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19th century evidence that some mammals lay eggs

Las pruebas del siglo XIX de que algunos mamíferos ponen huevos

Jars containing tiny platypus and echidna specimens, collected at the end of the 19th century by William Caldwell, have been discovered in the warehouses of the University Museum of Zoology in Cambridge.

At the time of their collection, these specimens were key to demonstrating that some mammals lay eggsa fact that changed the course of scientific thought and supported the theory of evolution.

This unique collection had not been cataloged by the Museum, so staff were unaware of its existence until recently. The exciting find came as Jack Ashby, deputy director of the Museum, was researching a new book on Australian mammals.

"It’s one thing to read 19th-century advertisements that platypuses and echidnas lay eggs. But having here the physical specimens, that refer us to that discovery almost 150 years agoit’s quite amazing"Ashby highlights in a statement.

"I knew from experience that there is no natural history collection on Earth that has a complete catalog of everything in it, and I suspected that Caldwell’s specimens should be here.", Add. And he was right: three months after Ashby asked the collections director, Mathew Lowe, to keep an eye out, a small box of specimens with a note suggesting they were from Caldwell was found in the Museum. Ashby’s investigations confirmed that this was so.

Until Europeans first encountered platypuses and echidnas in the 1790s, it was assumed that all mammals gave birth to live young. The question of whether some mammals lay eggs then became in one of the biggest questions of nineteenth-century zoology, and was hotly debated in scientific circles. The newly discovered collection of jars represents the enormous scientific effort that went into solving this mystery.

"In the 19th century, many conservative scientists did not want to believe that an egg-laying mammal could exist, because this would support the theory of evolution, that is, the idea that one group of animals was capable of transforming into another, Ashby recalls. –. Lizards and frogs lay eggs, so the idea of ​​a mammal laying eggs was dismissed by many people; I think they felt it was demeaning to associate with animals that they considered to be ‘lower life forms’"Add.

The newly discovered collection includes echidnas, platypuses and marsupials at different stages of life, from the fertilized egg to adolescence. Caldwell was the first to make complete collections of all life stages of these species, although not all specimens are in the Museum.

For 85 years, European naturalists had been trying to find evidence that platypuses and echidnas were laying eggs — even asking Aboriginal Australians — but all the results they sent home were either ignored or dismissed.

In 1883, William Caldwell was sent to Australia – with significant financial support from the University of Cambridge, the Royal Society and the British Government – to solve this ancient mystery.

In an extensive search, Caldwell collected some 1,400 specimens with the help of a large group of Australian Aborigines. In 1884, the team found an echidna with an egg in its pouch and a platypus with an egg in its nest and another about to be laid.

It was the ultimate proof that Caldwell was looking for, and the news went around the world. Apparently, the colonial scientific establishment was only willing to accept this result now that it had been confirmed by "one of their own".

Ashby says that for the last two centuries, scientists have systematically disparaged Australian mammals, portraying them as bizarre and inferior. He believes that this language continues to affect how we describe them today, and undermines efforts to conserve them.

"platypuses and echidnas they are not rare and primitive animals as many historical accounts describe them, they are as evolved as any other. What happens is that they have never stopped laying eggs – he stresses -. I think they are absolutely amazing and definitely worth looking at.".

Spiked-covered echidnas are Australia’s most widespread mammal. They cover the entire continent and have adapted to live in all climates, from snowy mountains to the driest deserts.

Platypuses are one of the only mammals that can detect electricity and one of the only mammals that produce poison. With a tail like a beaver’s, a flat beak and webbed feet like a duck’s, when the first specimens reached Europe people thought they were fakes that had been sewn together.

Both platypuses and echidnas exhibit a unique combination of traits that 19th-century scientists thought should only exist individually in mammals, reptiles, or birds. This made them protagonists of debates about evolution.

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