How Sharktoothify identifies shark teeth

Sharktoothify compares what is visible on a tooth, such as its position in the jaw, serrations, side cusplets, root and size, with a reference library of 44 shark tooth types. It gives a ranked list of likely matches with the evidence for and against each, and says plainly how sure it is. It cannot certify a tooth.

Two tools

The tooth key (free, no account, works offline)

You answer a few questions about the tooth, one at a time, each with a picture. The key narrows the reference library after every answer and shows the closest types with the features that support each.

Expert ID (from photos)

You send up to three photos: the main face, the other face or a close-up of an edge, and the root beside a coin for scale. Sharktoothify checks that it is a shark tooth at all (shells, crab claws, stones and mammal teeth are common look-alikes), reads the visible features, compares them with the reference library, and returns up to three candidates. Each candidate lists the evidence for it and the evidence against it, and the report says which extra photo would settle a doubt.

How confidence is decided

• High is allowed only when at least one decisive feature of that tooth type is clearly visible, nothing that rules it out is seen, and the photo is good.
• A blurry, dark or cropped photo caps confidence and triggers a request for a better photo.
• Teeth from look-alike groups (for example requiem sharks, or the megalodon line) are answered as a group when the photo cannot separate them.
• Size without a scale is treated as an estimate, never as proof.
• If it does not look like a shark tooth, the report says what it looks like instead and keeps confidence low.

What it cannot tell you

• Worn, broken or very small teeth, and teeth from the back of the jaw, often cannot be pinned to a species.
• Colour comes from the ground the tooth lay in, so it never identifies a tooth by itself.
• Replicas and altered teeth exist, and a photo cannot always show them.
• It cannot certify a tooth, set a value, or confirm legal status. Results can be wrong.

We do not publish an accuracy percentage. Results depend on the photo and on the tooth, and a single number would overstate what a photo can show.

Where the facts come from

Every tooth type in the reference library carries citations to published references such as Cappetta's Handbook of Paleoichthyology and Sharks of the World. The species guides on this site are generated from that same library. The records are marked as draft: they have been compiled carefully but have not yet been reviewed by an outside paleontologist, and the guides say so.

What is free and what costs money

The tooth key, the guides, counting your finds and the hunt planner are free. You get one free Expert ID a month once your email is confirmed. More lookups, ad-free Plus and the Vacation Pass are optional paid products, with prices shown before you pay and the cancellation page one tap away. Starting from $1.00 per lookup in a small pack, Plus $19.99 a month or $199.99 a year, and the Vacation Pass $19.99 once.

Your photos and your data

Photos are sent for analysis only when you ask for an Expert ID. The Privacy Policy lists exactly what is sent, to whom, and what is kept, and you can download or delete your data from your account.

Compiled from the published sources listed below. This guide has not yet been reviewed by an outside paleontologist. Last updated November 11, 2026.