Ankylosauridae & Nodosauridae Teeth - Can You differentiate?

[Troodon]

(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

 

[Xiphactinus]

Very cool. I hope to find a Niobrarasaurus tooth in Kansas someday.

[Troodon]

Please do, I'll be the first begging for it

[Triceratops]

Very informative. Thank you!

[Ridgehiker]

Curious. What are these types of teeth? Never sure if Ankylosaur or Pachycephalosaur. I find all types of variations of these teeth in various formations from 65 to 75 million years of age. Length 2cm with root.

[Troodon]

Tall one is Pachy. The other tooth is a Nodosaur. Genus/Species dependent on where you found them. The root structure can also help depending on jaw position. A Pachy's root typically tapers like yours. A Nodosaur root is straight.

Two nice teeth.

[Ridgehiker]

Tall one is Pachy. The other tooth is a Nodosaur. Genus/Species dependent on where you found them. The root structure can also help depending on jaw position. A Pachy's root typically tapers like yours. A Nodosaur root is straight.

Two nice teeth.

Thanks for the ID and the tips. It was just by chance I picked these two so it's fortunate there is one from each family. I thought they were the same.

At one time we used to call all of these type of teeth 'Ankylosaur' and thus why it's good to have the collecting info to more accurately rename the specimens according to age and formation.

[starman]

Interesting but lately there's been a lot of splitting. Taxa once lumped into Euoplocephalus are again considered valid. Also, a Lancian nodosaur may be some genus other than Edmontonia.

[Dracorex_hogwartsia]

Great write up! I see Pachycephalosaur teeth being sold as Ankylosaur teeth quite often. I saw one just today! Now the harder thing to do, is to be able to distinguish between a Pachycephalosaur and Thescelosaurus tooth. Not including the pre max teeth. If you have any thoughts on that please let me know.

Edited September 19, 2015 by Dracorex_hogwartsia

[Troodon]

Yes, lots of confusion with all these type of teeth why I did the post.

In my opinion, Pachy dentary teeth crowns have a prounced ridge down the middle of the tooth while Thesc are more fan like. I'm not home to take pictures of mine but these are nice examples from Paleodirect.

Pachycephalosaurus

Thescelosaurus

[Dracorex_hogwartsia]

That's the way I've always ID'd them too but both types of teeth are usually sold as Pachycephalosaur. What makes things more confusing, in Don Glut's first volume of Dinosaurs The Encyclopedia under Thescelosaurus, he shows pictures of Thescelosaurus neglectus teeth that look like both the teeth you provided pictures of. I just wonder if Pachy and Thesc teeth look so much alike that it's really impossible to tell them apart.

[Troodon]

That's the way I've always ID'd them too but both types of teeth are usually sold as Pachycephalosaur. What makes things more confusing, in Don Glut's first volume of Dinosaurs The Encyclopedia under Thescelosaurus, he shows pictures of Thescelosaurus neglectus teeth that look like both the teeth you provided pictures of. I just wonder if Pachy and Thesc teeth look so much alike that it's really impossible to tell them apart.

I looked at a couple of skulls with REAL teeth and they were all leaf shaped without the rise in the center. I don't have an answer but will continue to call them the way I have.

[Dracorex_hogwartsia]

I looked at a couple of skulls with REAL teeth and they were all leaf shaped without the rise in the center. I don't have an answer but will continue to call them the way I have.

IMG_2136.jpg

This is why I was happy to luck upon this website and to find you in particular. There are a lot of us that have been collecting for a lot of years and have some pretty nice stuff but you're in a completely different league. With your extensive collection and knowledge I trust your opinion way more than that book.

[Troodon]

Updated the first page to reflect current research and publications

[Olenoides]

Very helpful guide.  What's the expert opinion on this one from the Judith?  Pachy?

 

 

[Troodon]

17 minutes ago, Olenoides said:

Very helpful guide.  What's the expert opinion on this one from the Judith?  Pachy?

 

 

 

 

What size is it?

[Olenoides]

Just now, Troodon said:

What size is it?

 

About 9mm

[Troodon]

Not a Pachy its an Ankylosauridae in the subfamily of Ankylosaurinae.  Might have genus do you have a County where its from just want to make sure its not Hell Creek or Two Medicine Fm.  Beautiful tooth.

[Olenoides]

Hill County

 

 

8 hours ago, Troodon said:

Not a Pachy its an Ankylosauridae in the subfamily of Ankylosaurinae.  Might have genus do you have a County where its from just want to make sure its not Hell Creek or Two Medicine Fm.  Beautiful tooth.

 

[Troodon]

Thanks

Although multiple ankylosaurinae are probably present only one is described from the JRF

Zuul crurivastator so good to go with that

[Dracorex_hogwartsia]

On 8/9/2020 at 2:25 PM, Olenoides said:

Very helpful guide.  What's the expert opinion on this one from the Judith?  Pachy?

 

 

Beautiful tooth! Was this self collected?

[DD1991]

On 8/21/2015 at 11:21 AM, Troodon said:

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)

 

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

 

Penkalski (2018) has erected Anodontosaurus inceptus for the DPF Anodontosaurus. Future study may determine that inceptus warrants its own genus, for which an appropriate name would be "Unescopelta" (in reference to Dinosaur Provincial Park, a hunting ground for Campanian dinosaurs in Alberta, being a UNESCO World Heritage Site).

 

Also, Bakker (1998) erected the subgenus Chassternbergia for Edmontonia rugosidens, so a future paper may definitely elevate Chassternbergia to full genus, given that rugosidens is older than the Edmontonia type species. The holotype of the dubious nodosaurid Palaeoscincus costatus comes from the Judith River Formation of Montana, if anyone knows ankylosaur taxonomy and geography by heart, and was left of the list on purpose.

[Coco]

Marvelous !

 

Coco

[pachy-pleuro-whatnot-odon]

Indeed, very informative! Thanks for sharing this knowledge with us!

[jaredchl]

On 9/8/2020 at 2:25 PM, Olenoides said:

Very helpful guide.  What's the expert opinion on this one from the Judith?  Pachy?

 

 

its looks like Euoplocephalus tutus