The sharks now roam the open sea. But for 200 million years, they just lived near the sea floor

When you make a shark picture, you probably think of a big, powerful hunter who travels in the open sea.

Species like the Great White Shark, Tiger Shark and Bill Shark dominated the popular media, which have stories of rare and isolated events of attacks on humans (such as the tragic death of the surfaced Mercury Silicas last week on the northern coasts of Sydney).

Although these three species are certainly charismatic hunters, they represent less than 0.6 % of the living shark. More than 500 species of Living Shark showed amazing diversity of shapes and shapes, from a 20 -meter -long wheel shark to phone -shaped bolymanic lanterns sharks, Fleet Angel Shark, Hammer Heads, Sources, Goblin Shark and Wobigings.

But how did the sharks be so diverse? A new research that I led by the leadership investigated the evolution of physical shape in the shark, which is more than all the way to their ancient ancestors, 400 million years ago, to the present.

A time before the dinosaur

Today, we see that great changes in body shapes did not appear overnight – the shark lineage returns at a time before dinosaur.

Scientists often use fossils to regenerate shifts in physical shape and size in the evolutionary tree of different animals. Unfortunately, we can’t do the same thing with the shark.

The reason for this is that the sharks are made of cartilage instead of skeleton bone. Therefore, unlike artisans, birds or creeping animals, we do not have many complete focus of ancient sharks. Instead, we have a burden and burden of isolated teeth.

This means, so far, scientists are rarely aware of how shark types, when and why we see a great diversity that is ready today.

Instead of using the foam, we collected information about the physical appearance from the scientific reflection of more than 400 living shark species, and used a data method called the reorganization of the ancestral state to evaluate the physical appearance of the ancient shark.

We also collected information about the residences that prefer different shark species.

The ancient sharks were down

Our analysis shows that ancient sharks were probably foolish – that means they lived on or near the sea. The yellow sharks who wandered in the open sea and resembled today’s most famous hunters such as Great White, Tiger or Bill Shark, initially, were not born for 145-1 million years ago.

This means that, in the first half of their existence, the shark was restricted to residences near the sea floor.

Why? Interestingly, we found that four times the shark has made the open sea colonial shape, a change in body shape (including a deep body evolution and more symmetrical tail) that happened just before the change in the residence.

The time of these shifts has also been identified as historical climate change (including rising levels and tickets shifts), may have played a vital role in making these sharks more colonially more pillad residences.

This means that as the climate changed, residents living in ancient sharks also enabled the evolution of new forms of the body. And so much so that these deep bodies were better suitable for open water life with more symmetrical tail.

To better understand the ancient ecosystem

By turning back over time over time, we look like an ancient shark and how they can survive, we can better understand how the ancient environmental system works, and predict what they can respond to the change of human climate in the future.

More widely, these results show that not all sharks are the same. Most of the sharks – are ancient and living – are small and foolish, not big, dangerous high hunters.

So the next time you make a picture of the shark, think not only about the great whites and the lions, but also the ancient lower inhabitants who shaped the oceans long before the first dinosaur.

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