I Know Dino is on Patreon!

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Hello dear listeners. As you know, Garret and I are huge dinosaur enthusiasts, and we are excited to announce the launch of our Patreon page!

We really appreciate all your support these last few months, and now we’re hoping to raise some money so we can take things to the next level, starting with better equipment so we can have higher quality audio of our interviews.

If you’re interested, or just want to learn more (and see our awesome video, complete with dinosaur casts and dinosaur puppets), then please check out our page here! (And also https://www.patreon.com/iknowdino.) And feel free to share with your friends and family.

Thank you so much for your support so far. We’ve really enjoyed interacting with you on all our social media channels and via email. And we hope to keep this dinosaur thing going for a long time!

All the best,

Sabrina (and Garret)

This Week in Dinosaur News: New Dinosaur Pulanesaura eocollum, Dinosaur Video, The Good Dinosaur, and More

Here’s what came out this week in dinosaur news:

  • Wired talks about how The Good Dinosaur has photorealistic graphics, and is made to make you cry
  • Marvel is coming out with a new superhero and her dinosaur friend, called Moon-Girl and Devil Dinosaur, according to The Verge
  • Yorkshire Post reported on a new theory that dinosaurs were just lucky to have dominated have a mass extinction event
  • Phenomena reported on the enamel and folds in carnivorous theropods teeth that made it easier for them to tear flesh
  • The Slow Mo Guys and Field Day made a short video re-enacting dinosaurs mowing lawns before the asteroid hit earth, according to io9
  • TimesLive reported on a new dinosaur called Pulanesaura eocollum, also known as the rain lizard

I Know Dino Podcast Show Notes: Brachiosaurus (Episode 39)

Episode 39 is all about Brachiosaurus, a sauropod with longer forelimbs than hindlimbs.

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

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

In this episode, we discuss:

