Exhibit Spotlight: Albertosaurus sarcophagus
You should see one of these guys perform a Tombstone Pildriver with those tiny arms. Quite the spectacle!
Albertosaurus: a name so dignified and proper it almost sounds silly. Then you read its species name, sarcophagus, and things quickly get METAL!!! That's sort of how the general population reacts to this dinosaur. Yeah, yeah, smaller cousin of T. rex, so it's not as scary, kinda white bread, yada yada. Even a quick glance at the details, though, makes this animal look much scarier and more interesting. Come, face your fears and read on!
First, speaking of perception, let's look at our sculpture in the park. Produced near the end of the Dinosaur Renaissance (which spanned roughly from the '70s to the late '90s), it reflects some extremes of trends in paleoart during that period. Many artists of the time wanted to reflect a paradigm shift in paleontology from the sluggish, stupid, lizard-like depictions of the past by reacting the opposite way. They began depicting dinosaurs as speedy, smart, and bird-like. One deliberate and explicitly articulated tactic in shifting public perceptions away from the fat dumb dinosaur image involved depicting dinosaurs as super-model thin as possible. Our sculpture reflects this by outlining parts of the skeleton, like the gastralia (belly ribs) and holes in the skull, in excruciatingly malnourished detail. I doubt even a mummified Albertosaurus corpse would show off those belly ribs in such stark relief. This sculpture serves as a reminder that any artistic representation of extinct prehistoric animals, even when claiming to represent scientific restorations, reflects the distorting influence of human cultural values. Thoughtful restorations will find some way of acknowledging where that influence might show up in any given artistic rendering. Works that claim "most scientifically accurate" deserve close scrutiny as to their factual basis. Interestingly enough, sectors of the paleoartist community are already shifting the pendulum the other way, preferring the powerful look of heroically-proportioned depictions— "thicc bois," their spelling, not mine—to the wiry waifs of yesteryear. Regardless of personal aesthetic or iconic preference, every paleoart model ought to be judged on its ability to reconcile the depiction with the available evidence. At the Eccles Dinosaur Park, our ongoing development for the Stewart Museum seeks to train interested guests in learning aspects of paleontology that will help them explore the credibility of the art in the exterior park and beyond. Stay tuned!
The species name sarcophagus literally means “flesh eater,” but it’s also a synonym for “coffin.” Heh, this guy’s The Undertaker of dinosaurs (thus explaining the wrestling reference in the picture caption).
Since Albertosaurus inevitably ends up in Tyrannosaurus' shadow by virtue of their close evolutionary relationship, we might as well hit comparisons between them head-on. Was Albertosaurus smaller and more lightly-built than its iconic relative? Yes. But in this case, smaller than Tyrannosaurus is still big. More lightly-built than Tyrannosaurus is still powerful. Weight estimates for Albertosaurus range from a whippy 1.5 tons to a more robust 3 tons, placing it more in the average range for large carnosaurs (a name for the big carnivorous dinosaur body plan). Allosaurus, Torvosaurus, and Ceratosaurus reached similar sizes, and they ain't small, nor were they ecological pushovers. In terms of power, if we use bite force as a basis of comparison, the bone breaking tyrannosaurid tooth design of Albertosaurus required greater jaw strength than the blade-like designs used by Allosaurus, Torvosaurus, and Ceratosaurus. Pound for pound, Albertosaurus featured some impressive predatory characteristics that compare favorably against other animals in its class.
Keeping to the relatively smaller size of primitive tyrannosauroids may have lent Albertosaurus some advantages, not the least of which would be speed. When it comes to extinct animals, absolute top speed can be a tricky thing to calculate. Many studies don't even attempt a ballpark estimate. However, relative speed is much easier to gauge. Adult Albertosaurus could likely outpace adult Tyrannosaurus, though juveniles of both species may have reached similar top speeds. Compared to other carnosaurs in the same size range, though, the tyrannosaur legginess of Albertosaurus may have given it a clear advantage on speed. Whether long legs translate to higher relative speeds or better endurance at large sizes remains debatable, but the trend toward more heavily reinforced ankles in tyrannosaurs provides another clue. For Tyrannosaurus, a stronger ankle design could favor larger size and greater power. Where Albertosaurus met the same size range as other carnosaurs but kept the reinforced ankles, it may have co-opted the same basic design trend for a different purpose than T. rex, namely higher overall speed and/or endurance. Future studies must determine which interpretations of the available evidence best predict new finds, but for now interpreting Albertosaurus as a good balance of power and speed compared to other large dinosaurian carnivores is a defensible position. Interestingly enough, the older and more heavily-built Gorgosaurus (a similar animal regarded by some as another species of Albertosaurus), was even leggier. What exactly that comparison means for evolutionary trends and the ecological roles these animals puts yet another spin on the subject. The topic still holds lots of room for further exploration.
