Episode 331 is all about Nqwebasaurus, an herbivorous coelurosaur from the Early Cretaceous in what is now South Africa.
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In this episode, we discuss:
News:
- A new oviraptorid embryo shows that Oviraptor was not the “egg thief” it was once thought to be source
- A second specimen of Diamantinasaurus was described with a previously unknown braincase source
- More work on a Sphaerotholus buchholtzae find helps to show it is a valid species source
- Utahraptor State Park is officially approved after the governor signed the bill into law source
- In Montville, Connecticut, The Dinosaur Place in Nature’s Art Village recently reopened with COVID-19 safety measures source
- Dinorama: Miniatures Through the Mesozoic is at the Santa Barbara Museum of Natural History through April 25th source
- Connecticut’s Sky’s the Limit Hiking Challenge includes Dinosaur State Park this year source
- In Washington state, a woman got stuck on top of a T. rex statue at Granger Dinosaur Park source
The dinosaur of the day: Nqwebasaurus
- Basal coelurosaur that lived in the Early Cretaceous in what is now Eastern Cape Province, South Africa (Kirkwood Formation)
- Looks like typical small theropod
- Small to medium in size
- Type specimen is about 3 ft (0.9 m) long, though probably longer since caudal vertebrae is not complete (tail bones)
- Type specimen is also a juvenile so may have grown more
- Had long hands with three fingers
- Had a partially opposable thumb and a recurved claw
- Had long, slender feet with a very short fourth digit
- Not clear if it had feathers, but may have been partially feathered based on other relatives having feathers
- Type and only species is Nqwebasaurus thwazi
- Named by William de Klerk and others in 2000
- Genus name means “Nqweba lizard”
- Name comes from the Xhosa word “Nqweba”, the local name for area where the dinosaur was found
- Species name “thwazi” is Xhosa for lightning, as in a lightning fast lizard
- Nearly complete skeleton, including part of the skull, vertebrae, parts of the forelimbs and hindlimbs
- Specimen unofficially nicknamed “Kirky”
- First coelurosaur found in Africa, second carnivorous dinosaur found in South Africa (after Coelophysis rhodesiensis, named in 1969). Though, Nqwebasaurus was later found to be herbivorous
- Helps show herbivory evolved early in ornithomimosaurian evolution
- Gastroliths found in the stomach region, etched by stomach acids. Unusual for a carnivore but thought to help with digestion
- Then in 2012, Jonah Choiniere and others further prepared the holotype of Nqwebasaurus and found new skeletal material. Found Nqwebasaurus to be an herbivore. Some animals, including birds, oviraptorosaurs, the ceratosaur Limusaurus (which had no teeth) and some ornithomimosaurs have been found with gastroliths. But the gastroliths in Nqwebasaurus were the right size and distributed in a way that the dinosaur probably had a gastric mill (to help break down food), and the authors said recent assessments of herbivorous characteristics in ornithomimosaurs and coelurosaurs found that having a gastric mill “allows confident inference of herbivory in extinct non-avian dinosaurs” So, since Nqwebasaurus had a gastric mill, it’s thought to be herbivorous. Also helps that it had tooth reduction (fewer teeth in its jaws compared to other theropods)
- Nqwebasaurus tooth crowns were similar to those of derived parvicursorine alvarezsauroids, and it could be the two types of dinosaurs had the same strategy for eating
- Many similarities anatomically with Alvarezsauroidea (similar forelimbs and hindlimbs, simplified teeth), but 2012 phylogenetic analysis shows it as Ornithomimosauria. Would help to have more fossils
- Ornithomimosaurs progressively lost teeth over time, as they evolved
- Had small, conical, unserrated maxillary teeth (at least four)
- No teeth in the back of the maxilla (same as ornithomimosaur Pelecanimimus). This is consistent with data that suggests loss of teeth in ornithomimosaurs went from back to front
- Could be a transitional stage for both Nqwebasaurus and Pelecanimimus where they don’t need teeth in the back to eat but still need some front teeth
- The teeth were pretty far forward (procumbent) but could be diagenetic factors (change in sediments). However, in other theropods with shifts in tooth morphology “procumbency is a common occurrence” (teeth very far forward)
- Most basal member of Ornithomimosauria and one of the most basal clades of Coelurosauria
- Helps show that basal coelurosaurs were in Gondwana 50 million years earlier than previously thought, and that coelurosaurians may have been globally distributed early in their evolution
- Found by William de Klerk and Callum Ross in July 1996 during a joint expedition with Grahamstown Albany Museum and State University of New York Stonybrook
- In 2008, Catherine Forster and others said there was a second theropod taxon referenced in the 2000 paper but it was an isolated left femur, and too incomplete to name as a new taxon
- de Klerk and Ross saw fragments of fossils scattered on a sandstone slope, and when they followed the trail they found a shin bone, attached to a foot bone. They used a paintbrush to brush off dirt and saw the rest was embedded in rock
- Kind of a rushed day, since Ross was flying back to New York the next day. So they went to Grahamstown to get plaster of Paris and coat the fossil. Eventually they prepared the fossil in a lab and did CT scans
Fun Fact: It took 70 years for Oviraptor to have its reputation cleared from “egg thief” to a good parent.
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