Behold, the “Crazy Beast”

It might look like a badger, but internally the Crazy Beast has got some crazy-weird seemingly nature-defying anatomy.

This interesting article is suitable for students in Years 4, 5, 6, 7, and 10 studying Biological or Earth and Space sciences. It could be used when studying species evolution and adaptation alongside the changing Earth.

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Artist reconstruction of Adalatherium hui, a new gondwanatherian mammal from the Late Cretaceous of Madagascar. Credit: Andrey Atuchin

Why This Matters: Madagascar keeps throwing up evolutionary weirdness.

When in isolation, animals evolve bizarre features and behaviours. And sometimes, it gets really weird.

Madagascar already has its fair share of weird and wonderful fauna. But now researchers have uncovered a mammal the size of a cat, that resembled a badger, and roamed amid dinosaurs and giant crocodiles 66 million years ago.

But its badger-like appearance is superficial, say the researchers – its skeleton features some seemingly nature- and logic-defying morphology.

So much so, it’s been named Adalatherium, which translates from the Malagasy and Greek languages as “crazy beast”.

The discovery is the first near-complete skeleton of a gondwanatherian — a mysterious groups of mammals that lived on the ancient supercontinent Gondwana and in the Southern Hemisphere after it broke apart. All previous fossils of this group were only teeth or jawbones, or the single skull from another Madagascan fossil called Vintana – so scientists had almost no idea of what they looked like.

“We could never have believed we would find such an extraordinary fossil of this mysterious mammal,” says Alistair Evans from Monash University, who was involved in the research.

“This is the first real look at a novel experiment in mammal evolution.”

The discovery has been described in the journal Nature.

The fossilised skeleton of Adalatherium hui. Credit: Marylou Stewart

Crazy Beast anatomy breaks a lot of rules

“[K]nowing what we know about the skeletal anatomy of all living and extinct mammals, it is difficult to imagine that a mammal-like Adalatherium could have evolved; it bends and even breaks a lot of rules,” says David Krause from Stony Brook University in the US, who led the research.

According to Krause, its snout has primitive features that were last seen a hundred million years earlier in the lineage that evolved into modern mammals. While some of the features are very standard for a mammal, he adds that it has an “amazing mosaic” of features that he’s never seen before.

Adalatherium had more holes (called foramina) on its face than any known mammal, serving as conduits for nerves and blood vessels that supplied a very sensitive snout covered with whiskers.

Other unusual features include a very large hole at the top of its snout, more vertebrae than any Mesozoic mammal, a strangely curved leg bone, and unique teeth construction.

“The strangeness of the animal is clearly apparent in the teeth,” says Monash’s Evans.

“They are backwards compared to all other mammals and must have evolved afresh from a remote ancestor.”

Its size was also unusual for its era – most mammals that lived alongside dinosaurs were more mouse-sized, on average. Yet the Crazy Beast was a giant in comparison. It is thought to have weighed around 3 kilograms, and in this case, was probably not even fully grown.

“The front end tells a different story to the back”

A reconstruction of the skeleton of Adalatherium hui, from the side and top. Credit: Simone Hoffmann

With such strange anatomy its movements defy logic, according to Simone Hoffman from the New York Institute of Technology, who also worked on the research.

Adalatherium is the oddest of oddballs,” she says. “Trying to figure out how it moved is nearly impossible because, for instance, its front end is telling us a different story than its back end.”

After 20 years of piecing the mystery creature together since its discovery in 1999, the team is still deciphering the clues. With claws and oddly bowed legs, it could have been a powerful digger, but it could have run or even used other means of locomotion as well.

Other peculiar vertebrates the team has discovered on Madagascar over the past 25 years include a giant, armoured, predatory frog (Beelzebufo), a pug-nosed, vegetarian crocodile (Simosuchus) and a small, buck-toothed dinosaur (Masiakasaurus).

And they’re in good company with endemic Madagascan animals such as hissing cockroaches (Gromphadorhina portentosa), giraffe weevils (Trachelophorus giraffa), tomato frogs (Dyscophus), Satanic leaf-tailed geckos (Uroplatus phantasticus), panther chameleons (Furcifer pardalis) and streaked tenrecs (Hemicentetes semispinosus).

Just a few thousand years ago, 600-kilogram elephant birds (Aepyornithidae), gorilla-sized lemurs and pygmy hippopotamuses roamed the richly biodiverse landmass.

Madagascar’s odd animals are largely a result of its relative isolation. Gondwana began breaking up around 180 million years ago, forming Antarctica, Australia, South America and India. Madagascar likely broke away from India around 90 million years later.

With limited resources, less competition between species, and a relative scarcity of predators and parasites, islands promote evolutionary paths that result in unique physiology and behaviour.

Given Crazy Beast lived around 20 million years after that final separation, it’s the result of tens of millions of years of evolution on the isolated island.

“Ample time to develop its many ludicrous features,” says Krause.

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Years: 4, 5, 6, 7, 10

Topics:

Biological Sciences –  Ecosystems, Living Things

Earth and Space Sciences – The Changing Earth

Additional: Careers, Technology

Concepts (South Australia):

Biological Sciences –  Interdependence and Ecosystems, Diversity and Evolution, Form and Function

Earth and Space Sciences – The Earth’s Surface