This is a a pair of jaw sections, one with ten teeth present from a Lower Permian Synapsid (Mycterosaurus sp.) It was collection from cave fissure fill deposits in the Richard's Spur Quarry near Lawton, Oklahoma. The jaw section is on a 1.8x1.25" piece of rock and was microscopically prepared using air abrasives.
Artists reconstruction of Mycterosaurus. Creative Commons License