As paleontologists recently announced, that species, Kryoryctes cadburyi, has provided some really cool insights into ecology of the time. This strange animal probably lived a semiaquatic lifestyle about 108 million years ago in what is now southern Victoria. Palaeontologists found this early monotreme relative’s first and only humerus at Dinosaur Cove, Australia in the early 1990s. This discovery has sparked a lot of discussion about its possible lifestyle, including the question of whether it was fully terrestrial or at least partly amphibious. The clues revealed by the microstructure of its humerus make a powerful case in favor of the idea of a semiaquatic existence.
First formally named in 2005, Kryoryctes cadburyi’s way of life has confounded paleontologists for decades. Recent studies utilizing advanced imaging techniques, including CT scanning, have allowed researchers to examine the internal microstructure of the bone without causing damage. Even better, this non-destructive approach has revealed some truly thrilling discoveries about Kryoryctes cadburyi. Its skeletal anatomy is most similar to modern-day platypuses, suggesting it evolved adaptations for diving and foraging in an aquatic environment.
Discoveries from Dinosaur Cove
Paleontologists discovered the exceptional fossil of Kryoryctes cadburyi at Dinosaur Cove. This site has become well known for its incredibly diverse paleontological finds in southeastern Australia. Charles Sturt University professor Michael Archer, who has studied Australian Mesozoic mammals for decades, noted the rarity of such discoveries.
“Australian Mesozoic mammals are rare and are known mostly only from their teeth and jaws. Kryoryctes cadburyi is so far the only one known from a limb bone.” – Professor Michael Archer
This finding is a testament to the remarkable diversity of ancient vertebrate fauna. Further, it highlights just how important Dinosaur Cove is for understanding the evolutionary history of monotremes. Retention of the humerus bone to serve a similar function to ballast in other modern semiaquatic mammals greatly facilitates diving. This unique feature creates some really interesting speculation as to how these creatures made their environments work for them.
The internal microstructure of Kryoryctes cadburyi’s humerus exhibits incredible parallels to that of platypuses. This finding indicates that some evolutionary characteristics have persisted unchanged for millions of years. As Professor Archer said, this solitary bone offers a remarkable chance to glean new information about some of Australia’s earliest mammals.
“This humerus has provided an exceptional opportunity to gain insights into how early Australian mammals lived, and it tells quite a story–perhaps not one we expected to discover.” – Professor Michael Archer
Insights from Bone Microstructure
Scientists studied Kryoryctes cadburyi’s upper arm bone. They concluded that there were marked resemblances between its skeletal anatomy and that of extant monotremes like the platypus or echidnas. Emeritus Professor Suzanne Hand in that same area talked about the importance of bone histology in determining what type of life an animal had.
“We know that bone histology can say a lot about how an animal lives. This kind of investigation typically requires destructive sectioning of a bone, which is not possible to do with a unique fossil like Kryoryctes. Instead, we are applying powerful scanning techniques, including non-destructive synchrotron imaging of the fossil, in order to gather even more information to help unravel this ancient mystery.” – Prof. Hand
Micro-CT scanning of Kryoryctes cadburyi’s humerus unveiled a lovely internal structure. It demonstrates adaptations similar to the dive adapted platyphuses with dense bones that function similarly to ballast to help with diving. These adaptations suggest Kryoryctes cadburyi probably thrived in an environment that needed both aquatic and terrestrial capabilities. Such versatility would have provided it a huge leg up in its environment.
“The microstructure of the fossil Kryoryctes humerus is more like the internal bone structure seen in platypuses, in which their heavy bones act like ballast, allowing them to easily dive to forage for food. You see this in other semiaquatic mammals.” – Prof. Hand
Overall, these results contribute critical knowledge about Kryoryctes cadburyi. Furthermore, they elaborate upon our insights into the evolutionary history of monotremes throughout the Mesozoic era in which they flourished in Australia’s mammal faunas.
The Ongoing Mystery of Semiaquatic Living
Though these findings were indeed revolutionary, discussions about Kryoryctes cadburyi’s life are still ongoing. Some paleobiologists even suggest that this led it to change from a semiaquatic lifestyle to a largely terrestrial one. Some are more circumspect and stop short of making firm conclusions.
“We’re talking about a semiaquatic mammal that gave up the water for a terrestrial existence, and while that would be an extremely rare event, we think that’s what happened with echidnas.” – Emeritus Professor Suzanne Hand
Future examinations utilizing histology and other advanced techniques are planned to further investigate the microscopic anatomy of Kryoryctes cadburyi’s humerus. As scientists pursue this research, they hope to find additional hints as to this prehistoric animal’s ecology and way of life.