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I Know Dino Podcast Present Notes: Pachycephalosaurus (Episode 93)


    Episode 93 is all about Pachycephalosaurus, an ornithischian with a thick cranium.

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    On this episode, we focus on:

    • The dinosaur of the day: Pachycephalosaurus
    • Title means “thick headed lizard”
    • Kind species is Pachycephalosaurus wyomingensis
    • Lived within the late Cretaceous in North America (Montana, South Dakota, Wyoming)
    • Identified from a cranium with thick cranium roofs (extra full fossils discovered after it was first described)
    • Tylosteus, a dinosaur from western North America, is synonymous with Pachycephalosaurus
    • First Pachycephalosaurus fossils might have been discovered within the early 1850s
    • Donald Baird discovered a bone fragment in 1859 or 1860 within the Lance Formation in Montana. Joseph Leidy described it in 1872, however thought it was a part of an armadillo-like animal or a part of the dermal armor of a reptile. It was referred to as Tylosteus. Then greater than 100 years later Baird reexamined the bone and located it was a part of the bone on th eback of the cranium of Pachycephalosaurus
    • Normally the title Tyolsteus would stay as a result of it was named earlier than Pachycephalosaurus, however Baird petitioned to make use of Pachycephalosaurus as an alternative of Tylosteus in 1985 as a result of the title Tylosteus hadn’t been utilized in extra then 50 years, and was primarily based on undiagnostic supplies
    • Charles Gilmore named Pachycephalosaurus wyomingensis in 1931, primarily based on a partial cranium discovered within the Lance Formation in Wyoming. Gilmore assigned it Troodon wyomingensis however Charles Sternberg corrected this in 1945
    • Had enamel just like Troodon, which is why it was categorised as a Troodon
    • Barnum Brown and Eric Maren Schlaikjer discovered extra full materials and altered the title to Pachycephalosaurus in 1943. They named two species: grangeri (primarily based on a cranium from the Hell Creek Formation in Montana) and reinheimeri (primarily based on a dome from the Lance Formation in South Dakota). As of 1983, these species are thought-about synonyms of Pachycephalosaurus wyomingensis
    • Then Troodon‘s tooth was discovered to match Stenyonychosaurus, a theropod very completely different to pachycephalosaurids, so the brand new group was established, Pachycephalosauridae in 1974, as an alternative of Troodontidae (Pachycephalosaurus was the following genus with seniority)
    • It’s because the oldest Pachycephalosaurus fossils had been described in 1872
    • Two Pachycephalosauria most intently associated to Pachycephalosaurus are Dracorex and Stygimoloch, which can be junior types of Pachycephalosaurus
    • Stygimoloch was named in 1983, Dracorex in 2006
    • Dracorex hogwartsia was named in 2006 in honor of Harry Potter
    • In 2007, Jack Horner offered on the Society of Vertebrate Paleontology that Dracorex and Stygimoloch might have been juveniles Pachycephalosaurus as an alternative (dome and horns aren’t properly developed). Jack Horner and M.B. Goodwin revealed their findings in 2009. They stated the Pachycephalosaurus misplaced its spikes and grew domes because it matured. Extra proof of this from child Pachycephalosaurus skulls described in 2016 by David Evans and Mark Goodwin from two bone beds within the Hell Creek Formation. That they had knobs on their skulls, which exhibits they began off with knobs after which developed domes. Nick Longrich and colleagues revealed a examine in 2010 that supported the concept flat-skulled pachycephalosaurs had been juveniles, PLOS One: Excessive Cranial Ontogeny within the Higher Cretaceous Dinosaur Pachycephalosaurus by John R. Horner , Mark B. Goodwin. Revealed: October 27, 2009
    • Discovered that Dracorex and Stygimoloch had been juveniles of Pachycephalosaurus
    • In 2006 Robert Sullivan stated that the Tylosteus bone could also be extra like Dracorex than Pachycephalosaurus (although Dracorex could also be a juvenile Pachycephalosaurus)
    • Lived in the identical time and space as T-rex
    • Both herbivorous or omnivorous
    • Unclear what they ate. That they had small enamel that might not chew robust vegetation. In all probability ate leaves, seeds, fruit, and bugs
    • Had sharp, serrated enamel, good for shredding vegetation