  • The dinosaur of the day: Brachiosaurus, whose name means “arm lizard”
  • Brachiosaurus is a sauropod that lived in the Jurassic in North America
  • Described by Elmer S. Riggs in 1903, based on fossils found in the Colorado River
  • Species is Brachiosaurus altithorax, and Riggs said it was “the largest known dinosaur”
  • Brachiosaurus means “arm lizard”, named so because the length of its arms was unusual for a sauropod
  • Name “altithorax” means “deep breastplate” because it had a deep, wide chest cavity
  • Holotype is right humerus, right femur, right ilium, right coracoid, sacrum, trunk, two caudal (tail) vertebrae, and some ribs
  • Type species based on a partial postcranial skeleton (fossils collected in 1900)
  • Riggs and his team (from the Field Columbian Museum, now the Field Museum of Natural History of Chicago), went to the area after Riggs sent inquiries about fossil finds in 1899 to rural areas. S.M. Bradbury, a dentist and amateur fossil collector, responded
  • Type species were not the first Brachiosaurus bones found, but it was the first attributed to the species. A skull was found in 1883 in Colorado, sent to Charles Marsh, who used it in his restoration of Brontosaurus/Apatosaurus. In the 1970s Jack McIntosh and David Berman decided the skull was more like a Camarasaurus, but in 1998 Kenneth Carpenter and Virginia Tidwell analyzed it and found it to be somewhat in between a Camarasaurus and Giraffatitan bracai (considered Brachiosaurus brancai at the time). It’s not assigned to a species but it’s classified as Brachiosaurus
  • Skull was loosely attached to its skeleton (like other sauropods), so after it died, easy to detach, either via predators or erosion (explains mix up in skull for Brachiosaurus v. Camarasaurus)
  • Type species bones went on display at the Field Museum in 1908, but there was only 20% of the skeleton, so it wasn’t mounted. In 1993, “holotype bones were molded and cast” and missing parts based on Giraffatitan fossils. It was mounted in 1994 in the Field Museum, until 1999 when it was moved to United Airlines Terminal One in O’Hare International Airport so the museum could display the T-rex Sue. The same year, the museum mounted a second cast of Brachiosaurus outside the museum. Only the humerus and two dorals are real and on display in the museum
  • Type specimen is the most complete one found so far (which isn’t very complete)
  • The family, and the genus, has had some reclassificiations
  • Until 2009, Giraffititan was considered to be a Brachiosaurus
  • Giraffaititan is different from Brachiosaurus because it had different trunk vertebrae. Olshevsky made Giraffaititan its own genus and in 2009 Michael Taylor published a study on the differences and found 26 “distinct osteological (bone-based) characters), which is more than Diplodocus v. Barosaurus; Brachiosaurus had a 23% longer trunk vertebrae series and 20-25% longer body and a taller tail
  • Also a shoulder blade assigned to Brachiosaurus that used to be considered part of the species Ultrasauros (episode 20)
  • Kingham reassigned Brachiosaurus to the genus Astrodon in 1969, but not many accepted it
  • Brachiosaurus fossils found in Colorado, Oklahoma, Utah, and Wyoming
  • Rare sauropod of the Morrison Formation
  • Morrison Formation was semiarid, with dry and wet seasons and flat floodplains. It had river lining forests (otherwise no other trees) of conifers, tree ferns and more. Other sauropods in the area included Apaotsaurus, Barosaurus, Camarasaurus, Diplodocus
  • Brachiosaurus was rare in the area. John Foster found 12 specimens of Brachiosaurus versus 112 Apatosaurus and 179 Camarasaurus and 98 Diplodocus
  • 2012, a juvenile sauropod postcranial skeleton found in Morrison Formation in Wyoming, probably a Brachiosaurus
  • Because only incomplete specimens of Brachiosaurus have been found, a lot of estimates of how it looked are based on Giraffititan
  • Michael Taylor analyzed Giraffitian and Brachiosaurus in 2009 and estimated Brachisaurus was about 82 ft (25 m) long
  • May have weighed as much as 35 metric tons and 56 metric tons, though lots of size estimates are based on Giraffatitan (formerly Brachiocsaurus brancai) because it is more complete specimen
  • A 2014 study in PLOS Biology estimated Brachiosaurus weighed 62 tons (56 metric tons)
  • Had large air sacs in the neck and trunk (keep it lighter)
  • Very long neck, small skull, and large body (like most sauropods), but forelimbs were longer than hindlimbs and tail was shorter compared to its neck
  • Brachiosaurus skull was only 1/200th of its body volume
  • Up to 4-50 ft (12-16 m) tall
  • Very giraffe-shaped
  • Could not actually rear on its hindlimbs (like in Jurassic Park)
