Mystery Lance Formation Tooth

[Troodon]

Found a small tooth in matrix I had collected from a trip I did a few years ago to Niobrara County in Wyoming, the Lance Formation.  Went through my Hell Creek/Lance Books, Papers and Guide and had no luck with anything.   Tooth looks like a croc, shape and base but it has a spoon crown with a center ridge that is very different than most teeth I've seen and throws me for a loop.  Hopefully someone has seen something similar.   Thank you for any assistance.  

 

Lance Formation and its 7 mm long

 

 

 

[Carl]

Possibly a weathered tyrannosaur premaxillary tooth.

[PFOOLEY]

4 minutes ago, Carl said:

Possibly a weathered tyrannosaur premaxillary tooth.

 

That would be my guess as well.  

[Troodon]

Thanks guys.  That's what I first thought but the more I looked at it, it was different, and concluded it was not theropod.   My rational, right or wrong, is that the base of a theropod premax tooth is rectangular and has thin side walls.  This one has none of those characteristics its oval, with a solid base and a circular opening.   The other feature that swayed me away from Theropod is the height of the center ridge.   Small premaxllary teeth can have a raised bowed crown but this tooth has a very high center ridge with a deep spoon face.   Those are my thoughts.

[PFOOLEY]

Below is an image from Skeletal remains of Tyrannosauroidea (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan.

 

 

Figure "D" looks more round than rectangular.

 

You should ask Troodon...he is a wiz with this kind of thing.

[Troodon]

I did a

4 hours ago, PFOOLEY said:

 

 

You should ask Troodon...he is a wiz with this kind of thing.

 

Ha ha I did ask him and got the wrong answer 

 

Take a look at the face of the crown it's has a slight uplift but not has prounced has the one I show.  Agree with you on the base.  Maybe an infant tooth morphology is a bit different.

[Susan from PA]

Wow!  Beautiful find!  I'm going to have to go with a juvenile tyrannosaur premaxillary tooth as well.  To my knowledge, I can't think of anything else that fits. 

[Troodon]

Why tyrannosaur all the other theropods have premaxillary teeth?   

[Susan from PA]

6 minutes ago, Troodon said:

Why tyrannosaur all the other theropods have premaxillary teeth?   

This is true.  I failed to see the size posted as well, my bad.  It's been a long weekend.  This probably will not help, but here is a tooth that you and I identified as a juvenile Acheroraptor premaxillary tooth many months ago.  I'm sorry that I can't get a better picture.   It does have the large raised center ridge as well, but the tip is very worn. It is 6mm in length.  

 

 

[Troodon]

Yes the center is arched typical of dromaeosaurid's but there is no center ridge with deep pockets on either side.

[TNCollector]

I think it is a nanotyrannus pre-max tooth. Check out this image from this vendor. The thing to note here is that theropod teeth (or any teeth for that matter) have some statistical distribution of diversity. Although the spread is tight, it is possible to find the outliers. You certainly know better than me about these things, so I trust your input more than mine, but this is my two cents.

 

EDIT: Note, your specimen is also a bit more weathered, so the serrations and other delicate features seen on this image may not be present on your specimen.

 

[Troodon]

Everyone makes a great point with its similarity to theropod, Nano,  premaxillary teeth, thanks.   Susan even said what else can it be and would have to agree and hope it is.  My hangup, to my fault,  is that deep depression on either side of that ridge.  Most Nano premax teeth it's slight but it may be the morphology of a infant/new born that I have yet to see on a 7mm long tooth.  If it's from that young of an animal it's pretty cool.  Going to forward pictures based on all the feedback to Pete Larsen and get his comments.  If he responds will post them.  Thanks

[Carl]

12 hours ago, Troodon said:

Why tyrannosaur all the other theropods have premaxillary teeth?   

As I understand it, only in tyrannosaur premax teeth do both keels migrate lingually. Other theropod premax teeth retain the same carinal arrangement of the maxillary teeth: one labial and one lingual carina.

[Troodon]

Appreciate all the input and I'm in with you're diagnosis   I talked with a friend of mine in Calgary who found a tooth a hair smaller than mine with the same morphology.  This was a few years back and he remembers bringing the tooth to Phil Currie while he was still at the Tyrrell.  Phil looked at the tooth and immediately said it was a tyrannosaurid and only knew of a smaller one at the Smithsonian.  He indicated that these infant teeth have a different morphology in that they have a very high center ridge that reduces and widens with age.   I will pursue it with Pete Larsen to see if he has additional insight of teeth from the Hell Creek.

[zekky]

It looks like a tyrannosaur pre max imo. However, I don't think it's out of the realm to be a worn dromaeosaur premax, doubtful but possible. 

[hxmendoza]

Troodon it's the incisiform first maxillary tooth of a juvenile Tyrannosaur. I have a cast of the snout of the formerly known Stygivenator. From the LACM

 

Carr refers this specimen to a juvenile T. rex. Others place it in Nanotyrannus. Until proven conclusively, I still regard Nanotyrannus to be valid. Nanotyrannus  has an incisiform first maxillary tooth. Your tooth is a match for it. Though I own the cast, I have also had the pleasure of personally holding the original specimen in my hands. That first incisiform maxillary tooth has the high raised ridge and deep cupping with no serrations as your tooth has. 

 

Remember that Currie has proven that there are serrated and non-serrated premaxillary teeth in juvenile Tyrannosaurs. Being that this first maxillary tooth is premaxillary-like. It makes sense that it would be of the non-serrated variety. 

 

It's interesting that Gorgosaurus also has an incisiform first maxillary tooth. And Nanotyrannus was formerly known as Gorgosaurus lancensis. 

 

T. rex does not have an incisiform first maxillary tooth. At least as an adult. If Nanotyrannus does absolutely prove out to be a juvenile T. rex, than the missing incisiform first maxillary tooth may be a result of ontogenetic loss of this tooth. 

[Carl]

Outstanding detective work, everyone!