Comparison with a Modern Shark

Many souvenir shops in areas close to the oceans, and many "nature shops" sell nicely cleaned and prepared shark jaws. The example shown here was bought on Hawaii. I'm not 100% sure, but it looks like it once belonged to a grey shark (and correct me if I'm wrong). The guy who sold it to me thought these came from "shark farms" in Thailand, where sharks are raised (do you "raise" sharks?) for "shark fin soup"...

The whole jaw measures about 37cm (14.5") across.

As you can see (well almost see) the upper and lower jaws have markedly different teeth. The upper are triangular and serrated. The lower are smooth, pointy and curve inwards.

[ Note that these jaws have been folded flat by bending them at the point where the left and right halves meet. This explains the kink especially apparent in the lower jaw.]

Left you see a close-up of part of the upper jaw. It clearly shows how the serrated, triangular teeth are placed in the jaw. The roots of teeth in different rows overlap. The second tooth from the right is about to fall out.

The image on the right shows a close-up from the inside of the upper jaw, right in the middle where it has been bend open. You can see tiny teeth on each side of the center. These are para-symphyseal teeth. Had there only been a single central tooth, it would have been a symphyseal. You can also see at least three rows of teeth, with the youngest at the top. These will march forward as the older teeth drop out, and will themselves be replaced by new teeth that still have to form.

Amongst the fossil shark teeth at Brownie's Beach, Grey shark teeth are by far the most common.