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The story of two of the strangest animals on the planet has just been a little stranger, thanks to hints that reveals through a lonely fossil specimen, now say that scientists are a long -term ancestor. The new research could know what is known about the development of the most primitive mammals that is known today.
In Australia and New Guinea, Platypus and Echidna are called monotraums and are unique because they are the only mammals that lay eggs.
The amphibious platypus has an invoice and a net foot like a duck and a beaver-like tail. The little creature spends a lot of time looking for food in the water. The Echidna – appropriately known as The Spiny Antertiere – lives completely on land, is covered with pointed spring boxes and has a backfoot that are spotted backwards and absorbs dirt while the animals dig into the ground. No animal has teeth, and although both produce milk, they dissolve them through their skin so that babies (often referred to as puggles) shock them because they have no nipples.
“There is a lot of craziness to do these little things,” said Dr. Guillermo W. Rougier, professor of the Department of Anatomical Sciences and Neurobiology at Kentucky University of Louisville, who studies the evolution of early mammals.
“They are one of the defining groups of mammals,” said Rougier. “The typical mammal from the time of the dinosaurs probably has much more biology with a monotrem than with a horse, a dog, a cat or ourselves.” Therefore, he said, monotratreme deliver a window into the origins of mammals on earth.
Look into an old fossil
This petrified Humerus bone was discovered in the Dinosaur Cove in 1993. Inside, the Fossil had characteristics of the semiaquatic platypus, researchers found. – Museums Victoria
A new study published on Monday in the Proceedings magazine of the National Academy of Sciences opens a little further. Studies by Paleontologist Suzanne Hand, an emeritus professor at the School of Biological, Earth and Environmental Sciences at the University of New South Wales in Australia, reveals the inner structure of the only known fossil exemplary of the monotremen ancestors, more than before more than more than 100 million years ago lived.
The fossil, a humerus or upper arm bone was discovered in 1993 in the Dinosaur Cove in the southeast of Australia. From the outside, the specimen looked more like a bone from a land -resistant Echidna than a water -loving schnabel type. But when the researchers looked inside, they saw something different.
“By using advanced 3D image sponsorship approaches, we have so far been able to illuminate invisible features of this old bone, and these have revealed a rather unexpected story,” said the co -author of the study, Dr. Laura Wilson, lecturer at the School of Biological, Earthal Sciences at the University.
The team found that the fossils had the properties of the semiaquatic platypus: a thicker bone wall and a smaller central cavity. Together, these characteristics make the bones heavier, which is useful for aquatic animals because they reduce the buoyancy. Therefore, it is easier for the creatures to dive under water to feed food. In contrast, Echidnas, who only live on land, have much thinner, lighter bones.
The finding supports the popular but unproven hypothesis that Kryoryctes is a frequent ancestor of both the schnabel type and the Echidnas and that it may have lived in the water at least partially in the water at the time of the dinosaurs.
“Our study shows that the amphibian lifestyle of modern platypus had its origin at least 100 million years ago,” said hand, “and that Echidnas made a much later reversal into a completely terrestrial lifestyle.”
Development of schnabeln and Echidnas tell the story of mammals
A cross average comparison shows (from left) a Kryoryctes (A), platypus (b) and echidna (c) humerus bones. – Hand et al.
There are known examples of animals that develop from land to water-for example, it is assumed that dolphins and whales have developed from land animals and share a line with hippos. However, there are only a few examples that show the development of water to land. The transition requires “significant changes in the musculoskeletal system,” said Wilson, including the new positioning of the limbs for life on land and lighter bones in order to move less energy intensive.
A land-to-water transition could explain the bizarre backward feet of the Echidna, the hand said that he could have inherited from a floating ancestor who used his hind legs as rudder.
“I think that they are very elegant that these animals were adapted to a half -qualified life very early,” said Rougier, who was not involved in the study, even though he was in contact with the authors during their research.
The primitive history of these unusual animals, he said, was “really important” for our understanding of how mammals (including people) were created.
“Monotreme are these living relics from a very distant past. They and a platypus probably had the last ancestors together over 180 million years ago,” he said. “There is no way to predict the biology of this last common ancestors without animals such as monotrait.”
Amanda Schupak is science and health journalist in New York City.
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