The Big Dinosaur Podcast

In our 86th episode, we got to speak with George Jacobs, President & CEO of the Philip J. Currie Museum, and Jewels Goff, who does the education and outreach programs for the museum. To learn more about the museum, check out our video in part 1 of our #EpicDinosaurRoadTrip.

Episode 86 is also about Albertosaurus, a tyrannosaurid from Alberta, Canada.

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In this episode, we discuss:

• The dinosaur of the day: Albertosaurus
• Name means lizard from Alberta
• Tyrannosaurid that lived in the late Cretaceous in what is now Alberta, Canada
• First discovered in 1884 as part of an expedition by the Geological Survey of Canada, led by the geologist Joseph Burr Tyrrell. They didn’t have the right kind of equipment so they could only get part of the skull instead of the nearly complete skull.
• Tyrrell was 25 at the time and looking for coal when he found Albertosaurus in the Horseshoe Canyon Formation of Red Deer River in Alberta, Canada
• Then in 1889, Thomas Chesmer Weston found a smaller, incomplete skull nearby
• Both Albertosaurus skulls were assigned by Edward Drinker Cope in 1892 to Laelaps incrassatus (though Charles Marsh had changed Laelaps to Dryptosaurus in 1877 because Laelaps was the name of a mite. Cope did not accept Marsh’s name. Then Lawrence Lambe used the name Dryptosaurus instead of Laelaps when describing the bones in 1903 and 1904 (called them Dryptosaurus incrassatus)
• Then Henry Fairfield Osborn said that Dryptosaurus was based on generic tyrannosaurid teeth, so the Albertosaurus bones could not be for sure referred to Dryptosaurus. Also, their skulls were different from the type species of Dryptosaurus (aquilunguis)
• Henry Fairfield Osborn named Albertosaurus in a one page note at the end of his description of T-rex, in 1905
• Type species is Albertosaurus sarcophagus
• Named for the Canadian province Alberta, where the first fossils were found
• Species name means “flesh eating”
• Both Albertosaurus specimens are stored at the Canadian Museum of Nature, in Ottawa
• Later, some scientists thought it could be a nomen dubium, because the holotype was damaged, then in 2010 Thomas Carr established the holotype and paratype (found they had a unique common trait of an enlarged pneumatic opening in the back of the palatine bone)
• In 1928 William Parks described a new Albertosaurus species, named Albertosaurus arctunguis, based on a partial skeleton with no skull that Gus Lindblad and Ralph Hornell found in 1923 near Red Deer Rver. But since 1970 it’s been considered to be the same as Albertosaurus sarcophagus
• Other Albertosaurus species have been named, but they’re now considered to be synonyms, nomina dubia, or no longer assigned to Albertosaurus
• Charles Sternberg found another tyrannosaurid skeleton in 1913 in Dinosaur Park Formation in Alberta. Lawrence Lambe named it Gorgosaurus libratus in 1914 (more specimens found later in Alberta and Montana). Dale Russell said it was a junior synonym of Albertosaurus, based on not having significant differences. So Gorgosaurus libratus was renamed in 1970 to Albertosaurus libratus (still had an age difference of several million years, which is why the species is different)
• Philip Currie said in 2003 after comparing tyrannosaurid skulls said the two species were distinct and recommended they be separate genera (like Daspletosaurus and Tyrannosaurus)
• Some Albertosaurine bones have been found in Alaska and New Mexico, so Currie suggested there would be more clarification once they were described fully (not everyone agrees)
• Barnum Brown found a large group of Albertosaurus in 1910 at a different quarry along Red Deer River
• Brown didn’t have enough time to collect all the bones, so instead he and his team collected some bones from all the individuals they could identify. They became part of the American Museum of Natural History collection. There were at least 9 individuals in the quarry.
• Phil Currie relocated the bone bed in 1996 based on four photographs of Barnum Brown’s trip
• In 1997 the Royal Tyrrell Museum found the bonebed again and from 1997-2005 found 13 more individuals, including bones from a 2-year-old and an old adult. None of them were complete skeletons. They kept excavating until 2008 and estimated there were at least 12 individuals in the bonebed and at most 26.
• A total of 1,128 bones were secured (largest number of theropod fossils that we know of from the Cretaceous)
