Dromaeosaur or Nanotyranus tooth?

[AJ Plai]

Hi I have had this Hell Creek tooth that was previously ID as Dromaeosaur (possibly Dakota Raptor) for a while and the other day I decided to get my magnifying camera out to take a deeper look at the specimen as I have heard that some Dromaeosaur and small Nanotyranus teeth can be quite challenging to tell apart from one another. These are the close up pics of the specimen that I am still a little unsure about: 

 

 

Mesial side with serration showing a little carinae twist 

 

 

Distal side with straight carinae that stretches down to the base of the tooth in straight line:

 

Cross-section looks a little rectangular with what seem like a small pinch on the sides?

 

 

From the initial observation under the scope it does seem like this could be a Nanotyranus tooth instead of a Dromaeosaur but I would like to hear the experts thought and input on it just to be sure. Thanks in advance!

 

 

[AJ Plai]

Forgot to add the picture of the specimen not so up-close so you could see the shape of the tooth:

 

[DinoFossilsUK]

Any chance you could do a serration count (over 5mm) at the centre of the tooth on both sides?  Given the twist on the mesial carina I'd say it's a Tyrannosaur tooth.

[Daniel Fischer]

You should know that Nanotyranus is actually a young Tyrannosaurus. due to an interesting study by jack Horner.

 

[Top Trilo]

3 hours ago, Daniel Fischer said:

You should know that Nanotyranus is actually a young Tyrannosaurus. due to an interesting study by jack Horner.

 

This is still up for debate and it has not been agreed upon. this is @Troodon's thread and it discusses the opposite, why Nanotyrannus is a valid species. It is very informative and I would recommend reading it

 

[AJ Plai]

11 hours ago, DinoFossilsUK said:

Any chance you could do a serration count (over 5mm) at the centre of the tooth on both sides?  Given the twist on the mesial carina I'd say it's a Tyrannosaur tooth.

 

Hi I counted the serrations under microscope and it looks like the mesial serration count is about 21 per 5 mm. whereas the distal serration count is about 16 per 5 mm.

[ThePhysicist]

I would say this is a Tyrannosaur tooth based on the size and shape of the serrations. If you favor Nanotyrannus being valid, I would say the CHR (Crown Height Ratio) leans it towards being a Nanotyrannus. A "twist" in the mesial carina is also more common in Nanotyrannus I believe (than T. rex).

 

I would still wait for more experienced eyes to weigh in, as dinosaurs aren't one of my specialties (yet). 

Edited April 17, 2021 by ThePhysicist

[Troodon]

Do you have a locality where this tooth was found to verify its Hell Creek?

 

The two Dromaeosaurids in the Hell Creek do not get that large.  The largest DR tooth in the holotype was 23mm.   Their mesial carina also do not have a twist and are much more compressed.  The base profile matches that of a Tyrannosaurid not these Dromaeosaurids.  I agree with the others Nanotyrannus .

 

FYI : Dakotaraptor is one word

[AJ Plai]

On 4/17/2021 at 6:50 PM, Troodon said:

Do you have a locality where this tooth was found to verify its Hell Creek?

 

The two Dromaeosaurids in the Hell Creek do not get that large.  The largest DR tooth in the holotype was 23mm.   Their mesial carina also do not have a twist and are much more compressed.  The base profile matches that of a Tyrannosaurid not these Dromaeosaurids.  I agree with the others Nanotyrannus .

 

FYI : Dakotaraptor is one word

 

Hi Troodon, thank you for your input and the correction; I got this several years back from a lot of assorted fossils that I purchased from CK Preparation, if I remember correctly there were assortment of fossils that were all marked as HC specimens, although if there may be possibility of error of locality or not I couldn't confirm or be sure a 100% to be honest....

 

Do you suspect that it may be from another locality?

Edited April 19, 2021 by AJ Plai

[Troodon]

I know CK and they collect in Garfield Co.  Montana with its HC

[jpc]

4 hours ago, Troodon said:

I know CK and they collect in Garfield Co.  Montana with is HC

I also know them, and yes they are strictly Hell Creek collectors.