Diving into Fossil Penguin Brains

Here is a wonderful reconstruction of the fossil penguin we analyzed in our recent penguin brain evolution study, created by artist Santiago Druetta. The fossil species is hunting down an icefish, a type of fish also known from the 34 million year old fossil La Meseta Formation deposits that yielded the fossil penguin skull.  In the background swims a modern Chinstrap Penguin, a species named for the party-hat-string-like band of black feathers across its chin. The brains of these penguins are shown in the upper right corner.

But what species is the fossil?  Actually, we are not sure. This is because the many extinct species have been named from the La Meseta Formation and each was described by scientists based on limb bones. Because the skull we studied was found in isolation with no traces of the rest of the skeleton, we can’t be sure which species it belongs to with certainty. The skull is roughly the same size as the skull of an Emperor Penguin, but we know that many extinct penguins had small heads relative to their overall body size. Thus, the skull could easily belong to a giant penguin like Anthropornis nordenskjoedli or Palaeeudyptes gunnari.

The situation is even more complex when you consider that we looked at two additional fossil skulls from the La Meseta Formation in the study, and found evidence that each belonged to a different species than the main skull.  One has a very different external morphology. The other looks the same on the outside, but had such a different brain shape that we concluded it must belong to a third species. Regardless of the precise species identifications, these skulls have provided excellent new data on early penguin brain structure.

Life restoration of a 34.2 million year old Antarctic fossil penguin and the extant chinstrap penguin, with virtual brain endocasts of their brains based on X-Ray CT scan data (top right). Original artwork by Santiago Druetta.