  • Could not rear up on hindlegs. Heinrich Mallison found that though other sauropods could do that, Brachiosaurus had too long of front limbs and would not have been stable, and also it didn’t matter since it could already reach plants at such a tall height, compared to other sauropods
  • Neck was probably not very mobile but would have pointed upwards naturally
  • Considered to be a “high browser”, eating vegetation that was 30 ft (9m) off the ground
  • May have also eaten lower vegetation (10-16 ft or 3-5 m above ground)
  • According to Wilkinson and Graeme Ruxton in 2011, Brachiosaurus, with its 30ft long (9m) neck, may have saved time and energy by low browsing for food (‘reduces the overall cost of foraging by 80 percent, compared with dinosaurs with shorter necks’)
  • Probably ate ginkos, conifers, tree ferns, large cycads
  • Ate in up and down motion of jaws, with teeth shearing plant matter when they closed
  • 2008 study in the Royal Society said Brachiosaurus may have swallowed its food whole (teeth could strip plants but not break up large chunks)
  • Would take soft-tissue analysis to know for sure if they were high browsers or low browsers
  • However, being a high browser would mean it didn’t have to compete for food with other herbivores
  • Spoon-shaped teeth
  • Had 52 teeth, 26 on top and 26 on bottom
  • Ate 440 to 880 (200-400 kilograms) of food every day, though more recent estimates put it at 260 pounds or 120 kilograms per day
  • Probably traveled in herds and migrated for food
  • Probably liked flat land, too much energy to climb hills and less likely to fall
  • Brachiosaurus probably walked on its toes (digitigrade stance, like dogs and cats), compared to “plantigrade” like humans, where heels and toes touch the ground when walking
  • Had a claw on the first toe of each front foot and claws on the first three toes of its rear feet (each foot had five toes)
  • Was probably warm-blooded, like other sauropods, and the large nasal arch may have helped cool its brain (before the air sacs were known about and Brachiosaurus was thought to weigh a lot more, scientists thought it could not have been warm-blooded)
  • Scientists used to think because it was so large it had high body temperatures, but in 2011 they were able to calcualte its temperature to be 100.8 degrees F (38.2 C), based on ratios of some isotopes in Brachiosaurus teeth, so it probably kept cool with a lower metabolism as an adult
  • Lowering its body temperature and slowing metabolism would mean it would not have had to spend as much time eating
  • Had large hearts and high blood pressure to pump blood up its neck to its brain (heads were held up high), so its blood pressure was possibly 400 mm Mercury, 3-4 times higher than a humans’
  • Scientists used to think Brachiosaurus lived in the water, because its nostrils are at the top of its head, but Brachiosaurus had air-filled pockets in its bodies, so would have been too buoyant in water, according to a 2004 study in journal Biology Letters
  • Arch of bone over the snout and in front of the eyes
  • Nostrils were thought to be on an “enlarged bump in front of its eyes”, but in 2001 Lawrence Witmer analyzed muscle attachment scars on dinosaurs and present day animal skulls and found that Brachiosaurus nostrils were near the tip of its snout
  • The crest that scientists used to think was the nose on top of its head now may be a resonating chamber to amplify sounds it made
  • May have had a good sense of smell
  • Adults had no predators (largest predators were Allosaurus, Ceratosaurus and Torvosaurus, which were half its size)
  • Long tail could whip at predators
  • May have lived as long as 100 years
  • Had leathery skin
  • Eggs found in linear pattern, so probably laid eggs when walking (and probably didn’t take care of eggs)
  • Brachiosaurus has appeared in Jurassic Park and Walking with Dinosaurs, and a model from Jurassic Park was used in the 1997 special edition of Star Wars Episode IV: A New Hope
  • The “rontos” from Taooine were based on Brachiosaurus from Jurassic Park (in Star Wars)
  • 1991 GX7, a main belt asteroid, was named 9954 Brachiosaurus
  • Family is Brachiosauridae (found in North America and Africa and Asia)
  • Brachiosaurids were quadrupedal, with longer forelimbs than hindlimbs
  • They probably went extinct in the early Cretaceous, though there’s some evidence some may have lived in the late Cretaceous
  • Lots of debate over which animals are in this family
  • Former Brachiosaurus include Lusotitan, Giraffatitan
  • Other Brachiosaurids include Astrodon, Bothriospondylus, Dinodocus, Pelorosaurus, Pleurocoelus, and Ultrasaurus (but many are considered dubious)
  • Another Brachiosaurid is Europsaurus holgeri, a dwarf sauropod (only 20 ft long) that lived on an island off the coast of Germany
  • Another Brachiosaurid may be an Asian dinosaur, Qiaowanlong

