Dinosaur Jaw Gape of Allosaurus, Erlikosaurus and Tyrannosaurus

Summary: Diet and eating styles for Allosaurus, Erlikosaurus and Tyrannosaurus link to jaw gape, according to a study in Royal Society Open Science Nov. 4, 2015.

Figure 8: Gape angles at optimal and maximum tension limit for (a) Allosaurus fragilis, (b) Tyrannosaurus rex and (c) Erlikosaurus andrewsi; muscle resting length at 6-degree gape angle; bar diagrams with strain factors of individual muscles at optimal and maximum tension limit: Stephan Lautenschlager, CC BY 4.0, via Royal Society Open Science

How big mouths are, how strained muscles become and how wide jaws open account for the binge foods and the table manners of dinosaurs, according to a study published online in the Royal Society Open Science edition Nov. 4, 2015.

Dr. Stephan Lautenschlager, School of Earth Sciences postdoctoral researcher at southwest England’s University of Bristol and study author, bases his conclusions on digital models and computer analyses of three therizinosaur (scythe lizard) theropod (beast-footed) dinosaurs. He compares bigger mouths and wider jaws of meat-eating Allosaurus fragilis (fragile different lizard) and Tyrannosaurus rex (tyrant lizard king) with smaller mouths and tighter jaws of plant-eating Erlikosaurus andrewsi ([British Museum vertebrate paleontologist Charles Williams] Andrews’ death god lizard Erlik).

Biggest-mouth and widest-jawed notoriety does not go to Tyrannosaurus.

life reconstructions and skull models of Tyrannosaurus rex (top), Allosaurus fragilis(middle) and Erlikosaurus andrewsi (bottom): S Lautenschlager @PalaeoStephan via Twitter Nov. 6, 2015

The curved- and serrated-toothed, slender-skulled Allosaurus emerges as the trio’s winner with a 33-inch (83.82-centimeter) gape through maximum openings of 79 to 92 degrees. The study finds that “Swift ambush predators such as Allosaurus had the largest jaw gape among the studied dinosaur species, which is consistent with the requirement for a predator hunting larger prey.”

First-place fame in muscle strength goes to the dagger-toothed, huge-sized, large-skulled Tyrannosaurus with a dinosaur jaw gape of 70.5 to 80 degrees. Dr. Lautenschlager hypothesizes that “Tyrannosaurus, in comparison, was able to exert continuous muscle force during different gape angles, which would be necessary for an animal biting through thick flesh and crushing bones.”

The BLENDER three-dimensional modeling and visualization software digital model based on CT scans of fossil skulls and on jaw muscle reconstructions of features remaining on bones indicates a jaw gape of 43.5 to 49 degrees for the beak-snouted, leaflike-toothed, narrow-skulled, pot-bellied, short-armed Erlikosaurus.

Dr. Lautenschlager judges the results consistent with the study’s comparative measurement of jaw gape, mouth size and muscle force in two living dinosaur relatives, the meat-eating archosaurs (leader lizards) Alligator mississippiensis (American or Mississippi alligator) and Buteo buteo (common buzzard), since “We know from living animals that carnivores are usually capable of larger jaw gapes than herbivores, and it is interesting to see that this also appears to be the case in theropod dinosaurs.”

As the study demonstrates and proves for the first time, everything about jaws, mouths and teeth keeps the two apex predators, Allosaurus of 150 million years ago and Tyrannosaurus of 66 million years ago, secure and successful in their respectively gory, messy “strike-and-tear” and “puncture-and-pull” table manners regarding large, moving prey. Buccal, dental and mandibular configurations leave non-apex predator Erlikosaurus of 90 million years ago nervous and quick in grab-and-gulp table manners respecting cropping foliage and stripping branches of leaves.

It means that cinematographic art and imagination nudge prehistoric life and reality when Dr. Lautenschlager observes that “Theropod dinosaurs, such as Tyrannosaurus rex or Allosaurus, are often depicted with widely-opened jaws, presumably to emphasise their carnivorous nature.”

reconstruction of the Cretaceous dinosaur Erlikosaurus andrewsi -- original fossil (back), reconstructed digital skull model (middle), life-reconstruction (front): S Lautenschlager @PalaeoStephan via Twitter June 19, 2015

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

jaw gape angles: Stephan Lautenschlager, CC BY 4.0, via Royal Society Open Science @ http://d3hu9binmobce5.cloudfront.net/content/royopensci/2/11/150495/F8.large.jpg

life reconstructions and skull models of Tyrannosaurus rex (top), Allosaurus fragilis(middle) and Erlikosaurus andrewsi (bottom): S Lautenschlager @PalaeoStephan via Twitter Nov. 6, 2015, @ https://twitter.com/PalaeoStephan/status/662599685933277184

reconstruction of the Cretaceous dinosaur Erlikosaurus andrewsi -- original fossil (back), reconstructed digital skull model (middle), life-reconstruction (front): S Lautenschlager @PalaeoStephan via Twitter June 19, 2015, @ https://twitter.com/PalaeoStephan/status/611831054807244800

For further information:

Dunham, Will. 3 November 2015. "Watch your mouth: Allosaurus had monstrously gaping jaws." Reuters > Technology.
Available @ http://www.reuters.com/article/2015/11/04/us-science-dinosaur-idUSKCN0ST00320151104

Lautenschlager, Stephan. November 2015. "Estimating cranial musculoskeletal constraints in theropod dinosaurs." Royal Society Open Science, vol. 2, issue 11 (Nov. 2015): 150495. DOI: 10.109/rsos.150495
Available @ http://rsos.royalsocietypublishing.org/content/2/11/150495

Royal Society journal supplements. 5 November 2015. "Movie showing gape cycles and strain factors with a muscle resting length at 6 degrees." YouTube.
Available @ http://www.youtube.com/watch?v=510Cr91YnkQ

S Lautenschlager @PalaeoStephan. 6 November 2015. "This month's Lautenschlagerisation: Tyrannosaurus, Allosaurus and Erlikosaurus Inspired by rsos.royalsocietypublishing.org/content2/11/1 ..." Twitter.
Available @ https://twitter.com/PalaeoStephan/status/662599685933277184

S Lautenschlager @PalaeoStephan. 19 June 2015. "My first tweet should probably be a 'Laurenschlagerisation'. So here it is, Erlikosaurus in its full glory." Twitter.
Available @ https://twitter.com/PalaeoStephan/status/611831054807244800

University of Bristol. 3 November 2015. "The better to eat you with? How dinosaurs' jaws influenced diet." EurekAlert! > Public Releases.
Available @ http://www.eurekalert.org/pub_releases/2015-11/uob-tbt110215.php