Australia’s burrowing echidna advanced from a water-dwelling ancestor in an “extraordinarily uncommon” organic occasion, scientists stated in a brand new research of the peculiar egg-laying mammals.
With highly effective digging claws, protecting spikes and extremely delicate beaks, echidnas are properly suited to a life shuffling by the forest undergrowth. However a crew of Australian and worldwide scientists imagine lots of the echidna’s uncommon traits have been first developed hundreds of thousands of years in the past when its ancestors splashed by the water.
“We’re speaking a couple of semiaquatic mammal that gave up the water for a terrestrial existence,” stated Suzanne Hand, a palaeontologist from the College of New South Wales.
“Whereas that will be a particularly uncommon occasion, we predict that’s what occurred with echidnas.”
Echidnas and one other Australian oddity – the semi-aquatic platypus – are believed to have advanced from a typical ancestor referred to as Kryoryctes cadburyi that lived in Australia greater than 100m years in the past.
Researchers studied the only recognized bone fragment left by this ancestor which was found amongst a trove of fossils at Dinosaur Cove in southern Australia 30 years in the past.
Platypus bones have been just like this historic ancestor, Hand stated, with a thick and heavy construction that offered ballast for diving. Echidnas, by comparability, had very skinny bone partitions that made it simpler to stroll on land.
This indicated echidnas have been descended from a water-dwelling ancestor however had advanced to reside on land, the analysis discovered.
It was way more widespread for prehistoric mammals to go from land to water, Hand stated, pointing in the direction of seals, whales, dolphins and dugongs.
The researchers stated these findings seemed to be supported by different echidna traits. Echidnas have backward-facing hind toes that assist them shift mounds of soil when burrowing. These toes could have first developed as rudders serving to the echidna’s ancestor navigate fast-moving waterways, Hand stated.
Echidnas even have a “diving reflex” when submerged in water, which tells their physique to preserve oxygen, serving to them maintain their breath for longer.
Echidnas and platypus are monotremes, a uncommon group of mammals that lay eggs as a substitute of reside younger.
“We’re hoping we’ll uncover different ancestral monotremes that may assist unravel the early historical past of this most fascinating group of mammals,” stated Michael Archer, a co-author of the research.
The analysis was revealed in peer-reviewed journal PNAS.
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