Episode 558: Dinosaur Tracks & Escape Rooms. New track sites, swim tracks, and mating dance arenas around the world tell us about the behavior of theropods, ceratopsians, and sauropods. Plus David Spira joins from Room Escape Artist to share his favorite dinosaur themed escape rooms.

News:

• The Science Museum of Minnesota closed for a day in response to the local ICE presence (source). If you want to support Minnesotans go to www.standwithminnesota.com
• In Bolivia, there are almost 18,000 theropod dinosaur tracks that show evidence of running, sauntering, and swimming source
• An earlier study of the Carreras Pampa site also found that the theropods feet sunk in the mud source
• One set of footprints shows the fastest running theropod trackway in the Cretaceous source
• Scientists re-examined the longest known theropod trackway in China source
• Dinosaur Ridge, Colorado, has the largest known dinosaur mating dance arena source
• Tracks from 76 million years ago may show that ceratopsians and ankylosaurs hung out together source
• Paleontologists found a set of sauropod tracks that show it made a loop source
• Scientists found multiple trackways in Oxfordshire, England, from mostly sauropods walking at a steady pace source
• Theropod footprints were found in a crisscross pattern in Texas, U.S. source
• Thousands of prosauropod footprints from the Triassic were found in a national park in Italy source

Interview:

David Spira, co-creator of RoomEscapeArtist.com, which publishes well-researched, rational, and reasonably humorous escape room reviews, design tips, player tips, and industry commentary

Sponsors:

This episode is brought to you by the Colorado Northwestern Community College. Join them for two weeks digging up dinosaur bones in the field, preparing fossils in their lab, or in their new field geology program. For details go to CNCC.edu/paleo26

The dinosaur of the day: Segnosaurus

• Therizinosaurid that lived in the Late Cretaceous in what is now Mongolia and Japan
• Large, estimated to be about 20 to 23 ft (6 to 7 m) long and weigh 1.4 short tons
• A later estimate in 2020 found it to weigh 4.6 short tons
• Walked on two legs
• Had a small head, a beak, and a long, slender neck
• Had robust arms and three fingers on each hand, with large claws
• Fingers were not that long, but ended in large claws
• Arms were relatively short. From the 1979 paper that named it: “They comprise 69% of the length of the limbs of Deinocheirus, 73% — Therizinosaurus”
• Had four toes on each foot
• Had splayed toes
• Hips were adapted to support its large belly
• Probably couldn’t move very fast
• Over the years, lots of confusion as to how to classify this dinosaur (theropod, sauropod)
• In the beginning Segnosaurus considered to be a missing link between theropods and sauropods
• From the 1979 paper: “Please note that its inclusion among the ranks of theropods is conditional”
• Had robust hips, and the pelvis was shortened at the front (see this in bird-like theropods, but not most other theropods)
• Had an opisthopubic pelvis (pubic bone pointed backward toward the tail instead of forward)
• Foot bones looked similar to prosauropod foot bones (though they were proportionally larger)
• Early on, therizinosaurs considered to be amphibious (too bulky and slow for land), then later considered to walk on all fours like a sauropod, then later the claws on the hands considered to be used for defense or when young, to help climb trees in a way similar to sloths
• Later therizinosaur discoveries helped scientists figure out the group
• A 2012 study of braincases found that therizinosaurs had good smell, hearing, and balance, which may have helped with foraging, evading predators, and socially. May have gotten these traits from their carnivorous ancestors
• Hand claws not used for digging, because therizinosaurs had feathers on the arms
• Maybe could use foot claws for digging
• Therizinosaur embryos found in China were in nests with no adults nearby, so seems that as hatchlings they were precocial (could move and feed themselves) from birth
• Scientists also found 17 egg clutches together in Mongolia considered to belong to therizinosaurs. Having multiple clutches together may mean therizinosaurs nested together in colonies, as seen in some hadrosaurs, sauropods, and birds
• Therizinosaurs considered to be herbivores based on their delicate jaws, weak teeth, having beaks, having a large gut, and a small head
• Therizinosaurs could extend their arms pretty far forward, which would have helped reaching for plants
• Therizinosaurs moved jaws up and down to eat
• Segnosaurus lived alongside other therizinosaurs, Erlikosaurus, Enigmosaurus, and Duonychus, so they probably had their own niches
• Segnosaurus lower jaw was down turned at the front
• Had a low, long lower jawbone that was relatively robust compared to Erlikosaurus
• The back part of the jaws had no teeth (teeth were in the front two-thirds)
• Had the largest teeth of all known therizinosaur teeth
• Had leaf-shaped teeth (foliodont)
• Replaced teeth in waves from the back to front of the jaws
• Had some features of its teeth that were similar to other tetanuran theropods, which in those animals were considered to be abnormalities from trauma, or the way the tooth was replaced, or genetic factors (split carinae, or cutting edges on the teeth)
• In Segnosaurus all the teeth had this feature, so doesn’t seem to be an abnormality
• Teeth are close together
• Some of the teeth had three cutting edges
• Teeth have triple carinae (three ridges), which according to a 2016 study, was “otherwise unknown in Theropoda”
• Had large denticles on its teeth and more ridges compared to other therizinosaurs, which may mean it processed food more. May also mean Segnosaurus had more specialized feeding strategies
• Teeth were better at shredding compared to other therizinosaur teeth
• The downturned lower jaws and beaks helped its jaws not have much stress and strain on them when eating
• Segnosaurus could eat tougher vegetation compared to Erlikosaurus (which relied more on its beak to crop food), according to a 2017 study
• Type and only species is Segnosaurus galbinensis
• Multiple specimens found (well preserved but incomplete) in 1974 to 1975 in the Gobi Desert
• Named in 1979 by Altangerel Perle
• Genus name means “slow lizard”
• Species name refers to the Galbin region in the Gobi Desert
• Fossils found includes the lower jaw, neck and tail bones, parts of the ribs, hips, parts of the shoulder, and limb bones (arms and legs)
• Some of the fossils have been damaged since they were collected, and some of the bones that were described have since disappeared, and some of the bones were incorrectly assigned
• Fossils also found in Kumamoto, Japan (Jobu Formation), that include vertebrae, limb bones, and teeth. Originally considered to be Allosaurus, but later the fossils were reassigned to Segnosaurus
• Lived in a semi-arid climate with rivers and lakes
• Other dinosaurs that lived around the same time and place include the tyrannosaur Khankhuuluu, the ornithomimosaur Garudimimus, the dromaeosaur Achillobator, the ankylosaur Talarurus, the hadrosaur Gobihadros, the sauropod Erketu, the ceratopsian Graciliceratops (in addition to the other therizinosaurs)
• Other animals that lived around the same time and place include crocodyliforms and turtles

Fun Fact:

Turtles probably feared earthquakes, as a new track site with 1,000 paddle-shaped footprints likely shows turtles stampeding in panic after an earthquake.

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