Theropod Tooth ID/Info Request

[Dino Dad 81]

Hello!

 

I'm a new member (but not one that's likely to become a stranger). I'm eager to get any information/predictions you can offer on this tooth from the Powder River formation in Montana.

Some of the areas I've been digging into thus far are:

·        Ballpark age/maturity/size of animal

·        Area/position on the jaw

·        Likely causes of damage (e.g., wear from tooth-to-tooth contact, wear from general contact with other animals, trauma prior to death, damage post-death)

·        Any repair/restoration signs observed.

 

One of the main challenges I'm having is that I can't tell how complete this crown is, for measurement purposes--i.e., the tooth is cut short at the tip and at the bottom--which I don't think is the actual "base", since the serrations are still running).

 

Some pics and ballpark measurement attempts (inches) attached.

[pachy-pleuro-whatnot-odon]

Wouldn't be able to help, as this is outside of my area od expertise, but beautiful tooth!

[Dino Dad 81]

I'm a big fan of it as well--regardless of what more I learn about it. A big chunk of my heart has always been pulled towards paleontology, so I'm not surprised to see myself getting so fascinated by just about any fossil I put in front of myself.

Edited December 25, 2020 by Dino Dad 81

[PaleoNoel]

Most likely a Tyrannosaurid tooth based on the size and mesial twist. Looks like natural wear facet rather than a result of weathering on the tooth, potentially where it struck something like bone. 

Cool tooth!

I couldn't find the name Powder River formation when I searched for it, I did find a powder river basin around northeastern Wyoming and the surrounding states which includes formations such as the Hell Creek and Lance. If it came from Montana it's considered Hell Creek, equivalent to Wyoming's Lance in time and fauna, being between ~66-68 mya and with animals such as Tyrannosaurus, Triceratops, Edmontosaurus etc.

There are two morphologies of Tyrannosaur teeth in the Hell Creek, with the more robust being those of Tyrannosaurus and the more compressed blade like teeth being Nanotyrannus, which many in the academic community consider a juvenile rex despite collectors (especially on the forum) noting the overlap in size and serration density with the two morphs. Several privately owned specimens have not been available to study which could sway the debate.

@Troodon @jpc

[TyBoy]

Powder River is a county in Montana.  If thats where its from then its a Trex tooth.  Hell Creek Formation 

[Dino Dad 81]

In the spirit of not making assumptions until the veterans weight in, I figured I shouldn't mention it up front, but it is thought to be a T Rex tooth.

 

Does anyone have a feel for where the base is on this tooth? For example, is there any telling how much of the enamel-stripped section is still crown and not hitting root yet? The serrations are still running strong at the point where the enamel ends.

 

My novice research suggested it's a maxillary tooth and that the overall shape and the palatal view of labiolingual orientations of the crown long axes seemed to point to the smallest of those 3-4 most-massive teeth on each side. While those particular teeth have a beefier look, and bigger measurements in general on an adult T. Rex, the palatal view assessment didn't seem to fit any other teeth (my reference was AMNH 5027, where I'd be looking at mx2). 

 

To take my baseless assessment (no pun intended) a step further, my final hunch was that perhaps:

   (A) this may be one of those huge maxillary teeth, but on a younger-than-adult T. Rex

        or

   (B) that the tip and bottom of this particular specimen create a heck of an optical illusion and that, if reasonably extrapolated, this specimen may be from a larger crown than I thought (i.e., a maxillary tooth on an adult).

        or

   (C) I should stick to my day job

 

Well, it's fun to try...

 

 

The novice research suggested it's a maxillary tooth and that the overall shape and the palatal view of labiolingual orientations of the crown long axes seemed to point to the first of those 3-4 most massive teeth on each maxillary. It was hard to relate that palatal view to any other maxillary teeth, unless my novice eyes aren't seeing accurately. BUT those particular teeth have a beefier look, and bigger measurements in general for adults.

 

I may be way off the mark already, but, following that line of thinking, my best (super novice) guess was that this may be one of those huge maxillaries on a younger-than-adult T. Rex or that the top and bottom of this particular specimen are creating a heck of an optical illusion and that, if extrapolated out, this could be the tip of a huge maxillary on an adult.

