Episode 379 is all about Guaibasaurus, a Late Triassic basal sauropodomorph or theropod from what is now Brazil.
We also interview ReBecca Hunt-Foster, the Monument Paleontologist and Museum Curator at Dinosaur National Monument. She does research on the Late Jurassic Morrison Formation, the later Cretaceous Mesa Verde Group, and early-mid Cretaceous North American ornithomimids. Follow her on twitter @paleochick
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In this episode, we discuss:
- A new abelisaurid, Guemesia, was found in Northwestern Argentina source
- The first evidence of a respiratory infection is in a dinosaur was found in the sauropod Dolly source
- The Museum of the Rockies in Montana is hosting Dinosaurs and MOR source
- The Milwaukee Public Museum is hosting the temporary exhibit Tyrannosaurs: Meet the Family source
- The trailer for Doctor Strange in the Multiverse Madness shows Doctor Strange battling with Marvel dinosaurs source
The dinosaur of the day: Guaibasaurus
- Basal sauropodomorph that lived in the Late Triassic in what is now Brazil (Caturrita Formation)
- Debate over whether it was a basal sauropodomorph or a theropod (has characteristics of both)
- Looked like an early theropod, walked on two legs, had short arms, long neck, long tail, and a longish skull
- Estimated to be 6.6 ft (2) m long and weigh 22 lb (10 kg) in 2016 by Gregory Paul
- Estimated to be 10 ft (3 m) long and weigh 77 lb (35 kg) by Molina-Pérez and Larramendi in 2020
- Type species is Guaibasaurus ?candelariensis?
- Fossils found in an abandoned quarry
- Fossils included a well preserved postcranial skeleton (no skull) and a nearly complete left hindlimb
- Fossils were affected by weathering (neck and skull probably eroded)
- Two more specimens later referred to Guaibasaurus, including a nearly complete skeleton missing one forelimb, the feet, and neck, and a block (not yet fully prepared) with articulated fossils and a partial hand
- Named in 1999 by José Bonaparte and others
- Genus name means “Guaiba lizard”
- Genus name refers to the Rio Guaíba hydrographic basin where the fossils were first found. Fossils were collected as part of the “Pro-Guaiba Project,” a scientific program supporting research on Triassic fossils
- Species name refers to Candelária, a city near where the fossils were first found
- One specimen found with its hindlimbs tucked under its body and forelimbs flexed to the side (neck not really preserved, but the vertebrae at the base of the neck curve to the left, so the neck may have been curved toward the left)
- Similar to a bird’s resting position, like a chicken’s (also has been seen in other dinosaurs, such as the troodontid Mei long and the dinosauriform Saltopus)
- Means the resting position may have happened at the base of the Theropoda (or even Saurischia) clade
- May have been in that position to conserve body heat
- Max Langer and others said Guaibasaurus had unique features in the pelvis, as well as other features, such as long caudal trunk vertebrae (connects to the ribs)
- Found 24 vertebrae in the tail, but basal dinosaurs usually have 40 to 50 caudal vertebrae, so it’s likely 24 is only about half the tail
- Had some plesiomorphic (ancestral) traits as well, which may mean that even after other dinosaur clades were established, the more basal dinosauromorphs continued “to flourish until the end of the Triassic”
- For a while thought to be very similar, and closely related to the sauropodomorph Saturnalia (covered in episode 369)
- A 2020 phylogenetic analysis by Rodrigo Temp Müller and Maurício Silva Garcia found Guaibasaurus to be a sauropodomorph, and more closely related to Macrocollum and Unaysaurus
- Other animals that lived around the same time and place include the sauropodomorph Unaysaurus, pterosaurs, silesaurids, and rhynchosaurs
Fun Fact: Superprecocious birds can fly the same day they hatch.
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