Most people think of dinosaurs as big, ferocious and extinct reptiles.
That's largely true, but there are some misconceptions. Dinosaurs came
in all shapes and sizes. Dinosaurs were the largest land animals of all
time, but a great number of dinosaurs were smaller than a turkey.
Dinosaurs first appeared about 230 million years ago. They ruled the Earth for about 135 million years until an extinction event 65 million years ago wiped out all but bird-like dinosaurs. Scientists don't agree entirely on what happened, but the extinction likely was a double or triple whammy involving an asteroid impact, choking chemicals from erupting volcanoes, climate change and possibly other factors.
Yet only the big, classic dinosaurs are extinct. Birds are living dinosaurs, most experts believe. Think of that next time a pigeon strafes you.
Fossils show that some of the more advanced dinosaurs had feathers or feather-like body covering, but many of them didn't fly and probably didn't even glide. Archaeopteryx, which was for a long time considered to be the first bird (although this status is not certain), is the most famous example. Instead, feathers, rather than being an adaptation for flight, helped these bird-like non-birds stay warm as juveniles.
Many people think extinct flying reptiles called pterosaurs were dinosaurs. They were dinosaurs' closest relatives but technically not dinosaurs. Pterosaurs had hollow bones, relatively large brains and eyes, and, of course, the flaps of skin extending along their arms, which were attached to the digits on their front hands. The family includes Pterodactyls, with elaborate, bony head crests and lack of teeth. Pterosaurs survived up until the mass die-off 65 million years ago, when they were went the way of the dodo along with marine reptiles and other dinosaurs.
Dinosaurs first appeared about 230 million years ago. They ruled the Earth for about 135 million years until an extinction event 65 million years ago wiped out all but bird-like dinosaurs. Scientists don't agree entirely on what happened, but the extinction likely was a double or triple whammy involving an asteroid impact, choking chemicals from erupting volcanoes, climate change and possibly other factors.
Yet only the big, classic dinosaurs are extinct. Birds are living dinosaurs, most experts believe. Think of that next time a pigeon strafes you.
Fossils show that some of the more advanced dinosaurs had feathers or feather-like body covering, but many of them didn't fly and probably didn't even glide. Archaeopteryx, which was for a long time considered to be the first bird (although this status is not certain), is the most famous example. Instead, feathers, rather than being an adaptation for flight, helped these bird-like non-birds stay warm as juveniles.
Many people think extinct flying reptiles called pterosaurs were dinosaurs. They were dinosaurs' closest relatives but technically not dinosaurs. Pterosaurs had hollow bones, relatively large brains and eyes, and, of course, the flaps of skin extending along their arms, which were attached to the digits on their front hands. The family includes Pterodactyls, with elaborate, bony head crests and lack of teeth. Pterosaurs survived up until the mass die-off 65 million years ago, when they were went the way of the dodo along with marine reptiles and other dinosaurs.
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