Episode 121 is all about Gorgosaurus, a tyrannosaurid that lived in the Cretaceous in western North America.

Do you wear dinosaur t-shirts? Join our community on Patreon now to get an Allosaurus t-shirt!

https://www.patreon.com/iknowdino

Thank you to all our current Patreon supporters!

You can listen to our free podcast, with all our episodes, on iTunes at:

https://itunes.apple.com/us/podcast/i-know-dino/id960976813?mt=2

Zuul and Gorgosaurus at the ROM in Toronto, Canada

In this episode, we discuss:

News:

• A dead bloated hadrosaur drifts away and gets eaten by a Crocodylian
• Pycnonemosaurus may have been the largest abelisaurid found.
• Lawsuits for negligence filed for the Argentinosaurus at Field Station Dinosaurs that caught fire last year
• There’s a new documentary series called Ancient Earth, now on Curiosity Stream which includes features on the Triassic and Cretaceous
• First look at Jurassic World 2! Colin Trevorrow tweeted a photo of a young girl standing in a natural history museum full of dinosaurs
• Oldest known crocodylomorph eggs (Krokolithes dinophilus) were found in a dinosaur nest in Portugaul
• An interview with Miron Gusso from Dinosaur Zoo live
• A list of 11 dinosaur gifts for enthusiasts of all ages pop-up books to wine holders
• T-rex earings on sale with part of the proceeds going to charity
• New Struthiosaurus & Hungarosaurus ankylosaur bones and armor found in Hungary
• A huge new dinosaur mural planned for Exmouth’s Madeira Walk in the UK
• First dinosaur theme park opened in Pakistan
• Nottingham Museum’s Dinosaurs of China Team in the UK had Dino factor auditions, in search of someone to be their Sinraptor
• New pre-video loading YouTube animations may include a T-rex
• New book called Every Hidden Thing by Kenneth Opel follows a paleontological Romeo & Juliet in the bone wars
• Dinosaur kid’s book written by a 6 year old just got published
• Wales Online shared a list of places you can take kids (or friends) to see dinosaurs in Wales.
• The London specimen Archaeopteryx is part of a traveling exhibit in Tokyo, Japan, as part of the Treasures of the Natural World: Best of London’s Natural History Museum
• From now until April 11, illustrate how you think the 9-ton block of Utahraptors formed and you could win a book, card, and artwork
• The Institute for the Study of Mongolian dinosaurs is scouting potential museum locations and could use donations for the trip
• TELUS Optik has made a 5 episode series on dinosaurs and paleontology in Alberta & BC Canada
• Awesome new theropod tracks including a 4.5ft long crouching track from Abruzzi, Italy
• Discover the dinosaur unleashed was in the San Francisco area
• Listener Tristan has nature photography including dinosaur toys, fossils, and sites
• A new video by Colin Trevorrow on twitter with JA Bayona making a T-rex puppet roar
• Monopoly announced the new tokens in the game: a T-rex, a penguin, and a rubber ducky (technically all dinosaurs)
• Saurian has been delayed. Now targeting a release in Q2 of 2017 (before July)