This Week in Dinosaur News: New Dinosaurs in Spain, Dinosaurs and Daisies, Singing Dinosaurs, and More

Here’s what came out this week in dinosaur news:

  • The best visual effects in Jurassic World, according to Vox, and it involves effects you don’t realize are there
  • Times of India reported on scientists who identified 6 new species of dinosaurs in Spain based on 142 teeth
  • Discovery reported on how flowers may be older than previously thought, and dinosaurs may have died out and helped the ancestors of daisies grow
  • EurekAlert! reported on the tracks of two carnivorous dinosaurs in Germany, which show evidence of strolling and possibly being social
  • According to The Independent, in southern China, police found 213 dinosaur eggs in someone’s home
  • Daily Mail reported on how alligators can “sing” like birds, which means dinosaurs may have also been able to “sing”

I Know Dino Podcast Show Notes: Stegosaurus (Episode 38)

Episode 38 is all about Stegosaurus, one of the most famous dinosaurs, known for its plates and spiky tail.

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

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

In this episode, we discuss:

  • The dinosaur of the day: Stegosaurus, whose name means “roof lizard”
  • Not to be confused with Stegoceras (pachycephalosaurid, with a dome head)
  • Lived in the Late Jurassic, in western North America (though one found in Portugal in 2006)
  • At least 3 species found in Morrison Formation (from 80 individuals)
  • Stegosaurus was the first dinosaur named in the family Stegosauridae (it’s the type genus)
  • In the family Stegosauridae, Stegosaurus is the largest
  • Stegosaurus was found during the Bone Wars. Charles Marsh named Stegosaurus armatus in 1877, based on fossils found near Morrison, Colorado. At first Marsh thought it was an aquatic animal, similar to a turtle. The name “roofed lizard” comes from Marsh thinking the plates were flat on Stegosaurus’ back, like shingles on a roof. Lots of Stegosaurus fossils were found and Marsh wrote many papers. Like with many dinosaurs, at first multiple species were named, but now there are only a few valid ones
  • Stegosaurus armatus (armored roof lizard) was named based on two partial skeletons, two partial skulls, and 30 fragments of individuals. It had four tail spikes (Marsh originally thought it had 8) and somewhat small plates. It was about 30 feet or 9 m long (longest Stegosaurus species); found in Colorado, Wyoming and Utah in the Morrison Formation
  • Stegosaurus ungulatus (hoofed roof lizard); Marsh named in 1879 based on fossils found in Wyoming. It is possible these fossils are actually Stegosaurus armatus, but the fossils found in 2006 in Portgual are considered Stegosaurus ungulatus
  • Stegosaurus sulcatus (furrowed roof lizard), named by Marsh in 1887 from a partial skeleton. Many have thought it was the same as Stegosaurus armatus, but recent studies show it may be its own species. The type specimen had a spike, originally thought to be part of the tail, that some scientists now think was part of the shoulder
  • Stegosaurus stenops (narrow-faced roof lizard), named by Marsh in 1887, holotype found by Marshal Felch in Colorado in 1886. Species is known from at least one complete skeleton, so it’s the best known. Had four tail spikes and broad plates. Known from 50 partial skeletons of adults and juveniles, one complete skull, and four partial skulls. Only 23 ft or 7 m long, compared to Stegosaurus armatus, and has been found in Colorado, Wyoming and Utah
  • In 2008 Susannah Maidment and a team pushed to synomymize Stegosaurus stenops and Stegosaurus ungulatus with Stegosaurus armatus, as well as change Hesperosaurus and Wuehosaurus into Stegosaurus and renaming them Stegosaurus mjosi and Stegosaurus homheni. So there would be 3 Stegosaurus species (armatus, homheni, and mjosi), with Stegosaurus ranging from Late Jurassic in North America and Europe to Early Cretaceous in Asia). But most researchers do not agree.
  • Some nomina dubia (dubious names) and junior synonyms include Stegosaurus affinis (Marsh described in 1881, but based on only a pubis); Stegosaurus laticeps (Marsh described in 1881 from jawbone fragments); Stegosaurus duplex (name means two plexus roof lizard, Marsh named in 1887 based on the large area near its tail that Marsh called the “posterior brain case”) but it’s probaly just Stegosaurus armatus
  • Former Stegosaurus‘ include Stegosaurus longispinus (Charles Gilmore named) but is now the type species of the genus Natronasaurus; also Stegosaurus madagascariensis (described in 1926 based on teeth found in Madagascar, but is now considered to be something 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 type species of Loricatosaurus
  • Kenneth Carpenter and Peter Galton published a couple papers in the 2010 that Stegosaurus stenops may be a better type species than Stegosaurus armatus (since it is the best known, most well studied and has the most fossils and a near complete skeleton)
  • Kenneth Carpenter said there’s debate on the number of valid species, and if you’re a “taxonomic clumper” you may only see one Stegosaurus species as valid, since there can be so much variation in one species (like how dogs all belong to Canis lupus familiaris)
  • Most Stegosaurus fossils were found in the Morrison Formation
  • Morrison Formation was semiarid with wet and dry seasons and flat floodplains. Vegetation included conifers, ferns, green algae, fungi, mosses, horsetails, cycads, and ginkgoes
  • Other dinosaurs included Allosaurus, Torvosaurus, Brachiosaurus, Apatosaurus, Diplodocus, Camarasaurus, Camptosaurus, Dryosaurus (Stegosaurus often found near Allosaurus, Apatosaurus, Camarasaurus and Diplodocus)
