Troodon Posted September 3, 2015 Share Posted September 3, 2015 Updated Nov 25, 2022 Collectors, online sellers and some dealers periodically ask me to help them in the identification of tyrannosaur type teeth. So I thought I would put together a guide from Western North America (US/Canada) to help in identification. The following is the current understanding of those Tyrannosaurids described/known with the stratigraphic unit where they are found. If I missed any let me know. Albertosaurus sarcophagus : Horseshoe Canyon Formation cf Albertosaurus indet: Wapiti Formation Gorgosaurus libratus : Dinosaur Park Formation Gorgosaurus sp. or cf Gorgosaurus: Two Medicine Formation, Oldman Formation, Foremost Formation, Daspletosaurus horneri : Two Medicine Formation Daspletosaurus wilsoni: Judith River Formation Daspletosaurus torosus : Oldman Formation Daspletosaurus sp. or cf Daspletosaurus: Dinosaur Park Formation Dynamoterror dynastes: Menefee Formation Tyrannosaurus rex : Hell Creek Formation, Lance Formation, Frenchman Formation, Scollard Formation, Denver Formation, (Trex fossils are also known from: Livingstone Fm, Laramie Fm, McRae Fm, Willow Creek Fm) Tyrannosaurus sp.: Javelina Formation, Ojo Formation Nanotyrannus lancensis : Hell Creek Formation, Lance Formation cf Nanotyrannus : Frenchman Formation, Scollard Formation, Denver Formation Thanatotheristes degrootorum : Foremost Formation Tyrannosaurid indet. (spp): Judith River Formation, Mesaverde Formation (Group), Fruitland Formation, Aguja Formation Teratophoneus curriei: Kaiparowits Formation Lythronax argestes: Wahweap Formation Nanuqsaurus hoglundi: Prince Creek Formation Tooth Identification Aublysodon mirandus Premaxillary teeth, those without serrations. This dinosaur is considered nomen dubium and teeth ascribed to it belong to other Tyrannosaurs. Albertosaurus sarcophagus Probably the easiest to identify since its the only Tyrannosaurid described from the Horseshoe Canyon Formation. The most important item in acquiring one of these teeth is the provenance of where it was found. Alberta is not adequate to identify it. You need a specific locality like Drumheller or Tolman Bridge. BTW this is true for all the Tyrannosaurid's discussed in this topic. A disposition is also needed for all dinosaur teeth removed from Alberta. These teeth can get quite large from collection of SMM Gorgosaurus libratus (cf, sp.) The first step in identification is Provenance: you need to know State/Province along with the County (USA) or Locality (Canada) where the tooth was found. Differentiating isolated teeth between Gorgosaurus and Daspletosaurus is very difficult and in most cases its indeterminate. A paper that came out in 2005 which was authored by Phil Currie et al. studied isolated teeth from this period looking at tooth and serration morphology. Their conclusion was that "it is difficult to quantifiably distinguish these teeth reliably by taxon". Therefore identifying them as Tyrannosaurid indet. is the easiest approach in those faunas that Gorgosaurus may be present? There is a quantitative process described in a new paper that may help which will be discussed later. Please note that lots of collectors would like to use size to differentiate these teeth from Daspletosaurus. However Gorgosaurus teeth can get quite large as seen in this photo of a Maxilla with one tooth which is over 3 inches and located in the back of this jaw. Daspletosaurus horneri, D. wilsoni, D. torosus (cf, sp.) The first step in identification is Provenance: you need to know State/Province along with the County (USA) or Locality (Canada) where the tooth was found. A paper that came out in 2005 which was authored by Phil Currie et al. studied isolated teeth from this period looking at tooth and serration morphology. Their conclusion was that "it is difficult to quantifiably distinguish these teeth reliably by taxon". Therefore identifying them as Tyrannosaurid indet. is the easiest approach in those faunas that Daspletosaurus may be present? However, its reasonable to say that teeth over 4" are PROBABLY from a Daspletosaurus. There is a quantitative process described in a new paper that may help which will be discussed later. *****Since the Judith River and Two Medicine Formations fall within the range of all three of these species its going to be difficult to assign teeth to a specific species unless you know the age of the deposit it. Denver Fowler: "Hill County exposures are more easy to date because there we have the boundary between the upper Oldman Fm and the lower part of the Dinosaur Park Fm. Havre exposures were called Judith River Fm historically, but we should probably use Oldman & Dino Park