The Big Dinosaur Podcast

Episode 217 is all about Nanosaurus, a small herbivorous dinosaur from the Late Jurassic.

We also interview Tom Holtz, principal lecturer at the University of Maryland’s Department of Geology and the Faculty Director of the Science and Global Change Program. His primary focus is theropods, especially tyrannosaurids. He has also written several books, including Dinosaurs: The Most Complete Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages and Jurassic World Dinosaur Field Guide. Follow him on Twitter or Facebook.

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In this episode, we discuss:

• Our first new dinosaur of 2019 is Adynomosaurus, the “weak shouldered” hadrosaur from Northeast Spain source
• Bob the 90% complete Triceratops from North Dakota is back on sale source
• In Mongolia, two men were arrested while trying to sell a dinosaur fossil after posting it on Facebook source
• Dinosaurs Take Flight: The Art of Archaeopteryx opened at Oregon’s Museum of Natural and Cultural History source
• The American Museum of Natural History in New York has a new exhibit, T. rex: The Ultimate Predator opening on March 11 source
• The Natural History Museum in London and the Science Museum next door will have related exhibits opening in 2020 featuring dinosaurs source
• The app MyFossil allows you to upload fossil images from the field to compare and discuss findings and techniques source
• Tri-C, a community college in Cleveland, Ohio, has a new Triceratops mascot source
• The Atlantic has a fun gallery of “dinosaur statues of questionable accuracy” source

• Ornithischian that lived in the Late Jurassic in what is now Colorado (also Wyoming)
• Often illustrated as a “tiny dinosaur”
• Not much is known about it (mostly based on fossils that were later referred to Othnielosaurus)
• May have been 3-6.5 ft (1-2 m) long, though it’s uncertain
• Herbivorous
• Described in 1877 by Othniel Charles Marsh
• Marsh named three species: Nanosaurus agilis, Nanosaurus victor, (named together) Nanosaurus rex (named later in the same year, 1877)
• Marsh also named the family Nanosauridae
• Later Nanosaurus became thought of as a hypsilophodontid, because it was small and somewhat looked like Hypsilophodon (instead of Nanosauridae)
• Type species is Nanosaurus agilis
• Name means “small or dwarf lizard”
• Supposedly Marsh liked studying small dinosaurs from the Morrison Formation because Cope and his team had trouble finding them
• Oramel Lucas, a school intendant, found Nanosaurus agilis (ilium, thigh bones, shin bones, fibula, dentary impressions)
• Marsh’s description of Nanosaurus agilis was very short (no illustrations or even information on the locality where it was found, other than “Mesozoic deposits of the Rocky Mountains”), but he did say it was “the most diminutive dinosaur yet discovered”
• Possible that Marsh didn’t describe the locality of Nanosaurus agilis because Oramel Lucas worked for Edward Drinker Cope. Supposedly Marsh’s assistant Benjamin Mudge visited Lucas, who wasn’t too happy with Cope. Mudge convinced Lucas that his arrangement with Cope was only for large fossils, and that he could sell his small fossils to anyone (so he sold Nanosaurus agilis)
• Marsh illustrated some of the Nanosaurus agilis fossils in 1894ish, and gave more descriptions, saying it was very bird-like and “about half as large as a domestic fowl”
• Nanosaurus victor was thought to be larger than Nanosaurus agilis (fox sized versus cat sized)
• Nanosaurus rex was a little bigger than Nanosaurus agilis
• Marsh later renamed Nanosaurus victor as Hallopus victor (1881)
• In 1970 Alick Walker found that Hallopus victor was actually small bipedal crocodylomorph
• Nanosaurus rex was known from a complete thigh bone
• In 1973, Peter Galton and Jim Jensen described a partial skeleton as Nanosaurus rex (no head, hands, or tail)
• In 1978, Peter Galton found that the rock with Nanosaurus agilis fossils had two right femora, which showed two animals were there. He found the smaller femur was Nanosaurus rex and the larger one Nanosaurus agilis
• Galton named a new family Fabrosauridae to include Nanosaurus agilis (primitive ornithischians)
• Galton made Nanosaurus rex the type species of the hypsilophodontid genus, Othnielia, so Nanosaurus rex became Othnielia rex (named in honor of Marsh)
• Not everyone agreed with Fabrosauridae existing
• In 2007 Galton suggested Nanosaurus agilis be possibly a basal ornithopod instead
• To sum up: only Nanosaurus agilis is a valid species (Nanosaurus rex is now Othnielia rex and Nanosaurus victor is now Hallopus victor)

Fun Fact: Much of Europe was under water throughout the Mesozoic which means we don’t have many dinosaur fossils. However, Scandinavia and northwest Russia were out of the water for almost all of the Mesozoic and formed a pretty massive island in the Cretaceous. Unfortunately, the mountains there had already formed, and most of the rock is over a billion years old so we get very few dinosaurs from there as well.

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This episode is brought to you in part by Indiana University Press. Their Life of the Past series is lavishly illustrated and meticulously documented to showcase the latest findings and most compelling interpretations in the ever-changing field of paleontology. Find their books at iupress.indiana.edu