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I Know Dino: Stegosaurus

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    Episode 38 is all about Stegosaurus, some of the well-known dinosaurs, identified for its plates and spiky tail.

    You possibly can hearken to our free podcast, with all our episodes, on iTunes at:

    https://itunes.apple.com/us/podcast/i-know-dino/id960976813?mt=2

    On this episode, we focus on:

    • The dinosaur of the day: Stegosaurus, whose title means “roof lizard”
    • To not be confused with Stegoceras (pachycephalosaurid, with a dome head)
    • Lived within the Late Jurassic, in western North America (although one present in Portugal in 2006)
    • At the least 3 species present in Morrison Formation (from 80 people)
    • Stegosaurus was the primary dinosaur named within the household Stegosauridae (it’s the kind genus)
    • Within the household Stegosauridae, Stegosaurus is the most important
    • Stegosaurus was discovered through the Bone Wars. Charles Marsh named Stegosaurus armatus in 1877, primarily based on fossils discovered close to Morrison, Colorado. At first Marsh thought it was an aquatic animal, just like a turtle. The title “roofed lizard” comes from Marsh pondering the plates have been flat on Stegosaurus’ again, like shingles on a roof. Plenty of Stegosaurus fossils have been discovered and Marsh wrote many papers. Like with many dinosaurs, at first a number of species have been named, however now there are only some legitimate ones
    • Stegosaurus armatus (armored roof lizard) was named primarily based on two partial skeletons, two partial skulls, and 30 fragments of people. It had 4 tail spikes (Marsh initially thought it had 8) and considerably small plates. It was about 30 ft or 9 m lengthy (longest Stegosaurus species); present in Colorado, Wyoming and Utah within the Morrison Formation
    • Stegosaurus ungulatus (hoofed roof lizard); Marsh named in 1879 primarily based on fossils present in Wyoming. It’s doable these fossils are literally Stegosaurus armatus, however the fossils present in 2006 in Portgual are thought-about Stegosaurus ungulatus
    • Stegosaurus sulcatus (furrowed roof lizard), named by Marsh in 1887 from a partial skeleton. Many have thought it was the identical as Stegosaurus armatus, however latest research present it could be its personal species. The sort specimen had a spike, initially considered a part of the tail, that some scientists now suppose was a part of the shoulder
    • Stegosaurus stenops (narrow-faced roof lizard), named by Marsh in 1887, holotype discovered by Marshal Felch in Colorado in 1886. Species is thought from not less than one full skeleton, so it’s the perfect identified. Had 4 tail spikes and broad plates. Recognized from 50 partial skeletons of adults and juveniles, one full cranium, and 4 partial skulls. Solely 23 ft or 7 m lengthy, in comparison with Stegosaurus armatus, and has been present in Colorado, Wyoming and Utah
    • In 2008 Susannah Maidment and a group pushed to synomymize Stegosaurus stenops and Stegosaurus ungulatus with Stegosaurus armatus, in addition to change Hesperosaurus and Wuehosaurus into Stegosaurus and renaming them Stegosaurus mjosi and Stegosaurus homheni. So there can be 3 Stegosaurus species (armatus, homheni, and mjosi), with Stegosaurus starting from Late Jurassic in North America and Europe to Early Cretaceous in Asia). However most researchers don’t agree.
