Thirty-six million years ago, a penguin eight inches taller than the tallest modern penguin lived on the shores of Peru. Inkayacu paracasensis, a new species under analysis by paleontologist Julia Clarke from the University of Texas, was not your typical penguin. Not only was it taller than modern penguins, but at 130 pounds, it was on average 55 pounds heavier than its modern counterpart and had an extra-long beak for catching fish. Clarke and her team were excited to find that feathers were preserved on the tip of the left wing of the Inkayacu specimen – a rare occurrence in the fossil world. In fact, Clarke’s find is the first penguin fossil found to date that has preserved evidence of feathers. The ancient feathers are arranged in a similar fashion to that of the modern penguin – stacked tightly on the wing for a streamlined and rapid swim through the ocean waters. We know that this giant penguin was not a direct ancestor of modern penguins, but due to the similarity in wing arrangements, scientists are hypothesizing that a common ancestor must have had the characteristic feather pattern of Inkayacu.

penguin feathers2
Fossilized feathers of the Eocene penguin Inkayacu.
Red dots show where samples were taken for analysis.

The most striking departure from modern penguins is Inkayacu’s coloration. Using a relatively new technique, paleontologists were able to determine that Inkayacu’s feathers were red and gray, unlike the black/white “tuxedo” of today’s penguins. Certain molecules called melanosomes that exist in soft tissues like skin and feathers hold pigments that provide color to the structures in which they reside. Sometimes these melanosomes are preserved in fossils, enabling paleontologists to determine the shape of the molecules. Certain melanosome shapes are associated with certain colors that existed when the animal was alive. The shape of Inkayacu’s melanosomes were not as wide as those of modern penguins, indicating that this melanosome shape (and therefore feather color) appeared in the penguin lineage after modern penguins branched from the Inkayacu line about 50 million years ago. Inkayacu‘s melanosomes are similar to those of birds today that are gray and reddish brown. Scientists think that perhaps Inkayacu’s coloration was different because of the methods of its predators. Conceivably the colors that helped Inkayacu avoid predators became a hindrance to penguins later down the road.

Read more about melanosomes and color determination at Paleontology Online.

Read more about this discovery at Wired.com.

The research on Inkayacu was published in the journal Science.

Published On: October 25, 2012

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