Aglaocetus

Aglaocetus is a genus of extinct baleen whales known from the Miocene of Patagonia, the US Eastern Seaboard, Japan and the Low Countries. It was once considered a member of Cetotheriidae along with many other putative cetotheres, but was recently recognized as representing a distinct family from true Cetotheriidae.

There are three currently recognized valid species: Aglaocetus moreni, A. latifrons, and A. rotundus.

The type species, Aglaocetus moreni, was originally described as a species of Cetotherium, but later recognized as generically distinct from the latter. "Aglaocetus" patulus, described from the Calvert Formation by Remington Kellogg in 1968, was recovered by Bisconti et al. (2013) in a different phylogenetic position than the Aglaocetus type species. In 2020, A. patulus was renamed Atlanticetus.

Fossils of Aglaocetus have been found in:

Miocene

• Gaimán Formation (Colhuehuapian-Santacrucian), Argentina
• Diest and Berchem Formations, Belgium
• Eibergen Member, Netherlands