[Animals] All animals developed the ability to gallop from fish 472 million years ago

[#Wittels-]

Until now, it was thought that galloping, along with other forms of movement such as jumping, only developed after mammals appeared on Earth, about 210 million years ago.

 

For all quadrupeds, from horses to lions to giraffes, the gallop is a key form of movement, an essential part of their repertoire of movements while on the move. Galloping is indeed an efficient way to cover great distances, or to put up a fight when the going gets tough and predators are on the prowl.

But when exactly did it arise? When and how do animals develop the ability to gallop? According to the most widespread idea, galloping, along with other forms of movement such as jumping, developed just after mammals appeared on Earth, about 210 million years ago. But as Eric McElroy and Michael Granatosky explain in a study just published in the 'Journal of Experimental Biology

', the reality is very different, and the gallop could have developed much earlier, a whopping 475 million years ago. That is, more than 250 million years earlier than previously thought. So it is not something exclusive to mammals.

 

 

asymmetric gears
For the researchers, the gallop is just a specific type of movement that is part of a series of maneuvers known as 'asymmetric gaits', in which the rhythm of the footsteps is distributed unequally. These maneuvers also include jumping (like those of rabbits), the 'crutches' of amphibians when they drag themselves out of the water with their fins, and the 'bateas', which is what fish do when they push themselves with their pelvic fins on the sea and river bottoms.

In their study, McElroy and Grantosky explain that, in addition to mammals, there are many other animals that can gallop, like crocodiles, or jump, like some turtles do. Something that made them wonder if animals could have developed the ability to coordinate their limbs independently much earlier than expected. And what they found was that, indeed, the animals 'learned' to carry out asymmetrical marches approximately 472 million years ago, long before life left the seas to conquer the mainland.

 

 

A custom family tree
To reach this conclusion, the researchers reviewed the available scientific literature and created a bespoke family tree, which included mammals, marsupials, monotremes, reptiles, frogs, toads, and fish that are known to be currently capable of doing something. asymmetric gait type. "In total," explains McElroy, "we collected data on 308 species."

The two scientists assigned a value of '0' to species that only used regular walking, jogging, and running times, and a score of '1' to those that showed signs of some other asymmetric movement. McElroy and Grantosky then did a series of simulations to find out the probabilities that asymmetrical gaits appeared earlier or later in the evolutionary tree.

 

 

"It did not take us months to solve all the problems of the analysis -continues the researcher- but we discovered that it is most likely that about 472 million years ago, the first ancestors of almost all modern animals, including fish, can already move with some type of asymmetric gait prototype. It is unknown if these primitive animals used 'crutches' or if they jumped across the seabed, but there is no doubt that they were already capable of asymmetrically coordinating their limbs to propel themselves.

A real surprise, furthermore, was discovering that some current creatures, such as lizards, salamanders, toads and even elephants, have lost the ability to jump and gallop, and this despite having ancestors in their family tree that were capable. to carry out these movements.

 

Therefore, the ability to jump and gallop is not unique to mammals. Almost all animals alive today have ancestors that were capable of asymmetrical movement, although some lost it at some point in their evolutionary line. They may have lost the nerve to coordinate these maneuvers, or become too big, or too slow, to carry them out. In any case, we have all inherited the ability to coordinate asymmetric movements from some ancient fish that propelled itself across the sea floor with its fins long before any species set foot, or fin, on land.

 

Link: https://www.abc.es/ciencia/abci-todos-animales-desarrollaron-capacidad-galopar-peces-hace-472-millones-anos-202203090118_noticia.html