The study of ancient worms could offer a more solid understanding of evolutionary patterns and processes, according to new research. Scientists from the universities of Bath and Lincoln have revealed new findings on the evolutionary relationships and structure of priapulids – a group of carnivorous mud-dwelling worms living in shallow marine waters.
The research, carried out by evolutionary biologists Dr Matthew Wills, Dr Sylvain Gerber, Mr Martin Hughes (all University of Bath) and Dr Marcello Ruta (University of Lincoln), features in the October issue of Journal of Evolutionary Biology. Dr Wills first pioneered a study on existing and extinct priapulids in 1998. Fourteen years on, the team looked at a new and expanded data set of anatomical features to see how knowledge of these worms has been affected by new fossil finds.
He explained: “The fossils from the Cambrian period can cause a real headache for evolutionary biologists. Instinct tells us to expect simple organisms evolving over time to become increasingly more complex. However during the Cambrian period there was an apparent explosion of different major groups of animals, all appearing simultaneously in the fossil record. We looked at priapulid worms, which were among the first ever predators.
“What’s remarkable is that they had already evolved into a diverse array of forms – comparable to the morphological variety of their living cousins – when we first encounter them in the Cambrian fossil record. It’s precisely this apparent explosion of anatomical diversity that vexed Darwin and famously attracted the attention of Harvard biologist Stephen Jay Gould.”
Dr Ruta, from the School of Life Sciences at the University of Lincoln, continued: “Our work has shown that despite many new fossil finds, including many from China in the last decade, the picture remains largely unchanged. This is really important because the fossil record is notoriously incomplete. It is often difficult to know whether a pattern is just an artifact of this incompleteness, or biologically meaningful. Our study resolutely confirms the latter.
“Priapulids are fascinating animals with much potential in evolutionary studies. They have a long history, with the earliest known species being 505 million years old, and with some of their extinct relatives being even older. Via Marine worms reveal the deepest evolutionary patterns.