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JoeS

Theropod indet. tooth ID Lourinhã Formation

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JoeS

Hi all, I have a tricky tooth ID question. For now it is labeled as Theropod indet. and I guess this is as far as it gets, but I just want to check if someone else gets a Dromaeosaurid vibe =)

It was found in the Lourinhã Formation. Crown height is 6mm. Denticles per 1mm are 9 mesial and 7 distal. Mesial denticles are also much shorter, and the mesial carina ends at about half way from the anterior of the tooth (maybe 2/3 considering the tip is missing). Distal denticles are slightly hooked towards the anterior. I went through quite some papers from similar aged formations in Portugal/Spain and Morrison formation but without any real luck: Zinke 1998 describes possible Dromaeosaurid teeth that might fit the bill regarding denticle density and roughly TCH/FABL/BW when scaled to this tooth (6.09mm/3.61mm/1.95mm).
Any help is highly appreciated!

 

 

 

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Troodon

Can you provide the width of the tooth at the base, midline thanks

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JoeS

sure, thanks, I'll provide the exact measurement tomorrow - don't have a precision tool here now.

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Haravex

I don't feel this is dromaeosaurid tooth but I could be wrong as I am unfamiliar with the fauna in hand but at first look it seems like the serration shape is more suited to a ceratosaur. I'm sure troodon will have a better idea than me however just trying to give some input.

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JoeS

thanks, I appreciate it. Ceratosaur are indeed present in this formation - I did not consider them so far due to the high density of denticles present on the tooth in question - but I'll look into it, maybe teeth of juveniles are described.

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JoeS
23 hours ago, Troodon said:

Can you provide the width of the tooth at the base, midline thanks

Hi, the width of the tooth is 1.79 mm (midline, base as requested). hope this helps

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Troodon

Thanks but I do need one more figure,! the length at the base.   Thought I had that number from above.  Trying to understand the CBR to see if that gives me any clues to the ID of the tooth.

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JoeS
9 minutes ago, Troodon said:

Thanks but I do need one more figure,! the length at the base.   Thought I had that number from above.  Trying to understand the CBR to see if that gives me any clues to the ID of the tooth.

CBL is 3.6mm - thank you very much for looking into this!

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Troodon

Interesting tooth and isolated teeth like this one should be described as indeterminate because there is no slam dunk diagnostic  feature to assign it to a specific family.  In addition I believe this is juvenile given the very high serration count which make it more difficult when trying to compare it to larger teeth that are published.  I have no idea if the DSDI Denticle size density index changes with age.   But for fun I used the CRB, CHR and Density index to see what it would show and the closest morphtypes I can see are Megalosauroidea.  The denticle profile works.   I dont believe its Dromaeosaurid.

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JoeS
29 minutes ago, Troodon said:

Interesting tooth and isolated teeth like this one should be described as indeterminate because there is no slam dunk diagnostic  feature to assign it to a specific family.  In addition I believe this is juvenile given the very high serration count which make it more difficult when trying to compare it to larger teeth that are published.  I have no idea if the DSDI Denticle size density index changes with age.   But for fun I used the CRB, CHR and Density index to see what it would show and the closest morphtypes I can see are Megalosauroidea.  The denticle profile works.   I dont believe its Dromaeosaurid.

very insightful analysis, thank you so much for all your time invested. I'll follow up and maybe someday a new paper will shine more light onto it.
So far I did not venture into the world of dentition based datamatrices and morphometric analysis like this - I guess it is time ;)  thanks again!

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