What type of animal is a dinosaur?
Dinosaurs are prehistoric reptiles that have lived on Earth from about 245 million years ago to the present. Modern birds are one kind of dinosaur because they share a common ancestor with non-avian dinosaurs.
Nevertheless, Dimetrodon is not a dinosaur; it became extinct about 60 million years before the first dinosaurs evolved (almost the same amount of time that separates humans from Tyrannosaurus rex), and it is more closely related to living mammals, including humans, than it is to any extinct or living reptile.
Crocodiles are not dinosaurs, but both crocodiles and dinosaurs came from the crown group Archosaurs. Archosaurs were reptiles that included birds, crocodiles, pterosaurs, and dinosaurs. Modern-day birds are descendants of feathered dinosaurs, evolving over the last 65 million years.
The closest living relatives of Tyrannosaurus rex are birds such as chickens and ostriches, according to research published today in Science (and promptly reported in the New York Times).
Dinosaurs and many other extinct forms are more closely related to birds than to crocodiles, so this definition would not only include all birds, but all dinosaurs and probably all pterosaurs.
In fact, birds are commonly thought to be the only animals around today that are direct descendants of dinosaurs. So next time you visit a farm, take a moment to think about it. All those squawking chickens are actually the closest living relatives of the most incredible predator the world has ever known!
These relatives of Tyrannosaurus and Velociraptor can be found thriving all over the planet: We call them birds. From AMNH: In the view of most paleontologists today, birds are living dinosaurs.
In an evolutionary sense, birds are a living group of dinosaurs because they descended from the common ancestor of all dinosaurs. Other than birds, however, there is no scientific evidence that any dinosaurs, such as Tyrannosaurus, Velociraptor, Apatosaurus, Stegosaurus, or Triceratops, are still alive.
Plant life consisted mostly of ferns, conifers and small shrubs. Animals included sharks, bony fish, arthropods, amphibians, reptiles and synapsids. The first true mammals would not appear until the next geological period, the Triassic.
So, are chickens dinosaurs? No – the birds are a distinct group of animals, but they did descend from the dinosaurs, and it's not too much of a twist of facts to call them modern dinosaurs. There are many similarities between the two types of animal, largely to do with bone structure.
Is a turtle a dinosaur?
Sea turtles are living dinosaurs, having survived some 90 million years from the Age of the Reptiles.
This extinction was probably caused by a catastrophic asteroid colliding with Earth. It is thought that a an asteroid 4-9 miles (6-15 km) in diameter hit the Earth off the coast of Mexico.
Doing this helped provide more evidence for scientists to confirm that the chicken is currently the closest living relative to the T-Rex. Even before discovering the evidence from the fossil, some scientists observed that chickens and the T-Rex had similar characteristics.
It is an unlikely relationship, but the humble pigeon is a descendant of the group of dinosaurs that also includes the mighty T. rex. The two species share a remarkable biological past.
There are later descriptions of creatures in the Bible that could be referring to dinosaurs. One example is the behemoth of Job 40:15-19. Even in fairly modern history there are reports of creatures which seem to fit the description of dinosaurs.
While all birds are descended from dinosaurs, the mysterious cassowary is thought to be more similar to ancient dinosaurs than most other birds. Large bodied with fierce claws, these flightless birds also have casques, a helmet-like structure atop the head, which many dinosaurs are believed to have had.
Children may confuse a "dragon" as a type of dinosaur. Dragons exist only in stories and myths. However, dinosaurs were once real creatures. Discuss the difference between extinct and mythical animals.
Rhinos are not related to dinosaurs, even remotely. The biggest difference is that rhinos are mammals and dinosaurs are considered reptiles.
Millipedes: The First Land Animals.
The Jakapil kaniukura, shown here in an artist's illustration, is notable for its tiny arms and distinctive jaw. A species of dinosaur recently discovered in Argentina had an armored back, distinctive jaw and tiny arms — and was roughly the size of a dog.
Will dinosaurs ever be back on Earth?
DNA breaks down over time. The dinosaurs went extinct around 66 million years ago and with so much time having passed it is very unlikely that any dinosaur DNA would remain today. While dinosaur bones can survive for millions of years, dinosaur DNA almost certainly does not.
Unfortunately, dinosaurs probably cannot be cloned and brought back to life. Their DNA is too old since dinosaurs have been extinct for over 65 million years. Any genetic information is not likely to survive for one million years, so the dinosaurs are simply too old to be cloned.
Many that dwelled on land were dinosaurs. But no dinos swam in the seas. The oceans had their own cadre of reptiles. Many were top predators, the sharks and killer whales of their time.
Birds belong to the theropod group of dinosaurs that included T. rex. Theropods are all bipedal and some of them share more bird-like features than others. Archaeopteryx, discovered in 1861, was for a long time the only truly bird-like dinosaur – it's from the Late Jurassic era (150 million years ago).
Until the 1980s, discoveries of fossilized eggs and bones of young dinosaurs were extremely rare, but dinosaur eggs have now been discovered on several continents, and fossils of hatchlings, juveniles, and adults have been found for most major groups.