Allosaurus

Species: jimmadseni, europaeus, fragilis

Range: Late Jurassic (Tithonian, 150-145 MYA) of Utah, Wyoming, Colorado, Portugal, Spain, possibly France, Russia, Japan

Size estimate: 30-35 ft length, 5 tons

Discovery: Othniel Charles Marsh, 1877

Classification: dinosauria, saurischia, therapoda, tetanurae, allosauroidea

True to Life?

 

Since no one has ever seen a living dinosaur, and the missing pieces of the fossil record withhold important clues to their appearance, no artistic representation of a dinosaur ever gets it 100% right. On top of that, new discoveries can change our ideas of extinct creatures drastically. So, how close does this sculpture come to what we know of the original animal?

Allosaurus:

As Utah’s state fossil, Allosaurus gets the most exposure here at the park, with four skeletons, three sculptures, and more to come. Let’s look at each of the sculptures one by one.

 

Oak Grove

  • One of the earliest statues here at the park, this concrete sculpture adopts the same three-point stance as the other concrete bipedal dinosaurs from that era. A real Allosaurus would have to dislocate the tip of its tail to pose like this. Tail dislocations aside, a theropod might adopt a more upright posture to get a better look at its surroundings or to nibble at things in trees. It just wouldn’t walk efficiently this way, and would not adopt it as a normal part of its posture—it’s the same as crawling: humans can crawl on all fours, but it’s not the best way of getting around, and once we learn how to walk properly, we don’t do it often.

  • Though full of old-school charm, this sculpture also suffers from an old misconception that has plagued this less-famous cousin of T. rex. Famed movie maker Ray Harryhausen considered these two giant dinosaurian carnivores essentially interchangeable, and he’s not alone: many museum visitors seem to treat Allosaurus as a three-fingered, smaller version of Tyrannosaurus. As a result, this sculpture features very generalized detailing that shares many characteristics with the pop-culture conception of Tyrannosaurus. The bony eyebrows so important to Allosaurus’ look have been reduced to subtle bumps, the lower jaw has been thickened, and the head’s overall size has been exaggerated.

  • This sculpture does one thing better than any other Allosaurus in the Park: its teeth look relatively small and blade-like. The effect might have more to do with sculpting technique than scientific fidelity, but it nevertheless comes closer in this regard. Allosaurus bore surprisingly small teeth for a large carnosaur, which might facilitate its hawk-like method of plucking at prey. It could open its jaws surprisingly wide, almost like a saber toothed cat, except that its small teeth would allow it to take quick bites that inflicted a lot of damage, allowing it to wear down large prey animals like Stegosaurus or Brontosaurus.

  • A living Allosaurus would have a shorter, more compact torso, and a longer tail. Theropods walked like living see-saws balanced at the all-important hip joint: the secret to their upright posture and energy-efficient walking gait. This sculpture adopts the upright posture in part because it’s somewhat out of balance.

  • Allosaurus arms would hang lower down on its chest. Their shape suggests they were built to clutch things to the chest—perhaps to stabilize prey as the Allosaurus aimed a killing bite, perhaps to help leverage pieces of the carcass as it tore off chunks of meat.

  • Many dinosaurs retained a reduced first toe called the hallux. It may have served a role in helping to slough off dead skin (dinosaurs shed skin in patches) or for a nice scratch. The halluxes on this sculpture . . . well, they’re anything but reduced.

  • Behind the scenes: We nicknamed this sculpture Alice in reference to the character from the original “Land of the Lost” TV series. This picture shows Alice “reuniting” with some of the show’s original cast. DO NOT TRY THIS POSE YOURSELVES! Alice can get aggressive with strangers. Please stay on the paths throughout your visit.

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Fight Scene

  • Like Alice, the oak grove sculpture, this Allosaurus takes many of its cues from older tropes. It sports an exaggerated head size and features overgrown teeth as a result. The shape of the teeth more closely resembles those of sharks’ than real Allosaurus teeth, which curve towards the rear of the mouth. Such a shape hooks onto the things the animal bites, and often features in animals that have to grip struggling prey.

  • This sculpture features two pointy horns instead of the broad, triangular eyebrows known from Allosaurus skulls.

