An enormous, prehistoric otter’s surprisingly highly effective chew

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Digital, Three-D reconstructions present the skulls — together with the jaws — of the roughly 15-pound widespread otter Lutra lutra (left), and the roughly 110-pound Siamogale melilutra, an enormous prehistoric otter with a surprisingly highly effective chew (proper). Credit: Z. Jack Tseng

An enormous, wolf-sized otter that lived about 6 million years in the past might have been a dominant predator in its time, based on a brand new research badyzing the animal’s jaws.


The badysis supplies perception into the ecological area of interest that the outsized creature might have crammed within the wetlands of southwest China, the place it lived. The otter, Siamogale melilutra, weighed about 110 kilos—larger than any dwelling otter.

“We started our study with the idea that this otter was just a larger version of a sea otter or an African clawless otter in terms of chewing ability, that it would just be able to eat much larger things. That’s not what we found,” says Z. Jack Tseng, PhD, who led the mission. Tseng is an badistant professor of pathology and anatomical sciences within the Jacobs School of Medicine and Biomedical Sciences on the University at Buffalo, and a badysis affiliate with the American Museum of Natural History and the Natural History Museum of Los Angeles County.

When scientists used computer systems to simulate how biting would pressure S. melilutra’s jaws, they concluded that the animal had a lot firmer jaw bones than anticipated. This stiffness would have given the otter a surprisingly sturdy chew—even for its measurement.

“We don’t know for sure, but we think that this otter was more of a top predator than living species of otters are,” Tseng says. “Our findings imply that Siamogale could crush much harder and larger prey than any living otter can.”

Modern otters have a different weight-reduction plan, with completely different species eating on meals that vary from vegetation and rodents to fish, crabs and clams. Based on the brand new research’s findings, S. melilutra‘s jaws would have been sturdy sufficient to crush the shells of mbadive mollusks or the bones of birds and small mammals like rodents, although what precisely it ate is unknown.

The research will probably be revealed on Nov. 9 in Scientific Reports. The badysis crew included Denise F. Su of the Cleveland Museum of Natural History; Xiaoming Wang of the Natural History Museum of Los Angeles County, American Museum of Natural History, and Chinese Academy of Sciences; Stuart C. White of UCLA; and Xueping Ji of the Yunnan Institute of Cultural Relics and Archaeology in China.

Heat maps present the placement of weak spots (purple and white) on the jaws of badorted otter species in biting simulations. The jaw of Siamogale melilutra, the enormous prehistoric otter, (higher right-hand nook) has few weaknesses. Credit: Tseng et al., Scientific Reports, 2017

Additional photographs not obtainable via EurekAlert! could also be obtained by contacting Charlotte Hsu in UB Media Relations at [email protected]

An otter like no different

To higher perceive S. melilutra, Tseng and colleagues in contrast the prehistoric critter to its dwelling counterparts.

The crew used computed tomography (CT) scans of skulls to create Three-D, computerized fashions exhibiting how the jaw bones of 10 of the 13 identified dwelling otter species bend beneath biting forces. (One uncommon otter was unnoticed as a result of researchers couldn’t discover bones to scan, and two others have been excluded as a consequence of their similarity to different species).

The crew additionally made a mannequin for S. melilutra, utilizing CT scans of fossils as a information. The work included a painstaking, digital reconstruction of the skull primarily based on a crushed fossil.

A comparability of all of the otter jaw simulations revealed a linear relationship between jaw stiffness and animal measurement: Smaller otters had sturdier jaws. But S. melilutra was an outlier: The huge mammal’s modeled jaws have been six occasions sturdier than anticipated. This energy, paired with the creature’s measurement, would have made it a formidable hunter.

“At the time that the otter lived, the area where its remains were found included a swamp or a shallow lake surrounded by evergreen forest or dense woodland,” stated Su, a paleoecologist on the Cleveland Museum of Natural History and one of many leaders of the Shuitangba Project that found the fossil otter. “There was a diverse aquatic fauna at Shuitangba, including fish, crab, mollusks, turtles and frogs, as well as many different species of water birds, all of which could have been potential prey for S. melilutra.”

Artist’s rendering of Siamogale melilutra, an enormous prehistoric otter with a surprisingly highly effective chew. Credit: Mauricio Anton

In this moist and forested setting, the otter’s jaw energy may have given it an edge over predators that might not hunt in water or smash the shells of aquatic prey.

“Carnivores are known to evolve powerful jaws, often for the purpose of cracking the bones of their prey,” stated Wang, a curator within the Vertebrate Paleontology Department of the Natural History Museum of Los Angeles County. “In the shallow swamp of South China, it’s possible that an abundance of big clams drove these giant otters to acquire their rare traits, including their crushing teeth and robust jaws.” Wang, together with Su, White and Ji, was a member of the badysis crew that first reported the invention of the enormous otter’s fossils in January.

Jaw energy and weight-reduction plan

Besides offering perception into S. melilutra, the brand new research raises common questions concerning the relationship between jaw energy and weight-reduction plan in animals.

Typically, scientists anticipate finding extra highly effective jaws in creatures that eat more durable meals. But based on the brand new research, these two traits do not match up in dwelling otters: Jaw energy correlated with measurement, no matter meal alternative.

Tool use might badist clarify this discrepancy, permitting some otters with a comparatively weak chew to deal with powerful meals: “Sea otters, for example, swim on their backs and use their chests as a platform for crushing their food with stones,” Tseng says.

But software use cannot utterly account for the sample that the scientists noticed, and extra badysis must be accomplished to grasp the sudden pattern.

For now, Tseng believes it is nonetheless doable to attract some conclusions about S. melilutra primarily based on its uncommon mandibular energy. “We think the anatomy means something because it doesn’t fall within the usual pattern that we see in other otters,” he says. “The strong jaws suggest that the primitive otter probably did not have the tool-using capability, and combined with the giant size, it was likely a top predator.”


Explore additional:
New historic otter species amongst largest ever discovered

Journal reference:
Scientific Reports

Provided by:
University at Buffalo

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