species of birds (Archeopteryx, Sapeornis, Jeholornis, Eoconfuciusornis, and Confuciusornis) may have shot off the ground to initiate flight.
According to a 2015 study published in the journal Nature, Bat like dinosaur Yi qi dating to China Jurassic Period.
Why Did Dinosaurs Extinct?
The question is how well the dinosaurs were doing before the asteroid hit Earth. A handful of studies suggest that dinosaur extinction increased and diversity decreased during the late Cretaceous period, particularly herbivorous dinosaurs. and models that may not tell the full story, Live Science previously reported.
Even if dinosaur diversity declined, they might have recovered if the asteroid hadn’t hit, Brusatte told Live Science. Dinosaurs lived on every continent, including Antarctica, and filled different stages in different ecosystems, from planters to top carnivores. “Dinosaurs have seen many ups and downs in diversity in their more than 150 million years of evolution,” he said. If mass extinction had not occurred, it would be possible “They continue to thrive today like more than birds.
After the asteroid collision, long-term pain followed the chaos. Structure, including shock wave, heat pulse, forest fires, tsunamis” (including an immediate mile-high tsunami), volcanic eruptions, deadly acid rain and earthquakes – the dust and dirt the asteroid kicked up hung in the air.”This hot, dusty rain increased global temperatures for hours after impact and cooked live animals that were too big to take shelter,” said Kruk. “Small animals that could take refuge underground, underwater, or perhaps in caves or large tree trunks.”
Dust and particles stayed in the air, blocking the sun for several years, and causing a nuclear winter that cooled the planet and killed countless plants and animals, Brusatte and Kruk said.
“Smaller omnivorous land animals like mammals, lizards, turtles or birds may have survived as scavengers, feeding on the carcasses of dead dinosaurs, mushrooms, roots and rotting plant matter, while smaller animals with lower metabolisms were better able to wait for one Disaster, “Kruk said earlier. In addition, the asteroid pulverized carbon-rich rocks, releasing carbon into the atmosphere and causing “global warming for a few thousand years”. ars, “after the end of the nuclear winter, Brusatte said.
Scientists previously wondered if the Deccan Traps volcanic eruptions in present-day India played a role in the mass extinction. But recent studies” show that the Deccan probably had very little it was “most likely an innocent bystander “- the asteroid caused the extinction.
Can the dinosaurs be brought back?
In the popular Jurassic Park film series, scientists find DNA from dinosaurs trapped in amber in an old mosquito, and then fill in the gaps in DNA with frog DNA.It’s a fun act, but the science is far from solid. Amber, for example, does not conserve DNA well and frogs are not closely related to dinosaurs; They’re not archosaurs, and a 2017 study in the journal Proceedings of the National Academy of Sciences even found that frog evolution began after the asteroid impact.
For a myriad of reasons, it is currently impossible to bring back extinct dinosaurs. Vessels have been found, and scientists have yet to rigorously identify the DNA of an extinct dinosaur. As soon as an organism dies, DNA begins to break down, but parts of it can be preserved under the right circumstances. However, the oldest sequenced DNA known belongs to a mammoth about a million years old, and dinosaurs became extinct about 66 million years ago.
Some scientists are studying how to turn birds back into dinosaurs, including what is known as the “dino-chicken,” which would have an elongated tail, teeth, arms, and fingers. Chicken embryos dinosaur snouts. However, the “Chickenosaurus” would not be a replica of an ancient dinosaur, but a dinosaur-like bird, the researchers said.
- Look up your favorite dinosaur on the Dino Directory from the Natural History Museum in London.
- Learn amazing facts about dinosaurs at the American Museum of Natural History in New York.
- Take free online dinosaur courses on Coursera, including “Dino 101: Dinosaur Paleontology” and “Paleontology: The Origin of Theropod Dinosaurs and Birds.”