Episode 329 is all about Ozraptor, a rare Jurassic theropod from Australia.
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In this episode, we discuss:
News:
- A new troodontid, Tamarro, was described from Spain source
- A gastrolith may tell the story of a large herbivore migrating about 600 miles source
- The dig site of Magyarosaurus in Romania was found using a 100+ year old map source
- In China, paleontologists recently found the world’s smallest stegosaur footprint source
- Tristan Otto, the T. Rex skeleton, is staying at the Natural History Museum of Copenhagen until the end of 2021 source
- The Children’s Museum of Indianapolis has a Sue meets Bucky exhibit from now until July 25 source
The dinosaur of the day: Ozraptor
- Abelisauroid theropod that lived in the Middle Jurassic in what is now Australia (Colalura Sandstone)
- Not a dromaeosaurid (usually referred to as raptors)
- Probably typical theropod body, walked on two legs, carnivorous
- Holotype is UWA 82469 and consists of the lower end of a left tibia (shin bone)
- Fossil is about 3 in (8 cm) long and 1.6 in (4 cm) wide, at the lower end
- Estimate the full shin bone was about 7 to 8 in (17 to 20 cm) long
- Estimated to be about 6.6 ft (2 m) long
- Body length estimated by comparing similar bones in other theropods, like Allosaurus
- Fossil found in 1967 by four 12-year-old Scotch College schoolboys (Steven Hincliffe, Peter Peebles, Robert Coldwell and Trevor Robinson) near the coastal city Geraldton. They were there to collect fossils
- Found at the Bringo Railway Cutting site
- Boys showed the fossil to Rex Prider, a professor at the University of Western Australia
- Rex Prider sent a cast (still embedded in matrix) to researchers at the Natural History Museum in London, and Alan Charig thought it might be a turtle
- Fossil had been worn away at parts
- John Long and Ralph Molnar named and described it as Ozraptor in 1998. Long had the fossil prepared when he became curator of vertebrate paleontology at the Western Australian Museum
- Long was appointed in 1989 and started a review of Mesozoic vertebrates of Western Australia, which meant studying all material in the museum’s collections
- After preparation they said it was the shin bone of a theropod
- Apparently the fossil was encased in rock and Long pried it apart with a hammer and chisel
- Type and only species is Ozraptor subotaii
- Genus name means “Australian thief”
- Oz is the colloquial term for Australia
- From the paper: “One may therefore (metaphorically) think of Ozraptor as ‘the lizard of Oz’.”
- Species name is in honor of the fictional character, Subotai, a fast running thief and archer from the movie Conan the Barbarian
- Species name because Long said the rectangular depression and the morphology of the shin bone probably means it was an agile dinosaur
- Original 1998 paper spent a lot of time covering what made the fossil unique enough to be its own genus, even though it’s based on a single incomplete bone
- Distinct features: depression where the ankle bone (astragalus) is attached, and it’s almost square in shape (usually triangular), and the medial malleolus was weakly developed (bony bump on the inner side of the ankle)
- Original paper said that the shape of theropod ankle bones can be distinct enough to show different genera
- Also, since this is the first known Australia Jurassic theropod, it’s unlikely to be from something already known (closely known theropod at the time was Cryolophosaurus, found in Antarctica)
- Paper also said the theropod Kakuru was named based part of a right tibia, with a unique ankle (astragalar) facet
- Also said this shape could be used to recognize major groups of theropods, so in the case of Kakuru it indicates a yet unknown group of theropods
- So the same goes for Ozraptor
- Lots of comparisons to other theropods (ankle bone shapes and tibial morphology)
- For example, theropods with more triangular shape include Coelophysis and Sinraptor
- Found Ozraptor to be unique compared to Jurassic theropods, though found some similarities with some Cretaceous theropods
- First dinosaur formally named from Western Australia, apart from tracks
- First Jurassic theropod bone from Australia
- Dinosaur tracks had been found in Queensland previously, including at least one track from a small theropod, thought to be around the same size as Ozraptor
- At the time Ozraptor was named, pretty much all dinosaur bones found in Australia had been from the Cretaceous, plus one partial skeleton of the sauropod Rhoetosaurus found in southern Queensland that was from the Jurassic, and one probable sauropod caudal vertebra also found near Geraldton (Long reported it in 1992)
- Fossil found at the same site as the sauropod caudal vertebra
- Also found fossilized wood, bivalves, and plesiosaur bones
- Originally classified as Theropoda incertae sedis
- In 2004, Oliver Rauhut found Ozraptor to be the oldest known abelisauroid, based on a review of post-cranial material of a small theropod from Tanzania, as well as other theropods, including abelisauroids and ceratosaurs
- Abelisaur fossils from Tanzania were found to have similar characteristics to Ozraptor (like the depressed feature)
Fun Fact: Therizinosaurs were the true “sloths of the Cretaceous.”
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