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According to the most common definition among non-specialists, the two best known characteristics of mammals are that they do not lay eggs and that they contain mammalian glands. All of those placentas are viviparous, and their embryos are preserved and nurtured in the maternal uterus, which is in contact with the placenta. Then there are mammals, marsupials, which follow different embryonic development. But, in principle, no mammal lays eggs. Almost.
Attempts at severe taxonomy, similar to platypus, also known as platypus, which is poorly adapted to some zoological systems in well-known animals, can cause problems by definition: an egg mammal. The compelling story of its classification – complex from the beginning – has centered on the solution of a mystery for almost a century, which came in 1884 and is now considered a fundamental step in changing the way naturalists understand the taxonomy of animals. She handled it, a Article Recently, the magazine History today.
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The platypus – an animal native to northern Australia and Tasmania – has caused confusion among scientists in Europe since John Hunter arrived in England in 1798 with a dead specimen sent to Australia by the Governor of New South Wales. Some of those English nature enthusiasts, stunned by the duck’s crane, thick fur and web-side legs, suspected that the body – though less preserved in perfect condition – might be a “real” animal. They suspected it might be the creation of some Japanese taxpayer, some of whom were already convinced at the time. Products Of imaginary animals derived from the union of fish tails and monkey heads.
The following year, the English botanist and zoologist George Gearsley Shaw – gave it its name Platypus anadius – was able to prove that it was a real animal, but further research among English naturalists is still hampered by the fact that it does not seem to work. The model from Australia lacks internal organs, a condition that precludes the anatomical study required for taxonomy, based on the method introduced by the then influential Swedish naturalist and educator Carl Linnaeus and the similarities between organisms.
According to the five levels (kingdom, class, order, genus, species) proposed by Linnaeus for taxonomy, there were six classes within the animal kingdom, including mammals, birds, and reptiles and waterfalls. According to Linnaeus’ definition, mammals suckle babies through mammalian glands, have teeth, breathe through two lungs, and usually have four legs. They were mostly covered in hair and, in some cases, had tails. The birds, on the other hand, lay eggs covered with a shell of calcium carbonate, and had wings; They have no external ears, no external tests, no uterus, no thoracic diaphragm, no bladder. And the waterfalls usually lay membrane eggs, and there was no diaphragm, and sometimes they had “terrible venom”.
Linnaeus’ classification made a lot of sense, he says History today, But it had an extreme limit to begin with from the Creator’s assumption that all animals were always in their present form. By denying any causal relationship between different species, that assumption made the classifications for a species spontaneous and impossible. To try to solve the platypus puzzle, follow that approach and naturalists have no choice but to “fish”, combining elements here and there from different definitions or fully guessing what platypus’ place in creation is.
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In theory, according to Shaw and other English nature lovers it must have been mammals such as lazy, anteaters and toothless mammals. But there were many things that were not included, and that animal continued in some way to have the characteristics of a fish, a bird, and a quadruped. After all, it is not particularly similar to any other animal. In 1800 the German naturalist Johann Friedrich Blumenbach undertook a more rigorous study and, confused by the absence of mammalian glands, renamed the animal The Ornithorhings Conflict, Which means “conflict with the bird’s nose”.
Two years later, an Englishman named Everett Home noticed that the male platypus contained reptile-like sperm and a gloca, a single cycle that combined the urinary, digestive, and reproductive systems. Home wrote that this “distinguished mammals” from mammals in an “extraordinary way,” at the time it was believed that gloca was found only in reptiles, waterfalls, and birds, and that it lays eggs.
A complete change in the taxonomic approach was the publication of the book in 1809 Zoological philosophy The French naturalist Jean-Baptiste Lamarck described living human beings as being in constant change rather than permanent. Not only are they able to “acquire” new traits in response to certain environmental factors, they can also pass them on to offspring. Some limitations of this theoretical model, later demonstrated by the research of Charles Darwin, did not preclude naturalists from understanding the purpose and implications of Lamarck’s research: that over time many different animals are likely to change into another.
Instead of classifying animals by drawing from different definitions, Lamarck was able to not only detect changes in animals over time, but also define what types of traits are unique to a class or order, and not what they are not. The French naturalist Etienne Jeffrey Saint-Hilare argued at the time that mammals – due to the absence of mammalian glands – should be included in completely new vertebrates, which he called monotreams (Monotraumate), Which means “single cycle”. Shortly afterwards, in an attempt to confirm Jeffrey Saint-Hilare’s claims, German anatomist Johann McClellan undertook other studies of platypus, which would instead complicate matters further.
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McClellan discovered the presence of a venom gland in the male platypus, which is usually characteristic of reptiles and waterfowl, but above all, he also found that females had mammary glands. This, in the eyes of nature lovers, suddenly brought platypus more like mammals than it had recently. In 1832, Scotsman Lauderdale confirmed McClellan’s findings on the reptilian characteristics of the Moul Platypus and drew attention to the characteristics of other mammals: the female and male platypus had diaphragms and were warm-blooded.
That set of features seemed like an insurmountable paradox to most scientists. It is almost impossible to imagine that any organism could have active mammalian glands and lay eggs: it must have been one or the other, and it would have determined the members of the mammal or some other platypus. Many nature enthusiasts have made irrelevant hypotheses. McClellan firmly believed that Platypus had given birth to living children, while Jeffrey Saint-Hillary wanted to lay eggs. Another nature activist, Englishman Richard Owen, argued that eggs are inside the body.
Evidence was needed, and it did not come from Australian aborigines and immigrants, who said they saw platybuses laying their eggs. Over time, due to previous negative experiences, nature lovers have learned to place little faith in that type of report. To solve the puzzle it is necessary to identify an egg or, even better, to catch and kill a pregnant woman. Owen asked George Bennett, the curator of the Australian Museum, to shoot the animals and analyze them in an attempt to find answers, but the extent of Bennett’s failed attempts led Owen to fear that the move would soon lead to extinction. Classification of the animal.
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Twenty-five-year-old Scottish zoologist William Hay Caldwell, who closed the game on August 29, 1884, after four months of research on the northeast coast of Queensland, Australia. History today Defines “the most important telegram ever written on a platypus”. After he was able to shoot a female platypus, he discovered that he not only laid an egg, but also laid another when he was able to catch her. He opened it and found the answer to a question that had plagued nature lovers since 1798.
He then sent a message to the annual meeting of the British Association for the Advancement of Science (British Society for the Advancement of Science), In Montreal. It said: “Monotreams oviparas, egg meroplastic”. In other words: platybuses with large yellow nuclei like birds and reptiles lay eggs. But, above all, the embryos inside were already very developed, with different spines and brains, suggesting that there was some time in the parent’s body before the eggs were laid and maintained. After frying the eggs, the hairless pups cling to the mother and drink.
Caldwell’s experiment proved that the platypus was undoubtedly a mammal, but in its own order, older than the others. That order must have long ago branched off from the last common ancestor of mammals and reptiles, thus creating new distinctive traits, without completely losing its past.