• The Dry Island bonebed (where 26 Albertosaurus were found) consisted of one 28-year-old, 8 adults between ages 17-23, seven sub-adults between 12-16 and six juveniles between 2-11 years old
• Most of the known Albertosaurus specimens were around age 14
• The oldest and largest Albertosaurus was 28 years old and (33 ft) or 10 m long
• The youngest known Albertosaurus was 2 years old and 6.6 ft (2 m) long weighing 110 lb (50 kg)
• By age 2, Albertosaurus was larger than any other predator in the area, aside from adult Albertosaurus, so if they made it to age 2, they tended to live until they were fully grown, though as adults they had a higher mortality rate, possibly from stress for competing for mates and resources, and the stress of procreation
• Albertosaurus grew most rapidly between ages 12-16 (similar growth rates to similar sized tyrannosaurids)
• During the growth period Albertosaurus gained 250 pounds per year
• No herbivore bones found, so the bonebed was probably not a predator trap. Because of this Currie said it was evidence of pack behavior, though other scientists think they may have come together by drought or flood
• In 2010, Currie said they may have come together for other causes than pack behavior, such as a slowly rising water lever in an extended flood
• They may have also been like Komodo dragons, where they go into a feeding frenzy which leads to some of them being killed or cannibalized
• Younger Albertosaurus had longer legs than adults and were probably fast. Currie hypothesized that the juveniles drove prey towards the slower adults
• Probably not too fast as an adult (if they fell, they would be badly injured)
• May have walked as fast as 8-13 mph (14-21 kph)
• Lived in a semi-tropical environment with lots of vegetation
• Prey included hadrosaurs, ceratopsians, and ornithomimids
• Had 58+ banana-shaped teeth
• It had at least one replacement tooth for each tooth
• Had a maximum bite force of 3,413 Newtons
• Had serrated teeth and used a “grip and rip” approach to cut through flesh and bone
• Could crunch through bone
• May have used a “bite and slice” way of hunting
• Biting flesh put on stress on Albertosaurus teeth. William Abler suggested that Albertosaurus had a line of serrations on its teeth to (ampullas) keep the teeth from cracking. Ampullas are round voids at the base of the crack-like serration on the tooth that helped Albertosaurus‘ bite be stronger
• Albertosaurus may have bit each other’s faces. One was found with marks on its lower jaw
• In 2009, scientists said that smooth-edged holes in the jaws of Albertosaurus and other tyrannosaurids may be caused by a parasite similar to Trichomonas gallinae (infects birds). They have have bitten each other and spread the infection, and it would have made it difficult to eat food
• Albertosaurus was about 30 ft (9 m) long, though some were as big as 33 ft (10 m) long
• Had a large head and a long tail (to help balance)
• Had a short, S-shaped neck
• Skull was about 3.3 ft (1 m) long
• Had short bony crests above the eyes that may have been brightly colored (used to attract mates)
• Weighed between 1.3 and 1.7 tons
• Bipedal, with two-fingered hands
• Had four-toed feet, and the first digit (the hallux) was short and couldn’t reach the ground)
• Part of the subfamily Albertosaurinae in the family Tyrannosauridae. They tend to have more slender builds, smaller skulls, and longer leg bones, compared to dinosaurs in the other subfamily, Tyrannosaurinae
• Albertosaurus was about half the size of T-rex
• Smaller than T-rex, but still large for its ecosystem
• Albertosaurus lived a few million years before T-rex
• Tyrannosauridae (means “tyrant lizards”) are theropods
• Two subfamilies with up to 11 genera (number of genera is controversial, some think only 3)
• Lived late Cretaceous, Asia and North America
• Usually the largest predators
• Largest species was T-rex
• Not many complete specimens found for known tyrannosaurids
• But many genera have complete skulls
• Some tyrannosaurids had crests above eyes
• Small arms but long legs
• Juvenile tyrannosaurids had longer legs, more suited to running fast, but that changed as adults
• Fun fact: Many plants, mollusks, fish, amphibians, and reptiles are indeterminate growers; which means they don’t have genes like humans do to stop us growing after a certain age or size. It is possible that dinosaurs were also indeterminate growers meaning that they never really stopped growing (although their growth rate would have slowed down after reaching a certain size).

For those who may prefer reading, see below for the full transcript of our interview with George Jacob and Jewels Goff:Continue Reading …