Crocodiles Modern day crocodiles descended from prehistoric alligators such as Deinosuchus; low to the ground water-dwelling predators with a long snout, a powerful tail and lots and lots of teeth.
Deinosuchus (/ˌdaɪnəˈsjuːkəs/) is an extinct genus of alligatoroid crocodilian, related to modern alligators and caimans, that lived 82 to 73 million years ago (Ma), during the late Cretaceous period.
Crocodiles are part of a group of animals known as archosaurs, or “ruling reptiles." This group dominated land, sea, and sky across the planet for more than 150 million years. While they may look like lizards, crocs are more closely related to dinosaurs, including modern birds.
“Large carnivores today, most of them are mammals, and roars are the sounds they produce,” says paleontologist, Julia Clarke. “But when we think about T. rex, this is an animal most closely related to birds and alligators and crocodiles, and those animals make very different kinds of sounds.”
Today's crocodiles, which in scientific terms are part of the Crocodilia Order, first appeared about 95 million years ago. That was 30 million years before dinosaurs went extinct. Crocodiles and birds (yes, birds!) are the only two surviving members of Archosauria, which we'll discuss more of below.
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!
Scientists credit Triops cancriformis as the oldest animal species. Other species may not be quite so old, but the natural histories of the species are similar.
We'll probably never know for sure whether dinosaurs cooed like doves or boomed like cassowaries, but one thing is clear: they almost certainly didn't roar.
There are two main reasons. First, crocodiles can live for a very long time without food. Second, they lived in places that were the least affected when the asteroid hit Earth.
Well, crocodiles share a heritage with dinosaurs as part of a group known as archosaurs (“ruling reptiles”), who date back to the Early Triassic period (250 million years ago). The earliest crocodilian, meanwhile, evolved around 95 million years ago, in the Late Cretaceous period.
Crocodilians are reptiles, the first of which appeared around 320 million years ago. Reptiles arose directly from the amphibians, a diverse group of animals at that time.
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.
Crocodilians are the most closely related group. They evolved before dinosaurs and experts put crocodiles in the larger family group, archosaurs. Strictly speaking, birds are the only direct descendants of the giant, extinct dinosaurs, and crocodiles and alligators are close relatives.
There are two main reasons crocodiles survived the asteroid that killed the dinosaurs. First, crocodiles can live for a very long time without food. Second, they lived in places that were the least affected when the asteroid hit Earth.
Australia has two species of crocodiles, the saltwater or estuarine crocodile, Crocodylus porosus and the freshwater crocodile, C. johnstoni. Readable and well-illustrated reviews of the biology of world crocodilians may be found in Webb & Manolis (1989) and Ross (1989).
The Komodo dragon is a living dinosaur and the world's largest lizard. Komodo dragons can grow up to 3-4 metres in length and weigh over 100kg. Found on the Indonesian island of Komodo, there is a stable population of about 3,000 to 5,000 Komodo dragons in the wild.
Surviving crocodiles did not change throughout millions of years because they arrived at an equilibrium where they were efficient and versatile enough that they did not need to evolve to exist, reports the Conversation.
Fossil records suggest that at one point in history, there were more than 3,000 types of sharks and their relatives. Sharks managed to survive during extinction events when the ocean lost its oxygen – including the die off during the Cretaceous period, when many other large species were wiped out.
No! After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth. However, small mammals (including shrew-sized primates) were alive at the time of the dinosaurs.
But Trevorrow gave the T. rex a low-key intriguing story arc in “Dominion”: In the movie's prologue released online in November and set 65 million years ago, the T. rex is murdered by a Giganotosaurus and a mosquito drinks its blood – the same mosquito found in amber and whose dino DNA is used to clone the T.
Last but not least of the T-Rex's fears would be other adult tyrannosaurs of course! The only other predators that could match a tyrant king in battle is another Tyrannosaurus and while full on death battles wouldn't have been common place, bouts over territory, food, and mating rites were bound to happen.
No T. rex eggs or nests have ever been found, but fossils of other Tyrannosaur relatives suggest that they laid elongated eggs, roughly 20 or more at a time.
By many metrics, the most successful animal species is Homo sapiens: it has conquered the world and can fly around it in a matter of hours; it can live at the polar regions and the equator; plus, it is able to dive the depths of the sea, climb the highest mountains and even go to the moon.
Tardigrades have been around a long time.
Fossils date their existence on Earth to more than 500 million years ago. This means tardigrades have survived the planet's last five mass extinction events.
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). Paleontologists used material discovered in a chance find in 2003 to pin down the link.