    • Some nomina dubia (doubtful names) and junior synonyms embrace Stegosaurus affinis (Marsh described in 1881, however primarily based on solely a pubis); Stegosaurus laticeps (Marsh described in 1881 from jawbone fragments); Stegosaurus duplex (title means two plexus roof lizard, Marsh named in 1887 primarily based on the massive space close to its tail that Marsh referred to as the “posterior mind case”) but it surely’s probaly simply Stegosaurus armatus
    • Former Stegosaurus‘ embrace Stegosaurus longispinus (Charles Gilmore named) however is now the kind species of the genus Natronasaurus; additionally Stegosaurus madagascariensis (described in 1926 primarily based on enamel present in Madagascar, however is now thought-about to be one thing else, like a hadrosaur or ankylosaur); Stegosaurus marshi (described in 1901 and renamed Hoplitosaurus in 1902); and Stegosaurus priscus, described in 1911 and now the kind species of Loricatosaurus
    • Kenneth Carpenter and Peter Galton printed a pair papers within the 2010 that Stegosaurus stenops could also be a greater kind species than Stegosaurus armatus (since it’s the finest identified, most properly studied and has probably the most fossils and a close to full skeleton)
    • Kenneth Carpenter stated there’s debate on the variety of legitimate species, and should you’re a “taxonomic clumper” you might solely see one Stegosaurus species as legitimate, since there might be a lot variation in a single species (like how canines all belong to Canis lupus familiaris)
    • Most Stegosaurus fossils have been discovered within the Morrison Formation
    • Morrison Formation was semiarid with moist and dry seasons and flat floodplains. Vegetation included conifers, ferns, inexperienced algae, fungi, mosses, horsetails, cycads, and ginkgoes
    • Different dinosaurs included Allosaurus, Torvosaurus, Brachiosaurus, Apatosaurus, Diplodocus, Camarasaurus, Camptosaurus, Dryosaurus (Stegosaurus typically discovered close to Allosaurus, Apatosaurus, Camarasaurus and Diplodocus)
    • Different animals embrace snails, frogs, ray-finned fish, turtles, salamanders, pterosaurus, and early mammals
    • Matthew Mossbrucker discovered tracks that present Stegosaurus could have lived in herds amongst a lot of totally different aged Stegosauruses. One set of tracks had 4-5 child Stegosaurus transferring collectively and one other had a juvenile monitor with an grownup monitor over it
    • Stegosaurus had pebbly throat armor (lumps below its neck to assist protect it from predators)
    • Predators included Allosaurus and Ceratosaurus
    • Marsh at first thought Stegosaurus was bipedal, as a result of its fore limbs have been so brief, however then in 1891 he determined it was two heavy to stroll on simply two legs. Some scientists, nevertheless, suppose Stegosaurus could have been in a position to rear up on its hind legs, utilizing its tail to assist assist its weight, so it might eat increased up crops
    • Forelimbs have been shorter than hindlimbs, giving it an fascinating posture
    • Brief forelimbs, stored head low to the bottom (so ate low mendacity crops), with a stiff tail excessive within the air
    • Most likely weight balanced in the direction of its excessive hips and was carried by the hind legs, so Stegosaurus might make tight turns when defending itself
    • Couldn’t stroll quick, in any other case the again legs would overtake the entrance legs (max pace of 4-5 mph or 6-7 kmh
    • Hind ft had three toes, and fore ft had 5 toes (however the interior two toes had a blunt hoof)
    • Stegosaurus and family members have been herbivores, however had totally different enamel and jaws in comparison with different herbivores, so could have had a novel feeding technique. Stegosaurus had peg-shaped enamel (not grinding enamel) and jaws might solely do up-down actions; additionally no proof they swallowed gastroliths, so it’s not clear precisely how they ate their meals
    • No entrance enamel, as an alternative had a attractive beak (simpler to eat low rising vegetation
    • Tooth have been small, flat, and triangular; Stegosaurus floor up its meals and probably had cheeks to maintain meals in its mouth when it chewed
    • In 2010, scientists did an in depth pc evaluation of how Stegosaurus ate, utilizing 2 3D fashions of Stegosaurus enamel. Additionally calculated chew pressure and located it was lower than half the pressure of a Labrador retriever, so though it might bit via small younger branches, couldn’t chew via something over 12 mm in diameter
    • Fossilized enamel confirmed extra put on on the edges that have been sharpest, so Stegosaurus most likely bit on a plant, pulled again its head, after which enamel lower via the vegetation (probably swallowed gastroliths to assist digest)
    • Most likely ate mosses, ferns, horsetails, cycads and conifers (wouldn’t have grazed on grasses, since grass was not round till the late Cretaceous, after Stegosaurus went extinct)
