Allosaurus vs. Stegosaurus: Who Would Win?

Photo: MR1805 via Getty Images

It was in the late Jurassic North American fields and forests about 150 million years ago when the docile, small-brained, brilliantly armored Stegosaurus and the nimble three-fingered Allosaurus stood out for their tremendous proportions.

When a team from Dinosauria International LLC discovered two nearly complete fossils of Allosaurus and Stegosaurus in Wyoming in the springtime of 2007, they were thrilled. Never before had the two magnificent dinosaurs been found with each other in Upper Jurassic North America, where they had been said to have engaged in fierce competition for territory. A long-held belief among paleontologists is that Allosaurus and Stegosaurus fought each other.

Researchers have lately discovered more concrete proof of these historic battles. For example, a Stegosaurus neck bone with a U-shaped bite impression fits the form of an Allosaurus jaw. At the same time, an Allosaurus tail vertebra with a puncture wound hole resembling a configuration of a Stegosaurus tail spike was discovered by paleontologists.

Finally, the world of paleontology found confirmation of not only their coexistence but also of the conservation of their battle here. The Stegosaur was dubbed "Fantasia" in honor of a notable scene from an old Disney movie. The Allosaurus was dubbed "Dracula" because of its terrible teeth.

Now we ask ourselves, how would this fight have gone down? Would Dracula the Allosaurus dominate with sheer rage, or would Fantasia hold her ground and fend off the enemy with her formidable armor?

On The Red Corner: Dracula the Allosaurus

Photo: libre de droit via Getty Images

Allosaurus was one of the earliest dinosaurs discovered. Its abundant remains have made it a favorite of paleontologists and novice dinosaur watchers.

Allosaurus derives its name from the Greek words allos ("different" or "other") and sauros  ("lizard"). Scientists gave it this name because its vertebrae were unlike those found on any previous dinosaur identified at the point of its 1877 discovery.

In the case of Allosaurus fragilis (Latin for "fragile"), portions of the vertebrae were concave across both sides. They contained shallow hollow space, lending them an hourglass structure, which lowered the bones' durability while rendering them lighter. Modern birds share the same hollow chambers in their neck and anterior back vertebrae, which are thought to have carried air sacs for respiration.

Theropod (bipedal, carnivorous dinosaur) existed between 155.7 million and 150.8 million years ago in the late Jurassic Period. The  Allosaurus is the most abundant dinosaur fossil unearthed at Utah's Cleveland-Lloyd Quarry, with the greatest density of Jurassic dinosaur bones anywhere on the planet.

Allosaurus was an enormous carnivorous dinosaur. Based on a 1976 study of A. fragilis in the Utah Geological Survey Bulletin, the biggest individuals may have challenged the stature of T. rex, reaching up to 39 to 43 feet (12 to 13 meters) long and 15 to 16 feet (4.5 to 5 meters) high.

Weight projections for Allosaurus differ, but reconstructions of the famed A. fragilis specimen "Big Al" show the dinosaur reached upwards of 3,300 pounds (1,500 kilograms) at full adulthood, which occurs around the age of 15.

Like other massive carnivorous dinosaurs, Allosaurus has a short neck and narrow, elongated head that was largely out of proportion. Two muscular hind limbs and a big tail indicated that Allosaurus could travel at a top speed of roughly 21 mph (33.8 kph).

In contrast to most other theropods, this one possessed a pair of little horns above its eyebrows, which were expansions of the lacrimal bones in the cranium. On top of that, it had ridges from nose to horns. Several teeth in the dinosaur's jaws were serrated at the front and back edges.

On The Blue Corner: Fantasia the Stegosaurus

Photo: Daniel Eskridge via Getty Images

Large plant-eating dinosaurs such as Stegosaurus roamed western North America in the late Jurassic Period alongside the terrifying Allosaurus. It was roughly the size of a bus and had two rows of bony plates down its back, which made it look much larger.

Stegosaurus has become somewhat of a media and pop culture sweetheart because of the abundance of data scientists can use to recreate its unique look. In films and television, it has been seen trying to chase Faye Wray in "King Kong" and in two and three of the "Jurassic Park" blockbusters. Even a newspaper cartoon contributed to naming one of its anatomical parts.

As having one of the smallest brain-to-body ratios among dinosaurs, Stegosaurus was once thought to have possessed a tiny brain. Until recently, the scientific community considered that Stegosaurus' brain was the size of a walnut. Kenneth Carpenter, director of the USU Eastern Prehistoric Museum in Utah, claims that the brain of the armored dinosaur had the size and form of a bent sausage.

Largest in its genus and family was Stegosaurus armatus, which reached a length of 30 feet (9 meters). It is regarded as a "type species," the animal that serves as the principal illustration of the Stegosaurus genus. However, Stegosaurus stenops, the best-known and most-studied member of Stegosauria due to its wealth of fossils, including a virtually intact skeleton, might be more worthy of such a designation.

Stegosaurus, which translates to "roofed lizard," was coined by 19th-century paleontologists who thought its plates sat flat on its back like tiles on roofs. However, overwhelming evidence indicates that the plates alternate in two rows, pointed side up, from the dinosaur's neck to its tail. Its 17 plates, known as scutes, were comprised of a bone substance called osteoderms. However, they were not solid; they had lattice-like formations and circulatory veins running through them.

The agile tail of the Stegosaurus also featured spikes pointing outward from the sides.  According to New Scientist, a "Far Side" cartoon depicting cavemen calling the sharp spikes after the late Thag Simmons in 1982 inspired scientists to begin calling the spikes that way unofficially.

Based on two lines of evidence, specialists believe these spikes were utilized to protect against predators. For starters, it is estimated that 10% of the spikes experts found had to damage to the tip. Like in Dracula, scientists have also discovered thagomizer puncture scars in allosaur bones.

Scientists have also discovered thagomizer puncture scars in allosaur bones, like in Dracula's.

Stegosaurus had a slender, pointed snout. It possessed an odd head-down stance because its forelimbs were shorter than its rear limbs. This asymmetry in limb length shows that the dinosaur could not move quickly since its rear legs would have surpassed its front legs in stride.

Three, Two, One, Fight!

What if Dracula, the Allosaurus, sneaks up to our Stegosaurus Fantasia while the latter is busy munching on some nice low-growing shrubs?

Allosaurus dips its head, ramps up steam, and then shoves the massive Stegosaurus in the side with its enormous, bony skull, transferring countless megajoules of power to the opponent. 

Stegosaurus whips out with the thagomizer on the tip of its tail, leaving only cuts and bruises on Allosaurus' back legs; at the same time, it bends down toward the earth to avoid exposing its vulnerable underside to a well-executed attack. 

The Allosaurus is unfazed and attacks again, lowering its giant head and successfully toppling the Stegosaurus on its side this time.

The Allosaurus wins today's Jurassic throwdown, with Fantasia's belly exposed and Dracula's tummy rumbling.

The Stegosaurus, a slow-witted dinosaur, is practically as defenseless as an overturned turtle, tossing its head and thagomizer and yelping to other members of the herd.

A typical tiger would end the agony of its prey by biting it on the neck. However, Allosaurus has no qualms about digging into the stomach of Stegosaurus and devouring the animal's organs while it is still breathing.

A swarm of other hungry theropods, including little feathered dino-birds, swarms around the event, hungry for a piece of the slaughter but wise enough to wait until the much larger and menacing Allosaurus has finished its meal.

Cheers!

~GB