The Very Powerful Bite of Siamogale melilutra

Back in January, Everything Dinosaur reported upon the scientific description of a new species of giant otter from the Late Miocene of south-west China.  At around fifty kilogrammes in weight, the new species Siamogale melilutra, is a much more heavy-set and robust animal compared to extant otter species.  At the time, the scientists responsible for studying the fossil material, which included an almost complete but crushed cranium, speculated on what this super-sized member of the weasel family would have fed on.  Writing in the journal “Scientific Reports”, some of the scientists involved in the original description have followed up this research by publishing a new paper on the feeding capabilities of such a powerful carnivore.

This wolf-sized, aquatic predator had a surprisingly strong bite that might have made S. melilutra an apex predator.

A Digitally Reconstructed View of the Skull and Jaws of Siamogale melilutra

Digitally restored cranium of S. melilutra right lateral view.

A digitally reconstructed cranium of S. melilutra .

Picture Credit: Scientific Reports

Comparing Otter Skulls and Jaws

The researchers digitally recreated jaw models of extinct otters as well as ten extant species (living species of otters) and then subjected these models to engineering stress tests.  The researchers discovered that the jaw of Siamogale melilutra was six times stronger than expected.  Although, the teeth morphology and biting efficiency was found to be very similar to living otters, these very strong jaws open up the possibility that Siamogale melilutra fed on a range of animals that its modern-day contemporaries could not.  Sea Otters (Enhydra lutris) and the African Cape Clawless Otter (Aonyx capensis), specialise in feeding upon shellfish and have a durophagous diet.  Even accounting for the size difference between the Miocene giant Siamogale melilutra and these living otter species, the jaws of S. melilutra are much stronger.

Comparing the Stress on Jaws on Living and Extinct Species of Otter

Calculating the bite of Siamogale melilutra.

Stress during biting (otter jaw comparison).

Picture Credit: Scientific Reports

The picture above shows the results of computer modelling to indicate potential bite force stresses in a number of otter species.  Warmer colours depict high levels of bite stress, whilst cooler colours depict areas of lower stress.

(a) Pteronura brasiliensis (Giant South-American Otter)

(b) Lontra canadensis (North American River Otter)

(c) Lontra longicaudis (Neotropical Otter of Central America)

(d) Lontra felina (South American Marine Otter)

(e) Enhydra lutris (Sea or Marine Otter)

(f) Hydrictis maculicollis (Spotted-necked Otter)

(g) Siamogale melilutra – extinct Miocene species

(h) Lutra lutra (European Otter)

(I) Aonyx capensis (African Cape Clawless Otter)

(j) Aonyx cinerea (Asian Small-clawed Otter)

(k) Lutrogale perspicillata (Indian Smooth-coated Otter)

The research team conclude that S. melilutra has no living analog.  Its huge size and powerful jaws could have enabled this otter to exploit an environmental niche not found in living otter species.  It might even have been an apex predator.

To read Everything Dinosaur’s article on the scientific description of Siamogale melilutraSuper-sized Otter as Big as a Wolf

The scientific paper: “Feeding Capability in the Extinct Giant Siamogale melilutra and Comparative Mandibular Biomechanics of Living Lutrinae” by Z. Jack Tseng, Denise F. Su, Xiaoming Wang, Stuart C. White and Xueping Ji published in the journal “Scientific Reports”.

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