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.
Basilosaurus was once recognized as one of the largest known extinct cetaceans at 18 metres (59 ft) in length. The largest fossil toothed whale was the Miocene whale Livyatan melvillei which was estimated to be 13.5-17.5 meter in length. One notable feature of L. melvillei was its teeth which were 36 cm long and is unmatched by any other animal, extinct or alive.