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The Big Dinosaur Podcast

The Big Dinosaur Podcast

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I Know Dino Podcast Show Notes: Kaatedocus (Episode 226)

Episode 226 is all about Kaatedocus, the smaller cousin of Diplodocus and Barosaurus.

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In this episode, we discuss:

News:

  • A new basal ornithopod with skinny arms, Mahuidacursor lipanglef, was described in Argentina source
  • A hadrosaur was found in Montana with marks showing it was probably chewed on by a juvenile T. rex source
  • Tracks from the Middle Jurassic of China appear to be the first evidence of quadrupedal theropod walking source
  • Several institutions in New Mexico are working together this spring to photograph, scan, map, and model the Clayton Lake Dinosaur Tracksite source
  • Dinosaur Journey Museum in Fruita, Colorado, has a new 6ft 4in Apatosaurus femur on display source
  • The Natural History Museum at Tring in the UK has a new, free exhibition, that shows off the dinosaurs of the British Isles source
  • The U.S. Postal Service is coming out with new T. rex stamps this year source
  • The Canadian Mint has a new, limited edition glow in the dark dinosaur coin of a hatching Hypacrosaurus source

The dinosaur of the day: Kaatedocus

  • Sauropod that lived in the Late Jurassic in what is now Wyoming, US (Morrison Formation)
  • Looks similar to Diplodocus and Barosaurus
  • Classified as a Diplodocinae
  • Estimated to be about 46 ft (14 m) long
  • Lived earlier than Diplodocus and was smaller than Diplodocus, and helps with understanding the evolution of diplodocids
  • Also found further north than other diplodocids from the Morrison Formation, so it’s possible they moved south over time
  • Had a long whiplash tail, a long neck, an elongated head, and peg teeth (but there are subtle differences in the skull and vertebrae, like a U-shaped notch between the frontal bones)
  • Skull looks like a juvenile diplodocid (large eye openings and a rounded snout)
  • Had large teeth, and looked like it was smiling
  • Probably used gastroliths to help digest
  • Described in 2012 by Emanuel Tschopp and Octávio Mateus
  • Barnum Brown (known as Mr. Bones) led a team from the AMNH in 1934 on Barker Howe’s land in near Shell, Wyoming. In 6 months they found about 4,000 fossils in an area of 45 x 65 ft (14 x 20 m). Brown said the site was “an absolute, knockout dinosaur treasure trove!” Brown had heard about the site in 1932 from a local collector who had found some large sauropod leg bones that were partially exposed.
  • The expedition was funded by Sinclair Oil, and the finds from the trip became Sinclair’s logo (the green sauropod)
  • Brown decided to study the fossils on location to figure out the relationships between individuas. Roland Bird suggested they make a quarry chart and draw a map to show where each bone was found
  • In the quarry they also found more sauropods (and the first preserved skin tissues of sauropods), as well as ornithischians and Allosaurus. Seemed that there was a group of sauropods being stalked by carnivores and they ran into a watering hole that was a muddy death trap
  • After 2 months of making the map, they packed the bones into 140 cases and shipped them back to the museum (weighed 69,000 pounds). However, not many of the fossils were prepared or put on display. Many of the fossils were destroyed in a warehouse fire in 1940, the WWII happened. Brown never made it back to the quarry or got to study the bones
  • In 1989 Hans-Jakob Siber, founder of the Swiss Aathal Dinosaur Museum, reopened the Howe Quarry and found more bones, including some neck vertebrae and a partial skull of a sauropod, at first thought to be Barosaurus or Diplodocus
  • In 2012 Tschopp and Mateus looked at the bones that were left from the quarry and at AMNH. Tschopp said that “Howe Quarry is the reason I became a paleontologist.” (He’s still working on the collection from the quarry, and identifying bones based on Bird’s quarry map)
  • They named specimen SMA 0004 Kaatedocus siberi (in 2013 Schmitt and others referred another partial skull from the Howe Quarry to Kaatedocus)
  • Specimen includes a skull and cervical vertebrae
  • Type species is Kaatedocus siberi
  • Name “Kaate” means small in the Crow (Absaroka) language (one of the tribes in northern Wyoming). The word “docus” alludes to Diplodocus and the Greek word “beam”
  • The species name “siberi” is in honor of Hans-Jakob “Kirby” Siber, who organized and funded the excavation, preparation, and curation of the Kaatedocus holotype
  • The SMA 0004 is the only specimen from Howe Quarry to be described and properly identified, so far. Need more analysis to better understand diplodocid phylogony and faunal changes in the Morrison Formation
  • Tschopp and Mateus said they believed the specimen was a subadult because of its small size and the skull features
  • They also said Kaatedocus “is an example of Cope’s Rule, which predicts body size increase during evolution”
  • Other dinosaurs that lived around the same time and place include Barosaurus, Stegosaurus, Allosaurus
  • Can see Kaatedocus in the sauropods exhibit on the 4th floor of the AMNH, and fossils casts are part of the juvenile sauropod in the Theodore Roosevelt Rotunda

