Researchers found two 430-million-year-old mollusc fossils named Punk ferox and Emo vorticaudum in Herefordshire, England, revealing that early molluscs were more complex and adaptable than previously believed. The study, published in Nature, was led by Dr. Mark Sutton from the Department of Earth Science and Engineering at Imperial College London, according to EurekAlert.
Punk ferox and Emo vorticaudum exhibit unique combinations of characteristics that challenge longstanding views on molluscan evolution. "We have limited information about this group, and for a very long time, we assumed they were rather basic, simple, and primitive," said Sutton, according to New Scientist. The fossils belong to the Aculifera clade, which includes chitons and shell-less worm-like animals.
These worm-like animals, approximately two centimeters in length with long spines, stand out among early molluscs for their distinctive features. The fossils were preserved in the Herefordshire Lagerstätte, an area renowned for its preservation of Silurian fossils dating back about 430 million years, according to Cosmos.
The names Punk ferox and Emo vorticaudum were inspired by their appearance. According to Blick, Punk ferox was named due to the fancied resemblance of the spicule array to the spiked hairstyles associated with the punk rock movement, while Emo vorticaudum was named after the emo musical genre related to punk rock. "Punk in particular, with its spiky appearance, clearly resembles a rebellious punk rocker—and we thought Emo complemented it well," said Sutton, according to Oxford Mail.
The researchers used advanced imaging techniques, including X-ray scanning, to create detailed three-dimensional models of the fossils without causing any external damage. They took thin slices of the material and photographed each layer to construct a comprehensive picture of the organisms. "We have been able to create ‘virtual fossils’—3D digital models—providing us with a gold mine of information and helping us understand that the branch of molluscan evolution containing Emo and Punk was much more evolutionarily rich and diverse than we thought," said Sutton, according to Oxford Mail.
The Emo fossil is preserved in a folded posture, suggesting that it moved like an inchworm, using its spines to grip and push forward, according to New Scientist. "This inching hasn't really been shown in any fossil at all before," said Sutton, as reported by New Scientist. The spines on Emo vorticaudum's rear likely acted as gears to provide propulsion while crawling forward.
Both species likely moved on the sea floor rather than burrowing, as indicated by their smooth undersides. The team suggests that, in contrast to modern molluscs with their single foot, both Punk ferox and Emo vorticaudum may have progressed by inching forward like latter-day caterpillars, as reported by New Scientist.
The discovery challenges the longstanding view that early molluscs from the group known as Aculifera were basic and primitive. "The spikes are probably mostly protective," said Sutton, although it is possible that they were formed because the organisms needed to get rid of the calcium that accumulated in their bodies, according to New Scientist.
Luke Parry at the University of Oxford praised the findings. "Fossil molluscs that preserve soft tissues like this are incredibly rare, and so seeing what these unusual ancient animals looked like in 3D is just spectacular," he said. "This site in Herefordshire appears to be a treasure trove, like a wormy mollusc Pompeii," added Parry.
"Retrieving fossils that are so exceptionally well preserved and reveal details of the soft tissues is extremely rare," said Sutton, according to Oxford Mail. "Molluscs are one of the largest and most diverse animal groups on Earth," he added.
The researchers worked collaboratively with experts from Oxford University, the University of Leicester, Yale University in the US, and the Senckenberg Research Institute and Natural History Museum in Germany.
Punk ferox resembles worm-like molluscs with long spines but has a broad foot and gills like chitons. Emo vorticaudum, similarly worm-like with a long body and spines, features shells and a compressed body similar to chitons. This mix of features helps researchers better understand the mollusc evolutionary tree.
This article was written in collaboration with generative AI company Alchemiq