Carch? Indet?

[Dino Dad 81]

 

Hey all,

 

During a discussion about different locations in the Kem Kem, this tooth came up. It always puzzled me, but I figured it was just an odd Carch tooth. But the reaction I got sounded like it was worth taking some better pics of. Any thoughts?

• Kem Kem is all I've got
• CH: 26mm
• CBL: 16mm
• CBW: 7.75mm
• Mesial serration density: about 2.75/mm
• Distal serration density: about 2.75/mm

 

 

 

 

 

 

 

 

Thank you!!

[BirdsAreDinosaurs]

Interesting one. Not your typical Carch tooth. Yet based on the overall appearance, the thickness of the tooth and the size of the serration my guess would be that it is a Carch tooth. Perhaps just something that doesn't pop up that often, like a more anterior juvenile tooth for instance? But I would definitely wait for the opinion of more experienced forum members.

Edited July 25, 2022 by BirdsAreDinosaurs

[Dino Dad 81]

Hopefully this is as interesting of a development as it seems to me. I dug deeper into my Kem Kem mysteries and found this smaller tooth that compares really to the original one. It too has about 3 denticles per mm on both sides (very slightly smaller denticles than the original tooth). It's about 22mm and clearly has a higher CHR. Does this help?

 

 

 

 

 

 

 

 

[Dino Dad 81]

@Troodon

If you get a chance, we may need you.

Edited July 25, 2022 by Dino Dad 81

[BirdsAreDinosaurs]

Nice little tooth. For some reason I misread the info of the serration density of the first tooth. Now I would say indeterminate for both.

Edited July 26, 2022 by BirdsAreDinosaurs

[Troodon]

I always believe you cannot focus on one characteristic (density) especially if its not diagnostic to an ID and ignore all the others.  Teeth can vary position to postion and within a position.  Unfortunately everything I've seen published on Carch teeth are based on adult teeth but even that the sampling data is small .   So we really do not have a good understanding of juvenile teeth.   T rex teeth that I've measured show that serration density changed significantly based on the size of the tooth. 

 

On the first tooth the characteristics that line up to be a Carcharodontosaurid include:  CHR, CBR, presence of some blood grooves, overall shape. 

Other characteristics are harder to evaluate based on Hendrickx (2019) include:  DSDI (should be less 1 on some lateral teeth ), and the mesial carina not extending to the cervix again on some lateral teeth.  

 

Still think there is a good chance its a Carcharodontosaurid tooth.

Can you take a density measurement toward the top and base like to see how it changes.

 

[BirdsAreDinosaurs]

Thanks for your insights, Troodon. I agree that it is bad practice to focus on a single characteristic. In this case the serration density just tipped the scale for me towards indeterminate as I was not too sure about the ID anyway. I did however not realise that serration density can change significantly with the size of the tooth. So thanks, I learned something new.

[Troodon]

1 hour ago, BirdsAreDinosaurs said:

I did however not realise that serration density can change significantly with the size of the tooth.

I've found lots of variations even with same size teeth but size was the biggest differentiator.  It really stands to reason the density must change with size otherwise smaller teeth would not function properly.

CH: 36mm -- 2/mm

CH: 26mm -- 3.5/mm

CH:  8.5mm -- 4/mm

A pair of  CH : 14 mm -- was 2.5 and 3.5/ mm

Checkout the serrations on this Trex tooth, ...aberrant serrations occur.

 

[Dino Dad 81]

Thanks for the teachings @BirdsAreDinosaurs and @Troodon.

 

For what it's worth, I wasn't listing any details (e.g., densities) because I suspected they were diagnostic, but rather because they're a part of the package that can't be determined by the naked eye. To my less experienced eye for carchs, I felt the morphology was fairly off. Too recurved of a profile too curved in general on the lingual side. But I don't know much about carchs.

 

Here's a last pic to emphasize what I'm talking about.

 

[Troodon]

I really do not understand what you are saying in why these are different?  If the morphology is off what characteristics are those ? Density, Ratio's, Features etc

[Dino Dad 81]

I'm sure it's nothing worth considering at this point, as it would have come across in the pics if it mattered. But just for the sake of clarifying, I'm describing the curvature on the lingual side of the tooth that gives the illusion of it being even more recurved than it actually is. The curvature that creates such a pronounced shadow to the left of the yellow line in the pic below. It doesn't seem carch-like in my low level of experience.

 

[Troodon]

Okay got it.  Adds to the mystery of the teeth from the KK