Fun Fact: A few dromaeosaurs are the same size (weight) as modern raptors. Microraptor is about the same size as the peregrine falcon. Velociraptor & Dromaeosaurus are the same size as the Andean condor.

Transition of Power: A Summary of Apex Predators in Cretaceous North America

By Taylor McCoy

North America saw the rise and fall of numerous members of Theropoda. Many held the role of apex predator at different points in time. This study focuses on the alpha predators during the Cretaceous (namely Acrocanthosaurus atokensis, Siats meekerorum, Lythronax argestes, and Tyrannosaurus rex) and how they superseded each other in the changing environment.

Jurassic-Cretaceous Gap

The end of the Jurassic saw the extinction of a number of large theropods (Ceratosaurus sp., Allosaurus sp., etc). However, it appears to have taken some time for a new large theropod to arise after the Jurassic period ended roughly 145 million years ago. The first fairly large theropod to appear in North America at the start of the Cretaceous was the large dromaeosaur Utahraptor ostrommaysorum. Adult specimens are estimated at 5-7 meters long and close to 450-700 kilograms. However, Utahraptor didn’t appear until some 126 million years ago. What filled this gap is unknown at the moment. Considering the success of allosauroids during the late Jurassic, it’s possible some, currently unknown, species of that group continued to hold the role of top predator as a relic population.

Reemergence of Giants

After Utahraptor came the arrival of the first truly giant theropod since the Jurassic. Appearing on the scene between 110-116 million years ago was the carcharodontosaur Acrocanthosaurus atokensis. Far larger than the dromaeosaurs that preceded it, Acrocanthosaurus stretched up to 11.5 meters in length and likely exceeded 4900 kilograms in weight. As with most members of the group, Acrocanthosaurus exhibits traits ideal for hunting giant prey (namely sauropods). Depending on the region, sauropods suitable for predation included: Astrodon johnstoni, Brontomerus mcintoshi, and possibly even Sauroposeidon proteles(though this species may have exceeded 28 meters and 45000 kilograms). Evidence for this exists in the form of footprints found in Texas that show what was likely an Acrocanthosaurus running alongside a large sauropod. Other contemporary animals include the ornithopod Tenontosaurus sp. and the dromaeosaur Deinonychus antirrhopus.

Evidence suggests Acrocanthosaurus was the sole giant predator specialized in hunting sauropods. This specialization may have contributed to the downfall of the species. Sauropods were becoming increasingly rare. With the exception of species like Abydosaurus mcintoshi around 104.5 million years ago, sauropods would be absent from the continent until the appearance of giant titanosaurs roughly 68 million years ago.

Rise of a New Killer

After the extinction of Acrocanthosaurus, the role of alpha predator was open. The related megraptorids were quick to produce their largest member, Siats meekerorum roughly 98.5 million years ago. The holotype specimen of this theropod was already comparable to Acrocanthosaurus in size(11.9 meters long and 3600 kilograms), despite being immature at the time of death. Adults may have exceeded 12 meters and 5000 kilograms, though there is no direct fossil evidence for this as of yet. The absence of sauropods on the continent meant Siats was forced to focus on different prey. Ornithopods like Protohadros byrdi and Eolambia caroljonesa would have made for suitable options. Less suitable were the armored ankylosaurs of the time, represented by species like Nodosaurus textilis and Animantarx ramaljonesi.

The reign of Siats did not last forever though. New theropods, better adapted at hunting ornithopods and ankylosaurs, were on the rise. The introduction of ceratopsians also ushered in a new era of dominant herbivores. Siats was less equipped than the competition at tackling such prey. As a result, it was outcompeted and rendered obsolete.

