Daspletosaurus torosus Archives - The Big Dinosaur Podcast

In our 120th episode, we had the pleasure of speaking with Bruce Schumacher, the South Zone Paleontologist for the US Forest Service.

Episode 120 is also about Daspletosaurus, a tyrannosaurid that lived in the Cretaceous in North America.

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In this episode, we discuss:

In the news:

Amazing new lifelike dinosaur sculpture being made by Chris Ruprecht
Chronicle Collectibles has a new T-rex bust modeled after Jurassic Park
Feature on “Chewy” the dinosaur at Abbott Glass & Door Repair
The Burke museum is studying dinosaurs from the Petrified Forest
The Centennial Concert Hall had a presentation on Spinosaurus by Nizar Ibrahim
Spence Speaks Saurian claims that Rhedosaurus is “the greatest dinosaur that never lived”
Extinct Blog reports on The Rite of Spring segment of Fantasia that featured dinosaurs
James Gurney produced new artwork of Khaan mckennai and anchiornis
The WitmerLab’s Dissecting with Emily playlist continues to grow with new videos
Figure out your Dinosaur Name by using your birth month, first letter, and eye color
An article about Lesothosaurus nomen dubium and what it ate based on tooth wear
Dinosaur footprints re-investigated in the Tongfosi Formation uncover possible sauropod prints
A massive set of footprints in northeaster Thailand may show theropod group behavior
Preschoolers are helping to fundraise for a new dinosaur nicknamed “Elvis-saurus”
A park in New Zealand had dinosaurs in Augmented Reality for Park Week 2017
“She Found Fossils” children’s book about women in paleontology is on kickstarter
Wild Prehistory is holding a dinosaur dig party in Krasiejów, Poland
The sixth symposium on Dinosaur Eggs and Babies will be in Lisbon, Portugal in October
The Triceratops at the Smithsonian was originally the main exhibit, but now it’s getting eaten

The dinosaur of the day: Daspletosaurus

Name means “frightful lizard”
Tyrannosaurid that lived in the Cretaceous in what is now western North America
Only one named species: Daspletosaurus torosus
Species name means “muscular” or “brawny” in Latin
Found in Alberta, and other potential species (that still need to be described) have been found in Alberta and Montana
Discovered in 1921 in Alberta by Charles Mortram Sterberg (thought it was a new Gorgosaurus species)
Fully described in 1970 by Dale Russell, who named it Daspletosaurus
Type specimen is a partial skeleton that includes the skull, shoulder, one forelimb, pelvis, femur, vertebrae from the neck, torso, hip, and some tail vertebrae
Another specimen was found in 2001
There are 2-3 more species, though they haven’t been named or properly described
Russell also classified a specimen Barnum Brown found in 1913 as Daspletosaurus (found in Alberta, found parts of the hindleg, pelvis, and some vertebrae).
Brown had also found a nearly complete skull in 1914, and 40 years later the AMNH sold it to the Field Museum of Natural History in Chicago. It was labeled Albertosaurus libratus, but eventually reassigned to Daspletosaurus
Eight specimens have been found in Alberta, in Dinosaur Park Formation, and may be new species of Daspletosaurus (based on differences in the skulls)
In 2001 a partial skeleton was found in Two Medicine in Montana, and assigned to Daspletosaurus (though not a particular species)
Three other specimens have found found in Two Medicine, and are Daspletosaurus (though not yet assigned a species)
Seven known Daspletosaurus torosus specimens
Closely related to Tyrannosaurus
In the subfamily Tyrannosaurinae, along with Tarbosaurus, Tyrannosaurus, and Alioramus (more closely related to T-rex than to Albertosaurus)
10 million years older than T-rex
Sometimes considered to be a direct ancestor to T-rex, through anagensis (one species evolves into another by evolutionary changes within a lineage).
Gregory Paul reclassified Daspletosaurus torosus to Tyrannosaurus torosus, but most people don’t accept this
Some people think Tarbosaurus and Tyrannosaurus are sister taxa or the same genus, and Daspletosaurus is a more basal relative
One young Daspletosaurus specimen found in Alberta has bite marks on its face from another tyrannosaur. Bite marks healed
Another Daspletosaurus, an adult from Alberta, has tyrannosaur bite marks on its face
Bites may have been from other species or from other Daspletosaurus
In 2009, a study found evidence of an infection similar to Trichomonas gallinae in a few Daspletosaurus jaws, probably spread because of biting each other or eating animals that were infected
Healed bite marks may show it wasn’t meant to be fatal and was part of interacting (someone asserting dominance) or marks may have been from infection
One Daspletosaurus specimen had postmortem bites from a large theropod, possibly a Daspletosaurus (would have been cannibalism)
Daspletosaurus had small forelimbs, though they were still proportionately longer than other tyrannosaurs
Up to 26-30 ft (8-9 m) long, and weighing between 1.8-3.8 tons
Had a large skull, about 3.3 ft (1 m) long
Had heavy bones, and some bones (such as the nasal bones) were fused so they’d be stronger (but did have openings in the skull to reduce weight)
Had crests around its eyes
Had tall oval eyesockets
Had an S-shaped neck
Had four-toed feet, but the first digit didn’t touch the ground
Had a long, heavy tail
Forelimbs had two digits each
Grew nearly 400 pounds (180 kg) per year, about 10% of its adult weight
Had about 72 teeth that were long and oval (not blade-like)
Had the largest teeth of tyrannosaurids
Apex predator, probably ate Centrosaurus (ceratopsid) and Hypacrosaurus (hadrosaur)
Some places it co-existed with Gorgosaurus, but they may have inhabitated different niches
Daspletosaurus had stronger jaws than Gorgosaurus (but teeth strength were similar) so may have had different feeding styles or diet
Also, may have been some geographic separation (Gorgosaurus may have been more common a little more north, and Daspletosaurus more south)
Gorgosaurus may have eaten the hadrosaurs, and Daspletosaurus may have gone for the ceratopsids (more robust and less common than Gorgosaurus, and ceratopsids were harder to hunt). But, one Daspletosaurus found in Two Medicine had a juvenile hadrosaur in its gut
May have lived in groups, based on a bonebed found in Two Medicine (includes three Daspletosaurus, including an adult, juvenile, and intermediate, and five hadrosaurs, and they were buried at the same time in the same place). Hadrosaurs are scattered and have bite marks, so Daspletosaurus may have been eating them when they died. Unclear what killed them. Currie said Daspletosaurus may have been a pack, but not everyone agrees. Brian Roach and Daniel Brinkman said Daspletosaurus may have been like Komodo dragons, where they mob carcasses and attack and kill each other while feeding (study in 2015 found evidence of Daspletosaurus cannibalism)
Hadrosaurs in bonebed may have died from toxic gas (and were trapped), which attracted Daspletosaurus, who also died from toxic gas. Could also have been killed by other predators, fighting over food, or the hadrosaurs were killed and dragged away to a lair (unclear why that would be)
Tyrannosauridae (means “tyrant lizards”) are theropods
Lived late Cretaceous, Asia and North America
Usually the largest predators
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: In evolutionary terms: Synapomorphies are characteristics shared within a group of organisms. Autapomorphies are characteristics unique to a specific species.

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