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The Big Dinosaur Podcast

The Big Dinosaur Podcast

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Episode 379: Dinosaur National Monument with ReBecca Hunt-Foster

Episode 379 is all about Guaibasaurus, a Late Triassic basal sauropodomorph or theropod from what is now Brazil.

We also interview ReBecca Hunt-Foster, the Monument Paleontologist and Museum Curator at Dinosaur National Monument. She does research on the Late Jurassic Morrison Formation, the later Cretaceous Mesa Verde Group, and early-mid Cretaceous North American ornithomimids. Follow her on twitter @paleochick 

Big thanks to all our patrons! Your support means so much to us and keeps us going! If you’re a dinosaur enthusiast, join our growing community on Patreon at https://www.patreon.com/iknowdino.

You can listen to our free podcast, with all our episodes, on Apple Podcasts at: https://itunes.apple.com/us/podcast/i-know-dino/id960976813?mt=2

In this episode, we discuss:

News:

  • A new abelisaurid, Guemesia, was found in Northwestern Argentina source
  • The first evidence of a respiratory infection is in a dinosaur was found in the sauropod Dolly source
  • The Museum of the Rockies in Montana is hosting Dinosaurs and MOR source
  • The Milwaukee Public Museum is hosting the temporary exhibit Tyrannosaurs: Meet the Family source
  • The trailer for Doctor Strange in the Multiverse Madness shows Doctor Strange battling with Marvel dinosaurs source

The dinosaur of the day: Guaibasaurus

  • Basal sauropodomorph that lived in the Late Triassic in what is now Brazil (Caturrita Formation)
  • Debate over whether it was a basal sauropodomorph or a theropod (has characteristics of both)
  • Looked like an early theropod, walked on two legs, had short arms, long neck, long tail, and a longish skull
  • Estimated to be 6.6 ft (2) m long and weigh 22 lb (10 kg) in 2016 by Gregory Paul
  • Estimated to be 10 ft (3 m) long and weigh 77 lb (35 kg) by Molina-Pérez and Larramendi in 2020
  • Type species is Guaibasaurus ?candelariensis?
  • Fossils found in an abandoned quarry
  • Fossils included a well preserved postcranial skeleton (no skull) and a nearly complete left hindlimb
  • Fossils were affected by weathering (neck and skull probably eroded)
  • Two more specimens later referred to Guaibasaurus, including a nearly complete skeleton missing one forelimb, the feet, and neck, and a block (not yet fully prepared) with articulated fossils and a partial hand
  • Named in 1999 by José Bonaparte and others
  • Genus name means “Guaiba lizard”
  • Genus name refers to the Rio Guaíba hydrographic basin where the fossils were first found. Fossils were collected as part of the “Pro-Guaiba Project,” a scientific program supporting research on Triassic fossils
  • Species name refers to Candelária, a city near where the fossils were first found
  • One specimen found with its hindlimbs tucked under its body and forelimbs flexed to the side (neck not really preserved, but the vertebrae at the base of the neck curve to the left, so the neck may have been curved toward the left)
  • Similar to a bird’s resting position, like a chicken’s (also has been seen in other dinosaurs, such as the troodontid Mei long and the dinosauriform Saltopus)
  • Means the resting position may have happened at the base of the Theropoda (or even Saurischia) clade
  • May have been in that position to conserve body heat
  • Max Langer and others said Guaibasaurus had unique features in the pelvis, as well as other features, such as long caudal trunk vertebrae (connects to the ribs)
  • Found 24 vertebrae in the tail, but basal dinosaurs usually have 40 to 50 caudal vertebrae, so it’s likely 24 is only about half the tail
  • Had some plesiomorphic (ancestral) traits as well, which may mean that even after other dinosaur clades were established, the more basal dinosauromorphs continued “to flourish until the end of the Triassic”
  • For a while thought to be very similar, and closely related to the sauropodomorph Saturnalia (covered in episode 369)
  • A 2020 phylogenetic analysis by Rodrigo Temp Müller and Maurício Silva Garcia found Guaibasaurus to be a sauropodomorph, and more closely related to Macrocollum and Unaysaurus
  • Other animals that lived around the same time and place include the sauropodomorph Unaysaurus, pterosaurs, silesaurids, and rhynchosaurs

Fun Fact: Superprecocious birds can fly the same day they hatch.