  • Other animals include snails, frogs, ray-finned fish, turtles, salamanders, pterosaurus, and early mammals
  • Matthew Mossbrucker found tracks that show Stegosaurus may have lived in herds among a number of different aged Stegosauruses. One set of tracks had 4-5 baby Stegosaurus moving together and another had a juvenile track with an adult track over it
  • Stegosaurus had pebbly throat armor (lumps under its neck to help shield it from predators)
  • Predators included Allosaurus and Ceratosaurus
  • Marsh at first thought Stegosaurus was bipedal, because its fore limbs were so short, but then in 1891 he decided it was two heavy to walk on just two legs. Some scientists, however, think Stegosaurus may have been able to rear up on its hind legs, using its tail to help support its weight, so it could eat higher up plants
  • Forelimbs were shorter than hindlimbs, giving it an interesting posture
  • Short forelimbs, kept head low to the ground (so ate low lying plants), with a stiff tail high in the air
  • Probably weight balanced towards its high hips and was carried by the hind legs, so Stegosaurus could make tight turns when defending itself
  • Could not walk fast, otherwise the back legs would overtake the front legs (max speed of 4-5 mph or 6-7 kmh
  • Hind feet had three toes, and fore feet had five toes (but the inner two toes had a blunt hoof)
  • Stegosaurus and relatives were herbivores, but had different teeth and jaws compared to other herbivores, so may have had a unique feeding strategy. Stegosaurus had peg-shaped teeth (not grinding teeth) and jaws could only do up-down movements; also no evidence they swallowed gastroliths, so it’s not clear exactly how they ate their food
  • No front teeth, instead had a horny beak (easier to eat low growing vegetation
  • Teeth were small, flat, and triangular; Stegosaurus ground up its food and possibly had cheeks to keep food in its mouth when it chewed
  • In 2010, scientists did a detailed computer analysis of how Stegosaurus ate, using 2 3D models of Stegosaurus teeth. Also calculated bite force and found it was less than half the force of a Labrador retriever, so although it could bit through small young branches, could not bite through anything over 12 mm in diameter
  • Fossilized teeth showed more wear on the sides that were sharpest, so Stegosaurus probably bit on a plant, pulled back its head, and then teeth cut through the vegetation (possibly swallowed gastroliths to help digest)
  • Probably ate mosses, ferns, horsetails, cycads and conifers (would not have grazed on grasses, since grass was not around until the late Cretaceous, after Stegosaurus went extinct)
  • Stegosaurus was up to 30 ft (9 m) long; about the size of a bus
  • In 1994 a subadult Stegosaurus was found in Wyoming (15 ft or 4.6 m long, 7 ft or 2 m high, 2.6 tons or 2.3 metric tons). Can see it on display in the University of Wyoming Geological Museum
  • A 90% specimen found in 2003 in Wyoming by Bob Simon, president of the dinosaur excavation and preservation corporation Virginia Dinosaur Company and Dinosaur Safaris
  • Stegosaurus weighed more than 5 short tons (4.5 metric tons), but brain was about 80 g (made people think for so long that dinosaurs were not smart, until more recently (around Jurassic Park)
  • Long, narrow skull (but small compared to the rest of its body)
  • Braincase no larger than a dog’s, though it’s body was much bigger
  • Brain was thought to be the size of a walnut, but according to Kenneth Carpenter, director of th USU Eastern Prehistoric Museum in Utah, “its brain had the size and shape of a bent hotdog”
  • Had a low EQ (brain to body mass ratio), so not the smartest
  • Charles Marsh got a case of a brain cavity (also called an endocast) in the 1880s, and showed it was the smallest proportionally of all dinosaurs, at least the ones known at the time
  • Marsh described a “large canal in the hip region of the spinal cord” which could fit something more than 20 times bigger than the Stegosaurus’ brain. This led to the idea that Stegosaurus had a “second brain” in its tail to help control its body, especially when threatened. But this area has also been found in sauropods and “may have been the location of a glycogen body, a structure in living birds whose function is not definitely known” but it probably has something to do with energy storage
  • Known from its plates and spikes on the tail (probably used for defense)
  • Kite shaped plates on its rounded back, and two pairs of long spikes at the end of its tail
  • Plates may have been used for defense, display, and/or thermoregulation
  • Had 17 flat plates (dermal plates) that were osteoderms (bony-cored scales) similar to osteoderms in modern crocodiles and lizards. The plates came from the skin (not the skeleton), and the largest plates were 2 ft (60 cm) wide and 2 ft (60 cm) tall
  • Lots of arguments over how the plates were arranged on Stegosaurus.
  • Marsh at first thought the plates lay flat, but in 1891 said it had a single row of plates
  • Another idea is there were pairs of plates in a row along the back (seen most often in images, especially early ones before the 1970s, seen in the 1933 film King Kong this way) but no two identical sized and shaped plates have been found for the same Stegosaurus
  • Another idea was two rows of alternating plates (many accepted it by early 1960s, though some argue we don’t see this in other reptiles, so how could that evolve that way)
  • Robert Bakker speculated the plates were somewhat mobile, and Stegosaurus could flip them from side to side to deter a predator from attacking
  • In 1914 Gilmore said the spikes on the tail were for display only, but Robert Bakker later said the tail was probably pretty flexible (no ossified tendons) so probably used as a weapon (said they looked like a monkey tail, with no locking joints, so could fatally stab)
