Jump to content

Hell Creek Fm: How to ID Dakotaraptor steini


Troodon

Recommended Posts

Trying to differentiate a small to midsize Nanotyrannus and Dakotaraptor is pretty difficult.

 It appears that Dakotaraptor teeth are not common and sellers are quick to assign Nanotyrannus teeth to them.   You need to look at all the characteristics before making a determination on a tooth and it may turn out to be indeterminate.

 

 REMINDER we have a limited view of these teeth.   We have not see a complete dentition and most likely there some variations in dental positions.   What is listed below is our current knowledge based on isolated teeth and the few found with the holotype.   Like to thank Walter Stein for his input and allowing me to photograph a tooth in his collection. 

 

It's a Dromaeosaurid so it will have similarities to Acheroraptor but there are differences.

 

1)  Smooth Crown   

     These teeth do not have the vertical ridges found in Acheroraptor and are larger and beefier

 

2)  Serration Density

The serrations on the mesial (outer) edge are greater than the distal ( inside ) carina  (measured midline over 5 mm)

Mesial: 5-6 serration/mm

Distal: 4-5 serrations/mm 

These are from Adult Teeth -- juvenile teeth may be greater but there is always a difference

Caution: Small Nano teeth can be found with mesial densities greater than distal but are not has fine around 2 to 3 /mm

 

3) Carina Shape/Location

Distal: Extends to the base

Mesial: Often does not reach the base and is straight but reach is depended on position Can end 1/3 from the base.   We have yet to understand the morphology of the entire dentition but belive all carinae are straight

Nanotyrannus:  Mesial carina may have a slight sigmoidal twist not extend to the base depending on location in jaw

 

4) Shape of Crown/Base

Teeth are recurved and compressed.   Base is elongate, narrow oval or almond shape in cross-section.  Usually has a greater height to length ratio than Acherorapter or Nanotyrannus.   Should be 1.6 to 1.9   (Crown Height/Length Base) 

Nanotyrannus typically has a rectangular base in cross-section 

 

Dakotaraptor Oval (From Walter Stein Collection)

P6070143A.jpg.17015cce94244057e7d72a2e55382628.jpg

 

 

Dakotaraptor Oval/Almond Shaped (from my collection)

dk2.thumb.jpg.584cee94fb608e3ea0aad46025e4a661.jpg

 

Nanotyrannus 

post-10935-0-72189200-1441301535_thumb.jpg.b644ee6e28d3c86a8c660d9416663df8.jpg

 

5) Size 

Crowns  7/8" (2-2.3 cm) in the holotype.  

 

6) Denticle Shape

Dakotaraptor: Rounded tip

Nanotyrannus: Chisel Shape tip

 

Dakotaraptor 

post-10935-0-09832100-1469294224_thumb.jpg.f020b263c29057dca0ebcd585d80fea1.jpg

P6070144A.jpg.7a970e441f2d1b0ff6b1f6c0717230cc.jpg

 

 

Nanotyrannus 

Nano5D1.jpg.4356cdfe497e5f523e375e1b1bd8d1fc.jpgNano4M1.jpg.bf678146e56aea8a14513835803b9342.jpg

 

Caution

1 Some of the characteristics overlap between Dakotaraptor and Nanotyrannus so you need to take a look at all of them before you make a call

2 The sample size of Dakotaraptor teeth is very small so we really do not have a good sense of what all tooth positions look like especially with juvenile one.

 

 

Screenshot_2019-03-04-06-05-14.thumb.jpg.cf9af2e42837a223578b0750e8d03ba9.jpg

 

Mesial carina may not extends to the base (red line) but should be straight no twist

Screenshot_2019-03-04-05-57-26.thumb.jpg.50e95174bf5406cff01ce0023e34ee68.jpg

 

 

 

Examples 

 

DakotaR1.thumb.jpg.8cc91873fdef0107392a1a7c7a2a6d56.jpg

 

 

 

Foot claws

Only foot claws have been found see photo. The large claw is Digit II killing claw and the other claw is typical of the other three claws in the foot. NO hand claws have been found so we do not know what they look like.

post-10935-0-73985300-1446234618_thumb.jpg

  • I found this Informative 16
Link to comment
Share on other sites

Agree with you on being careful. Look at what happened with Acheroraptor. There was suddenly a giant surge of teeth that were being labeled as Acheroraptor once it was discovered.

Link to comment
Share on other sites

Thanks for informing us. And thank you Lord Trilobite for posting the paper

"Or speak to the earth, and let it teach you" Job 12:8

Link to comment
Share on other sites

Agree with you on being careful. Look at what happened with Acheroraptor. There was suddenly a giant surge of teeth that were being labeled as Acheroraptor once it was discovered.

I think why you saw the surge was that most of the Surornitholestes teeth in collections or with dealers turned out to be Acheroraptor. Not sure that will be the case here but it may a bit with Richardoestesia teeth fitting this bill.

Link to comment
Share on other sites

Yeah, I went though a several dozen small Hell Creek theropod teeth I had from both South Dakota and Montana today. None of them matched Dakotaraptor. All were either small nanos or large Acheroraptor. Certainly a rare component of the fauna there.

Link to comment
Share on other sites

Not good and you're correct these may be a difficult find in the Hell Creek. I'm sure most dealers like you are going through their inventory. Thanks for the update.

Link to comment
Share on other sites

Awesome. Fills a nice niche.

I have a tooth very close to the one on the right in the study picture. Denticles seem to match, mesial carina ends in the right place, it's compressed. However its not super curved, but the tip is missing from it.

Link to comment
Share on other sites

Awesome. Fills a nice niche.

I have a tooth very close to the one on the right in the study picture. Denticles seem to match, mesial carina ends in the right place, it's compressed. However its not super curved, but the tip is missing from it.