now." And maybe ditto for those teeth found in the Belly River Group of Alberta. Denver Fowler "I expect that D. wilsoni is stratigraphically equivalent to the lower part of the Dinosaur Park Formation. At the moment this is based on the fact that the Judith in eastern Montana was deposited at the time when the WI seaway was receded at its maximum (in the Campanian)" Denver's response to my question on this subject. "There isn't currently any evidence for stratigraphic (time) overlap between the species. However, the 2Med and Judith River likely represent enough time such that it would be possible to find D. torosus in the Judith and both D. torosus and D. wilsoni in the 2Med." (Posted by Denver Fowler) Tyrannosaurus rex/ Nanotyrannus lancensis (cf, sp.) Whether you agree or disagree that Nanotyrannus is a valid taxon what is very clear to me is that we have two distinct morphologies of tyrannosaurid teeth at the very end,of the cretaceous. I can say that because I have handled over 1000 teeth over the years ranging from 3 mm to 5 inches two morphs are present in all ranges up to around 2 inches. Serration density through sampling I've done with teeth in my collection do not appear by itself to be a differentiator between these two morphologies. Density will change with size becoming less on larger teeth and can be the same with equivalent size teeth with both morphologies. DSDI (Denticle Size Difference Index) is also not a differentiator and through my sampling and Carr (2004) and indicates that DSDIs decrease in progressively larger specimens, that is, there are fewer mesial denticles per given unit length than distal denticles in large specimens and there are as many or more mesial than distal denticles in small specimens. Also, the DSDI among dentary teeth is higher than that in the maxilla, indicating that mesial denticles are smaller in the dentary than in the maxillary dentition. So how do you tell the difference between these two morphologies. Well, if a tooth is larger than 2 1/2" and has bulk its clearly T rex, regardless of what the serrations say. It cannot be anything else. With small teeth since serrations density is not a differentiator the other characteristic of the tooth plays a key role. I've found that maxillary teeth can be the most difficult to differentiate and a few teeth are just indeterminate, at least with me. The best way to distinguish between the two morphology the shape at the base, compression of the crown and tip and if there is a pinch at the base. Shape at the base T rex dentary teeth and the very anterior maxillary teeth are oval at the base while Nano teeth are unique as tyrannosaurids and rectangular. However, T rex maxillary teeth can be rectangular so you will have to determine if there is a pinch at the base a characteristic found on Nanotyrannus teeth Here are examples of the cross sections of couple small Rex teeth under 1 1/2 inch and Adult Nano's Tyrannosaurus rex Dentary teeth are oval Maxillary Teeth are rectangular Nanotyrannus Bases are rectangular and show a pinch on both sides. Profile of the teeth is another characteristic Nanotyrannus teeth are compressed, with a pointed tip T rex teeth are fat, with a rounded tip, often the serrations wrap around from the mesial to distal carina to form a continuous carina Crown Height Ratios In the study I did, since nothing is published, with 30 Nanotyrannus teeth the average was 2.2 For Trex teeth the mean for Maxillary teeth is 1.75 and for Dentary its around 2 but all these can change depending on position Heterodonty in Tyrannosaurus rex: implications for the taxonomic and systematic utility of theropod dentitions Joshua B. Smith (2005) T rex Premaxillary Teeth can easily be confused with dentary D1 position. Here is a photo of how to determine what you have. Identifying Gorgosaurus and Daspeletosaurus Teeth using Dental Features A recent paper by Hendrickx et al. (Oct 2019) has provided us a way to try to identify certain teeth using dental features. Positional Daspletosaurus & Gorgosaurus teeth have distinct denticle features that can hopefully can be used to differentiate the species which currently does not exist. Together with @Omnomosaurus we are looking at studying this technique to determine if its a practical method for collectors to use for identification, obtain data on campanian tyrannosaurid teeth and try to understand if the results we are getting is any good? We will be using teeth from my collection and members for the study. @dinosaur man has a topic where a lot of member data will be collected. Step 1 The most critical part in using this process is knowing where the tooth sits in the jaw - Premaxillary, Mesial or