    • Stegosaurus was as much as 30 ft (9 m) lengthy; concerning the dimension of a bus
    • In 1994 a subadult Stegosaurus was present in Wyoming (15 ft or 4.6 m lengthy, 7 ft or 2 m excessive, 2.6 tons or 2.3 metric tons). Can see it on show within the College of Wyoming Geological Museum
    • A 90% specimen present in 2003 in Wyoming by Bob Simon, president of the dinosaur excavation and preservation company Virginia Dinosaur Firm and Dinosaur Safaris
    • Stegosaurus weighed greater than 5 brief tons (4.5 metric tons), however mind was about 80 g (made individuals suppose for thus lengthy that dinosaurs weren’t sensible, till extra lately (round Jurassic Park)
    • Lengthy, slender cranium (however small in comparison with the remainder of its physique)
    • Braincase no bigger than a canine’s, although it’s physique was a lot larger
    • Mind was considered the scale of a walnut, however in accordance with Kenneth Carpenter, director of th USU Japanese Prehistoric Museum in Utah, “its mind had the scale and form of a bent hotdog”
    • Had a low EQ (mind to physique mass ratio), so not the neatest
    • Charles Marsh obtained a case of a mind cavity (additionally referred to as an endocast) within the Eighties, and confirmed it was the smallest proportionally of all dinosaurs, not less than those identified on the time
    • Marsh described a “massive canal within the hip area of the spinal twine” which might match one thing greater than 20 instances larger than the Stegosaurus’ mind. This led to the concept that Stegosaurus had a “second mind” in its tail to assist management its physique, particularly when threatened. However this space has additionally been present in sauropods and “could have been the placement of a glycogen physique, a construction in residing birds whose perform isn’t undoubtedly identified” but it surely most likely has one thing to do with power storage
    • Recognized from its plates and spikes on the tail (most likely used for protection)
    • Kite formed plates on its rounded again, and two pairs of lengthy spikes on the finish of its tail
    • Plates could have been used for protection, show, and/or thermoregulation
    • Had 17 flat plates (dermal plates) that have been osteoderms (bony-cored scales) just like osteoderms in fashionable crocodiles and lizards. The plates got here from the pores and skin (not the skeleton), and the most important plates have been 2 ft (60 cm) huge and a pair of ft (60 cm) tall
    • Plenty of arguments over how the plates have been organized on Stegosaurus.
    • Marsh at first thought the plates lay flat, however in 1891 stated it had a single row of plates
    • One other thought is there have been pairs of plates in a row alongside the again (seen most frequently in photographs, particularly early ones earlier than the Seventies, seen within the 1933 movie King Kong this fashion) however no two similar sized and formed plates have been discovered for a similar Stegosaurus
    • One other thought was two rows of alternating plates (many accepted it by early Nineteen Sixties, although some argue we don’t see this in different reptiles, so how might that evolve that approach)
    • Robert Bakker speculated the plates have been considerably cellular, and Stegosaurus might flip them backward and forward to discourage a predator from attacking
    • In 1914 Gilmore stated the spikes on the tail have been for show solely, however Robert Bakker later stated the tail was most likely fairly versatile (no ossified tendons) so most likely used as a weapon (stated they regarded like a monkey tail, with no locking joints, so might fatally stab)
    • However, plates appear to overlap with tail vertebrae so could have restricted it considerably
    • Plenty of debate over the aim of the plates. Regarded as armor at first, however they’re too fragile they usually depart the edges of Stegosaurus unprotected; nevertheless they might have made Stegosaurus look larger and extra menacing to predators or spectacular to feminine Stegosaurus (although women and men had plates); could have helped management physique temperature
    • Is also used for warning, blood would rush to plates, making them “blush” a pink warning (might additionally use to draw mates)
    • Stegosaurus plates weren’t product of stable osteoderms, however had lattice-like constructions and blood vessels
    • 2005 evaluation in Paleobiology discovered the “microstructure of the plates recommend they weren’t used to radiate warmth”; 2010 examine printed within the Swiss Journal of Geosciences discovered the plates could have passively helped management physique temperature (as a result of the plates have been so massive with so many blood vessels, like how a toucan’s invoice naturally radiates physique warmth), however not the primary objective
    • The scale and form of Stegosaurus plates assist determine whether or not it was male or feminine.