Pictures, size so we can take a look

Link to comment
Share on other sites

  • 8 months later...

Two Dromaeosaurids exist in the Hell Creek/Lance Formation: Dakotaraptor and Acheropraptor.

Identification of Dakotaraptor teeth appears to be a bigger task than what it was when Acheroraptor was first described. Unlike Acheroraptor, very few teeth are available for comparative purposes so it limits what we know to what is described in DePalma's paper (pg 2). What it tells us is that Dakotaraptor teeth follow the general Dromaeosaurid morphology and gives us a range of what the denticle density should be for both the mesial and distal carina. It also states that the denticle density does not overlap Tyrannosaurus which has caused some confusion. Comparative images is limited to this one

post-10935-0-24584700-1469292131_thumb.jpg

The large size of the Dakotaraptor tooth creates an identification problem because they can easily be confused with comparable sized Nanotyrannus teeth, mostly juvenile. We also have no paper describing Nanotyrannus teeth so we do not fully understand their morphology. What member Zekky and I have determined is that unlike what the paper says there is a crossover of denticle density with certain smaller Nano teeth that make identifications problematic. Looking at my Nano teeth I have seen denticle density being identical on both carinae and depending on position the Mesial carina can be larger or smaller than the Distal side. In looking at the source of information for the DePalma's paper it appears that only Tyrannosaurus teeth were considered and excluded juvenile Nanotyrannus.

So how can we identify Dakotaraptor teeth. I do not have a slam dunk answer just some aids we can consider when evaluating a tooth. Not all teeth may have an answer and remember identification of isolated theropod teeth is not an easy task. You first need to start with a good tooth with CRISP serrations on both edges.

We are fortunate that member Susan from PA happens to have one in her collection :wub: and we are able to have access to these photos.

post-10935-0-34247200-1469294547_thumb.jpgpost-10935-0-34285100-1469294551_thumb.jpg

First - its a Dromaeosaurid so the Mesial Carina denticle density should be greater than the Distal side. Mesial Range : 19-27 denticles per 5 mm Distal Range : 16-19 denticles per 5 mm

It appears that the density difference between the two carina is not as great as Acheroraptor but we have limited information because only a few teeth were recovered with the holotype.

Second - its all about the shape of the denticles

Dakotaraptor's denticle ends are rounded and not chisel/flat shaped (rectangular) like Nano or Tyrannosaurid

Acheroraptor

post-10935-0-40146900-1469294266_thumb.jpg

Dakotaraptor

post-10935-0-09832100-1469294224_thumb.jpg

Nanotyrannus

post-10935-0-22627000-1469295026_thumb.jpg

Third - The cheek teeth (excludes incisor or premaxillary) of Dakotaraptor for the most part are very compressed and symmetrical. You do not see the twist on the carina of the Mesial side that creates the D shape on Nano Teeth.

Identifying teeth online is going to be an bigger problem because the photos may not provide the information you need to make that call. Be very cautious of sellers its not an easy ID.

  • I found this Informative 9
Link to comment
Share on other sites

  • 2 years later...
On 10/31/2015 at 9:08 AM, Troodon said:

Here is a Dakotaraptor tooth

post-10935-0-07180000-1446242797_thumb.jpg

What about this??? The description labels it as raptor tooth from Hell Creek.

s-l1600 (10).jpg

s-l1600 (11).jpg

s-l1600 (12).jpg

Link to comment
Share on other sites

You cannot ID a Dakotaraptor just based on photos you need to know the  serration density, view of the base and closeup of the denticles.  Just based on size it's a  Nanotyrannus, Dakotaraptor teeth did not get that large.

  • I found this Informative 1
Link to comment
Share on other sites

16 hours ago, zekky said:

I don't even think that tooth is from Hell Creek. Looks Carch from Kem Kem.

It looks a tad slender for Carch though.

Olof Moleman AKA Lord Trilobite

Link to comment
Share on other sites

I revamped my first page to help everyone identify these teeth.  A thank you to  Walter Stein of PaleoAdventure for his support with this modification. 

 
Feel free to post potential candidates and will be glad to take a look.. I will need the following information:

Crown Height - CH

Crown Base Length - CBL

Crown Base Width - CBW

Distal Serration Count -

Mesial Serration Count - 

Photo of both sides 

Photo of mesial carina 

Photo of base

Closeup of denticles 

 

Screenshot_20190415-125247.thumb.jpg.b28eab8ac15eb107fb62df54457a36fd.jpg

  • I found this Informative 2
Link to comment
Share on other sites

  • Troodon changed the title to Hell Creek Fm: How to ID Dakotaraptor steini

I've received a number of PM's requesting an ID on Dakotaraptor teeth as well as those under the ID topic.    All of these inquiries have turned out to be Nanotyrannus teeth.   Sellers are not trying to ripoff collectors they just don't know how to properly ID them.   Unfortunately a Nanotyrannus tooth mimics DR quite closely so I urge extreme caution when buying.   You need to obtain the following information when you are interested in one and it cannot be identified without this information:


 - photos of the base and mesial (outside) carina    

- serration density of both carinae like I describe in the above posts

- a closeup of the serrations

(Sorry its not easy and it will require cooperation from the seller)

 

 

I recently had discussions with Walter Stein and have looked at one of his to insure that what I have are DR.  I've updated the first part of this topic to help in identification with teeth from his and my collection.  Reminder just because your teeth has some characteristics for DR it needs to be consistent with all of them to be one and some may be indeterminate.

Please feel free to continue to post your interest in the ID section of the forum and prefer that you not PM me.   I would like everyone to see what's going on.

 

  • I found this Informative 2
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...