Worm monstrosity: A giant extinct worm

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Mats E Eriksson (Sweden)

In a new study published in Scientific Reports (Earth’s oldest ‘Bobbit worm’ – gigantism in a Devonian eunicidan polychaete) by Luke A Parry of Bristol University in the UK, David M Rudkin of the Royal Ontario Museum in Canada and me (Mats E Eriksson of Lund University in Sweden), an extraordinary new species of polychaetes (that is, bristle worms – the marine relatives of earthworms and leeches) is described.

The new species, Websteroprion armstrongi, is unique among fossil worms and possessed the largest jaws recorded from all of earth history, reaching over one centimetre in length and thus easily visible to the naked eye. Typically, such fossil jaws are only a few millimetres in size and must be studied using microscopes. Despite being only knows from the jaws, comparison of Websteroprion armstrongi with living species suggests that this animal achieved a body length in excess of a metre.

This is comparable to that of ‘giant eunicid’ species, colloquially referred to as ‘Bobbit worms’, a name that is bizarrely enough derived from the infamous story of eye-watering amateur surgery involving Lorena and John Wayne Bobbitt. Living ‘Bobbit worms’ are fearsome and opportunistic ambush predators, using their powerful jaws to capture prey, such as fish and cephalopods (squids and octopuses), and drag them into their burrows.

Figure 1
Fig. 1. A photograph showing the holotype of Websteroprion armstrongi. (Photo by Luke Parry.)

Gigantism in animals is an alluring and ecologically important trait, usually associated with advantages and competitive dominance. It is, however, a poorly understood phenomenon among marine worms and has never before been demonstrated in deep time based on fossil material in this group of animals. The new species demonstrates a unique case of polychaete gigantism in the Palaeozoic, some 400Ma. It also shows that gigantism in jaw-bearing polychaetes was restricted to one particular evolutionary branch within the Eunicida, but has evolved many times in different species in this order of worms.

The specimens were collected over the course of a few hours in a single day in June 1994, when Derek K Armstrong of the Ontario Geological Survey was dropped by helicopter to investigate the rocks and fossils at a remote and temporary exposure in Ontario. Sample materials, from what proved to belong to the Devonian Kwataboahegan Formation, were brought back to the Royal Ontario Museum, where they were stored until they caught the eyes of the authors. Therefore, this new study is also an excellent example of the importance of looking in remote and unexplored areas for finding new exciting things, but also the importance of scrutinising museum collections for overlooked gems.

Figure 2
Fig. 2. For this study, CT-scanning was applied, which revealed additional specimens completely concealed within the host rock. Different views of second left maxilla (green) and second right maxilla (red). (Reconstruction and image composition by Luke Parry and Mats E. Eriksson.)

Because the taxon was new to science, it had to be formally baptised. As suggested by David Rudkin, the species epithet honours Derek Armstrong, who collected the material (see above). However, we had completely different ideas for the new genus name, which honours Alex Webster, bass player extraordinaire of death metal pioneers, Cannibal Corpse.

Figure 3
Fig. 3. An artistic reconstruction showing W. armstrongi attacking a fish in the Devonian sea. (Illustration by James Ormiston.)

I have been a huge music fan since childhood and particularly of the ‘metal genre’, and have named fossils in the past after both King Diamond and Lemmy Kilmister. It had been high up on my wish list to name a fossil also after someone in Cannibal Corpse. Now the perfect opportunity presented itself with this exciting new taxon, and especially so because co-author Luke Parry is also a fan of metal music and has recently named a fossil species after Henry Rollins. Thus, being die-hard fans of Webster’s extraordinary playing technique and the music of Cannibal Corpse, Parry and I found it suitable to honour Webster with this extinct ‘monster worm’.

In the article in Scientific Reports referred to above, we explain the name by stating that it is “named after Alex Webster – a ‘giant’ of a bass player – combined with ‘prion’ meaning saw”. It can also be concluded that this primordial marine ‘giant’ must have been fierce and creepy looking, which fits well with the graphic, yet amusingly cartoonish lyrics of Webster’s band. It is appropriate also because, beside our appetite for evolution and palaeontology, all three of us authors are keen hobby musicians.

Figure 4
Fig. 4. Eriksson and Webster after a Cannibal Corpse gig in Malmö, Sweden in 2015. (Photo by Ulrika N Persson.)

This monstrous worm has now taken on a monstrous form, which can be seen at: Making of a monster: ‘Cannibal the Animal’.

About the author

Mats E Eriksson is a professor of palaeontology at the Department of Geology at Lund University in Sweden. He primarily works on Palaeozoic microfossils and tries to reconstruct and understand ancient organisms and ecosystems. Besides research and teaching, Mats has a deep interest in scientific outreach and adores it when different disciplines – such as science, arts and music – amalgamate.


Eriksson, M.E., Parry, L. & Rudkin, D.M. 2017. Earth’s oldest ‘Bobbit worm’ – gigantism in a Devonian eunicidan polychaete. Scientific Reports 7, 43061; doi:10.1038/srep43061.

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