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kinnza1

 Hello all,

 

Recently acquired 2 teeth, found and sold together, that I would love some insight and second opinions on.

 

Both teeth are described as Tyrannosaurid Indet, from the Judith River Formation. The seller described that he purchased them both together from the harvester, but due to the fact he was not the original collector, the information is isolated to the above information.

 

Smaller tooth is 15/16" long, dark chocolate color, and 1/4" wide. Serrations are present on front and rear edges, with serrations starting midway on the front edge.

 

Larger tooth is missing the front edge, appears sheared. Length is 1 1/8", width 5/16". Serrations present cleanly on rear edge, but again completely sheared from front edge. Color also deeper chocolate brown, but more horizontal banding. 

 

Can obtain more detailed and specific measurements of other needed dimensions if needed. 

 

Mainly I'm looking for a confirmation of Tyrannosaurid Indet distinguished from other theropods in the area at the time, as I have little experience positively IDing smaller tyrannosaurid material. I've actively worked on distinguishing Carcharodontosaur teeth from Rugops in the field in Morocco, but this is out of my field.

 

All help is greatly appreciated!

 

Will post more pictures in comments

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kinnza1

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Omnomosaurus

I'm anything but an expert, but I'd say they look the part for tyrannosaurid. We need a few more photos to take a good stab at identification though.

 

Could you take a photo of the cross sections of both teeth, and one each of the front & back views (with serrations facing front)?

 

If you can, a close up look at the serrations would also be great, to see their shape.

 

Would it also be possible to count the number of serrations over 5mm on the front & back (at least on the one tooth)? If they're roughly the same number on both sides, that's a strong hint it's tyrannosaur.

 

Also worth taking a look at this useful link:

 

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kinnza1

I can certainly measure the serrations once I have a moment to sit down with better measuring instruments.

 

More pictures on the way

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kinnza1

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Omnomosaurus

Great photos of the serrations there!

 

I'd say the second tooth (one with the worn mesial margin) is definitely Tyrannosaurid indet. from the chisel shape of those denticles and the oval cross section.

 

The first tooth looks like it might have a compression in the cross-sectional view (like a figure-of-eight shape), which is only usually seen in Nanotyrannus among the tyrannosaurids (not found in the Judith River Fm)....so this one could possibly be Dromaeosaurus - though I'm still leaning Tyrannosaurid.

 

If you could count the serrations over the space of 5mm from roughly the same place in the middle of the front & back of the tooth please, that'll answer it.

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Troodon

welcome to the forum

I think seeing the crown height and thickness of these teeth they would be tyrannosaurid but its good to double check to see if its not dromaeosaurid.   I would want to confirm that indeed they were from the JR formation can you provide the state and county where these were found.  Thanks.

 

Just an FYI, Rugops is not described from Morocco its from Niger.   There are indet. abelsaurids in Morocco that some sellers improperly call Rugops.

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kinnza1

Troodon, unfortunately the only information I have is from the middleman between myself and the original harvester. The original seller stated they were found in JDF, but I was unable to get more detailed information than that.

 

Also, the abelisaur material we collected in the field we just referred to as rugops, as abelisaur gets long winded after a while. Bad habits lol

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kinnza1
1 hour ago, Omnomosaurus said:

Great photos of the serrations there!

 

I'd say the second tooth (one with the worn mesial margin) is definitely Tyrannosaurid indet. from the chisel shape of those denticles and the oval cross section.

 

The first tooth looks like it might have a compression in the cross-sectional view (like a figure-of-eight shape), which is only usually seen in Nanotyrannus among the tyrannosaurids (not found in the Judith River Fm)....so this one could possibly be Dromaeosaurus - though I'm still leaning Tyrannosaurid.

 

If you could count the serrations over the space of 5mm from roughly the same place in the middle of the front & back of the tooth please, that'll answer it.

