Late Oligocene in the context of "Geologic timescale"

The Adriatic Sea (/ˌeɪdriˈætɪk/) is a body of water separating the Italian Peninsula from the Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Sea) to the northwest and the Po Valley. The countries with coasts on the Adriatic are Albania, Bosnia and Herzegovina, Croatia, Italy, Montenegro, and Slovenia.

The Adriatic contains more than 1,300 islands, mostly located along its eastern coast. It is divided into three basins, the northern being the shallowest and the southern being the deepest, with a maximum depth of 1,233 metres (4,045 ft). The prevailing currents flow counterclockwise from the Strait of Otranto. Tidal movements in the Adriatic are slight, although larger amplitudes occur occasionally. The Adriatic's salinity is lower than the Mediterranean's because it collects a third of the fresh water flowing into the Mediterranean, acting as a dilution basin. The surface water temperatures generally range from 30 °C (86 °F) in summer to 12 °C (54 °F) in winter, significantly moderating the Adriatic Basin's climate. The Adriatic Sea sits on the Apulian or Adriatic Microplate. In the Late Oligocene, the Italian Peninsula first formed, separating the Adriatic Basin from the rest of the Mediterranean. The western coast is alluvial or terraced, while the eastern coast is highly indented with pronounced karstification. There are dozens of marine protected areas in the Adriatic, designed to protect the sea's habitats and biodiversity—more than 7,000 species are identified as native to the Adriatic, many of them endemic, rare and threatened ones.

Cetotheriidae is a family of baleen whales (parvorder Mysticeti). The family is known to have existed from the Late Oligocene to the Early Pleistocene before going extinct. Although some phylogenetic studies conducted by Fordyce & Marx 2013 recovered the living pygmy right whale as a member of Cetotheriidae, making the pygmy right whale the only living cetotheriid, other authors either dispute this placement or recover Neobalaenidae as a sister group to Cetotheriidae.

South Asian river dolphins are toothed whales in the genus Platanista, which inhabit the waterways of the Indian subcontinent. They were historically considered to be one species (P. gangetica) with the Ganges river dolphin and the Indus river dolphin being subspecies (P. g. gangetica and P. g. minor respectively). Genetic and morphological evidence led to their being described as separate species in 2021. The Ganges and Indus river dolphins are estimated to have diverged 550,000 years ago. They are the only living members of the family Platanistidae and the superfamily Platanistoidea. Fossils of ancient relatives date to the late Oligocene.

South Asian river dolphins are small but stocky cetaceans with long snouts or rostra, broad flippers, and small dorsal fins. They have several unusual features. Living in murky river waters, they have eyes that are tiny and lensless; the dolphins rely instead on echolocation for navigation. The skull has large crests over the melon, which help direct their echolocation signals. These dolphins prey mainly on fish and shrimp and hunt them throughout the water column. They are active through the day and are sighted in small groups. Both species are listed as endangered by the IUCN Red List of mammals. Major threats include dams, barrages, fishing nets, and both chemical and acoustic pollution.