[TyBoy]

Let me stress that Identification of Tyrannosaurids is all about location...provenance.  Without a solid locality its uncertain what genus it could be and does not guarantee Trex

[Top Trilo]

I found this map of the Powder River Basin that extends into several counties

[jpc]

Hi and welcome to the Forum.  

 

Some good comments have been made already on the ID  I would be happy calling this a tyrannosaur tooth.  I am not sure how you tell the difference between maxilla and dentary. 

 

I will discuss the Powder River Formation.  As PaleoNoel mentioned, it does not exist.  The Powder River Basin is huge and mostly in Wyoming.  The map posted above is a rough estimate... it is a geological/geographic feature and does not have square boundaries, nor does it include the Black Hills.  But Powder River County in Montana is my guess as to what they meant by Powder River Fm.  It has plenty of Hell Creek Fm where tyrannosaur teeth can be found.  That is what I would go with... Hell Creek Fm of Powder River Co, MT. 

 

The damage to the tooth looks post shedding, not in life.  See that hollow area in the base... that tells us it is a shed tooth.  The tooth was not much longer in the base than the longest edge on this one, based on this.  

 

Nice find.

 

[Dino Dad 81]

Is the ambiguity in the description a red flag--or not that big a deal?

 

To cut to the rest of the chase, it was also thought that the specimen dates back to the upper Cretaceous period (68-66 MYA), "legally collected in the powder river formation in Montana," and comes from the right front maxilla. My own assessment of position might have been swayed by this, but it seems plausible that it's a small maxillary tooth in the front or back. But I suspect it'd then have to be a sub-adult, given sheer size.

 

@jpc 

Since it's a shed tooth, you suspect that the crown wasn't much longer than what's shown by the enamel that's currently intact. While it may not have continued much further, the presence of pretty solid serrations right up to the end of the enamel--especially on the back of the tooth-- means there's got to be another 20% or so to it, no?

Also, I thought the semi-smoothed'ness (and darkness?) of the tip damage suggests that the animal went on to use the tooth after the damage was done? I was under the impression that post-death damage has more jagged appearance (and possibly lighter in color?).

 

Any RED here was added by me:

 

[pachy-pleuro-whatnot-odon]

52 minutes ago, Dino Dad 81 said:

Also, I thought the semi-smoothed'ness (and darkness?) of the tip damage suggests that the animal went on to use the tooth after the damage was done? I was under the impression that post-death damage has more jagged appearance (and possibly lighter in color?).

If teeth break the same way bones do, the difference between ante-/peri-mortem and post-mostem trauma can be described using the following differentiation of characteristics:

 

Table 2 from Sala, Arsuaga, Pantoja-Pérez, Pablos, Martínez, Quam, et al., 2015. Lethal Interpersonal Violence in the Middle Pleistocene

 

 

 

 

 

 

 

 

Table 1 from Wieberg and Wescott, 2008. Estimating the Timing of Long Bone Fractures: Correlation Between the Postmortem Interval, Bone Moisture Content, and Blunt Force Trauma Fracture Characteristics

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What this means in practice - ignoring ante-mortem trauma bone-regrowth for sake of convenience in this explanation - is that ante-/peri-mortem trauma, due to the elasticity of the bone at this time, has edges that flow much more smoothly than the hard and right-angled fractures of dry bone. However, "fresh" bone fractures may show some "feathering" of the edges by way of bone chips adhering along the point of the force that caused the fracture. With dry bone fractures, instead you might see chips of bone having popped off of the bone, leaving areas of lighter colour behind. The below two images (taken from an article from a course on Forensic Archaeology and Anthropology - definitely worth the read as an introduction) illustrate this point:

 

Fresh bone fracture on the left, dry bone fracture on the right

 

 

 

 

 

 

 

 

Now it should be said that I don't think this will entirely hold up for dental enamel, since this is a much less elastic material than bone. Also, I'd suspect that any possibly adhering bone splinters from a fresh bone fracture will not have survived the taphonomic processes leading to fossilisation. However, based on the sharp angles of the enamel around the breaks and the flaking visible in certain places, I'd say that the tooth at least suffered some post-mortem damage.

 

On 12/25/2020 at 12:59 AM, Dino Dad 81 said:

 

 

Now, obviously this is to be expected. But I think it'd be much harder to identify ante-/peri-mortem damage on this tooth.