    • Small enamel, with leaf-shaped crowns
    • Had a pointed beak
    • About 15 ft (4.5 m) lengthy and weighed 990 lb (450 kg)
    • Bipedal
    • Had lengthy hindlimbs and small forelimbs
    • Had massive eye sockets that confronted ahead, so had good imaginative and prescient and possibly binocular imaginative and prescient
    • In all probability had a brief, thick neck and a heavy, inflexible tail
    • Had an S or U curved neck
    • Often called bone-headed or dome-headed dinosaurs
    • Had a big, bony dome on the highest of its cranium (10 in, 25 cm thick). Again of the dome had bony knobs and the snout had brief bony, blunt spikes that projected upwards
    • Scientists at one level thought that Pachycephalosaurus heads had been kneecaps (within the late 1800s) when not many dinosaur bones had been discovered
    • Thick cranium domes made scientists suppose Pachycephalosaurus fought one another by butting heads (disputed)
    • Scientists used to suppose that Pachycephalosaurus had been like bighorn sheep or musk oxen, besides bipedal, and that males rammed their heads into one another
      Now there’s a debate. It’s thought the cranium roof couldn’t have sustained the influence of ramming, and it wasn’t till lately scientists discovered proof of scares or harm on the skulls
    • The S or U formed neck meant they couldn’t instantly head butt
    • They might have fought by flank butting as an alternative, primarily based on the truth that they had been fairly vast (Sues proposed this idea in 1978, Ken Carpenter defined extra in 1997)
    • Goodwin and Horner did a examine in 2004 that confirmed the bone construction of the dome is spongy inside (might have crumbled from too many blows to the top)
    • PLOS One: Frequent Practical Correlates of Head-Strike Habits within the Pachycephalosaur Stegoceras validum (Ornithischia, Dinosauria) and Combative Artiodactyls by Eric Snively , Jessica M. Theodor. Revealed: June 28, 2011
    • CT scans of Pachycephalosaurs (Stegoceras and Prenocephale prenes) discovered they might face up to face to face impacts
    • Joseph Peterson did CT scans of Pachycephalosaurus cranium in 2012
    • A examine in 2012 confirmed cranial pathologies that most likely occurred from preventing. In 2013, Peterson et. al discovered that 22% of all domes of their examine had cranial pathologies from osteomyelitis, an an infection from trauma that results in an infection of bone tissue. Flat headed pachycephalosaurids didn’t have pathologies. This helps the concept they fought intra species (grownup males a minimum of). Additionally, pachycephalosaurid domes are made from fibrolamellar bone, which has fibroblasts that assist heal wounds. This strongly helps the concept they butted heads
    • Dome might have attracted mates
    • Can see Pachycephalosaurus in Jurassic Park films. In The Misplaced World it was portrayed as smaller (extra like Stegoceras measurement)
    • Pachycephalosaurus is among the 4 dinosaurs you possibly can play as within the sport Saurian
    • Pachy can also be in ARK: Survival Advanced. Wild ones within the sport are often passive, but in addition cost and headbutt. Domesticated ones are good for battle (due to head butting), and it’s quick
    • A part of the clade Pachycephalosauria (herbivorous ornithischians that lived within the Late Cretaceous in North America and Asia)
    • Though Pachycephalosauria are bipedal, they’re extra intently associated to ceratopsians than ornithopods
    • Pachycephalosaurus is the most important identified pachycephalosaurid
    • Pachycephalosauria is a clade of ornithischians
    • Title means thick headed lizards
    • Lived within the late Cretaceous in North America and Asia
    • Bipedal with thick skulls
    • Enjoyable truth: The e-book Articulating Dinosaurs by Brian Noble recounts the unique T-rex mount within the AMNH which is in a Barney-like upright place and Noble quotes Henry Fairfield Osborn saying, “The upright determine shouldn’t be properly balanced and might be more practical with the ft nearer collectively, the legs straighter and the physique extra erect. These reptiles have a collection of sturdy belly ribs not proven within the fashions. The fourth place locations the pelvis in an nearly not possible place…” So on this case a minimum of, they deliberately made the mount comparatively unrealistic in an effort to make it look extra spectacular…


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