Three toed horse tooth ID help

[diginupbones]

Could use a little help with this one. I think I have it narrowed down to Nannippus but haven’t found a close match with the info I have available. Thanks. APL=24mm. TRW=23mm. MSCH=37mm. Thanks   @Shellseeker   @Harry Pristis
 

[Shellseeker]

Need some info... where did this tooth come from?

Here is one of mine also an upper left: Huge size difference. It looks similar but maybe the large center circle will push us to another species.

[diginupbones]

4 minutes ago, Shellseeker said:

Need some info... where did this tooth come from?

Here is one of mine also an upper left: Huge size difference. It looks similar but maybe the large center circle will push us to another species

It’s another North Central Nebraska tooth. There’s also another circle on the left side, really an unusual tooth

[Shellseeker]

15 minutes ago, diginupbones said:

It’s another North Central Nebraska tooth. There’s also another circle on the left side, really an unusual tooth

Here is a good  thread that relates....

http://www.thefossilforum.com/index.php?/topic/72229-equus-identifications/

 

I saw one of @siteseer comments. 

Quote

From what I've learned about Florida horse teeth, Nannipus peninsulatus is not only found only in the Blancan, its teeth are also clearly larger than those of other Nannipus species.  It's also among the last-survivng, if not the last-surviving, three-toed horse in North America.

He may have insights here.  Also @fossillarry

[diginupbones]

41 minutes ago, Shellseeker said:

Here is a good  thread that relates....

http://www.thefossilforum.com/index.php?/topic/72229-equus-identifications/

Lots of good info in that thread. I’ll keep digging. Thanks

[diginupbones]

@Shellseeker  I had to get help from Dr Hulbert. What a valuable resource!  

 

With the caveat that identifying a single fossil tooth to the species level is never a certainty but is only “most probable”.  This is a right upper premolar (either third or fourth). Original crown height does not appear to be very high. The combination of very complex and numerous fossette plications, bifurcated pli caballin, and isolated protocone that is elongate-oval with an anterior spur together with the size of the tooth leads to an identification of Cormohipparion quinni. This species is known from late Barstovian, middle Miocene localities in Cherry and Brown counties, Nebraska. It was first used by M. O. Woodburne in 1996 for many of the specimens called Cormohipparion sphenodus by Bruce MacFadden in his 1984 monograph on North American hipparionine horses. According to Woodburne, MacFadden was correct that these specimens belonged to Cormohipparion, but that they were not the same species (or genus) as the type specimen of Merychippus sphenodus. For that reason he had to come up with a new species name for them.

 

As an admirer of fossil horse teeth, I agree with you that this one is beautiful.

[Shellseeker]

Just think... Dr Hulbert has been helping me identify small horse teeth and numerous other Florida fauna for a decade.  He is invaluable. I treasure his support of the fossil community and am always thankful for the gifts of knowledge he has bestowed on me. 

We share a love of tiny horse teeth. Here is a lower one from a Miocene layer that my partner found a couple of weeks ago.  I think it is Hypohippus, but have not passed it by Dr. Hulbert, as of yet...

[fossillarry]

Based on crown height(37mm) the Nebraska tooth would be considered hypsodont(high crowned). Based on the observation that the parastyle is relatively wide with a grove, the mesostyleis also relatively wide and the protocone has a slight anterior spur and the overall crown pattern.  I believe that your tooth is a left upper premolar 3/4 from Middle Barstovian Cormohipparion quinni. C.quinni is the successor to the early Barstovian C. goorisi a mesodont species. Shellseeker  I am afraid that the tooth you found is not from Hypohippus. It's to small and has cementum on the crown surface. Based on Early Miocene age,crown size and pattern and slight cement coating I think it more likely that this tooth is a lower left m1/2. of "Merychippus"gutheri. A very nice find.

[Shellseeker]

49 minutes ago, fossillarry said:

Based on crown height(37mm) the Nebraska tooth would be considered hypsodont(high crowned). Based on the observation that the parastyle is relatively wide with a grove, the mesostyleis also relatively wide and the protocone has a slight anterior spur and the overall crown pattern.  I believe that your tooth is a left upper premolar 3/4 from Middle Barstovian Cormohipparion quinni. C.quinni is the successor to the early Barstovian C. goorisi a mesodont species. Shellseeker  I am afraid that the tooth you found is not from Hypohippus. It's to small and has cementum on the crown surface. Based on Early Miocene age,crown size and pattern and slight cement coating I think it more likely that this tooth is a lower left m1/2. of "Merychippus"gutheri. A very nice find.

Larry.

I admire your expertise. You add a higher dimension of expertise,  especially on the topic of small horse teeth. 

I will give you proper credit when I send the photos to Richard...This is my 2nd Merychippus, the 1st was an upper tooth...

 

[Shellseeker]

On 8/29/2022 at 9:15 PM, fossillarry said:

Based on crown height(37mm) the Nebraska tooth would be considered hypsodont(high crowned). Based on the observation that the parastyle is relatively wide with a grove, the mesostyleis also relatively wide and the protocone has a slight anterior spur and the overall crown pattern.  I believe that your tooth is a left upper premolar 3/4 from Middle Barstovian Cormohipparion quinni. C.quinni is the successor to the early Barstovian C. goorisi a mesodont species.

Shellseeker  I am afraid that the tooth you found is not from Hypohippus. It's too small and has cementum on the crown surface. Based on Early Miocene age,crown size and pattern and slight cement coating I think it more likely that this tooth is a lower left m1/2. of "Merychippus"gutheri. A very nice find.

Larry,

Thanks for the excellent Identification on C. quinni.  It is my first of that species.

 

Merychippus is a very unusual find in the Peace River, (South Central Florida).. and I sent the photos to Richard to offer it as possibly one of the very few found in the Peace River..  His response:

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Anyone who even knows of the rather obscure species Merychippus gunteri should be lauded, but that ID is unlikely. Steve’s fossil has a very thick coating of cement, while M. gunteri has a thin layer of cement. Plus M. gunteri is restricted to the early Miocene (it is one of the most primitive and earliest species of Merychippus), and there are no land mammals of that age in South-central Florida. Steve’s tooth may have originally been much higher crowned than it appears to be and the base of the crown has broken off making it look low-crowned. I should be able to tell if this is the case if you take an image looking straight at the broken surface.

Richard

Emphasis mine,  so I will remember to check age of my finds in the future.  Here is the additional photos since I now have the tooth in hand and sent measurements to Richard just now...

[Shellseeker]

15 hours ago, Shellseeker said:

Emphasis mine,  so I will remember to check age of my finds in the future.  Here is the additional photos since I now have the tooth in hand and sent measurements to Richard just now...

Response:

Quote

Regarding the tooth, it is not a broken high crowned tooth but is from a “Merychippus” equid. Probably of middle Miocene age (early Barstovian land mammal age).

Richard

 

https://www.floridamuseum.ufl.edu/florida-vertebrate-fossils/land-mammal-ages/barstovian/

Quote

The Barstovian is divided into two subintervals: the Ba1 from 15.9 to 14.8 million years ago; and the Ba2 from 14.8 to 12.5 million years ago (Tedford et al., 2004). All of the Barstovian NALMA falls within the middle Miocene Epoch of the standard geologic time scale.

Index species for Ba1 in Florida: Perognathus minutus, Bouromeryx americanus, Acritohippus isonesus, Merychippus brevidontus, “Merychippus” goorisi

Note:  Richard had previously identified an Upper Cheek tooth from this site as M. goorisi