Lateral Here is a photo of to help in determining its location Paper https://www.researchgate.net/publication/261630184_Morphometry_of_the_teeth_of_western_North_American_tyrannosaurids_and_its_applicability_to_quantitative_classification Step 2 DSDI (Denticle Size Difference Index) needs to be determined DSDI = MC / DC MC = Number of denticles per 5 mm on the mesial carina at mid-carina DC = Number of denticles per 5 mm on the distal carina at mid-crown Mesial Carina is on the outer curvature Distal Carina is on the inside curvature Step 3 1) If your tooth is from a lateral position in the jaw and your DSDI is <0.8 your tooth may be considered a Gorgosaurus or cf Gorgosaurus depending on the locality of where it was found. 2) If your tooth is from a Mesial position in the jaw and your DSDI is >1.2 your tooth may be considered a Daspletosaurus sp. or cf Daspletosaurus depending on the locality of where it was found. Premaxillary Teeth 1) In my opinion all these teeth should be identified as "Tyrannosaurid indet" 2) The paper does make the following statement "In the young specimens of Daspletosaurus, the carinae of the premaxillary teeth are unserrated (TMP 1994.143.1; Currie, 2003) and show the beaded condition. My concern is that it does not specify what size young teeth are and its looking at TMP 1994.143.1 which is a Daspletosaurus sp in Dinosaur Park Fm. Do all Daspletosaurus premax teeth in other faunas have contain similar features? Gorgosaurus premax teeth are not mentioned. Study Currently 33 teeth from the collection of Troodon, Omnomosaurus, dinosaur man Localities included : Judith River Formation (18 teeth), Two Medicine Formation (13 Teeth), Dinosaur Park Formation (1 Tooth), One unknown Results: 1) None of the lateral teeth have had DSDI < 0.8 and could be described as Gorgosaurus 2) Three of the Mesial teeth had DSDI > 1.2 and could be described as Daspletosaurus 3) One of the Premaxillary teeth was not serrated but could not verify if it was a young tooth 4) So 9% of the population can be tentatively assigned Hendrickx et al paper https://palaeo-electronica.org/content/2019/2806-dental-features-in-theropods 32 1 Link to comment Share on other sites More sharing options...
Runner64 Posted September 3, 2015 Share Posted September 3, 2015 Once again, another great guide to dinosaur teeth. Will definetly be looking for mislabeled teeth now. Link to comment Share on other sites More sharing options...
ZiggieCie Posted September 3, 2015 Share Posted September 3, 2015 I hope they mark this for the hundreds of questions presented on is this a T-Rex tooth? Link to comment Share on other sites More sharing options...
PFOOLEY Posted September 5, 2015 Share Posted September 5, 2015 (edited) I acquired it as a "raptor" tooth from the Lance Formation...the animal was described as being like Velociraptor. I have admired it for some time and started doubting its label... ...then, your posts. I am thinking this is a Tyrannosaur tooth. Edit: minimized spacing at end of post. Edited September 5, 2015 by PFOOLEY 2 "I am glad I shall never be young without wild country to be young in. Of what avail are forty freedoms without a blank spot on the map?" ~Aldo Leopold (1887-1948) New Mexico Museum of Natural History Bulletins Link to comment Share on other sites More sharing options...
Troodon Posted September 5, 2015 Author Share Posted September 5, 2015 Beautiful tooth. We're almost there, need to see serrations on thge anterior side. Are you sure its Lance,looks more like Judith River preservation Link to comment Share on other sites More sharing options...
PFOOLEY Posted September 5, 2015 Share Posted September 5, 2015 Beautiful tooth. We're almost there, need to see serrations on thge anterior side. Are you sure its Lance,looks more like Judith River preservation Thanks, I like it. A number of years ago, I traded some Smithsonite for my first dinosaur fossils...this is one of them. The label said "Raptor tooth, Lance Formation"... that's as sure as I can be. 1 "I am glad I shall never be young without wild country to be young in. Of what avail are forty freedoms without a blank spot on the map?" ~Aldo Leopold (1887-1948) New Mexico Museum of Natural History Bulletins Link to comment Share on other sites More sharing options...
Troodon Posted September 5, 2015 Author Share Posted September 5, 2015 What I expected but it really does not matter its too fat and not enough recurve for it to be a raptor. You made a good deal, since you may be the proud owner of a Tyrannosaur tooth but I do need to see the anterior serrations. Want to make sure its not a type a dromaeosaur. 1 Link to comment Share on other sites More sharing options...