  • But, plates seem to overlap with tail vertebrae so may have limited it somewhat
  • Lots of debate over the purpose of the plates. Thought to be armor at first, but they’re too fragile and they leave the sides of Stegosaurus unprotected; however they may have made Stegosaurus look bigger and more menacing to predators or impressive to female Stegosaurus (though males and females had plates); may have helped control body temperature
  • Could also be used for warning, blood would rush to plates, making them “blush” a red warning (could also use to attract mates)
  • Stegosaurus plates were not made of solid osteoderms, but had lattice-like structures and blood vessels
  • 2005 analysis in Paleobiology found the “microstructure of the plates suggest they weren’t used to radiate heat”; 2010 study published in the Swiss Journal of Geosciences found the plates may have passively helped control body temperature (because the plates were so large with so many blood vessels, like how a toucan’s bill naturally radiates body heat), but not the main purpose
  • The size and shape of Stegosaurus plates help identify whether it was male or female.
  • It’s hard to tell whether dinosaurs are male or female (reproductive organs and soft tissues rarely found), so scientists guess based on modern animals
  • In 2015 (covered in the news in this podcast) in PLOS One a study said that Stegosaurus fossils (Stegosaurus mjosi) found in Montana with two types of plates (large and round v. tall and spiky) were not different species but different gender
  • Evan Saitta, lead author said the large wide plates were probably from males (for display), and the tall spiky ones were from females (used as deterrents)
  • They were found together, which shows they probably co-existed, and the plates had similar growth rings (so the dinosaurs were around the same age, and it’s not that the plates changed with age)
  • Early on scientists thought the tail spikes were upright, but now they think they stuck out to the sides
  • McWhinney and team published a study of tail spikes that showed that 9.8 % of Stegosaurus examined had tail spike injuries, helping support the idea that they fought with their tails (also an Allosaurus was found with a punctured tail wound)
  • Informally the tail spikes are called thagomizers, after a Gary Larson “Far Side” cartoon was published in 1982 showing cavemen calling the spikes thagomizers (line was “Now this end is called the thagomizer…after the late Thag Simmons”)
  • In 1977 paleontologists found a nearly complete juvenile Stegosaurus at Dinosaur National Monument (the most complete one found so far) with limb bones, shoulder blades, most of the hips, some ribs, and skull fragments (cast on display at Quarry Exhibit Hall)
  • Can see an adult and juvenile Stegosaurus stenops at the Denver Museum of Nature and Science (look like they’re being attacked by an Allosaurus fragilis)
  • Can see Stegosaurus ungulates at the Carnegie Museum of Natural History in Pittsburgh, PA or in the Nebraska Stage Museum in Lincoln, NE
  • Can also see a Stegosaurus stenops (nickname “Sophie”) at the Natural History Museum in London
  • Image of Stegosaurus in 1884 issue of Scientific American showed Marsh’s first thoughts on Stegosaurus, with tail spikes on its back, back 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 through the air
  • BBC’s 1999 Walking With Dinosaurs gave Stegosaurus some frontal swagger to show the shortness of its forelimbs compared to its hindlimbs
  • Stegosaurus is the state dinosaur of Colorado (as of 1982)
  • Stegosaurus became CO state dinosaur after a two-year write-in campaign by thousands of fourth graders
  • Stegosaurus is also in Jurassic Park II and III
  • Spike in Land Before Time
  • Although Stegosaurus is famous, there are less than 2 dozen types in the Stegosaurid family, so it’s a rare type of dinosaur
  • Stegosaurus was the first named genus in the Stegosauridae family (making it the type genus)
  • Closest relatives to Stegosaurus were Wuerhosaurus from China and Kentrosaurus from East Africa)
  • Stegosauridae is one of the two families in the infraorder Stegosauria (other famiy is Huayangosauridae)
  • Stegosauridae skulls were shallower compared to Huayangosauridae and there was a bigger difference between its short forelimbs and long hinglimbs, and had larger plates and tail spikes
  • Huayangosaurus is the only genus in Huayangosauridae, and lived 20 million years before Stegosaurus (Scelidosaurus from Jurassic England, lived 190 million years before and had features of stegosaurs and ankylosaurs
  • Stegosauria is in the suborder Thyreophora (armored dinosaurs that includes ankylosaurs)
  • Stegosauridae is further divided into subfamilies: Dacentrurinae and Stegosaurinae (Stegosaurinae are the larger ones)
  • Earliest stegosaur is Lexovisaurus from England
  • Other small, lightly armored dinosaurs related to stegosaurs direct ancestor include Emausaurus from Germany (small quardruped) and Scutellosaurus from Arizona, bipedal)
  • A trackway of an early armored dinosaur, from 195 million years ago was found in France
  • Stegosaurids lived in late Jurassic to early Cretaceous
  • Usually large
  • Their front legs were shorter than their back legs, so they were slow
  • Could probably shear branches with teeth
  • They have plates and tail spikes
  • Fun Fact: Why do teeth fossilize so well? Teeth are made from Dentin which is harder and denser than bone, they are surrounded by a very hard enamel shell which protects them, in many cases they fall out and are replaced regularly, and they aren’t very tasty so other animals are unlikely to break them down.

