No, this little beast is not half mammal, half reptilian (but it’s still super cool)



  No, this little beast is not half mammal, half reptilian (but still super cold)

Cifelliodon wahkarmoosuch lived during the Cretaceous period and belonged to a group that was closely related to mammals.

: Jorge A. Gonzalez

A small, hairy animal with a blunt snout and small, round eyes traversed what is now eastern Utah about 130 million years ago. And although the small beast was surely unusual and fascinating, there is one thing that it definitely was not: half mammal and half reptilian.

The headlines about the recent discovery described it as if it were a strange hybrid of reptile and mammal. But while it might be fun to imagine a beast with the front of a lizard and the back of a rat, it is not very scientific. [Real or Fake? 8 Bizarre Hybrid Animals]

The small animal, which was only 3 inches (7.6 centimeters) tall and weighed about 2.5 pounds (1.1 kilograms), belonged to a group known as haramiyidans, which emerged during the late Tribadic period (251 ago million to 199 million years old), and are known mainly from fossil teeth. Scientists have discussed whether the haramiyidans were primitive mammals or a sister group, closely related to mammals, but without some characteristics used by paleontologists to decide who is a mammal and who is not.

In a new study describing the small skull, which represents a new genus and species of haramiyidan called Cifelliodon wahkarmoosuch and is believed to be between 139 million and 124 million years old – the researchers determined that the haramiyidans were relatives of mammals, although not real mammals. Both the haramiyidans and the mammals have their origin in a group of reptiles known as synapsids, and although the haramiyidans closely resembled mammals, they retained more "non-mammalian" structures from their reptilian ancestors than the first true mammals, the scientists reported. [Image Gallery: 25 Amazing Ancient Beasts]

Terms like "reptiles similar to mammals" reflect the relationship between the ancestral and emergent characteristics that define groups of animals. Egg laying, for example, is a reptilian trait that is still found in some modern mammals, such as platypus and spiny anteaters. The so-called "true mammals" – mammals with placentas – are believed to come from a shrew-like animal called Juramaia sinensis that lived about 160 million years ago.

In life, the newly described haramiyidan had a long tail, teeth that could cut and crush vegetation and small eye sockets that suggested that his eyes were small and his vision was poor. However, his olfactory bulbs were unusually large, suggesting that it depended to a large extent on his sense of smell, according to the study.

  This extinct mammal relative probably had poor eyesight and depended on his sense of smell.

This extinct mammal relative probably had poor vision and depended on his sense of smell.

Credit: Jorge A. González

High-resolution X-ray scans also revealed the internal shape of the skull, which was "transitional between the primary mammals of the stem" and crown Mammalia, "the researchers wrote, which means that C. wahkarmoosuch – and other haramiyidans – fall somewhere among the first reptiles to evolve similar characteristics to mammals and the group that includes living mammals today.

Exceptional preservation of the skull, particularly its three-dimensional shape, offered clues to the haramiyidan The study's lead author, Adam Huttenlocker, an badistant professor of integrated sciences in clinical anatomy at the Keck School of Medicine at the University of Southern California, told USC News that the group had only been guessed before, when the only available fossils were scarce or crushed …

"The three-dimensional preservation of Cifelliodon [19459] 013] highlights the primitive brain, palate and feeding structure of this special group and reinforces its position near the base of the mammalian family tree, "said Huttenlocker. [19659005] The findings were published online May 23 in the journal Nature.

Original article on Live Science.


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