PFOOLEY Posted September 5, 2015 Share Posted September 5, 2015 I don't see serrations...need to get closer. "I am glad I shall never be young without wild country to be young in. Of what avail are forty freedoms without a blank spot on the map?" ~Aldo Leopold (1887-1948) New Mexico Museum of Natural History Bulletins Link to comment Share on other sites More sharing options...
Troodon Posted September 5, 2015 Author Share Posted September 5, 2015 Their probably worn, do you have a scope? 1 Link to comment Share on other sites More sharing options...
PFOOLEY Posted September 5, 2015 Share Posted September 5, 2015 Ooooh, they're there. 1 "I am glad I shall never be young without wild country to be young in. Of what avail are forty freedoms without a blank spot on the map?" ~Aldo Leopold (1887-1948) New Mexico Museum of Natural History Bulletins Link to comment Share on other sites More sharing options...
Troodon Posted September 5, 2015 Author Share Posted September 5, 2015 Nice photo, serrations a bit worn but I'm seeing what I need to (similar serrations on both sides). So it looks like you have a tyrannosaurid tooth, congratulations. If we believe it came from the Lance and being that plump, not compressed its a good chance its a maxillary tooth of a very young Rex. Label it as you choose. Over the years I've picked up many small teeth labeled raptor simply because of size 4 Link to comment Share on other sites More sharing options...
PFOOLEY Posted September 5, 2015 Share Posted September 5, 2015 Thank you for your informative post on what to look for. "I am glad I shall never be young without wild country to be young in. Of what avail are forty freedoms without a blank spot on the map?" ~Aldo Leopold (1887-1948) New Mexico Museum of Natural History Bulletins Link to comment Share on other sites More sharing options...
Troodon Posted September 5, 2015 Author Share Posted September 5, 2015 You made my day, that what those type of posts are for. Thank you Link to comment Share on other sites More sharing options...
-Andy- Posted September 5, 2015 Share Posted September 5, 2015 I just got a new T-Rex mandible tooth, so here's some pics as reference if you're ever getting one yourself. Indications of it being T-Rex are the size (3 3/4"), thickness, D-shape profile seen from third picture, and oval cross-section. 1 Looking forward to meeting my fellow Singaporean collectors! Do PM me if you are a Singaporean, or an overseas fossil-collector coming here for a holiday! Link to comment Share on other sites More sharing options...
Troodon Posted September 5, 2015 Author Share Posted September 5, 2015 Beautiful tooth and you need to look at nothing more than size, it says Rex no analysis needed. By the way, teeth from the mandible are called Dentary teeth and I would lean toward yours being a Maxillary tooth simply because its a bit compressed at the root. Dentary teeth are more oval. Either way its a wonderful addition to your collection. 4 Link to comment Share on other sites More sharing options...
-Andy- Posted September 5, 2015 Share Posted September 5, 2015 Beautiful tooth and you need to look at nothing more than size, it says Rex no analysis needed. By the way, teeth from the mandible are called Dentary teeth and I would lean toward yours being a Maxillary tooth simply because its a bit compressed at the root. Dentary teeth are more oval. Either way its a wonderful addition to your collection. Thanks for the analysis! You and other collectors should put some pics of their own Rex as well. It'd be great reference to others. Looking forward to meeting my fellow Singaporean collectors! Do PM me if you are a Singaporean, or an overseas fossil-collector coming here for a holiday! Link to comment Share on other sites More sharing options...
Troodon Posted September 5, 2015 Author Share Posted September 5, 2015 Thanks for the analysis! You and other collectors should put some pics of their own Rex as well. It'd be great reference to others. Agreed would love to see other collectors. I will put mine up. Link to comment Share on other sites More sharing options...
-Andy- Posted December 13, 2015 Share Posted December 13, 2015 Bumping this useful thread with pics of confirmed T-Rex teeth I found off Ebay. Teeth 1 - Harding County, South Dakota 3.15 inches, sold Teeth 2 - Carter County, Montana 3.2 inches, sold 1 Looking forward to meeting my fellow Singaporean collectors! Do PM me if you are a Singaporean, or an overseas fossil-collector coming here for a holiday! Link to comment Share on other sites More sharing options...