I Know Dino Podcast Show Notes: Maiasaura (Episode 37)

In our 37th episode of I Know Dino, we had the pleasure of speaking with paleontologist Jack Horner. Jack Horner is the curator of paleontology at the Museum of the Rockies, the Regent’s professor of paleontology, adjunct curator of the National Museum of Natural History, and he teaches the honors program at Montana State University. He is also the inspiration for the character Dr. Alan Grant in the original Jurassic Park. His first big discovery was in the 1970s of a nesting site for the dinosaur Maiasaura, which means “Good Mother Lizard.” Since then he has named several other dinosaur species, including Orodromeus, and he even has two dinosaurs named after him (Achelousaurus horneri and Anasazisaurus horneri). He has also discovered one of the largest T-rexes known (even larger than the famous T-rex named Sue). His research includes dinosaur evolution and ecology, emphasizing growth and behavior. He has written eight books about dinosaurs, including a children’s book, as well as over 100 professional papers, and numerous articles. And he has also given Ted Talks about dinosaurs.

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

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

In this episode, we discuss:

  • The dinosaur of the day: Maiasaura, whose name means “Good Mother Reptile”
  • A hadrosaurid (duck-billed) dinosaur that lived in Montana in the late Cretaceous
  • First fossils found in 1978, and genus named in 1979
  • Marion Brandvold and her son David Trexler found “Egg Mountain” (a nesting site) in Montana
  • Marion found the eggs, and Laurie Trexler found the holotype
  • Laurie Trexler found a Maiasaura skull, and Jack Horner and Robert Makela described the holotype
  • Species is Maiasaura peeblesorum
  • Name is based on the nests with eggs, embryos and young dinosaurs that were found, which were evidence that Maiasaura fed the young in the nest (first evidence of a dinosaur doing so)
  • Maia was a goddess in Greek mythology; using the feminine form of saurus, saura, to emphasize the motherness
  • Most dinosaurs have a male-oriented name (saurus v saura)
  • The fossils were found on John and James Peebles’ land, so species type is named after them
  • Hundreds of Maiasaura fossils have been found (over 200 specimens, all ages)
  • Other dinosaurs that lived in the area at the same time included the troodontid Troodonand, the hypsilophodont Orodromeus, the dromaeosaurid Bambiraptor, the hadrosaurid Hypacrosaurus
  • The herd of Maiasaura were buried in volcanic ash
  • Herds may have been as large as 10,000 Maiasaura
  • Maiasaura is one of the few dinosaurs where there is solid proof of living in herds
  • Lived in herds and had muscular tails (only defense)
  • Because there was such a large herd, they may have migrated seasonally to find more food
  • Area where the eggs were found is now known as “Egg Mountain” in the Two Medicine Formation in Montana
  • The nesting site is communal
  • Nests were close together, like modern seabirds (23 ft or 7 m in between nests, about the length of adult Maiasaura)
  • Eggs were about the size of ostrich eggs, and nests had 30-40 eggs in them (in a circular or spiral pattern)
  • Maiasaura was probably too heavy to sit on its nest
  • Incubated eggs using rotting vegetation (Maiasaura put the vegetation in the nest instead of sitting on top of the eggs)
  • As the vegetation rotted, it emitted heat
  • When eggs hatched, the baby Maiasaura did not have fully developed legs and could not walk (but they had partly worn teeth, so adults probably brought food to them)
  • In 1996, a new study was published that compared newly hatched birds and crododilians to dinosaur embryos and hatchlings, which found that hip bone development was more important than leg bone development, so the non-developed leg bones of newly hatched Maiasaura did not necessarily indicate a lack of mobility. The study concluded baby Maiasaura was more precocial (advanced) than previously thought and may not have needed as much parental care at first
  • However, in 2001 Horner found that growth rates and other developmental differences between Troodon, Orodromeus, and Maiasaura (Troodon and Orodromeus were precocial while Maiasaura was altricial or needing a lot of care)
  • Dr. Paul L. Else hypothesized that Maiasaura produced “crop milk”, like how some modern birds (pigeons, flamingos, produce a fatty liquid for their babies)
  • Crop milk had antibodies, fat, protein, etc.