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Episode 374: Was a new ankylosaur deaf?

Episode 374 is all about Spinophorosaurus, a sauropod from the Middle Jurassic of Niger that was originally thought to have a Stegosaurus-like spiky tail.

Big thanks to all our patrons! Your support means so much to us and keeps us going! If you’re a dinosaur enthusiast, join our growing community on Patreon at https://www.patreon.com/iknowdino.

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In this episode, we discuss:

News:

  • Stegouros, the ankylosaur we said had an “axe-like tail”, is better described as a macuahuitl tail source
  • A new sauropodomorph, Issi saaneq, was found in what is now Greenland source
  • A new study showed the ankylosaur Struthiosaurus had a poor sense of hearing and probably moved slowly source
  • The Mace Brown Museum of Natural History in Charleston, South Carolina is offering a new paleontology scholarship source
  • Frisco, Texas is building a new library, and it will include a life-sized model of a T. rex skeleton source
  • Sir David Attenborough has a new documentary coming out later this year, called “Dinosaurs: The Final Day” source

The dinosaur of the day: Spinophorosaurus

  • Basal sauropod that lived in the Middle Jurassic in what is now Niger (Irhazer Shale)
  • Looked like other sauropods, bulky with a long neck and tail, on four legs (had a somewhat upright posture)
  • Three specimens found
  • One of the most complete known basal sauropods
  • Subadult estimated to be around 43 ft (13 m) long, and the paratype estimated to be about 46 ft (14 m) long
  • Estimated to weigh about 7 metric tons
  • Had a short, deep, broad braincase
  • Had spatulate (spoon shaped) teeth
  • Had 13 neck vertebrae
  • Neck vertebrae similar to Jobaria and Cetiosaurus
  • Had small air-filled internal chambers in the dorsal vertebrae
  • Air sacs are known in much later sauropods
  • Had a rigid spine
  • Neural spines were wrinkled
  • Had a robust pelvis
  • Had a strong, rigid tail
  • Tail had more than 37 caudal vertebrae
  • Chevrons in the front of the tail were blade-like
  • Chevrons in the back of the tail were rod-like
  • Originally thought to have spiked osteoderms at the end of the tail
  • Right supposed osteoderm was larger than the left and a little different in shape, so they probably did not form a pair
  • Tail spikes, when they were thought to be spikes, were thought to be large and bony near the end of the tail, arranged in a similar way to Shunosaurus (a sauropod that lived around the same time in what is now China)
  • In 2012, Emanuel Tschopp and others found that the tail spikes were somewhat L-shaped and more like the L-shaped bones found at the Howe Quarry in the Morrison Formation than the tail spikes of Shunosaurus. Also they weren’t as rugose/wrinkled compared to other dinosaurs’ osteoderms. The L-shaped elements of Spinophorosaurus were a bit broader than the L-shaped elements from Howe Quarry, and had a triangular outline. And they found broken edges, so it’s possible the pair were the same size. Last, they were found below the scapula (shoulder blade), so suggested they were clavicles
  • Type species is Spinophorosaurus nigerensis
  • Described in 2009 by Kristian Remes and others
  • Genus name means “spine bearing lizard”, based on what was thought to be spiked osteoderms on the end of the tail (later thought to be clavicles)
  • Species name refers to the Republic of Niger
  • A couple individuals collected in 2006 and 2007 at the Rural Community of Aderbissinat
  • A juvenile was later also assigned to Spinophorosaurus
  • Lots of dinosaurs were found in Niger in the 1960s and 1970s
  • Paul Sereno excavated there between 1999 and 2003 and found Jobaria and Afrovenator
  • In 2003, the PALDES project (Paleontología y Desarrollo – “Palaeontology and development”) excavated the area, with the goal of combining paleontological research with a developmental program (improving infrastructure, education, and promoting tourism)