We know they were "cousins," but did Albertosaurus and Tyrannosaurus co-exist? That's tough to say. They did live at the same time. We have Canadian examples of T. rex. and scrappy fossils in the U.S. have been referred to Albertosaurus, but neither of these animals have been found in the same quarry as far as I can tell, so there's no direct evidence they interacted. Beyond the probability of some kind of geographic barrier, body type and their correlating ecological roles may have something to do with this apparent separation: if Tyrannosaurus were a lion analogy, Albertosaurus would have been a leopard. Where T. rex favored brute strength, Albertosaurus coupled respectable strength with greater speed and maneuverability. These differences would have led to different hunting strategies, and they probably took different prey. Of course, lions and leopards co-exist, so why not these two dinosaurs? That's a fair point: perhaps they did, and we just don't have evidence supporting that. Then again, a quirk of Tyrannosaurus maturity may come into play. One theory posits that juvenile Tyrannosaurus kept the body design of the primitive tyrannosaurs, which favored speed. This may have kept juveniles and adults from competing with each other for prey, but it would have put juvenile T. rex in direct competition with Albertosaurus. Given how most dinosaur environments preserve multiple large carnivores, but we have evidence for T. rex displacing at least Daspletosaurus from its former territories, it could be that tyrannosaurs just didn't play nice with one another. It's a complex question, and we need more evidence to figure how that history played out.
Unlike the lion/leopard pair, though, Albertosaurus has stronger evidence than T. rex for living and possibly hunting in groups. One quarry in particular preserved a group of both adult and juvenile Albertosaurus with very few fossils of other species included. It's not the strongest piece of evidence for group association in life, but it's awfully hard to explain this situation in other ways. So in addition to featuring good speed for a big dinosaurian carnivore, now imagine groups of ten or more of these animals flanking your accelerating time machine while the flux doohickey warms up, possibly coordinating their attack as they chase you down.
Speaking of groups, the proper term for a group of any kind of tyrannosaur—including Albertosaurus—is a “terror” of tyrannosaurs. This official term comes from a recent paper that describes a tyrannosaur trackway discovered in British Columbia. The trackway proves that some tyrannosaurs travelled together at least some of the time. Which tyrannosaur species made the tracks remains unknown, but features of the feet inferred from the tracks resemble Daspletosaurus more than Albertosaurus.
What did Albertosaurus look like on the outside? Skin and its covering, its color, and other soft tissues that don't preserve well as fossils play a huge role for artists in depicting animals no human eye has ever directly seen. Often times elements other than scientific analysis help fill in the holes, for better and worse. This facet of—pardon the pun—fuzziness in paleoart has led to sharp disagreements over the scientific plausibility of what we'll call "alternative models" of tyrannosaur skin. Concerning the now omnipresent question of feathers, the skin impressions scientists have recovered for Albertosaurus and its close relatives run contrary to the “fluffy” reconstructions many paleoartists have created recently. No evidence so far supports feathers, shaky evidence supports some kind of filamentous integument (skin covering resembling hair, as in mammals, spiders, turkey beards, and similar fuzz found in numerous other animal groups) somewhere on the body as a remote possibility (a 2.4% chance according to the only study conducted specifically on tyrannosaurs), and several lines of evidence run against it. However, since Albertosaurus and its closest kin are also icons of prehistory, and feathers have become status symbols in dinosaurian pop culture—representing the superiority of warm-bloodedness, the natural majesty of "real" animals as opposed to the primal monsters of yore, and the appeal of cuddly softness—controversy still rages.
This chart collects all currently published information on tyrannosaurid skin coverings.
Erickson, G. M., Makovicky, P. J., Currie, P. J., Norell, M. A., Yerby, S. A., & Brochu, C. A. (2004). Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs. Nature, 430(7001), 772-775.
Dececchi, T. A., Mloszewska, A., Larsson, H., Holtz, T. R., & Habib, M. B. (2019). The fast and the frugal: Divergent locomotory strategies drive limb lengthening in theropod dinosaurs. bioRxiv, 785238.
Carr, T. D., Varricchio, D. J., Sedlmayr, J. C., Roberts, E. M., & Moore, J. R. (2017). A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system. Scientific reports, 7, 44942.
McCrea, R. T., Buckley, L. G., Farlow, J. O., Lockley, M. G., Currie, P. J., Matthews, N. A., & Pemberton, S. G. (2014). A ‘terror of tyrannosaurs’: the first trackways of tyrannosaurids and evidence of gregariousness and pathology in Tyrannosauridae. PLoS One, 9(7), e103613.
Bell, P. R., Campione, N. E., Persons IV, W. S., Currie, P. J., Larson, P. L., Tanke, D. H., & Bakker, R. T. (2017). Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolution. Biology letters, 13(6), 20170092.