  • Only one small sample of Allosaurus skin fossils have been recorded so far. It shows this animal grew small, pebbly scales on at least parts of its body. We do not have evidence of larger feature scales or scutes for this particular genus, but ceratosaur and carcharodontosaur relatives both preserve evidence of such scale arrangements along with the pebbly texture known for Allosaurus. Comparisons with relatives don’t always work right, but in the absence of other evidence, they can produce reasonable guesses. For the past 30 years, some artists and paleontologists have speculated that Allosaurus bore feathers at some point in its life, but the evidence does not bear that out. The only confirmed skin impression reported for Allosaurus so far comes from the juvenile featured in the Stewart Museum, making fluffy baby Allosaurus unlikely. No known tetrapod (a group which includes mammals, birds, reptiles, and amphibians) switches skin covering types, and what we know of feather development severely complicates scenarios where babies bore both scales and fluff, losing the fuzz as they reached adulthood. Feathered Allosaurus models do not explain the evidence known for this animal.

  • Concrete construction forced another three points of contact to make the engineering work, but in this case, the artist managed to sell the tail-dragging pose as a consequence of the fight. In doing so, it also avoids the tail dislocation that makes Alice so grumpy and allows for more realistic proportions along the body.

 

Rogue’s Gallery

  • Though not a complete representation of the animal, this sculpture includes the most true-to-life details. It also represents the only example of the third Allosaurus species known: Allosaurus europaeus. Details distinguishing these species focus on the head, appropriately enough. The differences which would show in a sculpture center on the nose and eyes. The oldest species, A. jimmadseni, grew a low ridge or crest along its nose, and its jawline followed a roughly straight line from its teeth back to the joint—a “poker face,” if you will. A. fragilis, the most common species, lost the nose ridges and gained a downward bend to its cheekbone, resulting in a sort of “frown face.” As this sculpture shows, the only known and incomplete skull of A. europaeus shows both the frown and the nose ridges.

  • Sadly, this sculpture features generic, cone-shaped teeth. Real Allosaurus teeth have a much flatter cross-section, looking more like knives than cones. They also curve noticeably backwards.

  • The red applied to the crests above the nose and eyebrows is speculative. In many modern animals that use crests or other body parts for communication, color plays an important role. For humans, eyebrows play an important role in expressing emotion in particular. As a result, actors in live theater often use eyebrow pencil to darken their eyebrows so people on the back row can still see them and understand the emotions the actors want to convey. By contrast, people with fair eyebrows sometimes seem to others to lack emotion because their eyebrows are harder to see. For whatever reason, Allosaurus likewise seems to have grown its skull bones so as to highlight the eye. In life, these areas plausibly bore bright colors that would draw attention to the eye—red, yellow, orange, or possibly a strong contrast. If the animal were predominantly black, its crests might turn white to achieve the same effect.

  • Behind the scenes: The word “dragon” derives from word roots in Greek and Indo-European referring to sight, perhaps signifying “one with a deadly glance” or “one who watches.” The name Dracula means “little dragon,” and as anyone who has seen Universal’s movie version of his story can attest, Dracula’s eyes play a big role in the mood of that film. Focus on the eye is a common motif in other examples of Gothic horror, and gestalt psychologists have found that eye contact can trigger a fear response not only in humans, but in other animals as well. And here we have Allosaurus drawing attention to its eyes. Coincidence? Well, it probably didn’t directly inspire ancient dragon legends, but Allosaurus might have tapped into a common fear—a sort of interspecies collective unconscious spanning eons. Considering how the fear of the eye, and perhaps of being watched, predates our species by probably millions of years, there’s a very real possibility that Allosaurus benefited from looking scary in this way. Allosaurus shared its environment with two other giant dinosaurian carnivores, so the ability to scare weaker animals away from their kills or intimidate stronger animals so they wouldn’t do the same could lend significant advantages in obtaining food. Its contemporary Ceratosaurus appears to have employed a similar tactic, but their physically strongest rival, Torvosaurus, seems to have largely opted out, as if it didn’t need to engage in such psychological warfare. Maybe these crests leveled the Jurassic carnivore playing field for these three species, though such behavior may prove impossible to demonstrate. Take this idea, therefore, as food for thought.