Dolphin history is revealed by fossils from ancient marine sediments now exposed on land.

The species is known from upper Paleocene sediments exposed in the state of North Dakota, USA.

The species is known from the late Eocene to early Oligocene sediments exposed in the state of Alaska, USA.

The species is known from Middle to Late Jurassic sediments exposed in the province of Santa Cruz, Argentina.

The species is known from Oligocene sediments exposed in the Guangxi Zhuang Autonomous Region, China.

The varved sediments exposed in these sites had formed in glaciolacustrine and glacimarine conditions in the Baltic basin as the last ice sheet retreated northwards.

Ledopsis was named in 1884 and is restricted to Ordovician sediments exposed in Europe.

The species is solely known from the Early Oligocene sediments exposed in central Oregon, USA.

A geologic map of Washington shows the unique nature of such sediments being exposed to the full grinding force of the Pacific Ocean.

In winter, the volume of the meltwater was reduced, leaving the deposited sediments exposed to the wind.