Today there are at least 11,000 bird species. But with such a close relationship to the extinct dinosaurs, why did birds survive? The answer probably lies in a combination of things: their small size, the fact they can eat a lot of different foods and their ability to fly.
It is believed that due to the combination of slow incubation and the considerable resources needed to reach adult size, the dinosaurs would have been at a distinct disadvantage compared to other animals that survived the asteroid that struck Earth 66 million years ago.
The gradual evolutionary change - from fast-running, ground-dwelling bipedal theropods to small, winged flying birds - probably started about 160 million years ago. It was possibly due to a move by some small theropods into trees in search of either food or protection.
Birds Survived Mass Extinction That Wiped Out Dinosaurs Because Of Their Larger Brains. Summary: The Cretaceous--Tertiary mass extinction 65 million years ago may have wiped out the dinosaurs, but those that survived -- the ancestors of today's birds -- may have done so because of their bird brains.
Other theories are tied to the fact that living birds lay their eggs in nests, and species that went extinct laid their eggs on the ground. Another looks at how much food the species ate: smaller animals require less food, can hide from the elements better, and in general are better at surviving extinction events.
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.
Once the heat was off, mammals could come back out and make the most of the remaining food resources. There may not have been enough food for dinosaurs, but the more generalized tastes of mammals allowed them to hang on.
Most dinosaurs went extinct. Only birds remained. Over the next 66 million years, birds evolved in many ways, which enabled them to survive in lots of different habitats. Today there are at least 11,000 bird species.
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!
“There is broad agreement that the cause of the dinosaur and pterosaur extinctions were one and the same,” University of Texas, Austin paleontologist Brian Andres says. The aftermath of the asteroid impact is the large scale reason for both.
All lizards and reptiles are closely related to dinosaurs, but none more so than tuatara lizards. The last surviving animal within the Sphenodontia family, these lizards, native only to New Zealand, were around when dinosaurs walked the Earth.
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.
Fossil studies have long suggested modern birds were descended from T. rex, based in similarities in their skeletons. Now, bits of protein obtained from connective tissues in a T. rex fossil shows a relationship to birds including chickens and ostriches, according to a report in Friday's edition of the journal Science.
They would still probably be small, scrawny, and very generalized. But instead, the mammals were able to evolve and diversify and, well, ultimately, millions of years later, become some humans. So perhaps we would not have been here if it weren't for this extinction event 65 million years ago.
The 'Big Five' mass extinctions
There have been five mass extinction events in Earth's history. At least, since 500 million years ago; we know very little about extinction events in the Precambrian and early Cambrian earlier which predates this.
The exact nature of this catastrophic event is still open to scientific debate. Evidence suggests an asteroid impact was the main culprit. Volcanic eruptions that caused large-scale climate change may also have been involved, together with more gradual changes to Earth's climate that happened over millions of years.
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.
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.
Other than birds, however, there is no scientific evidence that any dinosaurs, such as Tyrannosaurus, Velociraptor, Apatosaurus, Stegosaurus, or Triceratops, are still alive. These, and all other non-avian dinosaurs became extinct at least 65 million years ago at the end of the Cretaceous Period.
Although that would be fascinating, the answer is almost definitely no. While there's only one generation between you and your grandparents – that is, your parents – there are many millions of generations between today's birds and their ancient dinosaurs ancestors.
Other than birds, Dinosauria doesn't include any living creature. So for a dinosaur to re-evolve in the future, it would have to come from a bird.
Paleontologists think feathers may have first evolved to keep dinosaurs warm. But while a young T. rex probably had a thin coat of downy feathers, an adult T. rex would not have needed feathers to stay warm.
For approximately 120 million years—from the Carboniferous to the middle Triassic periods—terrestrial life was dominated by the pelycosaurs, archosaurs, and therapsids (the so-called "mammal-like reptiles") that preceded the dinosaurs.
Birds: Birds are the only dinosaurs to survive the mass extinction event 65 million years ago. Frogs & Salamanders: These seemingly delicate amphibians survived the extinction that wiped out larger animals. Lizards: These reptiles, distant relatives of dinosaurs, survived the extinction.
Dinosaurs really did suffer from a variety of ailments. Dinosaurs scratched at parasites, endured bone infections, and even developed cancer. But we now know that there wasn't a dramatic uptick in dinosaur sickness between the Triassic and Cretaceous.