  • Else wrote an article called “Dinosaur lactation?” about crop milk, based on the relationship between dinosaurs and birds. Maiasaura were probably producers of crop milk because babies may not have been able to break down plants, and also this fortified milk substance may have helped the babies grow quickly
  • However, the way birds secrete their crop milk is different (pigeons have a crop organ, but emperor penguins have it come from the lining in their esophagus), and also crocodylians (closest living relatives to dinosaurs, other than birds) do not have this ability, so it’s unlikely Maiasaura could do this
  • Jack Horner found that “multiple horizons of nests layered one on top of each other” so the dinosaurs probably went to the same site “over multiple breeding seasons”
  • Maiasaura may have been similar to sea birds, where they usually live in smaller groups, but once a year live in the same area to raise its young
  • In their first year, the babies grew from 16 in (41 cm) to 58 in (147 cm) and then left the nest (rapid growth may mean they were warm blooded)
  • Babies looked very different from adults (larger eyes, shorter snout–much cuter, as seen in animals who need their parents in order to survive when they are young)
  • Juveniles (under 4 years) walked on two legs, adults on four legs
  • Front legs were much shorter than hind legs, so when Maiasaura ran, probably ran on back legs, using its tail for balance
  • In 2001 paleontologist David Dilkes said Maiasaura may have changed its posture as it grew older, based on muscle scars that show young Maiasaura ran on two legs and then walked on four legs when it got bigger
  • Jorge Cubo, Holly Woodward, Ewan Wolff, and Jack Horner reported that, after cutting open two bones (one of a one-year old Maiasaura and one of a four-year old), the bone growth shows the one-year-old being similar to bipedal animals, and the four-year-old as similar with quadrupedal animals
  • The bones had “rinds of extraneous bone that quickly grew over the outer surfaces”, showing a response to strains. Both dinosaurs probably broke their right fibulae, and extra bone grew in response to the strains on their tibias
  • This leads to more speculation on whether or not there are too many different types of named dinosaurs, and whether some of them may actually just be juveniles of others
  • Adult Maiasaura was about 30 ft (9 m) long
  • About 6-8 ft (2-2.5 m) tall and weighed 3-4 tons
  • Had a flat beak, thick nose, spiky crest in front of eyes (males possibly used to fight each other to impress females and attract mates)
  • Four fingers on hands and feet had hoof-like claws
  • Toothless beak, cheeks to hold in food
  • Adult Maiasaura probably ate about 200 pounds of food per day (leaves and seeds)
  • Maiasaura coprolites (from Wyoming) show that they ate lots of wood
  • Maiasaura is the state fossil of Montana (as of 1985)
  • In 1985, astronaut Loren Acton went on an 8-day mission called Spacelab 2, and took with him a piece of Maiasaura bone and eggshell into space (they are now in the Museum of the Rockies in Montana)
  • In 2010, there was an animated Japanese film (based on a book) called You Are Umasou, where a Maiasaura raises a baby T-rex
  • A hadrosaur, but not the largest hadrosaur
  • Maiasaura is most closely related to Brachylophosaurus, which is known as the “dinosaur mummy” because in 2000, a subadult named “Leonardo” was found, and it was a partially mummified skeleton
  • Maiasaura is a saurolophine hadrosaur, because the crest on its snout is solid
  • Two subfamilies: lambeosaurines (hollow crests) and saurolophines with solid crests (pre-2010 most hadrosaurines classified as saurolophines) (talk more about it on Episode 31: Corythosaurus)
  • Maiasaura is part of the subfamily of hadrosaurids, saurolophinae
  • Before the group was known as Hardosaurinae (hadrosaurs that for the most part didn’t have crests), but then the genus Hadrosaurus was found to be more primitive so the subfamily was renamed Saurolophinae
  • Saurolophinae dinosaurs either have no crests or solid crests (the other subfamily is Lambosaurinae, which have hollow crests)
  • Fun Fact: Fossilization requires specimens to be burried quickly (like in a marsh or quicksand), so we may not ever discover dinosaurs that lived on tops of mountains or in other conditions that don’t lend themselves to fossilization

For those who may prefer reading, see below for the full transcript of our interview with Jack Horner: Continue reading I Know Dino Podcast Show Notes: Maiasaura (Episode 37)

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