Are any of these Dromaeosaur?

[jikohr]

Hi everyone!

 

I recently acquired some little Therapod teeth from the Hell Creek of Carter County, Montana. They were advertised as "Dromaeosaurus" so I knew right away most were going to be little Nanos which I was fine with. I screened out the ones that were definite Nanos and was left with these three little mysteries. No ridge along the crown so Acheroraptor is out. the serration densities were a little unusual so I figured I post them to see if any might be Dakotaraptor or if I'm just seeing things. I posted a larger pic of the lingual twist of tooth one right under it since couldn't get it to show up well otherwise. So what do you all think? I can retake photos if need be if it will help as well.

 

Any insight is appreciated as always!

 

Tooth 1

 

 

Tooth 2:

 

 

Tooth 3:

Edited August 26, 2022 by jikohr
forgot to label the teeth

[JoeS]

Hi, nice teeth
Can you post close-ups of the denticles on the distal carina for all of them?
 

[jikohr]

1 hour ago, JoeS said:

Hi, nice teeth
Can you post close-ups of the denticles on the distal carina for all of them?
 

Absolutely

 

Tooth 1:

 

Tooth 2:

 

Tooth 3:

[Troodon]

9 hours ago, jikohr said:

No ridge along the crown so Acheroraptor is out.

 

Not sure we can make that statement since we do not know what the dentition looks like.   All we know is the morphology of a few maxillary teeth.   The same can be said about Dakotaraptor and in this case it's only a few isolated teeth.   So, teeth can be assigned to DR or AR only if they fit the holotype morphology otherwise its either indet dromaeosaurid or indet theropod.

If it's a small tooth don't forget to Richardoestesia gilmori in your possibilities, typically around 1 cm and has minute serrations.

 

I'm inclined to call these indet tyrannosaurids based on the shape of the denticles and other features.   Last one could be T rex but too small to make that call so its indet. 

[JoeS]

Mirroring what @Troodon said, there are Acheroraptor teeth out there that only show the faintest of ridges, hard to see. Likely from posterior positions.
tooth #2 checks all the boxes for Nanotyrannus I would say
tooth #3 is tough as it is so tiny. While I see where the T-Rex possibility comes from and I agree, what about cf. Richardoestesia gilmorei with those denticle counts? In Philip Currie's papers he shows that some have those slightly tilted denticles. Would you argue the denticles are not short enough to fit that profile @Troodon?
 

[Troodon]

43 minutes ago, JoeS said:

about cf. Richardoestesia gilmorei with those denticle counts? In Philip Currie's papers he shows that some have those slightly tilted denticles. W

 

I initially thought cf R. gilmorei and it may be but the ones published from older deposits do not have as robust mesial carina.  The are typically not dentulated or are faint.   The high density could just be a function of a 5mm tooth.  Since we have little published who knows on these tiny teeth from the HC.  Nice tooth.

 

From Currie & Larsen Multivariate Paper. 2013

[JoeS]

14 minutes ago, Troodon said:

the ones published from older deposits do not have as robust mesial carina

That's a good point - thanks!

[jikohr]

3 hours ago, Troodon said:

 

Not sure we can make that statement since we do not know what the dentition looks like.   All we know is the morphology of a few maxillary teeth.   The same can be said about Dakotaraptor and in this case it's only a few isolated teeth.   So, teeth can be assigned to DR or AR only if they fit the holotype morphology otherwise its either indet dromaeosaurid or indet theropod.

If it's a small tooth don't forget to Richardoestesia gilmori in your possibilities, typically around 1 cm and has minute serrations.

 

I'm inclined to call these indet tyrannosaurids based on the shape of the denticles and other features.   Last one could be T rex but too small to make that call so its indet. 

 

1 hour ago, JoeS said:

Mirroring what @Troodon said, there are Acheroraptor teeth out there that only show the faintest of ridges, hard to see. Likely from posterior positions.
tooth #2 checks all the boxes for Nanotyrannus I would say
tooth #3 is tough as it is so tiny. While I see where the T-Rex possibility comes from and I agree, what about cf. Richardoestesia gilmorei with those denticle counts? In Philip Currie's papers he shows that some have those slightly tilted denticles. Would you argue the denticles are not short enough to fit that profile @Troodon?
 

 

Thanks guys! Good to know about Acheroraptor and Richaroestesia as well.

So not a single one of the batch was raptor. I mean I'm fine with that personally it's just amazing isn't it? I think maybe 10% of the "Dromaeosaur" teeth I see out there from Hell Creek are actually Dromaeosaur and that's being generous.

So just to clarify, all three are indet. Tyrannosaur with #2 leaning Nano and #3 leaning Rex, or should I just say indet. Tyrannosaur? 

[Troodon]

I'm comfortable with 2 being Nanotyrannus.  The rest indet tyrannosaurid.

[jikohr]

40 minutes ago, Troodon said:

I'm comfortable with 2 being Nanotyrannus.  The rest indet tyrannosaurid.

Thanks man!