    • It’s onerous to inform whether or not dinosaurs are male or feminine (reproductive organs and gentle tissues not often discovered), so scientists guess primarily based on fashionable animals
    • In 2015 (lined within the information on this podcast) in PLOS One a examine stated that Stegosaurus fossils (Stegosaurus mjosi) present in Montana with two sorts of plates (massive and spherical v. tall and spiky) weren’t totally different species however totally different gender
    • Evan Saitta, lead creator stated the massive huge plates have been most likely from males (for show), and the tall spiky ones have been from females (used as deterrents)
    • They have been discovered collectively, which reveals they most likely co-existed, and the plates had related development rings (so the dinosaurs have been across the similar age, and it’s not that the plates modified with age)
    • Early on scientists thought the tail spikes have been upright, however now they suppose they caught out to the edges
    • McWhinney and group printed a examine of tail spikes that confirmed that 9.8 % of Stegosaurus examined had tail spike accidents, serving to assist the concept that they fought with their tails (additionally an Allosaurus was discovered with a punctured tail wound)
    • Informally the tail spikes are referred to as thagomizers, after a Gary Larson “Far Facet” cartoon was printed in 1982 displaying cavemen calling the spikes thagomizers (line was “Now this finish is named the thagomizer…after the late Thag Simmons”)
    • In 1977 paleontologists discovered an almost full juvenile Stegosaurus at Dinosaur Nationwide Monument (probably the most full one discovered thus far) with limb bones, shoulder blades, a lot of the hips, some ribs, and cranium fragments (solid on show at Quarry Exhibit Corridor)
    • Can see an grownup and juvenile Stegosaurus stenops on the Denver Museum of Nature and Science (appear to be they’re being attacked by an Allosaurus fragilis)
    • Can see Stegosaurus ungulates on the Carnegie Museum of Pure Historical past in Pittsburgh, PA or within the Nebraska Stage Museum in Lincoln, NE
    • Can even see a Stegosaurus stenops (nickname “Sophie”) on the Pure Historical past Museum in London
    • Picture of Stegosaurus in 1884 subject of Scientific American confirmed Marsh’s first ideas on Stegosaurus, with tail spikes on its again, again plates on its tail, and up on its hind legs and tail in a tripodal pose
    • In 1920 journalist W.H. Ballous wrote that Stegosaurus would flap its plates and glide via the air
    • BBC’s 1999 Strolling With Dinosaurs gave Stegosaurus some frontal swagger to indicate the shortness of its forelimbs in comparison with its hindlimbs
    • Stegosaurus is the state dinosaur of Colorado (as of 1982)
    • Stegosaurus turned CO state dinosaur after a two-year write-in marketing campaign by 1000’s of fourth graders
    • Stegosaurus can also be in Jurassic Park II and III
    • Spike in Land Earlier than Time
    • Though Stegosaurus is known, there are lower than 2 dozen varieties within the Stegosaurid household, so it’s a uncommon kind of dinosaur
    • Stegosaurus was the primary named genus within the Stegosauridae household (making it the kind genus)
    • Closest family members to Stegosaurus have been Wuerhosaurus from China and Kentrosaurus from East Africa)
    • Stegosauridae is likely one of the two households within the infraorder Stegosauria (different famiy is Huayangosauridae)
    • Stegosauridae skulls have been shallower in comparison with Huayangosauridae and there was an even bigger distinction between its brief forelimbs and lengthy hinglimbs, and had bigger plates and tail spikes
    • Huayangosaurus is the one genus in Huayangosauridae, and lived 20 million years earlier than Stegosaurus (Scelidosaurus from Jurassic England, lived 190 million years earlier than and had options of stegosaurs and ankylosaurs
    • Stegosauria is within the suborder Thyreophora (armored dinosaurs that features ankylosaurs)
    • Stegosauridae is additional divided into subfamilies: Dacentrurinae and Stegosaurinae (Stegosaurinae are the bigger ones)
    • Earliest stegosaur is Lexovisaurus from England
    • Different small, frivolously armored dinosaurs associated to stegosaurs direct ancestor embrace Emausaurus from Germany (small quardruped) and Scutellosaurus from Arizona, bipedal)
    • A trackway of an early armored dinosaur, from 195 million years in the past was present in France
    • Stegosaurids lived in late Jurassic to early Cretaceous
    • Normally massive
    • Their entrance legs have been shorter than their again legs, so that they have been gradual
    • Might most likely shear branches with enamel
    • They’ve plates and tail spikes
    • Enjoyable Truth: Why do enamel fossilize so properly? Tooth are made out of Dentin which is tougher and denser than bone, they’re surrounded by a really onerous enamel shell which protects them, in lots of instances they fall out and are changed usually, they usually aren’t very tasty so different animals are unlikely to interrupt them down.



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