Museum scientists reconstructed the brains of two 55 million-year-old Eocene seabirds from CT scans of their skulls.
Surprisingly, the brains showed that the shape and volume of the forebrain – the region that controls flying ability and behaviour – were as well developed as in modern birds. Increasing brain size correlating with improved cognition.
This development had probably taken place before the end of the Cretaceous when non-avian dinosaurs and ancient bird groups died out. Larger brains may have meant that the ancestors of modern birds were more adaptable and able to cope with rapid environmental change.
The Eocene seabird skulls also showed the early stages of an extra part of the forebrain called the ‘wulst’, which allowed even more structural complexity in the brain and led to the huge diversity of modern birds we see today.
This work was carried out with funding support from the Natural Environment Research Council (NERC).