(ORDO NEWS) — Scientists from Canada and the United States have discovered the remains of an animal that evolved to move on the ground in the absence of limbs.
It was not an ancestor of modern snakes, but since it lived a very long time ago – in the Carboniferous period – it can tell a lot about how amniotes got a long body shape and legs disappeared.
Amniotes are called the clade of four-legged creatures, which is characterized by the presence of embryonic membranes.
Unlike anamnias (for example, frogs), they all have only internal fertilization. These include reptiles, birds, mammals and their extinct relatives. Amniotes appeared just in the Carboniferous period, about 320 million years ago, and in appearance resembled modern lizards.
Scientists from the Smithsonian Institution in the United States, as well as the Universities of Calgary and Carleton (Canada), were able to show that almost immediately after the appearance of amniotes as such, they began to “experiment” with the loss of limbs and stretching their bodies.
It turns out that snake-like creatures lived on Earth for a very long time. Although some of the earliest fossils of modern snakes date back only to the Middle Jurassic deposits of England and date back to 167 million years ago.
The remains of an animal that researchers found in the Francis Creek Shale in Illinois are much older. Scientists have estimated their age at 307-309 million years. They presented their findings in the journal Nature Ecology & Evolution. The fossil has been named Nagini mazonense and is a new genus belonging to the molgophids group.
The creature reached about ten centimeters in length, had a rounded muzzle, a very elongated body, but did not have forelimbs and even a pectoral girdle. At the same time, he had hind legs, including feet and four fingers. Therefore, scientists suggested that N. mazonense represented some kind of transitional link.
Judging by the fossilized footprints of its movements, the researchers believe that the animal moved like modern snakes and rarely used its hind legs.
It is unlikely, however, that it was the ancestor of cobras, asps, vipers, snakes and other living representatives of the Serpentes suborder. Most likely, amniotes developed a snake-like form in the process of evolution more than once.
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