Palaeontologists have identified an extinct pygmy sperm whale from Peru with the most extreme facial asymmetry recorded in any whale: both of its bony nostrils were positioned entirely on the left side of its skull.
The species, named Scaphokogia huachafo, was described on Tuesday, November 10, in the journal Communications Biology. Measuring about 2.7 metres (nearly nine feet), it lived off the coast of southern Peru during the Late Miocene, between 6.3 million and 5.6 million years ago.
Lead author Dr Aldo Benites-Palomino first wondered whether the skull had been distorted by sediment after burial. He began examining the fossil during his doctorate at the University of Zurich and is now based at Friedrich-Alexander-Universitat Erlangen-Nurnberg.
“Both bony nostrils are shifted entirely to the left side of the skull, while the facial bones differ dramatically in size and position. The skull looks completely crooked,” Benites-Palomino said.
However, the skull’s sutures remained intact, showing that its unusual shape was not caused by poor preservation.
“It was genuine biology, not a result of poor preservation,” Benites-Palomino added.
The animal’s extreme appearance led the researchers to choose “huachafo” as its species name. The word is Peruvian Spanish slang for something tacky, bizarre or over-the-top.
“When we looked at the proportions of this whale – with its face strongly shifted to the left and its oversized, downward-curving snout – it broke every rule of symmetry and elegance seen in living cetaceans,” Benites-Palomino said.
Three-dimensional comparisons involving 31 whale species confirmed that members of the Scaphokogia group had the most highly distorted skulls among the cetaceans examined, according to findings reported by IFLScience.
Co-author Dr Gabriel Aguirre-Fernandez, of the University of Zurich, said the whale’s dense, tube-shaped snout pointed downwards at an angle of 31 degrees. Its flexible neck could bend upwards by as much as 55 degrees.
That combination may have helped the animal remain suspended above the seabed, with its neck acting as a form of natural ballast.
Unlike modern sperm whales, which dive into the deep ocean, Scaphokogia huachafo probably lived in shallower coastal marine environments. Researchers believe it used its unusually positioned sonar organs to search through soft sediment for prey.
Its lopsided anatomy therefore appears to have been linked not only to its striking appearance, but also to a specialised way of feeding near the seafloor.
