The Australian platypus is one in all Earth’s most uncommon creatures — however there was a time when it may not have stood out in a crowd. In roughly 100-million-year-old rocks in Australia, scientists have unearthed three new species of monotremes, a gaggle of egg-laying mammals that as we speak embody solely the platypus and one other Australian oddball, the echidna (SN: 11/18/16).
The fossil discoveries double the variety of recognized monotreme species throughout this temporary span of the Cretaceous Interval, hinting at a bygone Age of Monotremes, mammal biologist Timothy Flannery and colleagues report Could 26 in Alcheringa: An Australian Journal of Palaeontology.
Australia as we speak is regarded as a land of marsupials, mammals that nurture growing younger in pouches, together with kangaroos, koalas and wombats. However an entire “civilization” of various monotremes, starting from pig-sized to rat-sized, might have radiated throughout the continent first, says Flannery, of the Australian Museum in Sydney.
The trendy platypus, native to japanese Australia and Tasmania, is one of many weirdest creatures on Earth (SN: 12/3/14). The creatures have a toothless, ducklike invoice, a beaverlike tail and otterlike toes; their payments are additionally electro-sensory organs that enable them to detect prey in murky waters. Male platypuses even produce venom, delivered by way of spurs on the rear toes. The platypus’ Frankensteinian mixture of components was so shocking to 18th century European biologists that many initially thought it to be a hoax.
The three new Cretaceous species, together with new specimens of three beforehand recognized extinct monotremes, had been recognized from fossil tooth and jaws discovered within the Lightning Ridge opal fields in New South Wales. These modest fossils, notably when put next with beforehand discovered fossil monotremes, present a wealth of data, the group notes: the animals’ relative sizes, quantity and orientation of tooth, even possible place on the household tree.
One of many newfound species, formally named Opalios splendens, earned the nickname “echidnapus” for its mixture of options, that are present in fashionable echidnas and platypuses. These traits recommend it was an ancestor of each. One other of the brand new species, Parvopalus clytei, is among the many smallest monotremes ever discovered, roughly the scale of a rat. The third, Dharragarra aurora, is the earliest recognized species of platypus.
The discoveries additionally reveal a gradual development in monotremes from toothy to toothless. The earliest recognized monotreme, Teinolophos trusleri, was a beakless, shrew-sized creature that lived about 130 million years in the past. It had 5 molar tooth — however by 100 million years in the past, the newly found species recommend, some monotremes had solely three molars, whereas fashionable platypuses and echidnas are primarily toothless. That shift could also be associated to a change in eating regimen to softer, extra slippery meals — leaving crunchier fare like crustaceans and bugs to a newly arrived competitor from New Guinea, the water rat.
