Fossil seven gill shark teeth, Notorynchus primigenius

Cow shark teeth are amongst some of my favorite fossil shark teeth to find. The common name "cow shark" refers to six and seven gill sharks. Here we have a group of fossil seven gill shark teeth from Notorynchus primigenius, a species that lived during the Miocene through Pliocene epochs, 23.5 to 2.5 million years ago. Cow sharks have a unique dentition unlike other sharks in many ways. The most visually notable, is their tooth design, in having multiple large cusplets making up the main crown of the tooth. Their jaws are also backwards, in that, the upper teeth are used for grasping and holding , while the lower teeth are used for cutting and sheering. This is the opposite of most shark species. If you have ever seen a cow shark feed, they basically turn upside down to do so. For this reason, they also do not have a dorsal fin like most other sharks. Below are some pics of various teeth from this shark species. Largest tooth measures an inch.

Here is a tooth from the symphysis region of the lower jaw. By far my favorite tooth position in this sharks jaw.

A Lower tooth

Tooth from the upper jaw symphysis area

Tooth from the upper jaw