''Eschrichtius akishimaensis'', described in 2017, is one of two species, with the modern day

gray whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. gray back whale, Pacific gray whale, Korean gray whale, or California gray whale, is a baleen whale that migrates between feeding and bre ...

, of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Eschrichtius ''Eschrichtius'' is a genus of baleen whale containing two species: the gray whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. gray back whale, Pacific gray whale, Korean gray wha ...

'', and is the first and only fossil species of the genus, dating to around 1.77–1.95

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago ...

(mya) in the

Early Pleistocene The Early Pleistocene is an unofficial sub-epoch in the international geologic timescale in chronostratigraphy, being the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently estimated to span the time ...

. The bones were first found in 1961 by a father and son, Masato and Yoshio Tajima, in a riverbed in

Akishima, Tokyo is a city located in the western portion of Tokyo Metropolis, Japan. , the city had an estimated population of 113,542, and a population density of 6500 persons per km². The total area of the city is . Geography Akishima is located on the left ...

, lending it a nickname the Akishima whale, and put into storage at the

National Museum of Nature and Science The is in the northeast corner of Ueno Park in Tokyo. The museum has exhibitions on pre- Meiji science in Japan. It is the venue of the taxidermied bodies of the legendary dogs Hachikō and Taro and Jiro. A life-size blue whale model and a ste ...

until it was transferred to

Gunma Museum of Natural History is a museum of the natural sciences in Tomioka, Gunma Prefecture, Japan. History The museum first opened in 1978 under its old Japanese name, after repairs to the former . In 1996, the old museum closed, and its collection was transferred, befor ...

to be studied. The skeleton consists of a skull, neck vertebrae,

thoracic vertebra In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...

lumbar vertebra The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse p ...

tail vertebrae The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordate ...

chevrons Chevron (often relating to V-shaped patterns) may refer to: Science and technology * Chevron (aerospace), sawtooth patterns on some jet engines * Chevron (anatomy), a bone * '' Eulithis testata'', a moth * Chevron (geology), a fold in rock l ...

rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ches ...

s, and arm bones, and has a total length of about . The discovery has generated local enthusiasm in the city, having both a ''Kujira matsuri'' (whale festival) and a ''Kujira Park'' (Whale Park) in its honor, and plans for a life-size replica skeleton in a new educational facility to open March 2020.

References

Fossil taxa described in 2017 Pleistocene mammals of Asia {{Paleo-whale-stub Baleen whales Pleistocene cetaceans