Episode 315 is all about Rahonavis, A dromaeosaur or avialan from Madagascar which is unexpectedly related to South American dinosaurs.
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 Psittacosaurus was described with a very crocodile-like cloaca source
- The Melbourne Museum is getting the world’s most complete Triceratops skeleton (it’s 87% complete) source
- The Hanson Family Ranch in Wyoming is looking to build a new research station for the 100s of volunteers who visit source
The dinosaur of the day: Rahonavis
- Bird-like theropod that lived in the Late Cretaceous in what is now northwestern Madagascar (Maevarano Formation)
- Small and carnivorous
- About 2.3 ft (0.7 m) long and weighed about 1 to 5 lb (0.45 to 2.27 kg)
- Debate in the past over whether it belongs to the clade Avialae or if it was a dromaeosaurid
- Had quill knobs on its forearm, so thought to be avialan, but the rest of its body is like a dromaeosaurid
- Had a sickle-claw on its second toe
- Not clear if it could fly
- Had long arms
- Had a low crest on the head
- Type species is Rahonavis ostromi
- Genus name means “cloud menace bird”, from Malagasy rahona and Latin avis
- Species name in honor of John Ostrom
- Catherine Forster and others found a partial skeleton in Mahajanga Province in 1995 (joint expedition between State University of New York and University of Antananarivo)
- Most of the area is covered in dense grass, but part of the hillside was exposed by fire, and fossils from a titanosaur were exposed. While excavating the titanosaur Rahonavis fossils were found
- Named by Forster and others in 1998
- Originally called it Rahona, but changed after finding out the name Rahona was used for a moth
- Holotype includes hind limbs, parts of the tail, parts of the wing and shoulder bones, pelvis
- Rahonavis found on its right side, with caudal vertebrae, pelvis, most of hind limbs
- Left femur, vertebra, left scapula, right ulna, and right radius were part of the holotype but not found articulated with the rest of the body
- Originally thought to be closely related to Archaeopteryx because its pelvis is similar and shows flight adaptations, but this could have evolved independently
- Later studies found that the pelvic girdle was “typically theropodan”, (and didn’t have a hypopubic cup like Archaeopteryx), and also thought Rahonavis was a chimera with bird forelimbs and theropod hindlimbs (Vorona found nearby)
- Some scientists don’t think the forearm with the quill knobs belong to Rahonavis, and that the forearm could belong to a bird instead (primitive bird Vorona was found nearby)
- Forster and others said in 1998 the forelimbs may not have belonged to the same individual or taxon, but thought that was unlikely due to it being found so close to the specimen, and the taphonomic distributions of bones within the quarry where it was found
- In 2007 Luis Chiappe said that all the bones attributed to Rahonavis were buried in an area “smaller than a letter sized page”
- Chiappe said Rahonavis probably could fly, and said its ulna was large and robust compared to Archaeopteryx, and that with the quill knobs it probably had larger, more powerful wings than Archaeopteryx. Also the shoulder bones have evidence of ligament attachments that allow for flapping movements
- Chiappe said it probably would have been more “clumsy in the air than modern birds”
- Related to Overoraptor
- Talked about Overoraptor in episode 290, and how with the discovery and naming of Overoraptor this year, Overoraptor and Rahonavis are now in the same group that is in between Unenlagiidae and Avialae
- Motta and others who named Overoraptor called Rahonavis “problematic”
- At least two individuals found
- A dentary has been provisionally referred to Rahonavis
- Fragments of beta keratin have been found in the foot claw, and scans showed lots of similarities with the claw sheath of an emu
Fun Fact: Gem quality opalized sauropod teeth from Lightning Ridge, New South Wales, Australia represent at least 3 species of titanosauriform. Also, if you look at a globe you can see where Australia used to attach to Antarctica.
