I Know Dino: Stegosaurus

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

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On this episode, we focus on:

• The dinosaur of the day: Stegosaurus, whose identify 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)
• No less than 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, based mostly on fossils discovered close to Morrison, Colorado. At first Marsh thought it was an aquatic animal, much like a turtle. The identify “roofed lizard” comes from Marsh pondering the plates had been flat on Stegosaurus’ again, like shingles on a roof. Numerous Stegosaurus fossils had been discovered and Marsh wrote many papers. Like with many dinosaurs, at first a number of species had been named, however now there are just a few legitimate ones
• Stegosaurus armatus (armored roof lizard) was named based mostly 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 based mostly on fossils present in Wyoming. It’s attainable these fossils are literally Stegosaurus armatus, however the fossils present in 2006 in Portgual are thought of 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 kind 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 one of the best identified. Had 4 tail spikes and broad plates. Identified 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 staff 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 embody Stegosaurus affinis (Marsh described in 1881, however based mostly on solely a pubis); Stegosaurus laticeps (Marsh described in 1881 from jawbone fragments); Stegosaurus duplex (identify means two plexus roof lizard, Marsh named in 1887 based mostly on the massive space close to its tail that Marsh referred to as the “posterior mind case”) nevertheless it’s probaly simply Stegosaurus armatus
• Former Stegosaurus‘ embody Stegosaurus longispinus (Charles Gilmore named) however is now the kind species of the genus Natronasaurus; additionally Stegosaurus madagascariensis (described in 1926 based mostly on enamel present in Madagascar, however is now thought of 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 revealed a pair papers within the 2010 that Stegosaurus stenops could also be a greater sort species than Stegosaurus armatus (since it’s the greatest identified, most properly studied and has essentially the most fossils and a close to full skeleton)
• Kenneth Carpenter stated there’s debate on the variety of legitimate species, and in the event you’re a “taxonomic clumper” it’s possible you’ll solely see one Stegosaurus species as legitimate, since there will be a lot variation in a single species (like how canines all belong to Canis lupus familiaris)
• Most Stegosaurus fossils had 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 embody snails, frogs, ray-finned fish, turtles, salamanders, pterosaurus, and early mammals
• Matthew Mossbrucker discovered tracks that present Stegosaurus might have lived in herds amongst quite a few completely 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 underneath its neck to assist defend it from predators)
• Predators included Allosaurus and Ceratosaurus
• Marsh at first thought Stegosaurus was bipedal, as a result of its fore limbs had been so brief, however then in 1891 he determined it was two heavy to stroll on simply two legs. Some scientists, nonetheless, suppose Stegosaurus might have been in a position to rear up on its hind legs, utilizing its tail to assist help its weight, so it may eat larger up crops
• Forelimbs had been shorter than hindlimbs, giving it an attention-grabbing posture
• Quick forelimbs, saved head low to the bottom (so ate low mendacity crops), with a stiff tail excessive within the air
• In all probability weight balanced in the direction of its excessive hips and was carried by the hind legs, so Stegosaurus may make tight turns when defending itself
• Couldn’t stroll quick, in any other case the again legs would overtake the entrance legs (max velocity of 4-5 mph or 6-7 kmh
• Hind ft had three toes, and fore ft had 5 toes (however the inside two toes had a blunt hoof)
• Stegosaurus and kinfolk had been herbivores, however had completely different enamel and jaws in comparison with different herbivores, so might have had a novel feeding technique. Stegosaurus had peg-shaped enamel (not grinding enamel) and jaws may 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 had been small, flat, and triangular; Stegosaurus floor up its meals and presumably 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 chunk drive and located it was lower than half the drive of a Labrador retriever, so though it may bit by small younger branches, couldn’t chunk by something over 12 mm in diameter
• Fossilized enamel confirmed extra put on on the perimeters that had been sharpest, so Stegosaurus in all probability bit on a plant, pulled again its head, after which enamel lower by the vegetation (presumably swallowed gastroliths to assist digest)
• In all probability 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; in regards to the measurement 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 folks suppose for therefore lengthy that dinosaurs weren’t good, till extra not too long ago (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 greater
• 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 acquired a case of a mind cavity (additionally referred to as an endocast) within the Eighteen 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 wire” which may match one thing greater than 20 occasions greater 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 “might have been the placement of a glycogen physique, a construction in dwelling birds whose perform is just not positively identified” nevertheless it in all probability has one thing to do with power storage
