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Ankylosauridae & Nodosauridae Teeth - Can You differentiate?
Troodon posted a topic in General Fossil Discussion
(EDITED 5/24/22) to add an undescribed Nodosaurid to Hell Creek/Lance Fm. I see a lot of misunderstanding on what is being sold online at auctions and dealers sites. Some have it correct but most mix up the terminology. So here is Anky 101 aimed at Novice collectors and I will keep it simple. What you see sold in most markets are teeth from late Cretaceous North American locations mostly Montana, Wyoming and the Dakota's so I will focus on those areas. (Hell Creek, Lance, Two Medicine and Judith River Formations) Teeth from Canadian locations will have similar characteristics. There are two basic families of armored dinosaurs in these regions Ankylosauridae and Nodosauridae. Ankylosaurids are the brutes with big tail clubs. Nodosaurids have no clubs but are fierce looking with big spikes projecting from its sides. You don't want to meet up with either family. So when these teeth come up for sale most are very worn and it can get difficult to ID, so if possible avoid buying those. There is also a variation in the teeth with jaw position. Wear facets are also very common on these teeth. My photographs show complete teeth that have little wear so you can see what they typically should look like. Let me call them your generic teeth and are good representation of these families. There are multiple genus that you run into and the species is dependent on what formation you are in, see below with what is currently understood. Some have yet to be described to a species level due to lack of skeletal remains but teeth are plentiful. Differentiating teeth between the two families is quite easy. For Ankylosaurids crowns are small with long roots with two key characteristics, a bulbous base, see white arrow and a prominent central ridge on SOME species like Ankylosaurus in the Hell Creek others it covers the entire face of the crown. Other examples of North American Ankylosaurids Nodosaur Teeth: Are much larger, both taller and wider than Ankylosaurids, a shelf is visible below a pocket in the crown, no center ridge. Looks like a mit. Hell Creek Formation Two Medicine Fm Undescribed Nodosaur Judith River FM If you are interested in additional reading let me suggest Dinosaur Systematics by Ken Carpenter. Its also a good book describing theropod teeth. Our current understanding of species described: based on the revised analysis by Paul Penkalski, 2018. These views might not be share by some paleontologists but thats normal. Let me also say that with new discoveries and research some of this is subject to change. Hell Creek and Lance Formation Ankylosaurus magniventris (Ankylosaurid) Denversaurus schlessmani (Nodosaurid) Indeterminate Nodosaurid: I have seen enough evidence (partial skeleton) that there exits an undescribed Nodosaurid (cf Glyptodontopelta) Judith River Formation Zuul crurivastator (Ankylosaurid) Undescribed Nodosaur Two Medicine Formation Oohkotokia horneri (Ankylosaurid) Edmontonia rugosidens (Nodosaurid) Dinosaur Park Formation Euoplocephalus tutus (Ankylosaurid) Anodontosaurus lambei (Ankylosaurid) Platypelta coombsi (Ankylosaurid) Scolosaurus thronus (Ankylosaurid) Dyoplosaurus acutosquameus (Ankylosaurid) Edmontonia rugosidens (Nodosaurid) Panoplosaurus mirus (Nodosaurid) Horseshoe Canyon Formation Anodontosaurus lambei (Ankylosaurid) Edmontonia longiceps (Nodosaurid) Oldman Formation Scolosaurus cutleri ? (Ankylosaurid) Undescribed Nodosaurid Revised systematics of the armoured dinosaur Euoplocephalus and its allies Paul Penkalski https://www.researchgate.net/publication/323579149_Revised_systematics_of_the_armoured_dinosaur_Euoplocephalus_and_its_allies- 37 replies
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This is a chunk I found in the Horseshoe Canyon Formation, specifically in the Horseshoe Canyon area. It’s shape and ridges look almost identical to a small Ankylosaur/Nodosaur osteoderm, but the texture suggests a random chunk of ironstone. I’m leaning towards ironstone, but I think there’s a chance it could be a really smooth osteoderm. Would any of you guys be able to tell for sure? Thanks!
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