In a 5 mm span, the larger tooth with the damaged mesial edge, is at 15 serrations. The other, more complete tooth, comes in at 19 serrations on both the distal edge and the mesial edge

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Omnomosaurus
30 minutes ago, kinnza1 said:

In a 5 mm span, the larger tooth with the damaged mesial edge, is at 15 serrations. The other, more complete tooth, comes in at 19 serrations on both the distal edge and the mesial edge

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Thanks for doing that.

 

Hopefully Troodon agrees when I say, congrats, you've got yourself two Tyrannosaurid indet. teeth! :D

 

Can't really specify any further beyond that, since if the info you got from the seller is correct, then they're either Albertosaurus, Daspletosaurus or Gorgosaurus from Judith River (can't be narrowed down any further).

 

If the locality was given as Hell Creek or Lance Fm, I'd definitely peg the complete tooth as a Nanotyrannus, due to that slightly compressed base. That's only me speculating though.

 

They're a couple of nice teeth regardless, so hopefully you're happy with them!

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kinnza1

@Troodon any thoughts regarding serration measurements?

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Troodon
10 hours ago, kinnza1 said:

@Troodon any thoughts regarding serration measurements?

They support being Tyrannosaurid.  More concerned about the provenance without specific locality.

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kinnza1
6 hours ago, Troodon said:

They support being Tyrannosaurid.  More concerned about the provenance without specific locality.

Understood. I wish I had access.to the original information aside from what I've been given. Aside from Dromaeosaurus, are there other species known from JDF that present possible alternatives to Tyrannosaurids?

 

Also, just for fun I did take some other measurements. I'll call the more complete, darker tooth A, and the fragmented tooth B.

 

A:

Distal edge to mesial edge at base: 12.48mm

Width at base: 12.48mm

Length: 24.64mm

Denticles per 5mm on distal edge: 19

Denticles per 5mm on mesial edge: 19

 

B:

Distal edge to mesial edge at base: 15.07mm

Width at base: 7.65mm

Length: 26.35mm

Denticles per 5mm on distal edge: 15

 

Don't know how much useful information this adds if any, but figured I'd add them.

 

Also @Omnomosaurus, I did look closer at both teeth at the base and did notice some compression on the sides and a slight peanut shape in the cross section. Slight but noticeable.

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Troodon
14 minutes ago, kinnza1 said:

are there other species known from JDF that present possible alternatives to Tyrannosaurids?

No not with that morphology..size, shape and denticle shape.   The other info you gathered would be useful if there were others closer species to compare against.  

 

 

 

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kinnza1
Just now, Troodon said:

No not with that morphology..size, shape and denticle shape.   The other info you gathered would be useful if there were others closer species to compare against

 

 

 

So it sounds like tyrannosaurid indet would be the correct identification so long as the information I've gathered is correct? I'm guessing more so the specifics of locale are more to assist in a more specific determination beyond that?

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Troodon
3 minutes ago, kinnza1 said:

So it sounds like tyrannosaurid indet would be the correct identification so long as the information I've gathered is correct? I'm guessing more so the specifics of locale are more to assist in a more specific determination beyond that?

A complete Provenance is very important when buying a tooth. 

 

 

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kinnza1
4 minutes ago, Troodon said:

A complete Provenance is very important when buying a tooth. 

 

 

Normally I only buy from original harvesters and have much more detailed information. This one was an exception. Still hoping I can get more detail from the seller still, but more so my questions here reflect simply trying to rule out implausibilities or clear issues in alignment with the information I have compared to other datem points consistent with finds in JDF

Edited by kinnza1

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Troodon

I buy a lot from diggers in wyoming, montana and south dakota  and although they are good providing the locality of where items are found they can be very problematic with proper identification.   Never assume what they are telling you is 100% of the time accurate have it checked out..

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kinnza1
6 minutes ago, Troodon said:

I buy a lot from diggers in wyoming, montana and south dakota  and although they are good providing the locality of where items are found they can be very problematic with proper identification.   Never assume what they are telling you is 100% of the time accurate have it checked out..

