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Ceratosaurus?


Dino Dad 81

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Hello,

 

I came across this 1.3" tooth from the Morrison formation in Johnson county, Wyoming. Does it look like Ceratosaurus to you? I'm trying to confirm that the mesial carina extends to the base, but I think it does extend to the base (despite being worn), based on the last pic but it's hard to tell since it's out of focus. Looks pretty symmetrical and otherwise morphologically appropriate. DSDI looks to be in the 1.0 ballpark...

 

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This was my response to another member

" Like I say to everyone, I cannot ID Morrison fm teeth off of photos, to try, I will need everything that is in the attachment.   I will say this that although it's difficult to see believe the outside carina ends about 1/2 way down from the tip.  So it cannot be a Ceratosaurus.  Could be Torvosaurus or Allosaurid.

Screenshot_20221217_154314_Drive.thumb.jpg.359e0328fba7a58229aeee163eebd523.jpg.4c6ba02976522c0cae3dbe472406ce7e.jpg

 

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Got these pics. Poor focus, but looks like the anterior and posterior carinas go equally far down. If nothing else, it looks too symmetrical for allosaurus, right? So do you think it’s most likely Ceratosaurus or Torvosaurus?

 

 

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Oh yeah—these are both of the anterior carina (I thought the second was posterior at first). agreed, can’t he cerato.

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@Troodon

 

One question about Torvosaurus. How much do you THINK the serration density on a 1.3" tooth might differ from the Torvosaurus norm? If Torvo is usually about 2/mm, might it be as high as 3-4? Marsho would probably be full grown at this size so it would bey about 4-5/mm?

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No, just wondering if the difference in the serrations between the two species was great enough for it to tease out a juvie torvo from a marsho. I do think this tooth is too symmetrical to be allo.

 

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  • 2 weeks later...

@Troodon the tooth just arrived. I actually think the mesial carina extends to the base, but is cut short by wear--and it's most likely a Ceratosaurus maxillary. The serrations are relatively small, but so is the overall tooth. It's shape and symmetry seems to be Cerato or Torvo.

 

 

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  • CH: about 31mm (including estimate of the missing distal portion of the base)
  • CBL: about 14mm (including estimate of the missing distal portion of the base)
  • CBW: 7.8mm
  • Mesial serrations density: 3.0/mm
  • Distal serrations density: 2.8/mm

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Thanks!

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Differentiating teeth of Meglosauroids, Ceratosaurids and Allosauroids is difficult since they have similar CH, CRB and CHR and even denticles.  Ceratosaurus should be very compressed CRB <0.5 but like everything there are outliers.  Yours is 0.57.

It's all about where that mesial carina ends.  These photos dont support your comment that it goes to the base.   You need to make that call and its either yes or no.  Look at it under a scope and see what it looks like.

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@Troodon, thanks. Do you think Allosaurus can be ruled out by the symmetry and Marshosaurus ruled out by DSDI?


You didn't think there's a noticeable pattern of crater-resembling remnants here at the very base?

 

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Also, let me see of you approve of my measuring estimates--CH and CBL are very tough with the missing piece. Maybe this is more accurate:

 

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Edited by Dino Dad 81
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I showed you a bunch of allosaurus teeth from Portugal that are somewhat Symmetrical so its hard to rule anything out especially since we don't know where the mesial carina lands.    You are not giving me an answer on the carina just more photos that I cannot see anything.  Do the serrations go to the BASE

 

Let's talk about how to measure.

CW like the illustration I showed you above is at the mid point.

CL looks okay

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CH is from the base of the distal side to the tip

 

1672192990284.jpg.1cf708a17639ed1ca0c617347b45d519.jpg

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@Troodon, I wasn't sure we could do any better than narrowing further. Please let me know what you think based on the pics below of a pattern of appropriately space out marks. I'M NOT SAYING I'M CONFIDENT THEY'RE THERE, but this is the best evidence one way or the other in my opinion. Thanks so much for your help.

 

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he video

 

 

 

 

 

 

Edited by Dino Dad 81
Added markings to the video
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Thanks, @Troodon. I'm going to send it to get the repair done more neatly and perhaps get the missing distal base restored. Hopefully H will have a better read on the denticles. My hope was that they DON'T go down to the base and that it's a Torvo tooth--since I have none from that dino.

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