What is it about?
We show that a 108-million-year-old mammal humerus (arm bone) found 30 years ago at Dinosaur Cove in southern Victoria, Australia, from a species called Kryoryctes cadburyi, belongs to an ancestral monotreme, which was a semi-aquatic burrower like the platypus. This supports that the hypothesis that land-living echidnas evolved from a swimming ancestor.
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Why is it important?
Our research indicates that the amphibious lifestyle of the modern platypus had its origins at least 100 million years ago, during the Age of Dinosaurs. It also suggests that echidnas evolved from semi-aquatic ancestors, reverting to a life on land more recently.
Perspectives
Monotreme fossils are very rare, and rarer still are monotreme limb bone fossils like the humerus of Kryoryctes discovered 30 years ago in southern Victoria. New, non-destructive techniques have enabled our research team to study the internal microstructure of this precious 100 million-year-old humerus for the first time, and this in turn has provided an exceptional opportunity to gain insights into how early Australian mammals lived.
Suzanne Hand
University of New South Wales
Read the Original
This page is a summary of: Bone microstructure supports a Mesozoic origin for a semiaquatic burrowing lifestyle in monotremes (Mammalia), Proceedings of the National Academy of Sciences, April 2024, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2413569122.
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