[Dino Dad 81]

@pachy-pleuro-whatnot-odon, appreciate the info!

 

How do you feel that reconciles with the excerpt below from Schubert, Blaine W; Ungar, Peter S. 2005 (updated in 2014). Wear facets and enamel spalling in tyrannosaurid dinosaurs. Acta Palaeontologica Polonica 50 (1): 93-99?

I realize we're talking about whether this is antemortem wear/trauma or postmortem damage, but perhaps it's illustrative enough to help us conclude that what we see on this tooth is neither type of antemortem wear and, therefore, must be postmortem. Novice as I am, this sounds like it supports reasonable antemortem wear on this tooth--but I suppose it's all about how one interprets smoothed vs jagged marks.

 

"Spalled surfaces tend to be short and squat, with proximal edges irregular or perpendicular to the long axis of the tooth (Figs. 1, 2). These surfaces are found on all sides of the tooth, are conchoidal in nature, and typically extended to the apex. The edges of these surfaces are often rounded, presumably by antemortem wear. Spalled surfaces were common in both tyrannosaurids and extant reptiles, especially crocodilians. The wear surface described by
Farlow and Brinkman (1994) for a specimen of Varanus komodoensis (MCZ 24907) fits the criteria for this type.

Wear facets, in contrast, tend to be elongated and elliptical in shape, and follow the long axis of the tooth (Figs. 3, 4; Table 1). They vary in size from relatively small areas to much larger surfaces, with edges abutting anterior and posterior serrated keels. These are uniformly flat, and are found on labial or lingual surfaces of teeth—but not on both—and not on mesial or distal surfaces. These facets cut well into the dentine, and subsequent smoothing of exposed enamel edges is common.

Such wear facets are often seen on tyrannosaurid teeth, but, in no case did we see them on any of the extant specimens examined. A few teeth lacking facets or spalls also evince marked striation orientation homogeneity, with large parallel striations on one side of the tooth. Microwear patterning on these surfaces resembles that on facets, and is offset from the long−axis of the tooth by about 15 degrees. The shapes of these wear surfaces suggest that they may be “pre−facets”, resulting from attritional wear, but not to the extent of facet formation. This, when considered along with specimens showing variable facet sizes, may provide insight into the process of facet formation.
Finally, surfaces that show the shapes and positioning expected of an attritional facet occasionally lack parallel striations (e.g., Fig. 4). We suspect that these may be altered attritional facets. This pattern is as would be expected if an opposing tooth was shed, and the facet surface was subsequently worn by tooth−food abrasion, particularly where these surfaces preserve the smaller, heterogeneously oriented striations."

 

The first image is of spalling, which they attribute to antemortem behavior. The second is just a pic with a perpendicular-looking mark like the one on this tooth.

Wear_facets_and_enamel_spalling_in_tyrannosaurid_d.bmp

[pachy-pleuro-whatnot-odon]

14 hours ago, Dino Dad 81 said:

How do you feel that reconciles with the excerpt below from Schubert, Blaine W; Ungar, Peter S. 2005 (updated in 2014). Wear facets and enamel spalling in tyrannosaurid dinosaurs. Acta Palaeontologica Polonica 50 (1): 93-99?

As I don't have much time to respond now, let just post a link to the article for others to easily find it well. However, at a preliminary glance, I don't see any conflict between what they wrote and what I said. It's just that the way this looks and is inflicted on teeth it's somewhat different from bone. But let me get back to it a bit later...

[jpc]

18 hours ago, Dino Dad 81 said:

 

 

@jpc 

Since it's a shed tooth, you suspect that the crown wasn't much longer than what's shown by the enamel that's currently intact. While it may not have continued much further, the presence of pretty solid serrations right up to the end of the enamel--especially on the back of the tooth-- means there's got to be another 20% or so to it, no?

Also, I thought the semi-smoothed'ness (and darkness?) of the tip damage suggests that the animal went on to use the tooth after the damage was done? I was under the impression that post-death damage has more jagged appearance (and possibly lighter in color?).

 

 

My semi-educated guess (based on a few teeth I have found) is that the photo in your original post shows pretty much the full length of tht ooth.  The photo where the micrometer says "3.2".  I don't think there is much base missing except arond the other side.  