Tyrant Takeover

Originating in Asia and spreading across the northern hemisphere, the tyrannosauroids were quickly establishing dominance throughout their range. As carnosaurs like Siats continued to decline, tyrannosauroids grew in both size and number. The time immediately following Siats is a bit of a mystery. However, the recently discovered Timurlengia euotica from Uzbekistan gives insight into the rise of tyrannosauroids. Though still fairly small(~3-4 meters), Timurlengia exhibits an increase in brain size and sophistication. This particular species lived around 90 million years ago. It seems likely a North American form arose around the same time and represented the first steps being taken by tyrannosauroids to take on the role of apex predator. By 80 million years ago, North American variants were large enough to officially dethrone the local carnosaurs. One of the earliest large species was Lythronax argestes. Estimated at almost 8 meters long and 2500 kilograms, Lythronax was a prime example of size increase in tyrannosaurs. Better equipped to hunt well armed and sophisticated prey, Lythronax and its kind were perfect for the role of apex predator.

Over the next 10 million years, tyrannosaurs continued to spread and increase in size. Two lines represented the apex predators in western North America(more primitive forms persisted along the east coast). One was the slender, long legged albertosaurinae. The other, the more robust tyrannosaurinae. Over time, the tyrannosaurinae began replacing their albertosaurinae cousins. Eventually, the tyrannosaurinae culminated in the largest, most advanced member of the group. Evidence suggests this one species may have outcompeted all other tyrannosaurs, placing it squarely at the top of the food chain.

King of the Dinosaurs

Roughly 68 million years ago, a new predator arrived on the scene. The origins of this carnivore are still debated, with possible roots in North America and Asia. The most recent analysis suggests an Asian origin. Whatever the case, Tyrannosaurus rex quickly established its dominance in western North America. Finds indicate a range stretching as far north as Canada and as far south as Texas. Adults could exceed 12 meters in length and weighed in at over 7000 kilograms, arguably the heaviest theropod ever known. Tyrannosaurus had little competition. The next largest carnivore in the area was the large dromaeosaur Dakotaraptor steini. Though large for a dromaeosaur, Dakotaraptor still didn’t exceed 5.5 meters in length around 300 kilograms in weight. This is roughly half the overall length of an adult Tyrannosaurus.

Numerous species of potential prey existed at the time for Tyrannosaurus. Ceratopsians included Triceratops sp., Torosaurus sp., and Eotriceratops xerinsularis. Hadrosaurs were also present in the forms of Edmontosaurus sp., Hypacrosaurus sp., and others. Various kinds of ankylosaurs lived alongside Tyrannosaurus as well, though their armor would’ve made attack fairly difficult. The largest animal in the environment was Alamosaurus sanjuanensis, the first sauropod to appear since Abydosaurus. However, since adults could reach nearly 30 meters and exceed 67 tons in weight, large individuals were probably safe from attack(though juveniles and injured specimens were likely fair game). Ornithomimids, pachycephalosaurs and small ornithopods likely represented potential prey for juvenile tyrannosaurs.

Extinction of Giants

Around 65.5 million years ago, the reign of giant theropods was cut short due to an invader from space. Had the asteroid not struck, these efficient and adaptable carnivores likely would have continued to diversify and rule the continent of North America. The tyrannosaurs seem best equipped for this, but as the fossil record shows, extinction can topple even the greatest of dynasties.

References

Turner, C.E. and Peterson, F., (1999). “Biostratigraphy of dinosaurs in the Upper Jurassic Morrison Formation of the Western Interior, U.S.A.” Pp. 77–114 in Gillette, D.D. (ed.), Vertebrate Paleontology in Utah. Utah Geological Survey Miscellaneous Publication 99-1

Kirkland, J.I.; Burge, D.; Gaston, R. (1993). “A large dromaeosaur [Theropoda] from the Lower Cretaceous of Utah”. Hunteria. 2 (10): 1–16.

Stovall, J. Willis; Langston, Wann. (1950). “Acrocanthosaurus atokensis, a new genus and species of Lower Cretaceous Theropoda from Oklahoma”. American Midland Naturalist. American Midland Naturalist, Vol. 43, No. 3. 43 (3): 696–728. doi:10.2307/2421859. JSTOR 2421859

Farlow, James O. (2001). “Acrocanthosaurus and the maker of Comanchean large-theropod footprints”. In Tanke, Darren; Carpenter, Ken. Mesozoic Vertebrate Life. Bloomington: Indiana University Press. pp. 408–427. ISBN 978-0-253-33907-2.

