Mammoth "Spit Tooth"

Mammoth replacement teeth rotated into position from behind (not beneath). The functioning tooth continued to slowly rotate in the jaw, being pushed from behind by its replacement as it wore. Finally, a combination of osteoclasts (cells that break down the root) and pressure from behind loosened the tooth to the point where it was "spit" out by the mammoth.

Spit teeth from elephants (sensu lato) are characterized by eroded roots and extreme wear to the enamel plates or cusps. They are just worn out.

In this unbroken example you can see the dished-out rear of the tooth where it was in contact with its replacement. There is not much left of the original roots. You can see evidence of the rotation of this tooth in the jaw in its rounded grinding surface.