Fossilised Meal Illustrates Habitat Shift of Beaked Whales

Artists’ impression of three individuals of the extinct beaked whale Messapicetus gregarious. They feed on sardines close to the water surface, along the coast of what is now Peru. (Image: A. Gennari)
09/09/2015
Fossilised Meal Illustrates Habitat Shift of Beaked Whales
post by
Reinout Verbeke

Our colleague, palaeontologist Olivier Lambert, has found a 9 million year old fossil of a beaked whale and its last meal. This extremely rare find suggests that part of the beaked whales lived close to the water surface at that time, while the modern species are deep divers.

Modern beaked whales (ziphiids) are a group of odontocetes (echolocating toothed whales) that typically dive hundreds of meters (up tot 3000 meters!) to hunt for squid and fish. Their dentition is reduced and they suck the prey into their mouth (suction-feeders). Fossils already showed that early ziphiid species had a higher number of teeth, suggesting that they must have captured their prey using their jaws. But direct evidence on their diet was lacking so far.

An international team of palaeontologists, with our colleague Olivier Lambert, has unearthed in the desert along the southern coast of Peru the first association of an extinct toothed whale with its presumed prey: a few dozen of sardine-like fish preserved inside its chest region and around its head. Such fossilized stomach contents are surprisingly rare for marine mammals.

Changed habitat

The new find helps shed light on the evolution of beaked whales. The fossil sardines discovered are close relatives of the modern sardine Sardinops sagax, living nowadays along the coast of Peru. ‘They swim in large schools, close to the surface, so nine million years ago some beaked whales like Messapicetus gregarius seemingly didn’t forage in deep waters like extant species, but occupied an ecological niche in the upper part of the water column, says Olivier Lambert (RBINS). The extinction of M. gregarius and other epipelagic beaked whales may be related to the appearance of true dolphins. The successful diversification of the latter in shallower waters may have driven ziphiids to foraging in deeper areas'.

The study, in collaboration with Italian, French, Dutch, and Peruvian scientists, is published in the journal Proceedings of the Royal Society B.

 

Click the photo to see more pictures.

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