 

 

[Dino Dad 81]

So you think this part had enamel too originally? That may be my biggest question of all.

Any thoughts on adult vs sub-adult?

The initial uncertainty in this post regarding it even being a Rex made me pretty sure it’s sub-adult, but 3.2 straight line (probably 3.5 straight line if tip were there) might re-open that case.

[jpc]

21 hours ago, Dino Dad 81 said:

 

 

I think yours had enamel a little further down on this side, but shed teeth do not have enamel all the way down.  There seems to be enamel on the far sida (left of your yellow circle).  I think your enamel might have not gone much further than that. 

 

Here is one of mine.  You can see the serrations go down to the black line and the ridge they are on goes on a little bit longer, but the enamel stops right shortly after that (brown line).  Then there is the non-enamel portion... the remains of the root.  From this, maybe you can guesstimate how much is actually missing on yours.  The tip on this one is well worn (in life) as you can see by the worn off denticles going towards the tip.  I hope this helps.  

 

[pachy-pleuro-whatnot-odon]

14 hours ago, Dino Dad 81 said:

How do you feel that reconciles with the excerpt below from Schubert, Blaine W; Ungar, Peter S. 2005 (updated in 2014). Wear facets and enamel spalling in tyrannosaurid dinosaurs. Acta Palaeontologica Polonica 50 (1): 93-99?

I realize we're talking about whether this is antemortem wear/trauma or postmortem damage, but perhaps it's illustrative enough to help us conclude that what we see on this tooth is neither type of antemortem wear and, therefore, must be postmortem. Novice as I am, this sounds like it supports reasonable antemortem wear on this tooth--but I suppose it's all about how one interprets smoothed vs jagged marks.

So, I've had a glance over said article, and it seems to indeed mainly discuss two types of antemortem damage to tyrannosaurid teeth (which are, by no means, my area of expertise): spalling and attritional facets. Both of these types of damage conform well to the fresh bone fracture typology with respect to their edges being smooth and obtuse - that is, far from the jagged appearance of a dry bone break. What, moreover, is interesting as concerns this type of damage is that all areas of damage are oriented along the length of the tooth (that is, running apicobasally), which is a natural result of teeth being used by a motion along the same axis - teeth just simply move up and down. And though your tooth would initially seem to have some damage along its vertical axis, the edges nor remaining dentine surface are smooth. With spalling or wear facets, the damage would've been smoothed out from the repeated rubbing of teeth - which, in essence, polishes the bone underneath. It's comparable to the difference of repeatedly scooping a tiny spoon of ice cream and thus creating a gully, versus simply breaking off a large chunk of that same ice cream by force. In the former situation the ice cream below will be smooth, in the second instance it'll be rough.

 

To be honest, after reading that article, I'm now even more convinced that the damage on your tooth is postmortem damage, rather than antemortem...

[hxmendoza]

Subadult T. rex right premaxillary tooth. 
 

The damage appears to be from normal wear and some spalling. 
 

Powder River is not a formation, but an area. There is lots of Hell Creek Formation in Montana in this area. 
 

Quite comfortable with the locality info given and therefore, the ID.
 

 

[Dino Dad 81]

There's a lot of much appreciated feedback I'm eager to respond to. Here's quickie I wanted to shoot over to @hxmendoza:

 

Does the pic below preclude premaxillary?

[hxmendoza]

Your tooth is not a premaxillary tooth. 
 

I made a typo in my previous response. I meant to type right anterior maxillary tooth. 

 

And I also misspoke. Powder River is an area, but also a County in Montana. As @jpc said above. 

I was in a hurry while typing and should have proofread before submitting, so everyone please accept my apologies for rushing. 

 

These Powder River Rex teeth tend to generally come from a well known seller on the well known auction site. They usually originate from said seller. Though of course they are bought and then resold as well by others. So I’m pretty confidant the tooth would be from the Hell Creek Formation of Powder River County, Montana if that is the locality info that came with the tooth and is considered trustworthy. 

[-Andy-]

I got nothing to add other than to agree that it is a tyrannosaurid tooth, and is T. rex if proven to be in Hell Creek Formation

[dinosaur man]

Hi and welcome to the forum, sadly it’s extremely hard to tell the age and size of the animal it came from.  Btw amazing tooth!