Zanno, L. E.; Makovicky, P. J. (2013). “Neovenatorid theropods are apex predators in the Late Cretaceous of North America”. Nature Communications. 4: 2827. Bibcode:2013NatCo…4E2827Z. doi:10.1038/ncomms3827. PMID 2426452

Stephen L. Brusatte, Alexander Averianov, Hans-Dieter Sues, Amy Muir and Ian B. Butler (2016). “New tyrannosaur from the mid-Cretaceous of Uzbekistan clarifies evolution of giant body sizes and advanced senses in tyrant dinosaurs”. Proceedings of the National Academy of Sciences of the United States of America. in press.

Vergano, Dan (Nov 6, 2013). “Newfound ‘King of Gore’ Dinosaur Ruled Before T. rex“. National Geographic. Retrieved 22 November 2013.

Osborn, H. F. (1905). “Tyrannosaurus and other Cretaceous carnivorous dinosaurs”. Bulletin of the AMNH. New York City: American Museum of Natural History. 21 (14): 259–265. hdl:2246/1464. Retrieved October 6, 2008

http://www.livescience.com/53877-t-rex-was-invasive-species.html

Hutchinson, J. R.; Bates, K. T.; Molnar, J.; Allen, V.; Makovicky, P. J. (2011). “A Computational Analysis of Limb and Body Dimensions in Tyrannosaurus rex with Implications for Locomotion, Ontogeny, and Growth”. PLoS ONE. 6 (10): e26037. doi:10.1371/journal.pone.0026037

Hartman, Scott (July 7, 2013). “Mass estimates: North vs South redux”. Scott Hartman’s Skeletal Drawing.com. Retrieved August 24, 2013.

Switeck, Brian (April 13, 2012). “When Tyrannosaurus Chomped Sauropods”. Smithsonian Media. Retrieved August 24, 2013

I Know Dino Podcast: Deinonychus (Episode 14)

In our fourteenth episode of I Know Dino, we had the pleasure of speaking with Matt Martyniuk, a science teacher and paleoartist who has a prolific blog, several books, and more. Learn more about his work at mpm.panaves.com.  You can also visit him on Facebook and Twitter.

