A new species of diminutive baleen whale that lived between 3.5 and 2.5 million years ago (Late Pliocene) has been described by U.S. paleontologists led by Dr Robert Boessenecker, from fossils found in California.

The newly discovered prehistoric species belongs to Herpetocetus, a genus of now extinct dwarf whales in the subfamily Herpetocetinae.

Until now, there were four recognized species in this genus: Herpetocetus transatlanticus, Herpetocetus scaldiensis, Herpetocetus bramblei and an unnamed species from Japan.

They lived during the period from the Late Miocene to the Pliocene in north Pacific and north Atlantic oceans.

Fossil specimens of the new species, named Herpetocetus morrowi, were recovered from the San Diego Formation, northern California.

According to a paper published in the Zoological Journal of the Linnean Society, Herpetocetus morrowi was one of the smallest known baleen whales.

It was about 4.5 meters long, had an elongated snout and a roughly quadrate skull.

Dr Boessenecker and his colleagues say that Herpetocetus morrowi may have employed a feeding strategy very similar to that of the gray whale (Eschrichtius robustus).

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Joseph J. El Adli et al. 2014. Herpetocetus morrowi (Cetacea: Mysticeti), a new species of diminutive baleen whale from the Upper Pliocene (Piacenzian) of California, USA, with observations on the evolution and relationships of the Cetotheriidae. Zoological Journal of the Linnean Society, 170, 400–466; doi: 10.1111/zoj.12108