• Identified from its plates and spikes on the tail (in all probability used for protection)
• Kite formed plates on its rounded again, and two pairs of lengthy spikes on the finish of its tail
• Plates might have been used for protection, show, and/or thermoregulation
• Had 17 flat plates (dermal plates) that had been osteoderms (bony-cored scales) much like osteoderms in fashionable crocodiles and lizards. The plates got here from the pores and skin (not the skeleton), and the most important plates had been 2 ft (60 cm) vast and a pair of ft (60 cm) tall
• Numerous arguments over how the plates had 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 manner) 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 may that evolve that method)
• Robert Bakker speculated the plates had been considerably cellular, and Stegosaurus may flip them back and forth to discourage a predator from attacking
• In 1914 Gilmore stated the spikes on the tail had been for show solely, however Robert Bakker later stated the tail was in all probability fairly versatile (no ossified tendons) so in all probability used as a weapon (stated they regarded like a monkey tail, with no locking joints, so may fatally stab)
• However, plates appear to overlap with tail vertebrae so might have restricted it considerably
• Numerous debate over the aim of the plates. Regarded as armor at first, however they’re too fragile and so they go away the perimeters of Stegosaurus unprotected; nonetheless they could have made Stegosaurus look greater and extra menacing to predators or spectacular to feminine Stegosaurus (although women and men had plates); might have helped management physique temperature
• Is also used for warning, blood would rush to plates, making them “blush” a crimson warning (may additionally use to draw mates)
• Stegosaurus plates weren’t fabricated from strong 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 research revealed within the Swiss Journal of Geosciences discovered the plates might have passively helped management physique temperature (as a result of the plates had been so massive with so many blood vessels, like how a toucan’s invoice naturally radiates physique warmth), however not the principle objective
• The dimensions and form of Stegosaurus plates assist determine whether or not it was male or feminine.
• It’s arduous to inform whether or not dinosaurs are male or feminine (reproductive organs and gentle tissues not often discovered), so scientists guess based mostly on fashionable animals
• In 2015 (lined within the information on this podcast) in PLOS One a research stated that Stegosaurus fossils (Stegosaurus mjosi) present in Montana with two varieties of plates (massive and spherical v. tall and spiky) weren’t completely different species however completely different gender
• Evan Saitta, lead writer stated the massive vast plates had been in all probability from males (for show), and the tall spiky ones had been from females (used as deterrents)
• They had been discovered collectively, which reveals they in all probability co-existed, and the plates had comparable development rings (so the dinosaurs had been across the identical age, and it’s not that the plates modified with age)
• Early on scientists thought the tail spikes had been upright, however now they suppose they caught out to the perimeters
• McWhinney and staff revealed a research of tail spikes that confirmed that 9.8 % of Stegosaurus examined had tail spike accidents, serving to help 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 revealed in 1982 exhibiting cavemen calling the spikes thagomizers (line was “Now this finish is known as the thagomizer…after the late Thag Simmons”)
• In 1977 paleontologists discovered an almost full juvenile Stegosaurus at Dinosaur Nationwide Monument (essentially the most full one discovered to this point) with limb bones, shoulder blades, a lot of the hips, some ribs, and cranium fragments (forged on show at Quarry Exhibit Corridor)
• Can see an grownup and juvenile Stegosaurus stenops on the Denver Museum of Nature and Science (appear like 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 challenge 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 by the air
• BBC’s 1999 Strolling With Dinosaurs gave Stegosaurus some frontal swagger to point out the shortness of its forelimbs in comparison with its hindlimbs
• Stegosaurus is the state dinosaur of Colorado (as of 1982)
• Stegosaurus grew to become 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 sort of dinosaur
• Stegosaurus was the primary named genus within the Stegosauridae household (making it the kind genus)
• Closest kinfolk to Stegosaurus had 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 had been shallower in comparison with Huayangosauridae and there was a much 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 embody 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 had been shorter than their again legs, so that they had been gradual
• Might in all probability shear branches with enamel
• They’ve plates and tail spikes
• Enjoyable Reality: Why do enamel fossilize so properly? Tooth are made out of Dentin which is more durable and denser than bone, they’re surrounded by a really arduous enamel shell which protects them, in lots of circumstances they fall out and are changed commonly, and so they aren’t very tasty so different animals are unlikely to interrupt them down.