Fossil brains indicate underwater feeding in early seals

2023-08-18 16:38:24

Artist’s impression of the stem pinniped Potamotherium valletoni in its natural freshwater environment. – GABRIEL UGUETO (@SERPENILLUS).

MADRID, 18 Ago. (EUROPA PRESS) –

An ancient relative of modern seals likely used its whiskers to forage for food and explore underwater environments, according to a new study in Communications Biology.

The findings on Potamotherium valletoni, which had the appearance of an otter and lived more than 23 million years ago, provide more insight into how ancient seals transitioned from life on land to life underwater.

Although modern seals live in marine environments and use their whiskers to locate food by sensing vibrations in the water, relatives of ancient seals lived primarily on land or in freshwater environments. Some species used their forelimbs to explore their environment. Before this study, it was not clear when the seals and their relatives began using their whiskers to forage.

Alexandra van der Geer of Leiden University and colleagues investigated the evolution of whisker-feeding behaviors in seals by comparing the brain structures of Potamotherium with those of six extinct and 31 living carnivorous mammals, including mustelids, bears and relatives of seals. The brain structures were inferred from molds taken from inside the skulls.

The authors compared the size and structure of a brain region known as the coronal gyrus, which previous research suggested that it is involved in signal processing from the whiskers.

They found that Potamotherium had a larger coronal gyrus than living, ancient land mammals that use their forelimbs for feeding (such as the Asian small-clawed otter), but a similar-sized coronal gyrus as other ancient relatives of seals and semi-aquatic mammals. , such as the Eurasian otter, which uses its whiskers to explore its environment. This indicates that Potamotherium may have used its whiskers when foraging for food, possibly in combination with its forelimbs.

The findings suggest that whisker-based feeding was already present in ancient seal relatives before they transitioned to a fully aquatic lifestyle. The authors propose that the use of whiskers may have helped them adapt to foraging underwater.