Like Cheetahs, Ancient Ocean Creatures May Have Galloped


cheetahs fastest animals on landget in at speed more than 60 miles per hour. By comparison, salamanders run at a much more measured pace. While cheetahs are exponentially larger and stronger than salamanders, another big difference between the two is how they move – their gait.

When chasing prey, cheetahs move with an asymmetrical gait—especially galloping like horses—with their front and hind legs moving in pairs. On the other hand, salamanders run with a symmetrical gait, with their left and right limbs moving together.

Historically, scientists believed symmetrical gaits were evolutionarily older – salamanders become models about how the first terrestrial animals moved. Conversely, asymmetric gaits such as galloping and jumping were believed to have evolved independently in different species over time.

But new research points to a different story, where asymmetric gaits exist on our chin. Ancestors who lived 400 million years ago in ancient oceans, long before vertebrates landed. this Business It was published Tuesday in the Journal of Experimental Biology.

Asymmetrical gaits are the basis of the speeds reached by cheetahs. greyhound and kangaroos. “That’s why a lot of people thought these were purely mammalian innovations,” he said. Michael GranatoskyHe’s an evolutionary biologist at the New York Institute of Technology and co-author of the study.

However, evidence is accumulating to suggest that asymmetric gaits may not have emerged as recently as once thought, and that they are certainly not unique to mammals. Some species of crocodiles gallop, at least one species of sea turtle submerges, and there are fish walking on the ocean floor.

African lungfish they actually have very few spaghetti noodles for the legs, but they are walking under the substrate,” said Dr. Granatosky. “And in about 10 steps it will be half symmetrical and half asymmetrical.”

This motivated researchers to re-examine how asymmetrical movement develops. The team built a tree of evolutionary relationships between species from a sample of 308 living species of jawed vertebrates, including mammals, reptiles, and others. From there, they awarded each species a score of 0 if it couldn’t move asymmetrically, and 1 if it could. They then tested a number of potential asymmetric gait evolution models to see which fit the data best.

The model, which turned out to be most likely, did not impose any restrictions on how asymmetric gaits developed, allowing the gains and losses of asymmetric gaits to occur freely over time.

“It’s a much looser model,” he said. Eric McElroyA biologist from the College of Charleston and co-author of the study showed that 400 million years ago, the ancestors of jawed vertebrates were about 75 percent likely to have had an asymmetric gait, and that asymmetric gaits could both disappear and disappear. obtained as jawed species evolved.

This finding makes perfect sense Sudhir Kumar, a biologist at Temple University who was not involved in the study. “Nothing in evolution is sacred,” he said. “We gain and lose traits according to our environment, according to our behavior, according to our needs, and that’s what you see here – the way animals walk is not fixed. They evolve.”

Researchers will come about the holes in their analysis.

Dr. “When you try to make an estimate of how something that’s been dead for 400 million years moves, there’s a bit of assumption involved,” McElroy said. Referring to his research area, Dr. “We have an extreme mammalian bias in how we sample biomechanical data,” Granatosky added. Incorporating more data from non-mammalian species such as fish, he said, could significantly change his findings.

Although acknowledging the potential blind spots of the study, Pedro GodoyAn evolutionary biologist at Stony Brook University who was not involved in the study, Dr. “We can only fully understand the factors of the different types of gait if we do it in light of evolution,” he said.



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