Molluscs are one of life’s most diverse animal groups. Because of limited information, early Aculiferan mollusks are much less well-known than some of their relatives. The pathways of early molluscan evolution have long been controversial.
Researchers from Imperial College London have made an exciting discovery that reveals ancient mollusks were more complex and adaptable than previously known. They have discovered two rare 430 million-year-old fossils named Punk and Emo.
The team retrieved the fossils, which date back to the Silurian period, from Herefordshire. Punk has a large foot and gills resembling chitons but is also a worm-like mollusk with strong spines. Like worms, emo have lengthy bodies and spines. They also have shells and a compressed body like chitons.
Early mollusks from the group known as Aculifera – which include chitons and worm-like mollusks – were believed to be essential and primitive.
The newly discovered fossils are scientifically named Punk Forex and Emo vorticaudum. Their discovery challenges the abovementioned and long-held belief, suggesting that early mollusks possessed some unique features and were, in fact, quite complex and adaptable in their forms and habitats.
Researchers came to this conclusion after recreating the fossils in 3D. They created ‘virtual fossils’ using advanced imaging techniques that offered much information. It helps us understand that the branch of molluscan evolution containing Emo and Punk was much more evolutionarily rich and diverse than previously thought.
Specifically, the team used two techniques: X-ray scanning offered a detailed look at the internal structures without causing external damage. They then meticulously ground the fossils in extremely thin layers, taking pictures at every stage.
In addition to having certain distinctive characteristics and unusual movement patterns, researchers discovered that both fossils had smooth undersides, indicating they lived on the sea floor.
Since the Emo fossil is preserved in a folded position, it likely moved similarly to an inchworm, gripping and pushing forward with its spines. Researchers are still unsure of Punk’s mode of locomotion, but they discovered that it had a ridge-like foot that was unique among mollusks today.
Dr. Mark Sutton, from the Department of Earth Science and Engineering at Imperial College London, said, “The names Punk and Emo were actually our initial pet names for these ancient mollusks, inspired by some of their unique features and individuality. Punk in particular, with its spiky appearance, clearly resembles a rebellious punk rocker – and we thought Emo complemented it well.”
Journal Reference:
- Sutton, M.D., Sigwart, J.D., Briggs, D.E.G. et al. New Silurian aculiferan fossils reveal complex early history of Mollusca. Nature (2025). DOI: 10.1038/s41586-024-08312-0
