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Identification Tyrannosaurid Teeth From Canada & United States


Troodon

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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

20230224_111817.thumb.jpg.f1d32e845ebc4eb8bb22d247df03db83.jpg

 

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.   

 

Gorgosaurus.thumb.jpeg.c9dfca7784540a0a552950bedccbbf99.jpeg

EHLDm7rWoAANaa_.thumb.jpeg.2af1398bd357f345003f5aa7ccf16eed.jpeg

 

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."

 

20221125_073905.thumb.jpg.2a8c4e272166f74e948d42b03869a35c.jpg

(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

post-10935-0-13599200-1441301366_thumb.jpgpost-10935-0-78792500-1441301374_thumb.jpg

 

Maxillary Teeth are rectangular 

8F5ADF7A-8068-4FCD-9010-E4E846EAA5F4.jpeg.856ffb34019969a366dbd21376a4888b.jpg.7b1747284b523f9c60793811d47c73e5.jpg


 

 

Nanotyrannus

 Bases are rectangular and show a pinch on both sides.

 

Nano8TBa.jpg

 

Profile of the teeth is another characteristic

 

Nanotyrannus teeth are compressed, with a pointed tip

Nano8TFFc.jpgNano13TFFb.jpg

 

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

REX3TFFb.jpgRex4TBFF.jpg

 

 

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

 

trexmorph.thumb.JPG.36977ac3f1c73c6c036e9fdf554cc651.JPG

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.

 

Screenshot_20190408-103048.jpg

 

 

 

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

 

Screenshot_20170405-035353.thumb.jpg.a29a3626405e2a3ac639c738e421228e.jpg

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

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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.

post-11220-0-50616800-1441420263_thumb.jpg post-11220-0-10528000-1441420253_thumb.jpg

Edit: minimized spacing at end of post.

Edited by PFOOLEY
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"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    

 

point.thumb.jpg.e8c20b9cd1882c9813380ade830e1f32.jpg research.jpg.932a4c776c9696d3cf6133084c2d9a84.jpg  RPV.jpg.d17a6f3deca931bfdce34e2a5f29511d.jpg  SJB.jpg.f032e0b315b0e335acf103408a762803.jpg  butterfly.jpg.71c7cc456dfbbae76f15995f00b221ff.jpg  Htoad.jpg.3d40423ae4f226cfcc7e0aba3b331565.jpg  library.jpg.56c23fbd183a19af79384c4b8c431757.jpg  OIP.jpg.163d5efffd320f70f956e9a53f9cd7db.jpg

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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

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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. ;)

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"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    

 

point.thumb.jpg.e8c20b9cd1882c9813380ade830e1f32.jpg research.jpg.932a4c776c9696d3cf6133084c2d9a84.jpg  RPV.jpg.d17a6f3deca931bfdce34e2a5f29511d.jpg  SJB.jpg.f032e0b315b0e335acf103408a762803.jpg  butterfly.jpg.71c7cc456dfbbae76f15995f00b221ff.jpg  Htoad.jpg.3d40423ae4f226cfcc7e0aba3b331565.jpg  library.jpg.56c23fbd183a19af79384c4b8c431757.jpg  OIP.jpg.163d5efffd320f70f956e9a53f9cd7db.jpg

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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.

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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

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I just got a new T-Rex mandible tooth, so here's some pics as reference if you're ever getting one yourself.

post-4888-0-28496700-1441436740_thumb.jpg post-4888-0-04052700-1441436749_thumb.jpg post-4888-0-16735700-1441436752_thumb.jpg post-4888-0-10454100-1441436755_thumb.jpg

Indications of it being T-Rex are the size (3 3/4"), thickness, D-shape profile seen from third picture, and oval cross-section.

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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!

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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.

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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!

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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.

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  • 3 months later...

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

post-4888-0-74708100-1449977205_thumb.jpg post-4888-0-85199100-1449977206_thumb.jpg post-4888-0-88305000-1449977207_thumb.jpg post-4888-0-61637900-1449977208_thumb.jpg post-4888-0-40342400-1449977209_thumb.jpg

Teeth 2 - Carter County, Montana

3.2 inches, sold

post-4888-0-41581500-1449979104_thumb.jpg post-4888-0-27418900-1449979105_thumb.jpg post-4888-0-72100000-1449979106_thumb.jpg post-4888-0-55892200-1449979107_thumb.jpg post-4888-0-05577500-1449979108_thumb.jpg

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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!

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  • 3 weeks later...

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?

YIdaCz7.jpg

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 by AnatomicFlack
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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 by Troodon
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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!

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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:

nh5JM9M.jpg

Here is tooth #1: 1.2" Tooth

nNNYwzY.jpg

gvEtmkn.jpg

Here is tooth #2: 2" Larson Tooth

ymlVEJI.jpg

Z6PSR34.jpg

Here is tooth #3: a 1.15" Tooth Tip

mfxsn56.jpg

FuvLTq2.jpg

Here is tooth #4: a 0.85" Tooth Tip

wufyrpQ.jpg

38f54ho.jpg

Just for fun... here are a couple pics of my two favorite teeth.

2.5"

Kz9quMj.jpg

Gx74n9S.jpg

2" Pre-Max

fJGbXxu.jpg

14Susk6.jpg

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 by AnatomicFlack
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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.

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