  • In 2005, Ulrich Joger and Edgar Sommer were exploring the area, and locals told them about some large bones in a new locality. They found a rounded bone tip coming out of the surface, which turned out to be a complete femur of the holotype of Spinophorosaurus (also found a shoulder blade and a vertebra). Fossils were in hard, brittle siltstone, and removed with light blows from hammers
  • Worked with more locals and found most of the specimen in two days, which was mostly complete (in a death pose)
  • In a photo of the holotype at the dig site, it looks like the fossil dig sites at museums, where you brush away dirt and there’s a (nearly) complete dinosaur
  • They didn’t have the right equipment or permits, so they covered the fossils with debris to protect it and went back to Germany, with plans to do a full excavation via the Braunschweig museum
  • Got a permit in 2006, and the plan was in exchange, the museum would build a new school in the area
  • Also got sponsors, and the project was called “Projeckt Dino”
  • Around the same time, the PALDES team from Spain was working in the area
  • The mayor of Aderbissinat, Mohamed Echika, had given them permission to excavate the skeleton Joger and Sommer had been working on, and the skeleton ended up being shipped to Spain, without the German team knowing (they found an empty dig site)
  • The German team ended up finding the paratype specimen
  • Difficult excavation, not enough water (some people helping to dig fainted); temperatures got to 109–113 °F (43–45 °C)
  • After nearly a week, all but two of the people on the team were sick with diarrhea and circulation problems
  • Not much shade when digging
  • Also a few sandstorms, that were described as peeling their skin
  • Team finished on April 3, and Echika told them about what happened to the first skeleton. To make up for it, he led them to another fossil site, where they found the back end of possibly a Jobaria skeleton, but they had to leave it in the field until the next season (the PALDES team cancelled their plans to excavate, after the outbreak of the Tuareg rebellion from 2007 to 2009)
  • Worked together with the local Aderbissinat community, comprised of people of various cultures (Tuareg, Hausa, and Fulani people)
  • Dig was organized by a local Tuareg partner Ahmad Bahani and Tuareg Chief and Mayor of the village Tadibene Mohammed Echika
  • Dig happened during a civil war, and they were protected by Mayor Mohammed Echika and the army
  • Also lots of snakes, scorpions, monitor lizards, while digging (one person on site was a herpetologist so they knew what to do if bitten by a venomous snake). At night they used flashlights and went snake hunting
  • Also found petrified wood, conifers, crocodile teeth, and fish scales (area was swampy and wet when Spinophorosaurus lived)
  • Both the German (Braunschweig Museum) and Spanish (Elche museum) teams worked together to describe the dinosaur
  • Took 2.5 years to prepare the paratype
  • Paratype was about 70% complete, so the holotype helped fill in the remaining pieces
  • Between the two specimens, most of the bones in the skeleton are known
  • No forearms or hands found
  • Holotype includes a braincase, parts of the skull, and most of the skeleton
  • Paratype includes a partial skull and incomplete skeleton
  • Specimens managed by the Musée National d’Histoire Naturelle, Niamey, Niger (returned after being on exhibit briefly and 3D printing the skeleton)
  • First sauropod to have skeleton 3D printed
  • In 2012, Adrián Páramo and Francisco Ortega described a small sauropod that was found near the two Spinophorosaurus specimens. Had 14 vertebrae, including all the neck vertebrae and some back vertebrae, which were smaller compared to the other specimens and also parts weren’t fused, so considered to be a juvenile Spinophorosaurus