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: Deinonychus, which means “Terrible Claw”
  • Lived in the Cretaceous about 115–108 million years ago
  • Paleontologist Barnum Brown technically found the first Deinonychus fossil in 1931, but he was looking for the hadrosaur Tenontosaurus and forgot about the raptor (which he had named Daptosaurus)
  • Grant E. Meyer and John H. Ostrom in southern Montana discovered Deinonychus in 1964, and they were the first to talk about how similar dinosaurs are to modern birds
  • Ostrom and Meyer found several hundred Deinonychus bones in 1964; their description of an agile predator changed people’s notions about dinosaurs and made scientists speculate they were warm-blooded
  • Deinonychus has been found in the Antlers formation and Cloverly formation
  • Eight other Deinonychus fossils have been discovered in Montana, Utah and Wyoming (9 total specimens)
  • Deinonychus had good depth perception
  • Deinonychus was very bird like. It was light, fast, and walked on two legs (bipedal)
  • It had a flexible, curved neck, and sharp, serrated teeth
  • It had three fingers on each hand with large claws
  • It had four tows on its feet, and the second two had a sickle like claw (5 inches)
  • It had a large brain and was one of the most intelligent dinosaurs (measured by EQ, or brain size to body weight)
  • Deinonychus was 5 feet tall, 10 feet long, and weighed about 175 pounds
  • Compared to bigger Cretaceous theropods (T. rex, Spinosaurus), Deinonychus had a weak bite, but it was still as powerful a bite from a modern alligator
  • Dr. Robert Bakker wrote in his book The Dinosaur Heresies (1986) that Deinonychus had many similarties to birds
  • Dr. Philip Currie has recent research that dinosaurs similar to Deinonychus (Velociraptor, Utahraptor, Dromaeosaurus) probably had feathers covering all or at least part of their bodies (proto-feathers used for insulation and/or display)
  • Could probably run at 6 mph, not as fast as other theropods
  • The Velociraptors in Jurassic Park were actually Deinonychus
  • Velociraptor would come up to a bit above the knee on an adult average man while Deinonychus would reach a man’s chest
  • Deinonychus was one of the first raptors discovered from an almost complete skeleton. Scientists had found Velociraptor 40 years earlier, but only named it based on a skull and some parts of its hands and feet
  • This new idea that dinosaurs were agile partly inspired Gregory S. Paul, a paleo-artist, to create his 1988 book Predatory Dinosaurs of the World. He grouped Deinonychus fossils as Velociraptors, since the two had so many similarities (and Velociraptor was named first)
  • Paleontologists still think the two dinosaurs are different, but the book was very popular. Michael Crichton read the book (acknowledged it in the Jurassic Park novel) and he described Deinonychus in the book as Velociraptor (stayed that way in the films)
  • Larger Deinonychus’s could probably bite through bone
  • It used its tail to counterbalance when running and pivoting, which would have helped catch up to prey
  • Deinonychus fossils have been found near Tenontosaurus fossils, which makes some scientists think Deinonychus hunted in packs
  • Deinonychus may have hunted sauropods and ankylosaurids (in packs)
  • Tenontosaurus adults weighed two tons, which means the only way Deinonychus could have hunted it was in packs
  • Deinonychus may have used its arms to hold onto prey and tear off chunks with its teeth
  • Studying Deinonychus has given a lot of insight into how raptors behaved
  • The tail had a rigid “pole” that only moved at the base (tendons at the tail overlapped several vertebrae)
  • Deinonychus used its claw on the second toe of each foot to stab prey (Velociraptors used their claws for slashing)
  • Deinonychus may have used the claw to hit the neck, or used as defense against other dinosaur species or against other Deinonychus when defending its territory or trying to dominate the pack
  • The claw was held back and did not touch the ground when Deinonychus was walking (means it did have a specific purpose). Instead, it rotated the claw upwards and ran on its other toes
  • Deinonychus may have stabbed its prey and waited for it to bleed to death from a safe distance
  • Ostrom compared Deinonychus to an ostrich or cassowary
  • Can see Deinonychus at the American Museum of Natural History and the Harvard Museum of Comparative Zoology, though they are from different areas and have different shaped claws (may be two different species or genera)
  • Deinonychus is part of the Dromaeosaur family; though no Deinonychus fossil feathers have been found, Dromaeosaurs are known for having feathers
  • Their family name means “running lizards” and they are often referred to as raptors (they have very bird like habits)
  • They also had great vision and large brains and lived in the Cretaceous
  • Dromaeosaurs had a great sense of small, like tyrannosaurids and turkey vultures
  • They were mostly small to medium sized and they were bipedal
  • They had long tails, many with rod-like extensions. Tails were flexible at the base, probably used as a counterweight or to help stabilize while running
  • Dromausaurs may have been most closely related to birds
  • They had feathers. Some feathers were long, some were shorter and more down-like. The feather patterns were very similar to Archaeopteryx
  • Scientists think at least two dromaeosaurs could have flown or at least glided (Rahonavis ostromi and Microraptor gui)
  • Dromaeosaurs had light skulls, sharp backward curved teeth, long arms and hands with claws, and sickle-like second toe claws that never touched the ground in order to keep it sharp
  • May have used their sickle like claw to climb trees or large prey (as well as for stabbing)
  • Phillip Manning and a team tested the function of the sickle claw in 2009 by using X-ray imaging
  • The team compared how the sickle claw curved with the foot curvature of modern birds and mammals (curvature gives insight into an animals lifestyle; strongly curved means the animal climbs, but less curved means the animal spends most time on the ground)
  • Deinonychus has a 160 degree curvature, good for climbing
  • Still, some later, larger dinosaurs with very curved claws would have been too large to climb trees, so may have used it to latch on to prey instead
  • Phil Senter said in 2009 that dromaeosaur toes may have been able to get through tough insect nests, so some smaller dromaeosaurs (Rahonavis and Buitreraptor) may have eaten insects as part of their diet, and larger ones such as Deinonychus may have caught small prey in insect nests (though he did not test whether the claws could actually do those things)
  • Denver Fowler and his team in 2011 said dromaeosaurs may have used “raptor prey restraint” or RPR on smaller prey, by jumping on the prey, pinning it, and gripping it with its claws, taking bites while the prey was still alive (prey eventually bleeds out and organs fail)
  • Fun fact: Most baby dinosaurs had proportionally larger eyes and smaller faces than adults, which made them just as cute as other baby animals

For those who may prefer reading, see below for the full transcript of our interview with Matt Martyniuk:Continue Reading …

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