10 Facts About Albertosaurus

Albertosaurus may not be as popular as the Tyrannosaurus rex, but thanks to its extensive fossil record, this lesser-known cousin is by far the world's most well-attested tyrannosaur.

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Discovered in Canada's Alberta Province

Albertosaurus skeleton against a painting of its possible likeness — Jerry Bowley / Flickr / CC BY-NC-SA 2.0

Albert may not strike you as a very fearsome name and maybe it's not. Albertosaurus is named Canada's Alberta province—the vast, narrow, mostly barren stretch of territory perched atop the state of Montana—where it was discovered. This tyrannosaur shares its name with a variety of other "Alberts," including albertaceratops (a horned, frilled dinosaur), albertadromeus (a pint-sized ornithopod), and the small, feathered theropod albertonykus. Alberta's capital city, Edmonton, has also lent its name to a handful of dinosaurs.

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Less Than Half the Size of Tyrannosaurus Rex

Cast skeleton of albertosaurus in Colorado — MCDinosaurhunter / Wikimedia Commons / CC BY-SA 3.0

A full-grown albertosaurus measured about 30 feet from head to tail and weighed about two tons, as opposed to the Tyrannosaurus rex that measured in at over 40 feet long and weighed seven or eight tons. Don't be fooled, however. While albertosaurus looked positively stunted next to its better-known cousin, it was still a fearsome killing machine in its own right and likely made up with speed and agility for what it lacked in sheer heft. (Albertosaurus was almost certainly a faster runner than T. rex.)

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May Have Been the Same Dinosaur as Gorgosaurus

A model of gorgosaurus, who may instead be another example of albertosaurus — Walking With Dinosaurs / BBC

Like albertosaurus, gorgosaurus is one of the best-attested tyrannosaurs in the fossil record. Numerous specimens having been recovered from Alberta's Dinosaur Provincial Park. The trouble is that gorgosaurus was named well over a century years ago at a time when paleontologists had difficulty distinguishing one meat-eating dinosaur from the next. It may eventually be demoted from genus status and classified instead as a species of the equally well-attested (and comparably sized) albertosaurus.

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Grew Most Rapidly During Its Teenage Years

A albertosaurus skeleton — James St. John / Flickr / CC BY 2.0

Thanks to its profusion of fossil specimens, we know a lot about the life cycle of the average albertosaurus. While newborn hatchlings packed on the pounds pretty quickly, this dinosaur really experienced a growth spurt in its middle teens, adding over 250 pounds of bulk every year. Assuming it survived the depredations of late Cretaceous North America, the average albertosaurus would have reached its maximum size in about 20 years, and might have lived for 10 or so years after that given our current knowledge of dinosaur life spans.

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May Have Lived (and Hunted) in Packs

An albertosaurus model chasing after smaller dinosaurs — D'arcy Norman / Flickr / CC BY 2.0

Whenever paleontologists discover multiple specimens of the same dinosaur in the same location, speculation inevitably turns to group or pack behavior. While we don't know for sure that albertosaurus was a social animal, this seems to be a reasonable hypothesis, given what we know about some smaller theropods (such as the much earlier coelophysis). It's also conceivable that albertosaurus hunted its prey in packs—for example, it's possible that juveniles stampeded panicked herds of hypacrosaurus toward strategically located adults.

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Preyed on Duck-Billed Dinosaurs

Albertosaurus hunting chirostenotes — Abelov2014 / DeviantArt / CC BY 3.0

Albertosaurus lived in a rich ecosystem, well-stocked with plant-eating prey including hadrosaurs such as edmontosaurus and lambeosaurus, and numerous ceratopsian (horned and frilled) and ornithomimid ("bird mimic") dinosaurs. Most likely, this tyrannosaur targeted juveniles and aged or sick individuals, culling them mercilessly from their herds during high-speed chases. Like its cousin, T. rex, albertosaurus didn't mind dining on carrion and wouldn't have been adverse to digging into an abandoned carcass felled by a fellow predator.

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Only One Named Albertosaurus Species

Albertosaurus skull cast at the Geological Museum in Copenhagen — FunkMonk / Wikimedia Commons / CC BY-SA 3.0

Albertosaurus was named by Henry Fairfield Osborn, the same American fossil hunter who gave the world Tyrannosaurus rex. Given its venerable fossil history, you might be surprised to learn that the genus albertosaurus comprises only one species, Albertosaurus sarcophagus. However, this simple fact obscures a wealth of messy details. Tyrannosaurs were once known as deinodon. Over the years, various presumed species have been confused with one another, as with genera such as dryptosaurus and gorgosaurus.

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Most Specimens Were Recovered From the Dry Island Bonebed

Dry Island Buffalo Jump Provincial Park, Alberta — Outriggr / Wikimedia Commons / Public Domain

In 1910, the American fossil hunter Barnum Brown stumbled across what became known as the Dry Island Bonebed, a quarry in Alberta containing the remains of at least nine albertosaurus individuals. Incredibly, the Bonebed wound up being ignored for the next 75 years, until specialists from Alberta's Royal Tyrrell Museum revisited the site and resumed excavation, turning up a dozen additional albertosaurus specimens and over a thousand scattered bones.

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Juveniles Are Extremely Rare

Albertosaurus appears in scale alongside a human male — Eduardo Camarga

Although dozens of albertosaurus teenagers and adults have been discovered over the past century, hatchlings and juveniles are phenomenally rare. The most likely explanation for this is that the less-solid bones of newborn dinosaurs simply didn't preserve well in the fossil record, and the vast majority of deceased juveniles would have been gobbled up almost immediately by predators. Of course, it may also be the case that young albertosaurus had a very low mortality rate, and generally lived well into adulthood.

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Studied by a Who's Who of Paleontologists

Henry Fairfield Osborn, Fred Saunders, and Barnum Brown on the scow Mary Jane in 1911 — Darren Tanke / Wikimedia Commons / Public Domain

You can construct a veritable "Who's Who" of American and Canadian paleontologists from the researchers who have studied albertosaurus over the past century. The list includes not only the aforementioned Henry Fairfield Osborn and Barnum Brown, but also Lawrence Lambe (who lent his name to the duck-billed dinosaur lambeosaurus), Edward Drinker Cope, and Othniel C. Marsh (the latter pair of whom were famously enemies in the 19th century Bone Wars).