  • Dinosaur tracks found near the Spinophorosaurus skeletons, including six footprints from a medium sized sauropod and 120 two-toed theropod footprints (possibly by swimming theropods, which may be why one toe didn’t leave a mark)
  • Lots of similarities between Spinophorosaurus and Middle Jurassic Eurasian sauropods, like Shunosaurus and mamenchisaurids (similarities in the vertebrae and humerus), and lots of differences between Spinophorosaurus and Lower and Middle Jurassic South Gondwanan sauropods (shape of neural spines, humerus, vertebrae)
  • Spinophorosaurus helps show that features thought to be in derived sauropods found in East Asia are more like ancestral traits (plesiomorphic) in eusauropods, so there may be a connection between sauropods from the Jurassic in North Africa, Europe, and East Asia
  • Important sauropod development may have happened in what is now North Africa
  • Area was near the equator and wet in the summer, with lots of plants
  • In 2012, Fabien Knoll and others looked at the braincase of Spinophorosaurus
  • Did not have reduced vestibular apparatuses, sensory apparatus in the inner ear, which may mean it was important for vision and coordinating movements between the eyes, head, and neck
  • Benjamin Jentgen-Ceschino and others in 2018 reported a probably pathology in Spinophorosaurus due to injury
  • Found Spinophorosaurus had fast growing bone tissue
  • In 2015, Vidal and others made a 3D model to study how Spinophorosaurus moved and found it couldn’t move its tail much (had overlapping chevrons, like dromaeosaurs and ankylosaurs)
  • In 2020, Daniel Vidal and others looked at similarities between giraffe and sauropod necks as they grew up
  • Looked at the specimens of Spinophorosaurus (they were different ages), as well as an adult and newborn giraffe
  • CT scanned all the bones
  • Both Spinophorosaurus and giraffes get more flexible necks as they grow
  • Found that a subadult Spinophorosaurus could move its neck more than Plateosaurus and other previously analyzed sauropods, “enabling its neck to engage in many different postures unattainable by other sauropods”
  • Found Spinophorosaurus was probably a high browser, like giraffes, based on the relatively long humerus, and narrow snout, and having an overall range of motion similar to a giraffe. But found, that Spinophorosaurus was as flexible in the neck as a giraffe because it had almost twice the number of neck vertebrae of a giraffe (not as much flexibility in between vertebrae as a giraffe)
  • Based on its skeleton, could “browse on vegetation at nearly three times the height of its shoulders”
  • To drink water, Spinophorosaurus would needed to have splayed like a giraffe
  • Found Spinophorosaurus to have a more vertical posture than before, with its tall shoulders and an elevated neck “well above shoulder level”
  • Based partially on having the 20° wedged sacrum (vertebrae between the hips)
  • Spinophorosaurus’s snout was about 16.4 ft (5 m) above the ground
  • SVPow agreed with Vidal and others about their reconstruction, and how Spinophorosaurus had wedged sacrum so it had a more inclined torso and neck
  • That means the tail and torso are not parallel with each other
  • However, also mentioned that bones are not enough to show how vertebrae articulated, and models need to incorporate intervertebral cartilage (which Vidal and others mentioned, but said that since we don’t really know how much cartilage there was, so it’s likely we won’t ever know)
  • In 2018, Vidal and others tested hypothetical mating postures to see if Spinophorosaurus performed a “cloacal kiss”, “backwards mating”, or the male mounting from behind. Found the male could mount the female from behind while resting its front legs on the back (tail was flexible enough to get out of the way), but they could not perform a “cloacal kiss” unless they did “backwards mating” where they approach each other backwards and have their tail flexed sideways
  • A model of Spinophorosaurus outside the Braunschweig Museum is nicknamed “Namu”, after the museum’s name

