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Kikokuryu

I recently purchased a Theropoda indet. tooth from the Lourinhã Formation of Lourinhã, Portugal. I wasn't expecting much initially since it looked like an incomplete tooth and the seller tends to go the safe route with their IDs if it's too vague. But, the serration count was similar to that of the Marshosaurus-like megalosaurid teeth based on @Troodon's guide on the dinosaurs of Portugal.

 

Maybe it's just wishful thinking, but I wanted to see if anyone else had some input before I slap that good old theropoda indet. label on the display.

 

The distal serrations is split down the middle. Mesial serrations were kind of hard to count, but they are at least 20/5mm, the distal serrations are 16/5mm. Not sure if the split serrations are messing with the count, but it should be around that 16/5mm after counting it multiple times with various pictures. I don't know how much further the tooth would have gone had it been complete, but I think the mesial serrations do appear to end before reaching the base. Although I don't know if those serration densities still overlap with other theropods like Allosaurus.

 

848303458_PortugalTheropod.thumb.jpg.d38d0bfaf9caf9d10b11a5ec25575bad.jpg1853943291_PortugalTheropod8.jpg.918da1171802aabb7203ddd5a7ae1a2f.jpg

Split distal serrations and shape of the base which could be slightly off due to the split serration.

357377497_PortugalTheropod4.jpg.7b153c10b14ee21d59a483af7058f118.jpg

Distal serrations.

1823625907_PortugalTheropod1.thumb.jpg.2d39496f87d206e257d2ba0558fbb45e.jpg

Mesial serrations.

1904172051_PortugalTheropod2.thumb.jpg.a79207da595b75e2fdd55f3850326bdf.jpg

Mesial serrations ending?

982083890_PortugalTheropod7.jpg.6d644bf362da98fcc35f944f6ceb91d3.jpg

Close up on denticle shape on distal side.

895376663_PortugalTheropod6.jpg.ce81ee9e4e0dd56fae65414b798384c5.jpg

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I don't believe this tooth is a megalosaur tooth.  The mesial serrations seem to reach all the way to the base, megalosaurid teeth should not have this characteristic.  It also lacks transverse undulations.  I would lean towards allosaurid.

 

Edit: Serration density on your tooth is too large.  I would lean toward Theropod indet. now.

Edited by Runner64
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Not having a compete tooth complicates the diagnosis.   Can you provide me measurements of the Crown Height, Base and Width assuming the tooth is complete.  Assume the tooth base is at the lowest portion of that mesial side.  Need an estimate.  

Can you point to where the mesial carina ends on this image.  

1853943291_PortugalTheropod8.jpg.918da1171802aabb7203ddd5a7ae1a2f.jpg.e3d41f53c0a5a1a5ab7cea252d4257bd.jpg

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Kikokuryu
2 hours ago, Troodon said:

Not having a compete tooth complicates the diagnosis.   Can you provide me measurements of the Crown Height, Base and Width assuming the tooth is complete.  Assume the tooth base is at the lowest portion of that mesial side.  Need an estimate.  

Can you point to where the mesial carina ends on this image.

I believe this is where the mesial serrations ends. I've looked for a while under a scope, and under a light to see if there are any hints as worn serrations, but I don't think so. There is a chipped off section right inbetween that may and may not have had serrations.

 1837094733_PortugalTheropod12.thumb.jpg.1bf22c48c4e611584e9b58cc8f6782f2.jpg

Now, for measurements. Okay, so here's my terrible restoration as trying to figure out the crown height. Without resto, from the bottom of the base to the top is about 22mm, and with my poor resto, about 25mm. I hope I did this correctly. If not, I can always try again.

CH: 25ish mm

CBL: 12.5mm

CBW: 6mm

1007167859_PortugalTheropod11.thumb.jpg.5ed225a65d60675626b8eb3d11e3b168.jpg38481022_PortugalTheropod9.thumb.jpg.ba9b29c582038dcae81473922664184b.jpg

 

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Sorry not a Picasso :D but its perfect in what I'm looking for, thank you. Let me play with the info and see what I can come up with if anything.

 

Just an fyi 

The mesial carina being short does not automatically signal Meglosaurid.   With Portuguese theropod teeth this characteristics can be seen on  Dromaeosaurid, Tyrannosauroid, and Allosaurid morph types.

 

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Identification of Isolated teeth is not easy,   Using Malafaia et al. 2017 paper tried to compare this tooth to what they presented, my findings

 

Morph type 7 came out the the best not perfect but close.  

Denticles:

DSDI: =>1.2   Your specimen : 1.25

Mesial 19.5/5, Distal 15.7/5  Your specimen: Mesial 20/5, Distal 16/5

 

CHR Avg 2.18  Your specimen 2

CBR Avg .51 Your Specimen .48

 

Undulations:  Sligtht undulations are present in SOME specimens.  I dont see any in yours

 

Mesial carina centrally positioned, mid-height or restricted to apical end.  Your specimen mesial carina is centrally positioned but comes a bit lower than mid height. One of the images shows the carina a bit similar to yours if you reconstruct the broken base.

 

Capture.JPG.68331de074162d0351e42362683e9f9c.JPG Capture2a.jpg.4d4356cbde0cec1450b63ae39fd2cdab.jpg

 

 

Morph Type 7 is listed under Meglosauroidea 

I dont believe its Marshosaurus its not elongated enough and serration density not fine enough. 

Your call on how you would like to identify these teeth.   Positional Allosaurus teeth can have some similar characteristics.

 

 

 

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Kikokuryu
11 hours ago, Troodon said:

Morph Type 7 is listed under Meglosauroidea 

I dont believe its Marshosaurus its not elongated enough and serration density not fine enough. 

Your call on how you would like to identify these teeth.   Positional Allosaurus teeth can have some similar characteristics.

Thanks for the information. Is the paper free access or paywalled, and does the serration density overlap with known Allosaurus teeth?

 

Regardless, I'll probably stick to Theropoda indet. for now, and maybe make a spare label with Megalosauroidea indet. with a (?) as backup.

 

But, going under the assumption that the tooth is only missing said amount, it's good to know that a similar (though a bit off) morphology is officially documented, albeit, indeterminate.

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Here is the info on the paper.  Isolated theropod teeth can be very hard to diagnose to a species/genus because of the variation in the jaw and ontogeny.  

 

Analysis of diversity, stratigraphic and geographical distribution of isolated theropod teeth from the Upper Jurassic the Lusitanian Basin, Portugal.

Elisabete Malafaia, Fernando Escaso, Pedro Mocho, Alejandro Serrano Martınez, Angelica Torices, Ma´rio Cacha, Francisco Orteg

Received: 27 November 2016 / Accepted: 6 June 2017

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