Extinct weasel relative with confounding skull likely ate meat with a side of veggies

Related Articles

Related Articles

New research on an extinct weasel relative reveals what it might have eaten when it lived in North America and Asia about 20 million years ago.

The oddly shaped skull of Leptarctus primus has long led to conflicting theories about its diet. But the new work, based on biomechanical modeling and published this week in the Journal of Vertebrate Paleontology, shows that Leptarctus was likely a carnivorous predator, with capability for omnivory and a broader diet when prey was scarce, and had a skull that functioned similarly to that of the living American badger.

Leptarctus primus, which lived in the Miocene and was just a little larger than a housecat, has intrigued researchers because of its unusual and extremely robust skull.

 

“For a mammal, its skull is really strange,” said co-author Z. Jack Tseng, a research associate at the American Museum of Natural History and an assistant professor of pathology and anatomical sciences at the Jacobs School of Medicine and Biomedical Science at the University at Buffalo. “It’s heavily built–like a tank–with very thick zygomatic cheek bones. The top of its head looks like it’s wearing a helmet.”

Strikingly, Leptarctus primus has two parallel ridges that line the top of the head (other carnivorans typically have a single central ridge or have smooth skulls). For many years, paleontologists have debated the ecological niche of Leptarctus based on conflicting interpretations of the strong parallel skull ridges, distinctive skull shape, and the shape of its teeth and chewing wear. Previous interpretations of their feeding lifestyle ranged widely, across virtually every type of known feeding behavior in carnivorans (dogs, cats, hyaenas, bears, seals, and weasels and their relatives), including herbivore, carnivore, insectivore, and omnivore. But because of the lack of quantitative research into how Leptarctus skulls functioned, the question of their diets remained unanswered.

In this study, led by Alixandra Prybyla, who was a student in the Museum’s National Science Foundation Summer Research Experience for Undergraduates program while at Columbia University, the researchers took an engineering approach. The team compared an almost complete fossil skull of Leptarctus primus with 18 species of modern carnivorans with known diets as well as to other fossil species, using bite simulations based on CT scans of the skulls and virtual modeling of feeding mechanics.

According to John Flynn, study co-author, research team leader, and Frick curator of fossil mammals in the Museum’s Division of Paleontology, “Traditional methods of studying skull, tooth, and skeleton anatomy are still essential for understanding how fossil species lived. But high-resolution x-ray CT images and sophisticated computerized engineering modeling tools have completely transformed our ability to accurately reconstruct feeding habits in extinct animals.”

They found that among the other species analyzed, the skull of Leptarctus is mechanically most similar to the skull of the American badger. Despite some differences in their skull appearances, the computer simulations indicate that the badger is the best living biomechanical analog for understanding the dietary lifestyle of Leptarctus. Based upon those comparisons, the team determined that it was primarily a carnivore and an active predator, but that it could also have been an omnivore feeding on a wider range of plant and insect foods when necessary.

“It was probably hunting down prey and taking in whatever it had access to most of the time,” Tseng said.

Prybyla added: “This complete skull of Leptarctus represents an untapped wellspring of information on the history of ancient relatives of weasels, otters, badgers, and skunks. It’s wonderful what one specimen can illuminate for researchers. To spearhead a project of this magnitude as an undergraduate student was extremely empowering.”

The researchers will conduct future studies using similar engineering modeling tools to look at variations in skull feeding mechanics among other species in the leptarctine group, to determine how many different types of feeding adaptations may have existed among these unusual extinct predators.

AMERICAN MUSEUM OF NATURAL HISTORY

Header Image – A reconstruction of the head of Leptarctus primus attacking the Miocene rodent Cupidinimus. CREDIT © AMNH/N. Wong

Download the HeritageDaily mobile application on iOS and Android

More on this topic

LATEST NEWS

Giant Sand Worm Discovery Proves Truth is Stranger Than Fiction

Simon Fraser University researchers have found evidence that large ambush-predatory worms--some as long as two metres--roamed the ocean floor near Taiwan over 20 million years ago.

Burial Practices Point to an Interconnected Early Medieval Europe

Early Medieval Europe is frequently viewed as a time of cultural stagnation, often given the misnomer of the 'Dark Ages'. However, analysis has revealed new ideas could spread rapidly as communities were interconnected, creating a surprisingly unified culture in Europe.

New Starfish-Like Fossil Reveals Evolution in Action

Researchers from the University of Cambridge have discovered a fossil of the earliest starfish-like animal, which helps us understand the origins of the nimble-armed creature.

Mars Crater Offers Window on Temperatures 3.5 Billion Years Ago

Once upon a time, seasons in Gale Crater probably felt something like those in Iceland. But nobody was there to bundle up more than 3 billion years ago.

Early Humans Used Chopping Tools to Break Animal Bones & Consume the Bone Marrow

Researchers from the Sonia and Marco Nadler Institute of Archaeology at Tel Aviv University unraveled the function of flint tools known as 'chopping tools', found at the prehistoric site of Revadim, east of Ashdod.

50 Million-Year-Old Fossil Assassin Bug Has Unusually Well-Preserved Genitalia

The fossilized insect is tiny and its genital capsule, called a pygophore, is roughly the length of a grain of rice.

Dinosaur-Era Sea Lizard Had Teeth Like a Shark

New study identifies a bizarre new species suggesting that giant marine lizards thrived before the asteroid wiped them out 66 million years ago.

The Iron Age Tribes of Britain

The British Iron Age is a conventional name to describe the independent Iron Age cultures that inhabited the mainland and smaller islands of present-day Britain.

Popular stories

The Iron Age Tribes of Britain

The British Iron Age is a conventional name to describe the independent Iron Age cultures that inhabited the mainland and smaller islands of present-day Britain.

The Roman Conquest of Wales

The conquest of Wales began in either AD 47 or 48, following the landing of Roman forces in Britannia sent by Emperor Claudius in AD 43.

Vallum Antonini – The Antonine Wall

The Antonine Wall (Vallum Antonini) was a defensive wall built by the Romans in present-day Scotland, that ran for 39 miles between the Firth of Forth, and the Firth of Clyde (west of Edinburgh along the central belt).

Vallum Aulium – Hadrian’s Wall

Hadrian’s Wall (Vallum Aulium) was a defensive fortification in Roman Britannia that ran 73 miles (116km) from Mais at the Solway Firth on the Irish Sea to the banks of the River Tyne at Segedunum at Wallsend in the North Sea.