Fun Fact: There are a lot of ways of prey species to increase their odds of surviving, but predator satiation might be the most interesting.

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Episode 372: The axe-tailed ankylosaur

Episode 372 is all about Chindesaurus, Basal saurischian that lived in the Late Triassic in what is now Arizona.

Big thanks to all our patrons! Your support means so much to us and keeps us going! If you’re a dinosaur enthusiast, join our growing community on Patreon at https://www.patreon.com/iknowdino.

You can listen to our free podcast, with all our episodes, on Apple Podcasts at: https://itunes.apple.com/us/podcast/i-know-dino/id960976813?mt=2

In this episode, we discuss:

News:

  • A new ankylosaur, Stegouros elengassen, was described with amazing spikey tail weaponry from Magallanes, Chile source
  • The new sauropod, Rhomaleopakhus turpanensis, was named from the Xinjiang Uygur Autonomous Region, China source
  • Chief Shikellamy Elementary School in Sunbury, Pennsylvania have a new 6 ft Diplodocus femur on display source

The dinosaur of the day: Chindesaurus

  • Basal saurischian that lived in the Late Triassic in what is now Arizona, US (maybe also New Mexico and Texas)
  • Looks like a small theropod, walking on two legs and had a long tail
  • Type and only species is Chindesaurus bryansmalli
  • Found a partial skeleton in the Petrified Forest National Park in 1984 (was airlifted out in 1985)
  • In the 1920s, Charles Camp from the University of California at Berkeley collected fossils and took photos of the Petrified Forest. In the 1980s, Robert Long from Berkeley found Camp’s sites. Bryan Small, who was on the team collecting fossils, found the ankle bone of Chindesaurus
  • At the time Chindesaurus was found, it was thought to be the oldest dinosaur ever found
  • Holotype has a nickname, “Gertie”, after Gertie the Dinosaur
  • Also known as the “Chinde Point dinosaur”, because of where the specimen was found
  • Described in 1995 by R.A. Long and P.A. Murry
  • Genus name means “ghost lizard” or “lizard from Chinde Point”
  • Genus name comes from the Navajo word chindi, which means “ghost” or “evil spirit”
  • Species name is honor of Bryan Small, who found the holotype
  • Holotype includes vertebrae, limb bones, and hip fragments
  • Holotype was prepared at the University of California Museum of Paleontology in Berkeley, California
  • Fragmentary skeletons have been found in Arizona, New Mexico, and Texas, but not all of these may belong to Chindesaurus
  • Referred specimens are incomplete and include vertebrae and femur fragments, although one complete femur was found in 2006 in Ghost Ranch, New Mexico
  • However, some of these referred specimens may not be Chindesaurus, because they don’t have features unique to Chindesaurus
  • In 2019, Adam Marsh and others said only the holotype should be considered to be Chindesaurus
  • A partial lilium found in Texas (Tecovas Formation) was thought to be Chindesaurus and then in 1998, Hunt and others named it as a new taxon, Caseosaurus crosbyensis
  • However, in 2004 Langer said these two were the same species, and Nesbitt and others supported the idea in 2007, saying what made Caseosaurus and Chindesaurus different was just variation in size (but they didn’t formally synonmize the two, because the ilium of Chindesaurus is too fragmentary)
  • In 2018 Baron and Williams redescribed Caseosaurus and found it to be valid
  • Holotype of Chindesaurus may not be an adult, based on an unfused ankle
  • Long and Murry estimated Chindesaurus to be 9.9 to 13.1 ft (3 to 4 m), and to have a stout body, long legs, and a long neck
  • In 2012, Benson and Brusatte estimated Chindesaurus to be 6.6 to 7.5 ft (2 to 2.3 m) long
  • Also in 2012, Holtz estimated Chindesaurus to be about 6.6 ft (2 m) long and weigh about 50 to 100 lb (23 to 45 kg), or about the same as a wolf
  • No skull has been found
  • Had large tail vertebrae at the base that got longer towards the tip of the tail
  • Had long, low cervical vertebrae, so neck was probably light and slender
  • Had a large, crescent-shaped femur
  • Lots of debate over what type of dinosaur Chindesaurus was. At times thought to be a basal sauropodomorph, then later thought to be a herrerasaurid
  • In 2007, Nesbitt and others and Irmis and others suggested Chindesaurus was a basal saurischian
  • A phylogenetic analysis found Chindesaurus to be a sister taxon to Tawa hallae (previously Chindesaurus was thought to be a herrerasaurid and Tawa a theropod). Chindesaurus and Tawa were placed within basal Saurischia, before sauropodomorphs and theropods split off
  • In 2019 Adam Marsh and others redescribed Chindesaurus and found Chindesaurus and Tawa to be “a potentially diverse group of early theropods prior to the end-Triassic mass extinction”
  • In 2019, Morgan Schaller and others, researchers from the Rensselaer Polytechnic Institute and University of Texas Austin, found that oxygen levels rapidly increased over a 3 million year period around the time Chindesaurus lived
  • They analyzed small amounts of gas from rocks from the Colorado Plateau and the Newark Basin (about 621 mi or 1,000 km away from each other on Pangea and near the equator), which were around 215 million years old
  • Found that oxygen levels went from 15% to 19% and there was a drop in carbon dioxide levels (today we have 21% oxygen)
  • Probably was a global change in oxygen levels
  • Around the oxygen peak is when some of the first dinosaurs appeared in the tropics of what is now North America, like Chindesaurus (though dinosaurs were in what is now South America earlier, about 232 million years ago). Sauropods came soon after
  • Higher oxygen levels may have helped animals grow larger
  • At the very least, the environmental changes were good for evolutionary diversification, though there may have been other factors that helped
  • Chindesaurus lived on an ancient floodplain
  • Other animals that lived around the same time and place include archosaurs, pseudosuchians, tetrapods, phytosaurus, Coelophysis, lungfish, and clams
  • A short documentary, about 30 minutes, was made about Chindesaurus in 1988, called “A Whopping Small Dinosaur.” About the expedition and assembly of Chindesaurus

Fun Fact: Stegouros is the only named dinosaur from Magallanes, Chile and the southernmost of any dinosaur (excluding Antarctica).

