The Monthly Marine Fossil Dive: Mieridduryn

While new fossil discoveries sometimes feel like an achievement of the past, scientists are still constantly uncovering new creatures. Case in point: the Mieridduryn, a marine creature from the Middle Ordovician Period (about 464 million years ago). In November 2022, scientists Dr. Joseph Botting and Dr. Lucy Muir discovered two different-sized Mieridduryn fossils in Wales, United Kingdom. Since its recent discovery, the Mieridurryn has captivated scientists for its potential to be a new opabiniid species, a genus that emerged about 79 million years before the Mieridurryn.

The Mieridduryn’s two fossils are the first opabiniid-like creatures to be found in Europe. Similar to opabinnid relatives Opabinia and Utaurora, both fossils have squishy legs, with the smaller fossil having a tail fan with blades. However, Mieridduryn’s most notable feature – its spine-covered proboscis – hints that the Mieridduryn may actually be more closely related to the radiodont genus than the opabiniid genus. The spine-covered proboscis is not currently found in any opabiniid species; while it is found in radiodont species, such as Anomalocaris. Additionally, scientists note how the Mieridduryn fossils were eyeless, while opabiniid species typically have around five eyes. Yet a problem still remains: the Mieridduryn’s squishy legs and long snout are not found in any radiodont species. Dr. Joanna Wolfe, a research associate in the Department of Organismic and Evolutionary Biology at Harvard University, states that Mieridduryn may even end up belonging to a genus that still has not been discovered.

The Mieridduryn still lacks any proper classification, with its features currently not fitting into any known genuses. Yet, the importance behind Mieridduryn’s new discovery still remains. Mieridduryn's discovery allows scientists to develop a better understanding of how Earth’s early animals eventually evolved into arthropods, forming far more complex features. “Whatever the eventual conclusion, the fossils are an important new piece in the arthropod evolutionary jigsaw,” Dr. Joanna Wolfe concluded.

References:

News Staff. “Fossils of Two Bizarre Ordovician Animals Found in Wales.” ScienceNews, 16. 

Nov. 2022.

Weisberger, Mindy. “Tiny 'bramble snout' fossils found near Wales were 'weird wonders' that 

predated the dinosaurs.” LiveScience, 22 Nov. 2022.