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Episode 417: Thescelosaurus had spikes popping out of its forearms


    Episode 417: Thescelosaurus had spikes popping out of its forearms. Plus extra information from SVP together with why tyrannosaurs had small arms; how raptors have been like cheetahs; and potential theropod embryos with palatal enamel, osteoderms, and pores and skin.


    • Displays from the Dinosaur Macroevolution/Macroecology session of SVP 2022 supply
    • The Tender Tissues and Taphonomy talks from SVP 2022 supply


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    The dinosaur of the day: Caenagnathus

    • Caenagnathid oviraptorosaur that lived within the Late Cretaceous in what’s now Alberta, Canada (Dinosaur Park Formation)
    • Giant, and will have been about as massive as Anzu
    • Seemed just like Anzu
    • Seemed chook like, with feathers and lengthy legs
    • Additionally had an extended tail, and s-shaped neck, and possibly had a crest on its head
    • Considered across the identical measurement as Anzu due to the recognized specimens of Anzu and Caenagnathus, the pubes are about the identical measurement
    • Anzu was about 11 ft (3.5 m) lengthy
    • Anzu should still have been bigger (recognized specimens might not symbolize its max physique measurement, and the specimens discovered might have nonetheless been rising)
    • Estimated to weigh as much as 212 lb (96 kg)
    • Had an extended, flattened, toothless decrease jaw
    • Had a shallow jaw, which is totally different from different oviraptorosaurs which might be extra like an upturned beak. Might imply it ate extra vegetation
    • Caenagnathids in all probability have been generalist feeders that ate vegetation, small animals, and possibly eggs
    • Fossils discovered embody decrease jaws, tail vertebra, bones from the hand and limbs
    • Sort species is Caenagnathus collinsi
    • Genus title means “current jaw”
    • Species title “in honor of the late Dr. W. H. Collins, for a few years director of the Geological Survey of Canada”
    • Described by R. M. Sternberg in 1940
    • At first considered a toothless chook
    • Jaws have been present in 1936 and it was named Caenagnathus
    • Sternberg wrote that “The holotype is an admirably preserved decrease jaw, full apart from the ventral border of the proper ramus”
    • Holotype was discovered in the summertime of 1936, a area social gathering from the Nationwide Museum of Canada, beneath the route of C.M. Sternberg
    • In 1988, a special specimen that had been in storage since 1923 was rediscovered and studied, and it helped hyperlink a number of fragments of an oviraptorosaur into one dinosaur: Chirostenotes (lined in episode 404)
    • A number of debate and subsequent research discovering Chirostenotes and Caenagnathus to be separate
    • In 2010, Phil Senter did a phylogenetic evaluation of Coelurosauria and located Caenagnathus and Chirostenotes to be separate, “casting doubt on their synonymy”
    • Extra full caenagnathid specimens present in 2014 and 2015, like the invention of Anzu, helped present extra variations within the fragmentary specimens
    • In 2015, Funston and others re-examined caenagnathid fossils from Dinosaur Park Formation, and located extra Caenagnathus collinsi fossils, together with a tail vertebra, femur, and components of the ft
    • Funston and Currie in 2020 described one other Chirostenotes specimen with a decrease jaw, that supported Chirostenotes and Caenagnathus being separate
    • Variations within the ft and toes, between Caenagnathus and Chirostenotes
    • In 2020, Gregory Funston re-examined caegnagthid materials and redescribed Caegnathus collinsi (some disagreement over the variety of caenagnathids)
    • One of many specimens was no less than 12 years previous and practically executed rising
    • Most likely grew shortly at first, then slowed down
    • In 1993, Phil Currie and others named “Caenagnathus” sternbergi, based mostly on new specimens discovered within the Judith River Formation, however in a 2014 evaluation it was discovered to be a sister taxon
    • Different dinosaurs that lived across the identical time and place embody ankylosaurs, ceratopsians, ornithopods, pachycephalosaurs, ornithomimids, oviraptorosaurs, paravians, tyrannosaurs
    • Different animals that lived across the identical time and place embody amphibians, crocodylians, lizards, plesiosaurs, pterosaurs, turtles, mammals, fish

    Enjoyable Truth:

    Typically you could find progress marks in ribs to calculate a dinosaur’s age when the legs don’t have progress marks.

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