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Episode 367: Another ankylosaur with battle wounds

Episode 367 is all about Anchisaurus, a sauropodomorph whose bones were first thought to be human remains when they were found in 1818.

Big thanks to all our patrons! Your support means so much to us and keeps us going! If you’re a dinosaur enthusiast, join our growing community on Patreon at https://www.patreon.com/iknowdino.

You can listen to our free podcast, with all our episodes, on Apple Podcasts at: https://itunes.apple.com/us/podcast/i-know-dino/id960976813?mt=2

In this episode, we discuss:

News:

  • We discuss the Dinosaur Systematics & Colbert Prize sessions from the Society of Vertebrate Paleontology annual meeting source
  • A new hadrosauriform, Brighstoneus, has been described from the Isle of Wight, UK source
  • The Mary Anning Rocks campaign has submitted a planning application for a statue of Mary Anning and her dog source
  • The Perot Museum of Nature and Science in Dallas, TX has a reconstructed Alamosaurus source
  • The Royal Ontario Museum in Toronto, Canada has a new gallery of Earth history including dinosaurs source

The dinosaur of the day: Anchisaurus

  • Basal sauropodomorph that lived in the Early Jurassic in what is now Connecticut and Massachusetts, US (Portland Formation)
  • Until recently considered to be a prosauropod
  • Looked like a typical sauropodomorph, walked on two legs and had a long neck and tail
  • Bipedal but could go on all fours
  • Estimated to be 6.6 ft (2 m) long and weighed around 60 lb (27 kg)
  • Marsh’s Anchisaurus major (Ammosaurus, now considered to be Anchisaurus polyzelus) was between 8 to 13 ft ( 2.5 to 4 m) long and weighed up to 70 lb (32 kg)
  • Gregory Paul estimated Anchisaurus to be 7.2 ft (2.2 m) long and weigh 44 lb (20 kg)
  • Lived in an arid environment, with wet and dry seasons
  • Had blunt teeth, probably ate plants
  • But also had a large thumb claw, possibly for defense, or grabbing tree branches
  • May have been an omnivore
  • Thought to be a carnivore because of the claws. According to Richard Swan Lull in the 1950s, thought Anchisaurus was “an alert, active dinosaur preying upon the smaller vertebrates of his generation, as the powerful claws and well-developed teeth imply”
  • Had hands that were proportionally short to its arms
  • Fossils found very early, so has a long history
  • In 1973, Peter Galton wrote about the prosauropods of North America (and the history of Anchisaurus)
  • Fossils first found in 1818 “during blasting operations for a well in East Windsor, Connecticut”
  • Thought to be human bones in 1820, then in 1821, tail bones were reported, and Porter said they weren’t human
  • Wyman in 1855 said it was reptilian and Lull in 1912 referred the fossils to Anchisaurus colurus (will get to that name later)
  • First fossils found in the Connecticut Valley were fragmentary and poorly preserved and now thought be indeterminate, though some of its features suggest it’s not the same species as the ones from Manchester (found in 1884)
  • In 1855 Edward Hitchcock, an ichnologist, reported fossils found in Springfield, Massachusetts, found during “blasting operations at the water shops of the United States Armory”
  • Wyman described the fossils in 1858 but didn’t name it
  • Fossils now at Amherst College Museum of Natural History
  • Damaged from the blast, and some bones may have been accidentally thrown away by workmen or some people took them home, so fossils are incomplete
  • In 1863, Hitchcock’s son, Edward Hitchcock Jr. described the fossils in a supplement to his father’s work on fossil footprints
  • Hitchcock Jr. contacted Richard Owen, who told him to name a new genus based on the fossils. Owen suggested Megadactylus, which means “large finger” because it had a large thumb
  • Hitchcock Jr. gave it the species name polyzelus, which means “much sought for” in Greek. Refers to his father trying to figure out for years what animal made the tracks in his work
  • In 1889, Marsh described part of a skeleton found near Springfield, Massachusetts, that Hitchcock described in 1865 as Megadactylus
  • Wrote, “It is a typical member of the order Theropoda, and has apparently for its nearest allies in the old world, Thecodontosaurus, from the Trias of England, and Massospondylus, from the same formation in South Africa”
  • Cope described the specimen more in 1870 and Marsh renamed it to Amphisaurus (means “near saurian”) in 1882, then again to Anchisaurus (means “near lizard”) in 1885 (both names were “preoccupied”)
  • More fossils were found in 1884 near Manchester, Connecticut
  • In 1884, while bridges were being built, amateur paleontologist Charles Owen saw a block with part of a skeleton in it. He told Marsh, who acquired the block from Charles Wolcott, who owned the quarry. The block had the back half of the specimen
  • Marsh tried to get the front half, but the block with the front half was already part of a bridge
