Image of the Eriptychius fossil. Credit: Field Museum of Natural History and Ivan Samson.
Key points:
- A 3D representation of the skull of an ancient jawless fish, Eriptychius americanus, has filled a gap in the evolutionary history of the vertebrate skull.
- Early evolution of distinct structures to separate the brain from other parts of the head may have begun with Eriptychius.
- Applying modern imaging techniques to ancient fossils in museum collections can provide new perspective on vertebrate evolution.
Researchers have pieced together the skull of a 455-million-year-old ancient jawless fish, Eriptychius americanus, to fill a gap in the evolutionary history of the vertebrate skull.
The findings, reported in Nature, give new insight into how vertebrates evolved to protect their brains. Computed tomography (CT) revealed that Eriptychius americanus, found in ancient deposits in Colorado, had separated, independent cartilages encasing the brain.
The detailed 3D skull representation was the first of its type done on the Eriptychius specimen that was collected in the 1940s, described in the 1960s, and housed in the Field Museum of Natural History, Chicago.
Later species possessed a fully bound cage of cartilage that held the brain, but the study’s findings suggest that early evolution of structures to separate the brain from other parts of the head may have begun with Eriptychius.
“These are tremendously exciting results that may reveal the early evolutionary history of how primitive vertebrates protected their brains. Eriptychius americanus appears to be the first evidence for a series of cartilages separating the brain from the rest of the head,” explained senior author Ivan Sansom of the University of Birmingham. “This study emphasizes the importance of museum collections and the application of new techniques in studying them.”
This work fills a major gap in the understanding of the evolution of the skull of all vertebrates, including humans.