Inkayacu paracasensis is named after the Quechua words for “water king” and the Paracas National Park where it was discovered by Julia Clarke from the University of Texas. Clarke’s team are no strangers to giant fossil penguins. In 2007, they unveiled two extinct species: Perudyptes, about the size of the modern king penguin; and Icadyptes, which was larger than any living species and had an unusually long, spear-like beak. Like Icadyptes, Inkayacu also swam off the coast of ancient Peru, had a long beak, and was one of the largest penguins in history. It weighed around twice as much as the heaviest of today’s penguins – the emperor.
In many ways, Inkayacu is no more significant a find that Icadyptes was three years ago. It is neither the oldest nor the largest penguin fossil, it doesn’t hail from a new part of the world, and it provides few clues about the group’s evolution. However, it does have one stand-out feature that probably secured its unveiling in the pages of Science – its feathers.
National Geographic should have a 3-D animation up soon
The pursuit of accurate dinosaur colours just turned into a race, and a heated one at that. Just last week, I wrote about a group of scientists who claimed to have accurately identified the colours of some feathered dinosaurs by microscopically analysing three fossils. According to that study, Sinosauropteryx had a tail covered in ginger stripes. Now, another group have revealed the palette of an entire dinosaur, Anchiornis. This tiny predator had a dark grey body and the limbs bore long, white feathers tipped with black spangles. Its head was mostly grey with reddish-orange and black specks, and an extravagant reddish-orange crown.
Both reconstructions are based on microscopic structures called melanosomes. They’re partly responsible for the brilliant colours of modern bird feathers, they’re packed with pigments, and they happen to fossilise well. There are two major types. Spherical ‘phaemelanosomes’ contain a reddish-brown or yellow pigment while the rod-like ‘eumelanosomes’ have black-grey tints.
The technique of inferring colours from fossil melanosomes was pioneered by Jakob Vinther at Yale University. He used it to show that a Cretaceous bird feather probably had black and white stripes and, later, that another fossil feather had an iridescent starling-like sheen. But these were analyses of single papers and even last week’s paper coloured Sinosauropteryx by looking at just one part of a single individual.
Vinther isn’t impressed with his rivals. “They are in the Stone Age when it comes to understanding melanosome fossilization and interpretation of original colors,” he says. To him, it’s simply not enough predict colours based on the presence of one type of melanosome. Even the hues of single feathers can depend on a mix of the two melanosome types with different concentrations of pigments. So you need to know the distribution of melanosomes across an animal and even then, you still need to work out how that translates to different colours.
And that’s exactly what he’s done. When I spoke to Vinther last week, he said, “We are still far from putting colours on dinosaurs [but] the future is promising. Eventually we will have dinosaurs in technicolour. We are working seriously on that currently.” He wasn’t kidding!
He had been working on a new specimen of Anchiornis with the catchy name of BMNHC PH828. The tail is missing but the rest of the skeleton is beautifully preserved, including the skull and both sets of limbs with their elegant plumes. Rather than looking at individual body parts, Vinther took 29 samples from the specimen, representing every type of feather types across different body parts. In each one, he thoroughly analysed the size, shape, density and distribution of melanosomes.
To interpret this goldmine of data, he worked with his colleague Matt Shawkey to catalogue the melanosomes from a wide variety of living birds, from ravens to finches to mallards. This modern data set was a cross between a paint catalogue and a Rosetta stone. It told Vinther how different combinations of melanosomes led to different colours and allowed him to correctly paint his Anchiornis.