lower1. 1  to cause to descend; let or put down: to lower a flag. 2  to make lower in height or level: to lower the water in a canal. 3  to reduce in amount, price, degree, force, etc. 4  to make less loud: Please lower your voice.
Biggest Whale-Basilosaurus (60 Tons). Basilosaurus (Nobu Tamura). Unlike the other mammals on this list, Basilosaurus can't lay claim to being the largest-ever of its breed--that honor belongs to the still-extant Blue Whale, which can grow to as much as 200 tons.
The biggest land mammals ever to live evolved by around 39-40 million years ago (near the end of the Eocene Epoch) and flourished during the subsequent Oligocene Epoch (33.9-23 million years ago). The largest of them was a hornless rhinoceros (Indricotherium transouralicum) living in Eurasia that weighed 16.5 tons (15,000 kg.) and stood 18 feet (5.5 m.) at the shoulders.