Inkayacu
Encyclopedia
Inkayacu is an extinct genus
of penguin
. It lived in Peru
during the Late Eocene, around 36 million years ago. A nearly complete skeleton was discovered in 2008 and includes fossilized feathers, the first known in penguins. A study of the melanosome
s, pigment
-containing organelle
s within the feathers, indicated that they were gray or reddish brown. This differs from modern penguins, which get their dark black-brown feathers from unique melanosomes that are large and ellipsoidal.
, which is about 1.2 metres (3.9 ft) long.
The melanosomes within the feathers of Inkayacu are long and narrow, similar to most other birds. Their shape suggests that Inkayacu had grey and reddish-brown feathering across its body. Most modern penguins have melanosomes that are about the same length as those of Inkayacu, but are much wider. There is also a greater number of them within living penguins' cells. The shape of these melanosomes gives them a dark brown or black color, and is the reason why modern penguins are mostly black and white. Despite not having the distinctive melanosomes of modern penguins, the feathers of Inkayacu were similar in many other ways. The feathers that made up the body contour of the bird have large shafts, and the primaries along the edge of the wings are short and undifferentiated.
, Peru. A nearly complete skeleton was uncovered in the Paracas National Reserve by an expedition team led by Rodolo Salas and studied by a team led by Julia Clarke of the University of Texas. Large penguins, including the species Perudyptes devriesi and Icadyptes salasi, had been described from the area the previous year. The first evidence of melanosomes is fossilized feathers was published in late 2008, being reported from an Early Cretaceous
bird. Paleontologist Jakob Vinther, an author of the 2007 paper on the first fossilized melanosomes known, found melanosomes in the feathers of Inkayacu soon after the fossil was discovered.
. If melanin is present in the feathers to add rigidity, it would be expected that all feathers on living penguins would be black.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of penguin
Penguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
. It lived in Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
during the Late Eocene, around 36 million years ago. A nearly complete skeleton was discovered in 2008 and includes fossilized feathers, the first known in penguins. A study of the melanosome
Melanosome
In a biological cell, a melanosome is an organelle containing melanin, the most common light-absorbing pigment found in the animal kingdom.Cells that synthesize melanins are called melanocytes, and also the retinal pigment epithelium cells, whereas cells that have merely engulfed the melanosomes...
s, pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
-containing organelle
Organelle
In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer....
s within the feathers, indicated that they were gray or reddish brown. This differs from modern penguins, which get their dark black-brown feathers from unique melanosomes that are large and ellipsoidal.
Description
Although it was an early penguin, Inkayacu closely resembled its modern relatives. It had paddle-like wings with short feathers, and a long beak. Inkayacu, along with other extinct penguins from Peru, are often referred to as giant penguins because of their very large size. Inkayacu was about 1.5 metres (4.9 ft) long, in contrast to the largest living penguin, the Emperor PenguinEmperor Penguin
The Emperor Penguin is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching in height and weighing anywhere from . The dorsal side and head are black and sharply delineated from the white belly,...
, which is about 1.2 metres (3.9 ft) long.
The melanosomes within the feathers of Inkayacu are long and narrow, similar to most other birds. Their shape suggests that Inkayacu had grey and reddish-brown feathering across its body. Most modern penguins have melanosomes that are about the same length as those of Inkayacu, but are much wider. There is also a greater number of them within living penguins' cells. The shape of these melanosomes gives them a dark brown or black color, and is the reason why modern penguins are mostly black and white. Despite not having the distinctive melanosomes of modern penguins, the feathers of Inkayacu were similar in many other ways. The feathers that made up the body contour of the bird have large shafts, and the primaries along the edge of the wings are short and undifferentiated.
Discovery
Fossils of Inkayacu were first found in 2008 on the Pacific coast of IcaIca Region
Ica is a region in Peru. It borders the Pacific Ocean on the west; the Lima Region on the north; the Huancavelica and Ayacucho regions on the east; and the Arequipa Region on the south. Its capital is the city of Ica.- Geography :...
, Peru. A nearly complete skeleton was uncovered in the Paracas National Reserve by an expedition team led by Rodolo Salas and studied by a team led by Julia Clarke of the University of Texas. Large penguins, including the species Perudyptes devriesi and Icadyptes salasi, had been described from the area the previous year. The first evidence of melanosomes is fossilized feathers was published in late 2008, being reported from an Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
bird. Paleontologist Jakob Vinther, an author of the 2007 paper on the first fossilized melanosomes known, found melanosomes in the feathers of Inkayacu soon after the fossil was discovered.
Paleobiology
Inkayacu inhabited a sea that existed in Peru during the Late Eocene. Paddle-like limbs enabled an aquatic lifestyle. The large tightly packed melanosomes within the cells of living penguins gives the feathers added rigidity, which may be an adaptation for coping with the stresses of underwater flight. Because Inkayacu has smaller and fewer melanosomes, it may not have been able to swim very deep, possibly remaining near the surface. However, it is also possible that the melanosomes of modern penguins do not give them an advantage underwater, since the feathers on their undersides are primarily white, lacking the rigidity of melaninMelanin
Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...
. If melanin is present in the feathers to add rigidity, it would be expected that all feathers on living penguins would be black.