Fossils reveal three extinct species of egg-laying mammals

After analyzing fossils found at the Australian Museum in Sydney, a group of paleontologists has classified three new species of oviparous mammals – that is, those that lay eggs.

The fossils belong to an order of mammals called monotremes, whose main feature and difference from other mammals is the ability to lay eggs. Monotremes were one of the first groups of mammals to appear on the planet, marking the transition from reptiles to mammals.

Today, there are only two species of this group: the platypus and the echidna, which are found only in Australia and New Guinea. According to the authors of the new study, the fossils found represent the first signs of the era of monotremes.

The results were published in Alcheringa: Australian Journal of PaleontologyHe described three new types: The splendor of Opalius, Aurora Darajara And the Stereopodon galmanii. They have all been identified in nine fossils dating back 100 million years.

All the fossils were collected in the 1980s at Lightning Ridge in New South Wales, Australia, and were kept in the museum’s collection until they were finally studied and classified. (This, by the way, is a relatively common practice in paleontology)

Fossils have been preserved in opal ores. 100 million years ago, when the fossils formed, Lightning Ridge was an area of ​​forests and swamps, still on the supercontinent of Gondwana.

This study could help paleontologists understand the evolution of the monotreme group, and when modern-day platypuses and echidnas diverged from their common ancestor. Hey Opalius is greatFor example, it shares some characteristics with the two existing species, such as the detection of electric fields (in the case of the platypus), and the shape of the beak and jaw (as in the case of echidnas).

The other types of monotremes found there have been previously classified, and at least four have been identified from a single piece of fossil opal. This suggests that the Lightning Ridge area has greater monotreme diversity than previously imagined.

“At Lightning Ridge we see serrated monoliths [que estão ausentes nos monotremados modernos]. It takes 40 million years for a family of mammals to appear, so these discoveries suggest that there has already been a long depth of evolution at Lightning Ridge. new world Chris Helgen, a researcher at the Australian Museum and one of the authors of the study.