Episode 257 is all about Kritosaurus, a hadrosaur that was found over 100 years ago in New Mexico.
We also interview Scott Hartman, a paleo artist and lecturer at the University of Wisconsin, Madison for the Department of Integrative Biology. He’s done hundreds of skeletal drawings and his work has been featured in books, museums, and academic publications. Follow him on facebook or twitter @skeletaldrawing or skeletaldrawing.com
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In this episode, we discuss:
News:
- News from poster sessions and 2nd day of talks at the 2019 meeting of the Society of Vertebrate Paleontology source
- Early Mesozoic herbivores filled in ecological niches that were left because of extinctions
- Regurgitalites (fossilized vomit) are out there, and they can give just as much information as coprolites (fossilized poop)
- Chemical testing of bones is looking to be a promising method of finding lost fossil localities
- Scott Hocknull described three successful case studies of getting the public involved with dinosaur discoveries during construction projects and mining operations
- Stuart Sumida showed an animation of evolution, using a Dimetrodon and other relatives
- Ariel Marcy has a new collaborative game about the scientific method, similar to the game Pandemic
- Taissa Rodrigues taught high schoolers in Brazil about evolution through paleo art
- Emanuel Tschopp found that sauropods from the Morrison Formation did not overlap as much as previously thought
- Kayleigh Wiersma showed that some sauropods may have had beaks in addition to their teeth
- Les Hearn and Amanda Williams published a paper about pain in dinosaurs, and found a lot of dinosaurs survived injuries that would have hurt their mobility and ability to hunt or run away from predators source
- The Field Museum in Chicago has new sensory stations, including one where you can smell Sue the T. rex’s breath source
- There’s a grassroots effort in Westchester New York to protect land with dinosaur tracks and fossils source
- Austin, Texas, as a weird neon green dinosaur, known as Mangiasaurus rex source
- Special Spaces Cleveland and the Jurassic World Live tour worked together to design a dinosaur bedroom for Ezra Boggs, a 6-year-old with cancer source
- Lego has a new 910 piece Dinosaur Fossils set source
The dinosaur of the day: Kritosaurus
- Hadrosaurid that lived in the Late Cretaceous in what is now New Mexico, US (Kirtland Formation)
- Estimated to be around 30 ft (10 m) long, based on comparisons to other genera
- Herbivore, and was both bipedal and quadrupedal
- Had a broad beak to crop plants
- Could eat plants with a grinding motion similar to chewing
- Continually replaced teeth (had dental batteries with hundreds of teeth)
- This is based on relatives (only fragments have been found)
- Type species is Kritosaurus navajovius
- Genus name means “separated lizard” and refers to how the cheek bones in the incomplete type skull are arranged
- Sometimes it’s been translated as “noble lizard” (referring to the “Roman nose” which in the original specimen was originally restored flat since the region was fragmented and disarticulated
- Barnum Brown found the type specimen in 1904 in San Juan County, New Mexico
- Most of the front of the skull was fragments or eroded, and Brown reconstructed it based on Edmontosaurus and left out many fragments (saw the fragments were different from Edmontosaurus but said it was because they were crushed)
- Brown wanted to call the animal Nectosaurus but then found out that name was already being used
- After Gryposaurus was described in 1914, Brown changed his mind about the specimen’s snout, and give it a Gryposaurus-like arched nasal crest, and synonymized Kritosaurus with Gryposaurus
- This stayed the case until 1990, and there were three species: Kritosaurus navajovius, Kritosaurus incurvimanus, and Kritosaurus notabilis (formerly Gryposaurus notabilis, then reassigned Kritosaurus notabilis in 1990s). Hadrosaurus breviceps (known only from a dentary) was assigned to Kritosaurus by Lull and Wright, but this isn’t accepted anymore
- Because of the synonymization, most depictions of Kritosaurus until 1990 look more like Gryposaurus (there was more Gryposaurus material)
- In 1990, Jack Horner and David Weishampel separated Gryposaurus and Kritosaurus, based on Kritosaurus’ partial skull (how the skull looked is unknown)
- Kritosaurus incurvimanus is now considered to be a synonym of Gryposaurus notabilis
- Horner described two skulls in 1922 from New Mexico that were different from Gryposaurus and referred them to Kritosaurus, but in 1993 Adrian Hunt and Spencer Lucas said they were separate genera, Anasazisaurus and Naashoibitosaurus
- Not everyone agrees with this
- Albert Prieto-Márquez in 2013 found that the type specimens of Kritosaurus and Anasazisaurus were the same, based on the elements found in both specimens, and said Anasazisaurus was a synonym of Kritosaurus but its own species: Kritosaurus horneri
- A Kritosaurus skull was later found in Texas, and a partial skull from Coahuila, Mexico, has been referred to Kritosaurus navajovius
- Type specimen of Kritosaurus consists of a partial skull and lower jaws, and some postcranial elements (most of the muzzle and upper beak are missing)
- Jim Kirkland and others found a partial skeleton described as Kritosaurus but Prieto-Marquez found it to be an indeterminate saurolophine (it was larger than other known specimens, at 36 ft (11 m) long)
- Had a heavy, rectangular-ish maxilla, and the lower beak had tooth-like outlines
- Had a unique crest (based on the skull of the Anasazisaurus specimen) with some bone from the nasals that came between and above the eyes and folded back under itself
- Had a flat head and solid crest
- Nasal crest may have been used for species recognition or social ranking, and may have had inflatable air sacs
- Other dinosaurs that lived around the same time and place include Alamosaurus, Parasaurolophus, Pentaceratops, Nodocephalosaurus, Saurornitholestes
Fun Fact: Nothronychus graffami is the most complete therizinosaurid, including its massive claws.
