Remains of Adalatherium. Credit: Simone Hoffmann and Kathrine Pan
The strange properties of this mammal have puzzled scientists as to how it could develop; “It breaks many rules and even breaks them.”
Adalatherium is part of a very large mystery about the evolution of early mammals in the southern hemisphere, and most of its other parts are still missing.
New research published today Journal of Vertebrate Paleontology The southern supercontinent, now known as Africa, South America, Australia, Antarctica, the Indian subcontinent, and the Arabian Peninsula, depicts a strange 66-million-year-old mammal that gives new insights into the evolutionary history of mammals from Gondwana.
It’s called AdalatheriumTranslated from Malagasy and Greek, it means “wild savage” and is based on the most exclusive, almost complete, delicately preserved skeleton for all mammals discovered in the southern hemisphere before the extinction of the dinosaurs.
A 20-year study shows that Adalatherium was “giant” compared to most sturgeon or mouse-sized mammals Chalk period.
Reconstruction of Adalatherium hui from the Late Cretaceous of Madagascar. Credit: © Denver Museum of Nature and Science / Andrey Atuchin
Its “weird” features combine more trunk vertebrae than most mammals, more muscular back limbs (similar to modern crocodiles) with bold sprinting forelegs pressed under the body (as seen in most mammals today), living or exhausted. completely different from the teeth of any other known mammal, such as a rabbit’s and hind teeth, and a strange gap in the bones above the nose.
Dr. David Krause (Denver Museum of Nature and Science) and Dr. A team of 14 international researchers led by Simone Hoffmann (New York Institute of Technology) has published a comprehensive description and analysis of this giant mammal that lives among dinosaurs. Crocodiles near the end of the Cretaceous period in Madagascar (145-66 million years ago).
The 234-page monograph, which consists of seven separate chapters, is part of the prestigious Vertebrate Paleontological Society’s (SVP) Memoir Series, an annual special edition that provides a more in-depth treatment of the most important vertebrate fossils. The discovery was first announced in the journal Nature earlier this year.
AdalatheriumFrom Madagascar, it belongs to a group of extinct mammals known as gondvanatherians, first discovered in the 1980s and until recently represented by only a few isolated teeth and jaw fragments. However, these small fossils already show that gondvanatherians are very different from other modern mammals. Gondvanatherians were so enigmatic that it was not clear how mammals fit into the family tree.
Now the research team is presenting the first skeleton for this mysterious group that once roamed South America, Africa, Madagascar, the Indian subcontinent and even much of Antarctica.
Completeness and perfect protection of the skeleton Adalatherium opens new windows about how the Gondwanats looked and lived, but the strange features still surprised the team.
“It’s hard to know what we know about the skeletal anatomy of all living and extinct mammals, to think that one mammal likes it. Adalatherium could develop; bends and even breaks many rules, ”explains Krause.
Despite being rebuilt as life Adalatherium The surface resembles a mill badger, the “normality” is only deep in the skin. The skeleton under the surface is not strange.
As Hoffmann said, “Adalatherium it’s just weird. For example, it was difficult to understand how he was moving, because the front tells us a different story from the back. ”
Muscular hind legs and large toenails on the hind legs can indicate this Adalatherium was a strong digger (like a badger), its forelegs are less courageous and more like the feet of live mammals that can run faster.
The limbs Adalatherium also shows that its posture is a hybrid between living mammals and older relatives. The front legs were pressed under the body (as in most mammals today), but the hind legs were more common (as in crocodiles and lizards).
This strangeness did not stop.
Teeth Adalatherium, is an indicator of reconstructed, plant-derived animals using high-resolution microcomputed tomography and extensive digital modeling, not surprisingly.
I just didn’t Adalatherium it has ever-growing front teeth, similar to those of a rabbit or a rodent, but the posterior teeth are completely different from the teeth of any other mammal known to be living or extinct. If only these teeth were found, the mystery of what this animal is would probably not be solved! In addition to the visible chaos, there is a hole in the upper part of the nose where there is no parallel.
Approximately 3.1 kg in the size of a Virginia opossum Adalatherium was too big for his period. Although not as large by today’s standards, it was larger than most mammals and mice living in Cretaceous.
The geological history of Gondwana gives clues as to why Adalatherium very strange.
Adalatherium It was discovered about 66 million years ago in rocks near the end of the Cretaceous. At that time, Madagascar was an island separated from Africa for 150 million years and the Indian subcontinent for 20 million years. “The islands are items of strangeness,” says Krause, “so there was plenty of time Adalatherium to develop many extraordinary peculiarities in isolation. ”
“Adalatherium Hoffmann adds that it is part of a much larger mystery regarding the evolution of early mammals in the southern hemisphere.
Above all, discovery Adalatherium He stressed how much should be learned from the new findings of early mammals in Madagascar and other parts of the southern hemisphere.
Reference: “Introduction Justiceherium hui (Gondwanatheria, Mammalia) From the Late Cretaceous of Madagascar ”by David W. Krause, Joseph R. Groenke, Simone Hoffmann, Raymond R. Rogers and Lydia J. Rahantarisoa, December 18, 2020, Journal of Vertebrate Paleontology.
DOI: 10.1080 / 02724634.2020.1805455