The Swiss Plateau region, or “Mittelland,” was once an ocean where dolphins swam 20 million years ago. The Paleontological Institute at the University of Zurich has uncovered two previously unknown species linked to current sperm whales and oceanic dolphins, which they identified using ear bones.

Approximately 20 million years ago, when the climate warmed, sea levels increased and swamped Europe’s low-lying regions. Switzerland was part of an island environment with fish, sharks, and dolphins, as well as mussels and sea urchins on the seabed at the time.

Paleontologists at the University of Zurich have investigated over 300 whale and dolphin fossils from this time period. Strong currents pulled the animal skeletons across the ocean floor and scattered the bones, according to the important natural history and paleontology collections in Switzerland, which mostly contain fragments of teeth, vertebrae, and ear bones found in the Upper Marine Molasse.

Hearing capacity reconstruction

The bones from the inner ear are the most fascinating remains for research since they allow each species to be classified. The issue is that these types of bones are uncommon to come across.

“Nevertheless, we managed to identify two families of dolphins previously unknown in Switzerland,” according to paleontologist Gabriel Aguirre, summarizing the study results.

Researchers used micro-computed tomography to generate 3D reconstructions of the ears by reconstructing the soft organs around the hard ear bones.

“This helped us better analyze the dolphins’ hearing ability,” explains Aguirre.

The prehistoric mammals are related to today’s sperm whales and oceanic dolphins, according to the research.

Image Credit: Jaime Chirinos

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