How to identify a pterosaur tooth

Paul Pursglove (UK)

Take a close look at the three teeth labelled A, B and C in Fig. 1. All of these teeth could have been sold by unscrupulous fossil dealers as pterosaur teeth. So, which is the real pterosaur tooth? Pterosaur teeth are very rare fossils and they tend to be difficult to identify in isolation. However, they do command a high price to a collector. Most people who research pterosaurs will take time to study the teeth and to compare them with reference collections and scientific papers which are held in repositories at universities and major museums. So let us look at some of the general rules for identifying the teeth of pterosaurs.

Triassic pterosaurs

These little beasties are as rare as it gets. They are only known from a few sites worldwide, and the major finds come from the Zorzino Limestone of Cene, near Bergamo in Italy and from the Preon Valley. Other isolated specimens are known from Greenland, Luxembourg, Austria and Texas. There is also a speculative specimen from the Rhaetic bone beds in the UK. Most of these pterosaurs have three cusped teeth which are very distinctive. I am not aware of any Triassic pterosaur teeth in private collections.

Jurassic pterosaurs

These pterosaurs are more numerous, but tend to be predominated by Dimorphodon, Pterodactylus or Rhamphorhynchus-like specimens. Rhamphorhynchus is a good example of the pterosaurs that have long dagger-like teeth; several other species have very similar teeth, which can occasionally be found in isolation. Diagram D shows a skull of Rhamphorhynchus and a diagram of the opposition of the upper and lower teeth.

The teeth of Rhamphorhynchus (Fig. 2) are oval in section. This shape continues throughout the whole length of the tooth. There is an enamel cap on the upper quarter of the single cusp and the enamel often continues to the root in a narrow strip along the leading and trailing edge of the tooth (see Fig. 3E). The root is hollow and the enamel is very thin. Where the teeth meet when the jaw is closed, there is likely to be a wear facet, often diagonally across the mid-region of the big teeth, but almost never seen on the smaller back teeth.

The pterodactyloid pterosaurs (Fig. 3) often have pterosaurs often have strong jaws with a reduced number of teeth. These pterosaur teeth are almost never found in isolation, but are often fossilised in jaw or jaw fragments. The teeth tend to be oval in shape and often quite short.

Dimorphodon, from the Lias beds of the early Jurassic, is a pterosaur with tightly bound teeth in its jaw. No isolated teeth are known, but they may exist. They are very rare indeed.

Cretaceous pterosaurs

During the Cretaceous period, pterosaurs were in decline. There were not many family groups left at this time. Many of these creatures became very large, often with a worldwide distribution. The smaller pterosaurs were in rapid decline towards the upper cretaceous, as they were in competition with the early birds. Only the larger species seem to survive to the end of the period.

The jaws of some species are toothless, Pteranodon being a good example. Other species of large pterosaur have distinctly large teeth, which can occasionally be found as individual broken teeth in sedimentary deposits of Cretaceous rocks. The variation in tooth type and shape is wide ranging, but all teeth have common features.

Many pterosaur teeth that appear on the open market are not genuine pterosaur teeth. They are often Plesiosaur teeth or fish teeth that look like pterosaur teeth. One of the most common misidentifications of pterosaur teeth comes from the lower jaw of a sabre-toothed salmon (Enchodus petrosus). This is common in Cretaceous marine deposits and other species can be found from the late Jurassic to the Eocene. The lower sabre tooth can be up to 2cm long in larger specimens and the upper palatine fang can be often as big as 3cm. These teeth show a diagnostic slight depression near the base of the tooth. This feature may be absent if the teeth are incomplete.

Most fossil teeth are replaced by minerals (Fig. 6), so it can be impossible to determine the thickness of tooth enamel. Typically, a pterosaur tooth will have very thin enamel, often as little as 0.1mm to 0.4mm thick. A typical marine reptile will have a tooth enamel thickness of 1mm or more. Fish teeth may have even thicker enamel.

Teeth A, B and C (in Fig. 1) – well, they are all fish teeth and not a pterosaur tooth in sight!

Identification of pterosaur teeth is really a job for the experts. Identification is not satisfactory from photographs. Therefore, ideally, someone should look at the tooth to make sure that it is a close match to a type specimen in a museum or university collection. I recently looked at a batch of pterosaur teeth for a colleague and, out of 34 teeth, I did not find a single, genuine pterosaur specimen.

If you want to have a pterosaur tooth or any other pterosaur specimen identified, your best course of action is to consult your local museum or university. If they do not have a specialist palaeontologist, then photographs can be sent to one of the museums that do have specialists.

About the author

Paul Pursglove is involved with The Pterosaur Database, www.pterosaur.co.uk.