(ORDO NEWS) — For a long time, scientists believed that the ancestors of echidnas and platypuses appeared in Australia at the time of the dinosaurs, and reached South America much later.
But recently, paleontologists have discovered a platypus-like animal that lived in Cretaceous Argentina.
Monotremes , which include modern platypuses, echidnas and prochidnas, are an unusual subclass of mammals, whose representatives today live only in Australia and on several adjacent islands.
However, fossil monotremes also lived in South America, and for a long time scientists believed that their ancestors reached this continent through Antarctica at the beginning of the Cenozoic era, when mammals already reigned on Earth.
A new discovery from the late Cretaceous period of Argentina forced researchers to reconsider their views: a tiny fragment of the lower jaw of an animal with a single tooth was found, the characteristic features of which made it possible to undoubtedly attribute the owner of the jaw to primitive monotremes.
The new species of mammals was named patagorhynchus ( Patagorhynchus pascuali ), or “Patagonian platypus” (the latter’s Latin name is Ornithorhynchus , that is, “bird-bearer”).
Although in the case of the modern platypus only juveniles have teeth, whereas in adults they are replaced by horny plates, its fossil relatives were most often toothy: for example, in the Cenozoic obdurodon, teeth were strong enough to crack the shells of crayfish and mollusks .
Despite the scarce paleontological material, scientists were able to establish that the Patagorynchus lived in a swampy area, abundant in water, and fed mainly on various invertebrates, like a modern platypus. Other mammals lived side by side with it, as well as early birds, frogs, snakes, turtles and dinosaurs.
The discovery of the patagorhynchus proves that already in the Cretaceous, monotreme mammals were widespread.
The extinction of dinosaurs did not open the way for these animals to new continents, but only changed the ecosystems in which they lived at that time.
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