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I Know Dino Podcast Present Notes: Ornitholestes (Episode 80)


    Episode 80 is all about Ornitholestes, a carnivorous theropod with a small head.

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    On this episode, we focus on:

    • The dinosaur of the day: Ornitholestes
    • Identify means “chicken robber”
    • Small theropod
    • Lived within the Late Jurassic, in Western Laurasia (now North America)
    • Henry Fairfield Osborn described the skeleton in 1903
    • First theropod found within the 1900s
    • Holotype expedited by Peter Kaisen, Paul Miller, and Frederic Brewster Loomis
    • Recognized from one partial skeleton with a crushed cranium (discovered on the Bone Cabin Quarry in Wyoming, close to Medication Bow, in 1900)
    • Partial skeleton contains elements of the vertebral column, forelimbs, pelvis, and hindlimbs
    • Later, there was an incomplete hand considered Ornitholestes, however is taken into account Tanycolagreus
    • Tanycolagreus was discovered only some hundred yards from Ornitholestes (that’s why the hand was assigned to it, at first)
    • Sort species (solely species) is Ornitholestes hermanni
    • Named after the American Museum of Pure Historical past preparator Adam Hermann (directed the restoration and mounting of the skeleton)
    • Theodore Gill steered the genus identify
    • Charles Gilmore stated Ornitholestes was an identical to Coelurus (1920), and in 1934 Oliver Perry Hay stated there was solely a distinction on the species degree, and renamed Ornitholestes, Coelurus hermanni; in 1980 John Ostrom revived the genus Ornitholestes
    • Bipedal carnivore
    • Had a head proportionally smaller than most different carnivorous dinosaurs
    • Had a brief snout and sturdy decrease jaw
    • Had conical entrance tooth, again tooth have been recurved and serrated (Henry Osborn stated there have been 4 tooth within the premaxilla, Gregory S. Paul in 1988 stated the cranium had solely three remaining premaxillary tooth)
    • Had massive eye sockets, that have been greater than 25% of the cranium’s size
    • Massive eyes might have been used to hunt at evening
    • Small cranium means it could have been tough to catch prey with its mouth (in all probability used arms)
    • Had robust arms
    • Might tuck fingers near physique, just like the way in which a chicken holds its wing
    • In 2006 Phil Senter did a biomechanical research utilizing Ornitholestes casts (the appropriate forelimb) to determine its vary of movement (discovered it might swing in a 95 diploma vary, and will bend its elbow at a 53 diploma angle, which is extra acute than Maniraptoriformes (can bend forearms to 90 levels), however absent in primitive theropods like Coelophysis and Allosaurus
    • Forearm couldn’t type a straight angle, so the forearm was completely rotated upward
    • Could have used its forearms to know prey (with each fingers)
    • Osborn described Ornitholestes as having “speedy greedy energy” of fingers, “balancing energy” of tail, and huge, conical entrance tooth (he noticed as adaptation to prey on up to date birds); then in 1917 Osborn steered Ornitholestes was an early transition from carnivore to herbivore, however Charles Knight drew Ornitholestes chasing Archaeopteryx (and different illustrations like this have continued to seem)
    • Ornitholestes got here from western U.S., Archaeopteryx recognized from central Europe
    • Had a brief physique
    • About 6.6 ft (2 m) lengthy
    • Weighed about 33 lb or 15 kg
    • Could have eaten birds, fish, small vertebrates, mammals, lizards, frogs, salamanders, hatchling dinosaurs, or gone after different small theropods (if it hunted in packs, might have been capable of prey on juvenile Camptosaurus)
    • Most likely ate about 1.5 lb or 700 grams of meals a day
    • Could have been prey for bigger theropods (Ceratosaurus and Allosaurus)
    • Had a brief, S-shaped neck and a protracted, whiplike tail (over half the size of its physique)
    • Had lengthy forelimbs, about 2/3 the size of its hind legs
    • Had pretty brief hind legs; Osborn calculated that the shin bone was solely 70% so long as the thigh bone (shin bone was lacking)
    • Considered a quick runner, however decrease leg bones considered shorter than the femur (so in all probability didn’t chase after different small dinosaurs)
    • In 1969 John Ostrom stated that the innermost toe (digit II) was bigger than digits III and IV, and that digit II might have had a modified sickle claw, like Deinonychus (however digit II is in poor situation so it’s laborious to know for certain)
    • Depicted as having a small crest on its snout (considered for show), however now thought there was no crest
    • Has a damaged bone close to the nostril that appears to bulge upward, which made Gregory S. Paul suppose it had a nasal horn “moderately like a hen’s comb in appears to be like” in line with his Predatory Dinosaurs of the World in 1988; however in 2003 Oliver W.M. Rauhut and in 2005 Kenneth Carpenter stated it didn’t have a nasal horn however that the bulge was from the cranium being crushed after the dinosaur died
    • Percy Lowe stated in 1944 Ornitholestes might have had feathers
    • Due to Sinosauropteryx (primitive coelurosaur present in 1996) had furlike feathers, most paleontologists suppose all coelurosaurs in all probability had some sort of insulating feathers; John Foster in 2007 stated Ornitholestes in all probability had extra primitive feathers than birds, used for insulation and probably brooding eggs, and would have coated a lot of the physique
    • If Ornitholestes had feathers used for insulation, in all probability had a quick metabolism and was fairly energetic
    • Due to its measurement, Ornitholestes was thought-about a coelurosaur, however in 1986 Jacques Gauthier redefined Coelurosauria
    • Friedrich von Huene named the infraorder Coelurosauria in 1914 (for some time it was a taxon wastebasket for small theropods)
    • However in 1986 Jacques Gauthier redefined Coelurosauria
    • In 1988 Gregory Paul stated Ornitholestes had an identical cranium to Proceratosaurus (Center Jurassic theropod, present in England), and he put the 2 collectively in Ornitholestinae, a subfamily of Allosauridae; however Proceratosaurus is a tyrannosaur so this classification is untenable
    • Now Ornitholestes thought-about Coelurosauria, as outlined by Gauthier (some suppose it’s essentially the most primitive member of Maniraptora)
    • Coelurosauria group is considered nearer to birds than extra primitive theropods, similar to Allosaurus
    • Coelurosauria means “hole tailed lizards”
    • Clade contains theropods extra intently associated to birds than carnosaurs
    • Could have appeared within the late Triassic
    • Many are recognized from the late Jurassic
    • Most feathered dinosaurs that have been found are coelurosaurs
    • Coelurosaurs have a sacrum (vertebrae that attaches to the hips) longer than in different dinosaurs, a tail that stiffens in the direction of the tip, a bowed decrease arm bone, and a tibia longer than the femur
    • Enjoyable truth: Fossils are the right candidates for CT scans. Once a fossil is scanned it’s quite simple to make a 3-D mannequin, after which you may 3D print out as many copies as you need! It’s nonetheless not fairly nearly as good as conventional casting methods due to 3-D printing decision limits, nevertheless it’s getting higher on a regular basis!