Horse tooth

[garyc]

I know these teeth are very difficult to identify. Based on its size I believe it is a lower tooth from a three toed horse.  The crown is  about 15.8mm. @Shellseeker @Harry Pristis

[GPayton]

I'm no expert by any means as I've never encountered a horse tooth on the Brazos that I was absolutely certain was from the three-toed variety, but I believe for it to lean towards that kind of ID the tooth would need to display an isolated protocone on the occlusal surface. However I'm not sure whether the isolated protocone occurs only on upper teeth or if it can be found on the lower teeth as well, like the one you have. 

[Lorne Ledger]

The size looks about right, it's possible.   I have found pre equus horse teeth on the brazos river before.  Here is one from Fort Bend County with the typical isolated protocone, small tooth but still pretty nice.  I think only the upper teeth demonstrate the isolated protocone, but I haven't done much research on that and I have also never found a lower with an isolated structure.  

[Shellseeker]

On 11/5/2020 at 5:22 PM, garyc said:

I know these teeth are very difficult to identify. Based on its size I believe it is a lower tooth from a three toed horse.  The crown is  about 15.8mm

 

Gary,

You should read this thread all the way thru.  I think that your tooth is Cormohipparion,  just unsure of the species. You should validate which Cormohipparion species (Quinni as example) existed in Texas and then match to size.

A protocone, isolated or otherwise is only on upper teeth, not lowers.

To me this is outside the range of Nannippus. I normally think of Nannippus as APL between 13 and 15 mm.

 

[garyc]

Thanks for the replies! Jack, at first glance at the pics in the thread you provided, I was inclined to agree with you on the cormohipparion label. However, the more I compare my tooth to the pics, I’m now leaning toward nannipus. Are there specifics traits that I should look for in the enamel pattern to determine which is a better fit? @Shellseeker

[Shellseeker]

Gary,

What I basically do with small Horse teeth is recognize the specific horse genus that were in my hunting area, look the likely tooth position, thinking about the likely size of that tooth,  and then go to books and research papers to form an opinion.

It is far from perfect, because I do not have the experience of finding lots of these small teeth, and I am not always aware of mammal age of what I find.

So, one of my learning experiences was with Nannippus peninsulatus. I was finding a number of them, and on some of my discussions with Hulbert , we agreed that the location was Florida Blancan. Separating the m3 or p2 which were naturally larger, I got the impression that N penisulatus was in the range of 12-14 mm APL.

I discovered another location where I was finding other Nannippus species like aztecus or westoni and misidentified them as peninsulatus, until Hulbert corrected me.

 

Richard put out a paper in 1993 titled Late Miocene Nannippus (Mammalia: Perissodactyla) from Florida.  It has pictures like this that convinced me that of the Nannippus that I might find in Florida,  they would have an APL under 15 mm.

You can get the paper at researchgate.

It has this table.  These are measurements of upper molars. But you get the idea. You indicate your tooth was 15.8 mm and I immediately discounted Nannippus,  but that may be different for the Nannippus species found in Texas. 

 

My suggestion is 1) Read his paper on Nannippus.  If you believe the right call is Nannippus, send the tooth to Richard for validation. I generally force myself to look at the possibilities that might be found in Bone Valley, and provide Richard a "guess" on what I believe the tooth is:  N aztecus, lower right p3. By doing that , I insure that I have done everything I can to try and get it right and learn from every find.

I am frequently wrong, and in those cases provides a number of points on why he thinks otherwise.

 

[garyc]

Thanks for your very thorough and informative response, Jack! @Shellseeker

[Shellseeker]

Thanks,

Took me a while to find this....

[fossillarry]

These are Nannipus teeth from Florida. The teeth on the left are N weston from the Love site Late Miocene and the teeth on the right are N. aztecus from the Palmetto Fauna Bone Valley area Early Pliocene.

[Shellseeker]

@garyc

I think what fossillarry is pointing out is that some /many of both the N westoni and N aztecus teeth reach or exceed the BAPL length of 15.8 mm on your Brazos tooth.

Just reinforces the need to contact an expert who has access to comparative teeth.    Jack

[fossillarry]

Actually I took these photos of Nannippus before anyone else started posting to this thread.  I have been learning how to add photos to my comments so I added them even though it's a little late for identify the the first tooth in question. Although I will point out that the teeth on the left in  my photo(N.westoni) has a large protostylid, while the teeth on the right(N astecus) do not, which is the condition of the of the unknownt pictured tooth.  The only other species of Late Miocene hipparion(besides Nannippus) that does not have a protostylid is Pseudhipparion simpsoni which is smaller and has other differences.   .