I found broken in half on a construction site. Bigger piece is about ~4-1/2" and the smaller piece ~3-1/2". My expert identification is teeth, expertise pending on correct identification. Identification this IS from a shark that lived off the coast of GONDWANA! or not...
<img src="http://i.imgur.com/emZkA9z.jpg" title="source: imgur.com" />
<img src="http://i.imgur.com/emZkA9z.jpg" title="source: imgur.com" />