Why Are There No More Animals As Big As Dinosaurs On Earth?

Pre-historic times were dominated by giant animals, ranging from dinosaur, giant crocodiles and snakes, to car-sized armadillos. But in this era not many animals are seen that grow to a giant size.

A number of fossil discoveries are evidence of the existence of many giant animals that once lived on Earth Earth.

Although it is known that many giant beasts lived several million years ago, it is not clear why there are not many giant beasts today.

“It’s very multi-factorial,” said Greg Erickson, a vertebrate paleobiologist at Florida State University in Tallahassee who specializes in ancient reptiles. Live Science.

Some of the major differences between dinosaurs and animals now mentioned could help explain why the giant animals disappeared from Earth.

Along with other large reptiles, dinosaurs were adaptable throughout their growth period. They hunt small animals as children and hunt larger prey as adults.

This is possible because they change the row of their teeth during their growth period.

“They change their teeth constantly, like sharks do. But along the way they can change the type of teeth,” says Erickson.

For example, crocodiles change their needle-like teeth into stronger teeth. Meanwhile, mammals do not have this ability.

In other words, as some reptile chicks grow into adults, they swap their relatively small juvenile teeth for larger weapons, which allow them to hunt for larger food items.

Then according to University of Edinburgh paleontologist Steve Brusatte, dinosaurs also had air sacs that probably extended from their lungs to their bones, creating large, sturdy but lightweight animals.

This gave the dinosaur skeleton a strong and flexible, but light weight.

“It helps them get bigger and bigger and bigger. The way it is similar to a skyscraper getting bigger and bigger because of the internal support structure,” Brusatte said.

Mammals do not have such air sacs, which can attach to bones and relieve them

“So the size of an elephant or slightly larger, that’s probably the limit where mammals, at least on land … you can’t really see mammals, get as big as dinosaurs,” Brusatte said.

Separately, Felisa Smith of the University of New Mexico, Albuquerque said giant mammals had a hard time releasing heat in today’s warm climates.

Reported New ScientistSmith believes dinosaurs could have grown into giants because they generated less heat in their bodies.

However, some other experts are not so sure of Smith’s conjecture. Doland Prothero, a paleontologist at Occidental College Los Angeles, said the evolutionary process is better seen from the unfolding of lineages than by looking at the largest species.

“I’m not sure we really know why there are so many very large beasts at any given time,” Prothero said.

(lom/lth)

[Gambas:Video CNN]

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