  • Marsh named it Anchisaurus major in 1889 (“the larger one”)
  • In 1969 the bridge was demolished and John Ostrom got the block with the front half of the skeleton (probably the same one? hard to know). He’d been looking for the block for two years, and learned bridge builders had bought the block and used it in a local project. So he surveyed more than 60 bridges and figured out where the fossils were. Then when the bridge was scheduled to be demolished, he got permission for his team to examine it beforehand
  • Three well-preserved skeletons found near Manchester, Connecticut, as well as two fragmentary specimens
  • Marsh described the skeletons in multiple papers and based on them named Ammosaurus (“sand saurian”) in 1891, Anchisaurus colurus (“the mangled one”) in 1891, and Anchisaurus solus in 1892
  • Anchisaurus solus is nearly complete
  • In one of his papers, Marsh wrote, “one of the most slender and delicate dinosaurs yet discovered, being only surpassed in this respect by some of the smaller bird-like forms of the Jurassic”
  • Also renamed Anchisaurus major as Ammosaurus in 1891
  • The specimens from Manchester are now thought to be the same as Anchisaurus polyzelus
  • They’re housed at the Peabody Museum of Natural History
  • In 1906 Friedrich von Huene said Anchisaurus polyzelus resembled Anchisaurus colurus (both had elongate dorsal vertebrae) but still thought them to have enough differences to be different species
  • Huene also referred Anchisaurus polyzelus to Thecodontosaurus based on similar radius, tibia, and fibula (Thecodontosaurus polyzelus)
  • Lull in 1915 disagreed. Also said that if Huene were correct, all Anchisaurus would be a synonym for Thecodontosaurus, since Anchisaurus polyzelus is the type species
  • In 1932, Huene corrected this by referring Anchisaurus solus to Ammosaurus and made Anchisaurus colurus the type species of Yaleosaurus
  • He referred Anchisaurus solus to Ammosaurus because of the similarities in the ilium, tibia, and dorsal vertebrae
  • In 1953 Lull accepted Yaleosaurus as valid but still recognized Anchisaurus polyzelus and Anchisaurus solus
  • Holotype of Anchisaurus polyzelus does not include skull material
  • In 1976 Peter Galton renamed Gryposaurus capensis bones found in South Africa (named in 1911) as Anchisaurus capensis
  • But now it’s thought to be a juvenile Massospondylus carinatus
  • Galton also recognized Anchisaurus polyzelus (found in Charles Wolcott’s quarry in Connecticut) and Ammosaurus major (found in Portland Beds)
  • Galton referred Anchisaurus solus to Ammosaurus major
  • Also found Anchisaurus colurus to be a junior synonym of Anchisaurus polyzelus and Yaleosaurus to be a synonym for Anchisaurus
  • In 2008, Gauthier and Gall found Ammosaurus major to be a junior synonym of Anchisaurus polyzelus
  • In 2010, Adam Yates wrote “A revision of the problematic sauropodomorph dinosaurs from Manchester, Connecticut and the status of Anchisaurus Marsh”
  • Found that Anchisaurus polyzelus is the only valid one (other paleontologists had agreed, earlier)
  • Found all the Wolcott Quarry specimens to be the same species
  • Also found they could all be referred to Anchisaurus polyzelus
  • Wolcott quarry was since been filled in
  • Wolcott quarry specimens now at the Peabody Museum
  • In 2007 Sereno said Anchisaurus was a nomen dubium, but Yates did not agree (not enough diagnostic characters “beyond those of basal Sauropodomorpha” found in the fragmentary holotype)
  • Yates said Anchisaurus had seven distinguishing characters relating to the skull, vertebral column, and pelvis, including a slender sacral rib, and unusual proportions of the posterior dorsal centra
  • Yates also supported Anchisaurus being a basal sauropodomorph
  • To recap, the type species is Anchisaurus polyzelus
  • Genus name means “near lizard”
  • Anchisaurus was a replacement name for Amphisaurus, which was a replacement name for Megadactylus (already the names for other animals)
  • Ammosaurus, Anchisaurus solus, Anchisaurus colurus (also known as Yaleosaurus) are now considered to be synonyms of Anchisaurus polyzelus
  • All three dinosaur skeletons were from the same Early Jurassic-age Wolcott Quarry in Connecticut, but Marsh named them all different species: Anchisaurus major (1889), Anchisaurus colurus (1891) and Anchisaurus solus (1892)
  • Hard to tell that Anchisaurus polyzelus and the Wolcott Quarry skeletons were the same dinosaur because they didn’t have too many overlapping parts of the skeleton to compare. But Yates found similarities in the hip blade and part of the fused vertebrae, which showed they were all related
  • Anchisaurus was named first, so the name sticks
  • In 2015, the type specimen of Anchisaurus colurus became the neotype of Anchisaurus and formally became the species Anchisaurus polyzelus
  • Tracks that seem to match with Anchisaurus’s feet have been found in Nova Scotia, but hard to know for sure

