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TEST DATA NEEDED - Quantitative Method for Identifying Campanian Age Tyrannosaurids of North America

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dinosaur man

This experiment is by @Troodon, @Omnomosaurus and me @dinosaur man.

 

 

Quote

@Omnomosaurus wrote:

 

 

A recent paper titled, 'Dental Features in Theropods' (Oct 2019), Hendrickx, C. et al, identifies a potential methodology for identifying previously indeterminable Tyrannosaurids from the Campanian deposits of North America. 

It has been decided that this potential method should be tested for reliability in practice using as much data as possible that can be collected from members of the forum willing to participate. For those members willing to contribute, the methodology can be found below:

 

 

Quote

@Troodon wrote:

 

 

Identifying Gorgosaurus and Daspeletosaurus Teeth using Dental Features

 

A very 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 process 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 post 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 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 it does not specify what size young teeth are, 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

 

Once measurements have been collected, please post your findings in this thread. Also include clear photos of your test examples where possible too.

 

This post will be updated as relevant data is collected.

 
Hendrickx et al paper

 

 
Thank you for participating!!

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dinosaur man

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Runner64
4 hours ago, dinosaur man said:

Unfortunately I don’t have any that would be useful for this study. Perhaps others may though

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dinosaur man

Ok Thank you

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paulyb135

I will take some measurements next week for you 

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Abstraktum

Thats my Tyrannosaurid tooth from Judith River Formation / Montana. 

 

Around 7 cm / 2.75 in

 

Can I help with that? :)

However not that much serration visible. Will have to take a closer look if there is enough to count.

 

Clipboard01.thumb.jpg.e55b575586f417e55c3fb174badba827.jpg

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dinosaur man
4 hours ago, Abstraktum said:

Thats my Tyrannosaurid tooth from Judith River Formation / Montana. 

 

Around 7 cm / 2.75 in

 

Can I help with that? :)

However not that much serration visible. Will have to take a closer look if there is enough to count.

 

Clipboard01.thumb.jpg.e55b575586f417e55c3fb174badba827.jpg

Thank you for now, can’t wait to see what it could possibly be after you do your serration count, if there enough are visible.

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zekky

15/16"  DSDI 1.125

 

Judith River Formation

20200105_095635.jpg

20200105_095646.jpg

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Troodon

If this topic is to be useful and you would like to participate we are going to need along with locality : CH, CBL and CBW in mm.   Mesial and Distal density and where the mesial carina ends.  In addition photos of the base and position in the jaw.  Appreciate any input, thanks.

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dinosaur man
On 1/11/2020 at 11:12 PM, zekky said:

15/16"  DSDI 1.125

 

Judith River Formation

20200105_095635.jpg  20200105_095646.jpg

Sorry @zekky for getting back to you so late your tooth could be Daspletosaurus but like Troodon said we are going to need the other information.

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