Like I mentioned, more so just looking to ensure nothing I have is clearly ruled out of possibility. I know without provenance and context any distinction is vague lol. They were cheap, even without quality diagnostic information. Just removing improbabilities

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kinnza1

@Troodon disregarding assumed locality, are there other North American theropods known to have the same compressions on the facial and lingual faces of the tooth that are characteristic of Nanotyrannus? And if so, any that share similar serration attributes and dimensions to the teeth I've posted?

 

To @Omnomosaurus point, the more I look at Tyrannosaurid material others have posted, the more diagnostic the compressions seem to be in regards to excluding other Tyrannosaurids in favor of Nanotyrannus.

 

Curious if assuming location is bogus, what that could mean or what possibilities that may include.

 

Obviously, while understanding all the implied issues of completely lacking real context lol.

 

Just thinking hypothetically

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Troodon

Tyrannosaurid teeth in North America are primarily identified by locality found.  Compressed teeth that have a rectangular base are typical of maxillary positions.  

In the Lance and HC formations Tyrannosaurid teeth that are have that rectungular base, are pinched are typically Nanotyrannus but one must always look at all the other characteristics to make sure its not a maxillary Trex.   Dakotaraptor teeth appear to easily confused by sellers since there are some similarities to small <1"  Nanotyrannus teeth.

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Omnomosaurus

As Troodon said, locality is the most important thing. If the seller is usually trustworthy, then you shouldn't doubt the provenance too much (though a bit of scepticism is always healthy).

 

Nano teeth from the Hell Creek & Lance formations are most easily identified by the compression at the base making an obvious "figure of eight" or "bean" shape in the cross-sectional view, compared to smaller Rex teeth. Then the smaller diagnostics are usually, but not always, needed just to make sure.

 

Yours reminded me of Nano straight away because of the size & "pinched" bases, but they're not the most obvious compressions I've ever seen (all teeth vary a little, after all). It is possible to have rectangular bases on the Tyrannosaurs of Judith River, just like Rex, but assuming yours are definitely from where the seller said, they couldn't possibly be anything other than one of the 3 Tyrannosaurids there.

 

It's a very good point about Dakotaraptor too, if you ever decide on buying any small tyrannosaur teeth from Hell Creek; there is always a chance they could be a misidentified tooth from one of these large dromaeosaurs.

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kinnza1

You guys are awesome.

 

So switching gears, what characteristics distinguish Dakotaraptor from smaller Tyrannosaurid teeth?

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Omnomosaurus
22 minutes ago, kinnza1 said:

You guys are awesome.

 

So switching gears, what characteristics distinguish Dakotaraptor from smaller Tyrannosaurid teeth?

 

Thanks, kinnza1! There are some fantastically knowledgeable people around here that can help with most things (I'm quietly convinced they're wizards haha).

 

Everything you could want to know about identifying Dakotaraptors can be found in this amazing guide from Troodon:

 

 

When looking at photos of teeth for sale online, I mainly focus on the denticle shape (if you can see it clearly enough), and whether there is a twist to the carina of the mesial edge....

 

From what I remember off the top of my head:

 

twist in the carina = tyrannosaur

no twist = chance of Dakotaraptor

 

From there look for serration shape:

 

Chisel shaped = tyrannosaur

Rounded = more likely Dakotaraptor

 

You have to go into all the diagnostics to be certain, but those checks I mentioned above are small things that can be done through photos to give you a slightly better chance of not getting caught out.

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kinnza1

Interesting.

 

So what I'm taking from this is:

 

Based on the teeth themselves provide, they appear to be most consistent with a Tyrannosaurid Indet diagnosis. But the lack of more specifics in locale present a problem in definitively ruling out the possibility of being from Dromaeosaurids.

 

Edited by kinnza1

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