Tiny Judith River Theropod Teeth

[Kikokuryu]

These teeth were sold as a baby tyrannosaurid and a dromaeosaurid/bird respectively. Some other specimens from this lot have been posted here if I recall. But they are from North of Havre, Montana close to the Canadian border. Apparently they are from quite an old collection from around 1950-70s. The provenance should place it solidly in Judith River Formation.

 

Since these teeth were selling somewhat quickly, I just grabbed them and decided on figuring it out later. The first tyrannosaurid tooth does have some similarities to Dromaeosaurus with the mesial twist, but I could be wrong.

 

The second tooth is a bit more confusing. I'm guessing it is Zapsalis-type with those striations which would make it Saurornitholestes. I don't think it's bird compared to bird teeth from other deposits. It's probably not one of those Campanian microraptorians either, and it's probably too big even at this size to be bird or micro.

 

1st tooth: Length=6.3mm; Distal Density=17.5/3mm; CBL=2.9mm; CBW=1.8mm

2nd tooth: Length=5.8mm; Distal Density= ±11-12/mm (?); CBL=2.6mm; CBW=1.3mm

 

Serration density for the 2nd tooth might not be too accurate since it was extremely difficult to even get to that number. Not sure how to go about getting CH, but it's probably a little bit more than the length since the tips are worn. 1st tooth might be good as is since with that small root section, that probably makes up for what would be a longer crown.

 

 

1st Tooth

 

2nd tooth

Edited October 25, 2022 by Kikokuryu

[Troodon]

The first tooth looks like Dromaeosaurus albertensis

The second might be a cf Richardoestesia isosceles, want to check may just be indeterminate.

[Troodon]

8 hours ago, Kikokuryu said:

Not sure how to go about getting CH, but it's probably a little bit more than the length since the tips are worn.

 

The serration density tooth #2, thats around 11/12 per mm ?

 

CH is what you see in the illustration and worn tips are not considered.

[Kikokuryu]

3 hours ago, Troodon said:

The first tooth looks like Dromaeosaurus albertensis

The second might be a cf Richardoestesia isosceles, want to check may just be indeterminate.

Thanks. I'm guessing you mean to recheck and either get a more accurate serration density or get the CH?

 

Do Richardoestesia sometimes have striations? I discounted that possibility based on that, but that's interesting to know if that is the case.

 

1 hour ago, Troodon said:

CH is what you see in the illustration and worn tips are not considered.

Ah, okay. I wasn't 100% sure on whether you had to "restore" the tip to it's unworn state when getting the CH measurement. I guess I'll have to go back and shave off a few millimeters on some crown heights I have recorded for other teeth.

[Troodon]

No on the density I just want to make sure it was around  11 per mm.  CH is not important with these identification it's more about other characteristics.That was just an fyi.   Richardoestesia teeth should be dentulated on the distal side, possibly on the other but usually limited to distal, I think the mesial is?  Hard to see?  It's a weird tooth.

 

 

[Kikokuryu]

2 hours ago, Troodon said:

No on the density I just want to make sure it was around  11 per mm.  CH is not important with these identification it's more about other characteristics.That was just an fyi.   Richardoestesia teeth should be dentulated on the distal side, possibly on the other but usually limited to distal, I think the mesial is?  Hard to see?  It's a weird tooth.

I don't know if I can manage to get really good shot of the mesial carinae with the magnification I currently have since I can't even see it with my naked eye. I feel like the occasional denticle-like shots are actually just the light playing tricks. In other shots, it doesn't seems to have anything. The top 2 are images of the tooth being rotated in a video until I got a clear shot of it. The bottom 2 are still photos where, I feel like it's just the light making it look like denticles. The mesial carinae itself does extend pretty far down up to around that really faint line closer to the bottom.

 

I tried a few different ways to get the distal density. The 11-12 is around the midline. I tried to get a different area that's more clear, and it's probably not accurate either that shows 14-15/mm closer to the tip. It could be more like 12-13 if I didn't translate between the blurry image with the calipers to the more clear image. At the very least, the denticles are very fine.

 

I'm fine with Theropoda indet., but it was worth a shot trying to see if it fits into anything.

 

[Troodon]

The super fine serration density of the tooth points to Richardoestesia sp.   I think they are present on the outer edge.  The teeth can vary by locality so thats my best call