The three newly identified species display a combination of features not previously seen in other organisms or fossils. MonotremesAccording to Professor Chris Helgen from the Australian Museum Research Institute and his colleagues.
Six monotremes living at the same time and place 100 million years ago in Lightning Ridge, New South Wales, Australia. Clockwise from bottom left: Opalios splendens; Stiltdon Elizabeththe largest monotreme of its time. Coricodon Richeywith molars shaped like hot cross buns. Steropodon garmaninow known from additional milky white fossils. Parvopulus CritiaeiIt was the smallest monotreme of its time. Daragala AuroraIt is the oldest known species of platypus. Image by Peter Schouten.
Professor Helgen and his co-authors said: Lightning Ridge Opal FieldsNew South Wales, Australia.
The fossils date to the Cenomanian stage of the Cretaceous period, between 102 million and 96.6 million years ago.
They were discovered by Elizabeth Smith and her daughter Clyttie. Australian Opal CentreThey have spent decades working and searching the opal fields.
“Opal fossils are rare, but opalized monotreme fossils are even rarer, because for every single piece of monotreme there are a million pieces of something else,” Elizabeth Smith said.
“You never know when or where they're going to show up.”
“Our work reveals that 100 million years ago, Australia was home to a diverse range of monotremes, of which the platypus and echidna are their only surviving descendants,” Professor Tim Flannery, from the Australian Museum, said.
“Today Australia is known as the land of marsupials, but these new fossil discoveries are the first evidence that Australia was once home to a diverse range of monotremes. It's like discovering a whole new civilisation.”
It is one of the newly described species Opalios splendensIt retains characteristics of the earliest known monotremes, but also some that foreshadow adaptations in modern monotremes such as the echidna and the platypus.
“Opalios splendens “This fossil occupies a position on the evolutionary tree before the evolution of the common ancestor of modern monotremes,” Professor Helgen said.
“The overall structure is probably very similar to a platypus, but the jaw and snout features are a bit like an echidna, so you could call it an 'echidna.'”
“The evolutionary story of egg-laying mammals, for the earliest monotremes, is one of toothed to toothless. Teinolophus trasleriIt dates back to Victoria, 130 million years ago.”
“What we're seeing at Lightning Ridge is that 100 million years ago, some monotremes still had five molars, but some had gone down to just three.”
“Today, echidnas have no teeth and platypuses are essentially toothless,” Professor Flannery said.
“Adult platypuses have no teeth, but young ones have primitive molars.”
“We think we've solved the mystery of when and why adult platypuses lost their teeth after nearly 100 million years.”
“Competition with the Australian brown rat, which arrived in Australia within the past 2 million years, may have led the platypus to seek out softer, slippery foods that could be processed with the leathery paws used by adults today.”
“What's unusual about this uniquely Australian story is that a single photograph shows six species of egg-laying mammals coexisting at Lightning Ridge more than 100 million years ago.”
“They all have evolutionary destinies that could go in different directions, and they are all distant ancestors and relatives of currently living monotremes.”
“The discovery of three new monotreme genera helps to piece together their remarkable evolutionary story,” said Dr Matthew McCurry, Curator of Palaeontology at the Australian Museum.
“The Cenomanian Lightning Ridge fauna of New South Wales contains six monotreme species, including three newly described, making it the most diverse monotreme assemblage on record.”
“The fact that four species are known from one specimen suggests that diversity is still underrepresented.”
“This discovery increases the known diversity of monotremes by more than 20 percent.”
“Very few monotreme fossils remain, so new fossil discoveries will tell us more about where monotremes lived, what they looked like, and how environmental changes affected their evolution.”
“All important monotreme fossils known today fit into this evolutionary story. TeinorophosIt is a small, shrew-like creature that lived in Antarctica from 130 million years ago until the present.
“The platypus and echidna are iconic Australian species,” said palaeontologists Thomas Ricci and Patricia Vickers-Ricci of the Museum Research Institute of Victoria.
“The discovery of multiple new species in a small area suggests that the family tree of egg-laying monotremes is much more complex than extant platypuses and echidnas alone would suggest.”
“As fieldwork continues in Australia's Mesozoic, we continue to improve our understanding of how life changed over time, and to me, this is what makes science so exciting.”
Team paper Published in Archaeological Research, Australian Journal of Palaeontology.
Source: www.sci.news
