Dino Dilemma

The tooth seen from different angles. Scale is 50mm

A few weeks ago, Dr David Martill from the University of Portsmouth visited the Museum’s collections to look at pterosaur fossils. While he was carrying out his research, he stumbled upon a tiny little tooth, about 1 cm in height, which looked like it might belong to a dinosaur.

Megalosaurus was a theropod, like the owner of the mysterious tooth

Megalosaurus was a theropod, like the owner of the mysterious tooth

We showed the tooth to Dr Roger Benson, an expert on dinosaurs at the Department of Earth Sciences in Oxford. He confirmed that it belonged to a type of dinosaur called a theropod, because of its recurved shape and the presence of a series of serrations, called denticals, along one of its edges. The serrations are worn, making them difficult to see, which might explain why the tooth had not been identified as coming from a dinosaur before now. Theropods are the group of meat-eating dinosaurs that gave rise to birds, and include T. rex, Velociraptor and the UK’s own Megalosaurus. The tooth would have been from a small animal, probably less than a metre long. We can’t tell if it was from a small species or just a young dinosaur.

So why is such a diminutive dinosaur tooth potentially so exciting? The reason is that it might come from the Lhwyd Collection. If it does, it would make it the oldest surviving documented dinosaur tooth in the world.

Specimens from the collection were described by Lhywd in 1699 in his book Lithophylacii Britannici ichnographia, a catalogue of British fossils and minerals in the Ashmolean Museum, where he was Keeper from 1691 until his death in 1709. The collection was transferred to the Museum of Natural History after it opened in 1860. Sadly the collection became neglected, and at one stage the number of known Lhywd specimens in the collections was down to just two. However, thanks to the painstaking work of James Edmonds, one of the curators, in the late 1940s, the collection was brought back together, and the Museum now has around 80 of the specimens from the catalogue.

Lhwyd 92 catalogue entry

Lhwyd 92 catalogue entry

The problem is we can’t be completely sure that the tooth Dr Martill found is from Lhywd’s collection. Lhwyd wrote numbers on all his specimens, which correspond to the numbers in his catalogue (shown here), and this tooth is indeed labelled with the number 92. The handwriting on the dinosaur tooth, and the pen used to write the number are extremely similar to those used on other specimens from the Lhywd collection. It was also found with other numbered specimens from the Lhywd Collection. However, when we checked the catalogue entry, we found that the number 92 doesn’t correspond to a tooth, but to a piece of fossil coral.

Our next thought was that maybe the tooth was originally numbered 1292, but the 12 at the beginning had become worn away through handling. Examination under UV light, to increase the contrast between the writing and the tooth, revealed no sign of other numbers, and in any case the number 92 was written centrally on the tooth, rather than to the right as you would have expected if it had been the end of a longer number.

Tooth lateral 92 visible

Here you can see 92 written on the tooth

We know that Lhwyd’s collection sometimes included several specimens under the same number, and there is another tooth in the collection labelled 1292. This specimen, a shark tooth, is slightly larger than the theropod tooth, so is it possible that Lhwyd wrote the full number on the larger specimens but abbreviated it to 92 for the smaller ones? Hard to say. It seems we have come tantalisingly close to a very exciting discovery, but for now it remains a mystery still to be solved.

Hilary Ketchum & Eliza Howlett, Collections Managers, Earth Collections

One response to “Dino Dilemma

  1. Pingback: Identifikován nejstarší objevený zub teropoda | DinosaurusBlog·

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