Unerupted Equus Teeth

[Shellseeker]

As some of you know , I volunteered to analyze a box of horse teeth for a fossil friend. Still working on it, but came up with a question for the Horse whisperers:

Horses have a set of adult teeth that start around 4-5 inches and are worn down over years.  New teeth are erupted at a maximum size. When the teeth wear out , the animal dies of starvation. 

I seem to have found a bunch of teeth that refute that understanding. I have 20-30 such non erupted teeth and many measure around 1.5 inches long and a few of them have roots. What am I missing .. How can the majority of unerupted teeth I have be so short? What am I missing ?

 

 

 

 

[Harry Pristis]

These teeth are not quite analogous to the commonly-found tapir enamel cap.  In equus, the full enamel is not yet developed when the tooth goes into battery.  Here's how Hulbert (pers. comm.) described the condition:

In most hypsodont (high crowned) horses, the base of the crown is open and enamel and dentine are being added to the tooth when it erupts and as it begins to wear. Equus takes this to a further degree than most other horses, and keeps the base of the crown open and adding more enamel while at the same time the tooth is wearing down at the occlusal surface. This lasts for a year or more until the base of the crown closes and the roots begin to form. This stage (as in your example) is rare to find in river sites in such a complete state, as the base of the crown is weak and usually breaks. More often they can be found in land sites, still inside the jaw bone.