Lontra weiri (Weir's otter) is a fossil species in the carnivoran family Mustelidae from the Hagerman Fossil Beds of Idaho. It shared its habitat with Satherium piscinarium, a probable ancestor of the giant otter of South America.[1] It is named in honor of musician Bob Weir, and is the oldest known member of its genus.[2] Prior to its discovery, Lontra was thought to have evolved from Lutra licenti, which dates from the Pleistocene of East Asia.[3]
Weir's otter was intermediate in form between Lutra (Old World river otters) and modern members of its genus. It was a small otter, similar in size to the modern marine otter (Lontra felina), which has a head-body length of 33 to 44 inches and can weigh up to 12 pounds.[4] It is known from most of a right mandible and a left humerus.