Houston | Losing the ability to fly did not cause major changes in the brain structure of penguins, according to a new study that examined the skull of the oldest known penguin fossil. The skull is from a penguin that lived in New Zealand over 60 million years ago during the Paleocene epoch. It likely lived much like penguins today, researchers said. But while today’s penguins have been diving instead of flying for tens of millions of years, the change was relatively new for the ancient penguin.
It is the oldest [penguin] following pretty closely after the loss of flight and the evolution of flightless wing-propelled diving that we know of, said James Proffitt from University of Texas in the US. The shape of bird skulls is influenced by the structure of the brain.
To learn about early penguin brain anatomy, researchers used X-ray CT-scanning to digitally capture fine features of the skull’s anatomy, and then used computer modelling software to create a digital mold of the brain, called an endocast. They thought that loss of flight would impact brain structure – making the brains of ancient penguins and modern penguins similar in certain regions. However, after analysing the endocast and comparing it to modern penguin brain anatomy, no such similarity was found, researchers said.
The brain anatomy had more in common with skulls of modern relatives that both fly and dive such as petrels and loons, than modern penguins. It is possible that millions of years of flightless living created gradual changes in the brain structure. But the analysis shows that these changes are not directly related to initial loss of flight because they are not shared by the ancient penguin brain, researchers said. What this seems to indicate is that becoming larger, losing flight and becoming a wing-propelled diver does not necessarily change the [brain] anatomy quickly, said Proffitt.
The way the modern penguin brain looks does not show up until millions and millions of years later, he said. However, similarities in the brain shape between the ancient species and diving birds living today suggest that diving behaviour may be associated with certain anatomical structures in the brain, researchers said.
The question now is do the old fossil penguins’ brains look that way because that is the way their ancestors looked, or does it have something maybe to do with diving? said Proffitt.
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