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I found this small theropod tooth (missing the tip) in the Horseshoe Canyon Formation of Alberta a few months ago. I’m not sure on the identity of the tooth, as it’s rather Troodontid or Dromaeosaurid. It has the crown and denticle shape of a troodontid, but the serration density of a dromaeosaurid (about 3 serrations per mm). The serrations are a bit worn down fyi. Any help would be greatly appreciated, thanks!

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I think troodontid with worn distal serrations but I could also be convinced it’s Dromaeosauridae.

 

Whats the size?

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47 minutes ago, Runner64 said:

I think troodontid with worn distal serrations but I could also be convinced it’s Dromaeosauridae.

 

Whats the size?

About 9mm long, though it is missing the tip which prob would’ve made it 10mm

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Hey, this looks exciting! Can you count (and image) the mesial denticles and post an image of the base of the tooth and of the other side? Can you confirm that the distal denticles are hooked towards the tip of the tooth? With the 3 denticles per mm on the distal side (is this a definite number?) it falls into Dromaeosaur territory, you could potentially look at a Atrociraptor marshalli tooth?! Maybe I am jumping the gun, I am just excited for you =)
 

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The denticle shapes look just like dromaeosaurid to me. The ridges reminds me of Saurornitholestes teeth and it just so happens Atrociraptor comes from Horseshoe Canyon and is a Saurornitholestinae

 

I'd say this is Atrociraptor. Congratulations

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2 hours ago, Top Trilo said:

Not sure what it is it but it looks a lot like your avatar ;)

Yep, my pfp is confirmed Troodontid from the Dino Park Formation!

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59 minutes ago, JoeS said:

Hey, this looks exciting! Can you count (and image) the mesial denticles and post an image of the base of the tooth and of the other side? Can you confirm that the distal denticles are hooked towards the tip of the tooth? With the 3 denticles per mm on the distal side (is this a definite number?) it falls into Dromaeosaur territory, you could potentially look at a Atrociraptor marshalli tooth?! Maybe I am jumping the gun, I am just excited for you =)
 

Sure! I can’t confirm the serrations hook toward the tip because they are pretty worn, but the serration “stubs” do point slightly towards there. Here I have a pic of the base and other side of the tooth, and on the latter you can see the outline of the worn medial serrations, which are at about 4 per mm. And yes, I have confirmed the 3 per mm on the distal side. Finally, Atrcoiraptor marshalli is the only known dromaeosaur from the Horseshoe Canyon, and pretty rare at only 1 described specimen known! 

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EF545A6A-E29D-4984-9514-0EBAA0DB059D.jpeg

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1 minute ago, Alex Eve said:

Sure! I can’t confirm the serrations hook toward the tip because they are pretty worn, but the serration “stubs” do point slightly towards there. Here I have a pic of the base and other side of the tooth, and on the latter you can see the outline of the worn medial serrations, which are at about 4 per mm. And yes, I have confirmed the 3 per mm on the distal side. Finally, Atrcoiraptor marshalli is the only known dromaeosaur from the Horseshoe Canyon, and pretty rare at only 1 described specimen known! 

 

Seeing this picture has made me reconsider a little. Are there faint ridges down on the side of the tooth, or is the side completely smooth?

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5 minutes ago, -Andy- said:

 

Seeing this picture has made me reconsider a little. Are there faint ridges down on the side of the tooth, or is the side completely smooth?

The sides are completely smooth, with the exception of this very slight depression on the distal end (can be seen in the light better, but sort of shows up in this pic)

EEC616B8-9F64-4549-9BC1-45E853D4A3F5.jpeg

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3 denticles distal and 4 mesial per mm does fall into what is described for Atrociraptor. What throws me off is the cross-section... maybe because it shows a section anterior to the base, which is not really preserved on the tooth, still...
I only have one reference image of a Atrociraptor base posted by a TFF member with a shape I would expect:
5fed49a3c9aff_Screenshot2020-12-30at22_45_10.png.6c01b0e73001902e5f63310cf7dfe00d.png

Let's hear some more opinions ;) @Troodon @hxmendoza

 

 

Edited by JoeS
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3 minutes ago, JoeS said:

3 denticles distal and 4 mesial per mm does fall into what is described for Atrociraptor. What throws me off is the cross-section... maybe because it shows a section anterior to the base, which is not really preserved on the tooth, still...
I only have one reference image posted by a TFF member with a shape I would expect:
5fed49a3c9aff_Screenshot2020-12-30at22_45_10.png.6c01b0e73001902e5f63310cf7dfe00d.png

Let's hear some more opinions ;) @Troodon @hxmendoza

 

 

Yea this is the exact problem I’ve ran into! Shape of a Troodontid but serration density of Dromaeosaurid

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Interesting tooth, compare to these troodontid and dromaeosaur teeth I found in the Judith River fm.

Slightly older but similar fauna. Personally I think yours is Dromaeosaur, but I could easily be wrong.

Troodontid

IMG_E3232.thumb.JPG.82d680e67eb5324e2eae07214da2d741.JPG

Dromaeosaurid (cf. Saurornitholestinae)

IMG_E4463.thumb.JPG.5ab991d8ac8833dbfd640195577039e4.JPG

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  • 2 weeks later...
hxmendoza

This is a Saurornitholestine tooth. 
 

Since it’s from the Horseshoe Canyon Formation it is likely Atrociraptor marshalli.

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4 hours ago, hxmendoza said:

This is a Saurornitholestine tooth. 
 

Since it’s from the Horseshoe Canyon Formation it is likely Atrociraptor marshalli.

What would make it Saurornitholestine? Can dromaeosaurs have the Troodont shaped cross section as well?

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16 minutes ago, Alex Eve said:

Can dromaeosaurs have the Troodont shaped cross section as well?

Hey, I have looked into this a little. As stated previously, I do think that the posterior end of the tooth is missing as well, that's why the cross section looks not that compressed.
Here an image of a cross section from a broken Saurornitholestes tooth I found on the web. Looks similarly oval.

1500x1125.thumb.jpg.135b724d4c09c43fd71a816919fecf60.jpg

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2 hours ago, JoeS said:

Hey, I have looked into this a little. As stated previously, I do think that the posterior end of the tooth is missing as well, that's why the cross section looks not that compressed.
Here an image of a cross section from a broken Saurornitholestes tooth I found on the web. Looks similarly oval.

1500x1125.thumb.jpg.135b724d4c09c43fd71a816919fecf60.jpg

Oh alright, that answers all my questions then! I thought that cross section shape was strictly Troodontid, but I guess not. Thanks for the help! Glad I can now confirm this is an Atrociraptor marshalli tooth!

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