Episode 373 is all about Beipiaosaurus, A feathered therizinosauroid form the Early Cretaceous of what is now China.
We also interview Sibusiso Biyela, a science writer and communicator, and an advocate for decolonizing science. He recently started working on a project to bring scientific terminology to six African languages including a great article about Ledumahadi in Zulu. Follow him on twitter @AstroSibs
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In this episode, we discuss:
News:
- One of the most complete dinosaurs ever found was discovered in a fossilized unhatched egg in Ganzhou, China source
- A new Tarchia species, Tarchia tumanovae, was described with a nearly 6ft long tail club source
- The Mary Anning statue in Black Ven may be unveiled by her 223rd birthday source
- The Royal Australian Mint has released an Australovenator coin source
The dinosaur of the day: Beipiaosaurus
- Therizinosauroid theropod that lived in the Early Cretaceous in what is now Liaoning, China (Yixian Formation)
- Looked stocky, with big hands/claws and a long tail (walked on two legs)
- Herbivorous
- Had shorter neck than other therizinosaurs
- Feet had three toes (different from other, more advanced therizinosaurs, with four toes)
- Inner toes were smaller
- Estimated to be about 7.2 ft (2.2 m) long and weigh 99 to 201 lb (45 to 91 kg)
- Had brownish feathers that probably covered its body
- One of the largest known dinosaurs with evidence of feathers (before Yutyrannus was found)
- Fossils found in 1996 by Li Yinxian, a local farmer, who found a partial skeleton in Sihetun, Liaoning
- Described in 1999 by Xu Xing and others
- Type species is Beipiaosaurus inexpectus
- Genus name means “Beipiao lizard”, after a city near where it was found
- Species name means “unexpected” and refers to its surprising features
- Holotype includes a partial skeleton of a subadult (cranial fragments, mandible, teeth, vertebrae, dorsal ribs, pygostyle, chevrons, incomplete furcula and scapula, coracoids, forelimbs, ilia, incomplete pubis, incomplete ischium, femur, tibiae, incomplete fibula, metatarsals, skin impressions, and more)
- Quarry where the fossils were found was re-excavated later and more fossils found: pelvic girdle and caudal vertebrae
- Second specimen described by Xu Xing and others in 2009 (partial skeleton with preserved feathers, including a complete skull, sclerotic ring, mandible, vertebrae, humerus, coracoids, ulna, metacarpals, carpals, and more, though back of the skull was badly crushed)
- In 2014 Li and others mentioned a third specimen, a partial skeleton with a badly crushed skull, most of the vertebral column, arms, and more, and traces of feathers around the neck
- Had a relatively large head, compared to other therizinosaurs
- Lower jaw was about the same length as the femur
- Pygostyle had five fused vertebrae
- According to Lindsay Zanno, had unique characteristics including the last four dorsal vertebrae (spine) are fused, from at least the 7th vertebra to the tail vertebrae are fused into the pygostyle, skull is large and about as long as the thighbone
- Claw bone on the third digit of its finger is the longest one (different from other therizinosaurs, where the second digit claw is the longest)
- In 2021, Liao Chun-Chi and others analyzed the skeleton of Beipiaosaurus, and included additional vertebrae that hadn’t been described before
- Tail had more than 30 caudal vertebrae
- Had neural spines near the front of the tail
- Found three possible synapomorphies (characteristic from an ancestor shared by its descendants) for Therizinosauroidea and Therizinosauridae, including a straight ulna (arm bone), which is straight in most therizinosaurs but bowed in Falcarius, a therizinosauroid
- Most of its body covered in downy feather-like fibers
- Had a secondary coat of longer, more simple feathers, known as elongated broad filamentous feathers (EBFFs), that rose up from the downy feathers
- Tail also covered in feathers
- A 2003 study defined feathers and found Beipiaosaurus didn’t have true feathers, but filaments that were related to feathers
- Did not fly, but feathers may have been for display or to attract mates
- In 2009, Xu Xing and others reported on the new feather type along the skull, neck, trunk, and around the forelimbs of Beipiaosaurus
- Found short, slender filamentous feathers and elongated broad filamentous feathers (EBFFs)
- EBFFs were single, unbranched filaments
- Did not use feathers for thermoregulation, based on the distribution of the feathers and morphology
- EBFFs were longer than normal filamentous feathers and were stiff and probably hollow, at least at the base
- EBFFs were about 4 to 6 in (10 to 15 cm) long, and were broad (up to 0.1 in or 0.3 cm wide)
- EBFFs were also only on parts of the head, neck, tail, and body where modern birds typically have display structures, so they were probably used for display
- EBFFs have also been found in the therizinosaur Jianchangosaurus, and may show they were for display and were common in early therizinosaurs
- Based on filaments found on Beipiaosaurus, Psittacosaurus, and some pterosaurs, may mean that the common ancestor had early feathers. First feathers may have appeared in the Middle Triassic, around 235 mya
- In 2018, Maria McNamara and others found fossilized skin flakes on Beipiaosaurus, Sinornithosaurus, Microraptor, and Confuciusornis (looked similar to modern birds)
- Found corneocytes, cells full of keratin, and compared them to birds. Found similar cell structures, but the fossil dinosaur corenocytes were more densely packed with keratin and lacked fat (lipids), which may mean Beipiaosaurus didn’t get as warm as modern birds
- Modern birds have the fatty corneocytes with loosely packed keratin, so they can cool down quickly when flying. Beipiaosaurus probably didn’t get as warm because it couldn’t fly
- Found they (including Beipiaosaurus) probably shed skin as dandruff
- Sister taxon to Falcarius
- Lived in a warm, humid climate with dry seasons
- Average temperatures were 50 degrees F (10 degrees C)
- Lived alongside Jianchangosaurus, which may mean therizinosaurs commonly co-existed and had different feeding strategies
- Other dinosaurs that lived around the same time and place include Dilong, Yutyrannus, Sinornithosaurus, Caudipteryx, Sinocalliopteryx, Confuciusornis, Psittacosaurus, Dongbeititan
- Other animals that lived around the same time and place included snails, slugs, shrimp, insects, fish, birds, mammals, and lizards
Fun Fact: Birds, and some non-avian dinosaurs, performed a three step “tucking” process within their eggs to improve hatching performance.
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