The Big Dinosaur Podcast

Episode 210 is all about Yangchuanosaurus, an Allosaurus-sized carnivore from the Jurassic of Sichuan, China.

Big thanks to all our patrons! Your support means so much to us and keeps us going! If you’re a dinosaur enthusiast, join our growing community on Patreon at https://www.patreon.com/iknowdino.

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

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

In this episode, we discuss:

News:

• A New Ceratopsid Dinosaur, Crittendenceratops, was discovered in Arizona source
• A new Chinese titanosauriform, Liaoningotitan, was fortunately named the same as mounts that have already gone on display source
• Amphicoelias fragillimus was renamed Maraapunisaurus fragillimus after a reanalysis showed it wasn’t nearly as large as previously thought source
• A doctor in Texas got to keep his Tarbosaurus skull after a judge found that the US government took too long to file forfeiture paperwork source
• Two Medicine Dinosaur Center, in Bynum Montana, is building a Amphicoelias (now Maraapunisaurus) measuring 136ft long source
• The Natural History Museum of LA is getting the traveling exhibition Antarctic Dinosaurs on April 3 source

The dinosaur of the day: Yangchuanosaurus

• Yangchuanosaurus was a metriacanthosaurid theropod that lived in the Jurassic in what is now China
• Very similar to Allosaurus
• Skull of the type specimen was 2.7 ft (82 cm) long
• Type specimen estimated to be about 26 ft (8 m) long
• A referred specimen was estimated to be up to 35.4 ft (10.8 m) long
• Had forward facing eyes
• Largest predator in its habitat
• Other dinosaurs that lived at the same time and place include sauropods Mamenchisaurus and Omeisaurus, stegosaurs Chialingosaurus, Tuojiangosaurus, and Chungkingosaurus
• Had a bony ridge on the nose, and had hornlets and ridges, like Ceratosaurus
• Bipedal, with short arms, a strong neck, and a large head with poweful jaws and serrated teeth
• Had a long tail, that was about half its length
• Feet had three toes with a large claw and a smaller fourth toe
• Name means Yangchuan lizard
• Named in 1978 by Dong and others
• Named after Yongchuan, the area in China where it was found (Yongchuan District, Sichuan)
• Found in the Shaximiao Formation
• Found in June 1977 by Sinung Chen, who was leading the Daba Reconstruction Public Works Corps to renovate the Daba Dam at the Shanyou Reservoir
• Found a complete skull and skeleton
• Type species is Yangchuanosaurus shangyouensis?
• Species name refers to the Shangyou Reservoir Dam
• Skull of type specimen was completely preserved
• First nearly complete dinosaur skeleton, found in China
• Dong and others described the second species from the same area in 1983, Yuangchuanosaurus magnus, based on a complete skull and skeleton (named a separate species mainly because of the size difference and because the 1983 specimen had another fenestra in the skull)
• In 2012, Carrano, Benson, and Sampson found that both species were the same species, and the differences may have been ontogenetic (different growth phases)
• In 1988 Gregory S. Paul suggested Yuangchuanosaurus to be the same as Metriacanthosaurus, but most people don’t agree
• In 2012 Carrano and others assigned a third specimen to Yuangchuanosaurus shangyouensis (found a partial postcranial skeleton without a skull, in the Wujiaba Quarry near Zigong city in Sichuan, as part of the Shangshaximiao Formation)
• It was found in 1978 and listed as a new species of Szechusanosaurus, called Szechuanosaurus yandonensis, but there’s no description or illustration, so it was a nomen nudum. In 1983 Dong and others described it as Szechuanosaurus campi (but Szechuanosaurus is a dubious species, known only from four teeth)
• In 2012, Carrano and others said the specimen couldn’t be assigned to Szechuanosaurus because the holotype had no diagnostic characteristics, plus the specimen didn’t have any teeth preserved (and couldn’t be compared with the four teeth of the holotype)
• In 2001 Dan Chure found that specimen was a nex taxon, informally known as Szechuanoraptor dongi, and that the third species of Szechuanosaurus, Szechuanosaurus zigongensis should also be grouped with it (Szechuanosaurus zigongensis was first described in 1993 by Gao)
• The 2012 Carrano study found that same third Yuangchuanosaurus specimen and Szechuanosaurus zigongensis could not be the same species because they had no shared distinct features, and Szechusanosaurus zigongensis came from the Xiashaximiao Formation, which is the lower part of the Shangshaximiao Formation. A phylogenetic analysis found the third specimen to be most closely related to Yuangchuanosaurus shangyouensis, so it was assigned to that species
• Szechuanosaurus zigongensis was found to be closely related, and became the second species of Yuangchuanosaurus, Yuangchuanosaurus zigongensis
• Four Yuanchuanosaurus zigongensis specimens have been found (includes teeth, hing limbs, and more), from the Xiashaximiao Formation in the Dashanpu Dinosaur Quarry
• Also potentially a third species of Yangchuanosaurus, Yangchuanosaurus hepingensis (named by Gao in 1992), but this may now be considered to be Sinraptor
• Yangchuanosaurus fossils were almost lost in a flood in 1981, when water rose and covered the laboratory floor at the Chongqing Museum of Natural History in China. Technicians were ready to swim to save the fossils, but the waters receded in time

Fun Fact:

Garden Park, Colorado (about 30 miles SW of Colorado Springs) is one of the sites where Cope & Marsh both funded quarries during the Bone Wars. It’s also home to “Cope’s Nipple” where Camarasaurus was found.

Sponsors:

This episode is brought to you in part by TRX Dinosaurs, which makes beautiful and realistic dinosaur sculptures, puppets, and animatronics. Get a baby T. rex sculpture or other rewards by joining their Kickstarter! kck.st/2FRwB9p