Caspian Sea
The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not a freshwater lake. It contains about 3.5 times more water, by volume, than all five of North America's Great Lakes combined. The Caspian was once part of the Tethys Ocean, but became landlocked about 5.5 million years ago due to plate tectonics. The Volga River (about 80% of the inflow) and the Ural River discharge into the Caspian Sea, but it has no natural outflow other than by evaporation. Thus the Caspian ecosystem is a closed basin, with its own sea level history that is independent of the eustatic level of the world's oceans.
Caspian horse
Although there are no records of breeding prior to 1965, the foundation animals included in the International Caspian Stud Book were proven by Louise Firouz to breed true to type and their descendants have, for the most part, retained Caspian characteristics. They are therefore an established breed. Improved living conditions outside Iran have produced Caspians that have grown larger than their Iranian foundation parents; modern Caspians range between 10hh (102 cm) and occasionally 12.2 hh(127 cm), averaging 11.2 hh (117 cm).