Fun Fact: The Chicxulub crater that wiped out the dinosaurs created sinkholes (cenotes) that provided freshwater to the ancient Mayans.

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Episode 353: Scavenging Allosaurus & Carnotaurus Skin

Episode 353 is all about Alwalkeria, a small, basal saurischian, from the Late Triassic of what is now India.

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In this episode, we discuss:

News:

  • T. rex had complex nerves in its jaw which may have given it a sensitive bite source
  • A new analysis of Carnotaurus skin found details of both “feature scales” and “basement scales” around its body source
  • A new paper describes Allosaurus as an “Apex Scavenger” rather than a predator source
  • A Triceratops prorsus horn was recently donated to the Royal Tyrrell Museum in Alberta, Canada source
  • The Atlantic City Convention Center in New Jersey will have a “Dino Stroll” featuring animatronic dinosaurs source
  • Phil Tippett is selling a segment of his 1984 short film Dinosaur! as a Non-Fungible Token (NFT) source
  • There’s going to be a VR Jurassic Snap game, assuming the kickstarter goes well source

The dinosaur of the day: Alwalkeria

  • Basal saurischian that lived in the Late Triassic in what is now India (Maleri Formation)
  • Bipedal, and small
  • Had an elongated head, long arms and long tail
  • In 2010 Gregory Paul estimated it to be about 5 ft (1.5 m) long and weigh 4.4 lb (2 kg)
  • Probably an omnivore based on the teeth, and may have eaten plants, insects, and small vertebrates
  • Had heterodont (different shaped) teeth in the upper jaw
  • Front teeth were straight and slender, like Eoraptor
  • Teeth in the sides of the jaw were like carnivorous theropods, curved backwards, but they were not serrated
  • Teeth are similar to Eoraptor. Both have gaps between the teeth in the premaxillary and maxillary bones, in the upper jaw
  • Type species is Alwalkeria maleriensis
  • Originally named in 1987 by Sankar Chatterjee as Walkeria maleriensis, in honor of paleontologist Alick Walker, but turned out that name was used for a bryozoa (also known as moss animals, they live in shallow water in colonies)
  • In 1994, Sankar Chatterjee and Ben Creisler renamed the dinosaur Alwalkeria maleriensis
  • Genus name means “for Alick Walker”
  • Species name refers to the Maleri Formation
  • Holotype is incomplete and includes parts of the jaws, incomplete vertebrae, most of a femur, and an ankle bone (astragalus)
  • Description called it “imperfectly known fragmentary material”
  • Partial skull is about 1.5 in (4 cm) long
  • In 2005 Rauhut and Remes said Alwalkeria was a chimera, with parts of the skull being a crurotarsan (archosauriform), vertebrae being from other reptiles, but the femur and astragalus being from a dinosaur, and the astragalus having saurischian features
  • Originally thought to be a basal theropod similar to Coelophysis and Procompsognathus, then a herrerasaurid, then a basal saurischian
  • Fossils found in red mudstone
  • One of the earliest known dinosaurs from India

Fun Fact: According to a new paper, giant tortoises hunt and eat birds.

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