The dinosaur of the day: Gorgosaurus

• Name means “fierce lizard”
• Tyrannosaurid that lived in the Cretaceous in western North America
• Fossils found in Alberta and possibly Montana
• One species: Gorgosaurus libratus (other species have been assigned, though they were not correct)
• Species name means “balanced”
• Described in 1914 by Lawrence Lambe
• Holotype is a nearly complete skeleton and a skull, found by Charles M. Sternberg in 1913 in Dinosaur Park Formation in Alberta, and was the first tyrannosaurid found with a complete hand
• At least 12 Gorgosaurus specimens have been found
• AMNH collected hundreds of dinosaur specimens around that time, and found four complete Gorgosaurus skulls, three with skeletons. Matthew and Brown described them in 1923
• Matthew and Brown described a 5th skeleton (Charles Sternberg found in 1917 and sold to AMNH). It was smaller than other specimens, and similar to other juvenile tyrannosaurids, with longer limb proportions and a lower, lighter skull, but they said it was a new species, Gorgosaurus sternbergi (now considered to be a juvenile Gorgosaurus libratus)
• Most closely related to Albertosaurus (also distantly related to T-rex)
• Part of the subfamily Albertosaurinae (more closely related to Albertosaurus). Albertosaurinae had more slender builds, were smaller, had lower skulls, and longer tibias
• Very similar to Albertosaurus, but subtle differences in teeth and skull
• Some people think Gorgosaurus libratus is Albertosaurus (Gorgosaurus would be a junior synonym, since Albertosaurus was named first)
• In 2003 a team found that Gorgosaurus was different from Albertosaurus (had slightly longer legs, and skull was a little different. Gorgosaurus was mostly found in older rocks than the majority of Albertosaurus fossils, so some think Gorgosaurus was an ancestor to Albertosaurus)
• William Diller Matthew and Barnum Brown thought Gorgosaurus and Albertosaurus were the same in 1922, and Dale Russell formally reassigned Gorgosaurus to Albertosaurus libratus in 1970, but not everyone agrees (including Phil Currie, who said there are undescribed tyrannosaurids from Alaska, New Mexico and other parts of North America that could help answer the question). Gregory Paul said Gorgosaurus may be ancestral to Albertosaurus sarcophagus
• Some species were incorrectly named Gorgosaurus, including a small tyrannosaurid from Hell Creek (named by Charles Gilmore in 1946 as Gorgosaurus lancensis and since renamed Nanotyrannus by Bob Bakker in 1988, which some people now think is just a juvenile T-rex). In 1955, Evgeny Maleev named Gorgosaurus lancinator and Gorgosaurus novojilovi from two tyrannosaurids found in Mongolia, but in 1992 Kenneth Carpenter renamed the one Maleevosaurus novojilovi, and now they’re both considered to be juvenile Tarbosaurus bataar
• In 1856, Joseph Leidy described two tyrannosaurid teeth (nothing else of the animal found) and called them Deinodon. Matthew and Brown said in 1922 they were the same as Gorgosaurus teeth, but since there were no other fossils they did not synonimize them, and called it Deinodon libratus (however, tyrannosaurid teeth in general look the same, so not for sure it is Gorgosaurus). Deinodon is usually considered to be a nomen dubium now
• Some tyrannosaurids from Two Medicine and Judith River in Montana are probably Gorgosaurus (not clear if it’s Gorgosaurus libratus or a new species).
• One specimen, now at the Children’s Museum in Indianapolis, has a number of pathologies (healed leg, rib fractures, infection that led to permanent tooth loss, and possibly a brain tumor)
• Holotype had some pathologies, including healed fractures and a deformed toe, possible from a fight with another dinosaur
• Another Gorgosaurus had many pathologies (fractures, multiple ribs healed from fractures, lesions from a bite on the face), evidence that it was healing before it died
• Another Gorgosaurus had bite marks on its face, as well as a “mushroom-like hyperostosis of a right pedal phalanx” that may be similar to a pathology found on an unidentified ornithomimid
• Gorgosaurus was an apex predator that fed on ceratopsids and hadrosaurs
• Co-existed with Daspletosaurus (similar in size, but possibly there was some niche differentiation)
• Rare for two tyrannosaur genera to co-exist. Some thought Gorgosaurus hunted the hadrosaurs and Daspletosaurus went for the ceratopsids, but one Daspletosaurus was found with a hadrosaur in its gut, and a Daspletosaurus bonebed had three Daspletosaurus with five hadrosaurs (no evidence of Gorgosaurus pack behavior)
• Gorgosaurus appears to be more common in the north and Daspletosaurus in the south
• Skull was a little smaller than Daspletosaurus (39 in or 99 cm long), but large for its body (had large fenestrae to reduce weight)
• Grew up to 26-30 ft (8-9 m) long and weighed about 2.5 tons
• Gorgosaurus was a juvenile for about half its life, and then had rapid growth spurts. Since no intermediate size predators have really been found, the juveniles probably filled a niche (similar to Komodo dragons)
• Smaller Gorgosaurus that were found had longer tibias than femurs, so were fast running
• As a juvenile, Gorgosaurus probably went after ornithomimids (faster prey)
• Adult Gorgosaurus had long hindlimbs (largest Gorgosaurus femur was 41 in or 105 cm long)
• Had two-fingered forelimbs (forelimbs were small, proportionately)
• Had two digits on each forelimb, and four digits on each hindlimb (first digit didn’t touch the ground)
• Had a blunt snout, and nasal bones were fused
• Had a circular eye socket
• Had crests in front of eyes, like Albertosaurus and Daspletosaurus
• Had 26-30 maxillary teeth and 30-34 teeth in the lower jaw
• Had a heavy tail
• Phil Currie found skin impressions in 2001, and it was smooth (like secondarily flightless birds skin) and didn’t have scales (though scales were found on the specimen, but were widely dispersed and small, and other patches of skin had denser, larger scales). This helps show that bigger dinosaurs didn’t have feathers, since larger animals naturally lost less heat due to the smaller surface area to body volume ratio
• 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: 

Birds don’t only use feathers for flight, display, camouflage, physical protection, sensory inputs, water proofing, and insulation in the cold, but also for staying cool in the sun. A study back in 2004 compared kangaroos and emus in harsh sun in the Australian Outback and found that kangaroos could dissipate 75–85% of solar radiation with their fur but Emus could dissipate nearly 100% of solar radiation with their feathers despite the fact that have darker colors. This allows emus to stay in the sun while Kangaroos stay in the shade in the summer.

Allosaurus T-shirt (Limited Time!)

We have an Allosaurus t-shirt on sale at Teespring. Hurry, it’s only up for sale until March 27! Special thanks to artist Josh Cotton, the Doodling Dino, for the awesome drawing. Get it here:

teespring.com/iknowdino