Troodon Posted December 14, 2015 Author Share Posted December 14, 2015 Two nice teeth. No guide needed for these two bad boys. Top one is beautiful 1 Link to comment Share on other sites More sharing options...
AnatomicFlack Posted January 1, 2016 Share Posted January 1, 2016 (edited) Hey Guys, I'm very new here, but been collecting for a bit. I'm nowhere near any fossil sites, so my "collecting" is all done online. I actually purchased that second tooth shown above. I have a few other T-Rex teeth that are pretty much undisputed, but I have a few I would like to get your opinion on if that's ok. I'm going to just share a shot of my Tyrannosaur/Theropod shelf here and wait before I bombard you guys with images of the teeth for identification. I can handle the macro photography of them, but which angles would best help positive identification? You can see the tooth mentioned on the rear right of the glass dome. It's the largest tooth I have, but the one on the rear left in the dome is still my favorite at just about 2.5" but has a nice heft and classic shape to the serrations. One of the specific teeth (in question) is the one to the far right of the dome... I bought it from a seller who actually acquired it in trade, many years ago, from Pete Larson. The tooth is very heavily reconstructed/restored though, but the shape to me feels too narrow to be T-Rex. I also figure any shots I take, that are definitely T-Rex, could certainly help others in future to accurately identify other teeth. Happy to have found the community. -Nick Edited January 1, 2016 by AnatomicFlack 1 1 Link to comment Share on other sites More sharing options...
Troodon Posted January 2, 2016 Author Share Posted January 2, 2016 (edited) Nice collection, if you would like an opinion on a specific tooth please take photos of both sides and the base so I can get a good look at it. Edited January 2, 2016 by Troodon Link to comment Share on other sites More sharing options...
AnatomicFlack Posted January 2, 2016 Share Posted January 2, 2016 Thanks. I will post some pics tonight. Link to comment Share on other sites More sharing options...
-Andy- Posted January 3, 2016 Share Posted January 3, 2016 Nick! You are the one who bought the Pete Larson tooth! I was bidding against you haha. Fantastic collection btw. First time I've seen any collector(besides Troodon) with enough Rex to make a whole section on his own. Looking forward to meeting my fellow Singaporean collectors! Do PM me if you are a Singaporean, or an overseas fossil-collector coming here for a holiday! Link to comment Share on other sites More sharing options...
AnatomicFlack Posted January 3, 2016 Share Posted January 3, 2016 (edited) Hey Andy... Sadly the history of the tooth ended up more interesting than the actual tooth. You'll see from the pics. I have all the images I snapped tonight here: (I didn't want to overload the thread with too many photos, so I'm only going to post one side profile, and root shot from each tooth, the album has both side profiles, and on the larger teeth the carina profiles) http://imgur.com/a/P4yH9 (For anyone interested in being able to make out individual denticles (not kidding), here is the full resolution album) http://imgur.com/a/FFYtE Here is the whole collection: Here is tooth #1: 1.2" Tooth Here is tooth #2: 2" Larson Tooth Here is tooth #3: a 1.15" Tooth Tip Here is tooth #4: a 0.85" Tooth Tip Just for fun... here are a couple pics of my two favorite teeth. 2.5" 2" Pre-Max I'm happy to try and take other shots, of these or the other teeth, if they would be helpful others identify in the future. Thanks in advance! -Nick Edited January 3, 2016 by AnatomicFlack 1 Link to comment Share on other sites More sharing options...
Troodon Posted January 3, 2016 Author Share Posted January 3, 2016 Nick took a look at the four teeth you had a question on. Tooth #1 I would lean toward it being a T-rex, probably a maxillary tooth. Tooth #2 the Larsen tooth I would label it as a Tyrannosaurid. Reason, the restoration and condition has altered some of the diagnostic features I look at the base and tip. The tooth is also compressed with fine serrations which do not help the case for Rex. Could be one but not a slam dunk for me why I said Tyrannosaurid. Tooth #3 & 4 Identifying teeth based on tips is very problematic simply because you need to see the whole tooth to accurately make that call. I would lean toward #3 being a Rex because of the bulk, shape of serrations and that they go around the tip. I'm not that confident with #4 and label it as Tyrannosaurid. Again nice collection. 1 1 Link to comment Share on other sites More sharing options...
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