family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
of
baleen whale
Baleen whales (), also known as whalebone whales, are marine mammals of the order (biology), parvorder Mysticeti in the infraorder Cetacea (whales, dolphins and porpoises), which use baleen plates (or "whalebone") in their mouths to sieve plankt ...
(Parvorder
Mysticeti
Baleen whales (), also known as whalebone whales, are marine mammals of the parvorder Mysticeti in the infraorder Cetacea (whales, dolphins and porpoises), which use baleen plates (or "whalebone") in their mouths to sieve plankton from the wate ...
) with a single extant species, the
gray whale
The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of , a weight of up to and lives between ...
(''Eschrichtius robustus''), as well as four described fossil genera: '' Archaeschrichtius'' (
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
), ''
Glaucobalaena
''Glaucobalaena'' is an extinct genus of eschrichtiid that lived during the Pliocene epoch.
Distribution
''Glaucobalaena inopinata'' is known from the Sabbie d'Asti Formation of Piedmont
Piedmont ( ; ; ) is one of the 20 regions of Ita ...
'' and ''
Eschrichtioides
''Eschrichtioides'' is an extinct genus of baleen whale known from the early Pliocene of Northern Italy. Its type species, ''E. gastaldii'', had a complex taxonomic history, starting as a cetothere, then as an extinct member of '' Balaenoptera' ...
'' (
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Gricetoides'' from the Pliocene of North Carolina. Some phylogenetic studies have found this family to be invalid, with its members nesting inside of the clade
Balaenopteridae
Rorquals () are the largest clade, group of baleen whales, comprising the family (biology), family Balaenopteridae, which contains nine extant taxon, extant species in two genus, genera. They include the largest known animal that has ever lived, ...
. The names of the extant genus and the family honours Danish zoologist Daniel Eschricht.
Taxonomy
In his morphological analysis, found that eschrichtiids and
Cetotheriidae
Cetotheriidae is a family of baleen whales (parvorder Mysticeti). The family is known to have existed from the Late Oligocene to the Early Pleistocene before going extinct. Although some phylogenetic studies conducted by recovered the living py ...
(''
Cetotherium
''Cetotherium'' ("whale beast") is an extinct genus of baleen whales from the family Cetotheriidae.
Taxonomy
The family Cetotheriidae and the genus ''Cetotherium'' (sensu lato) have been used as wastebaskets for all kinds of baleen whales, mo ...
Metopocetus
''Metopocetus'' is an extinct genus of baleen whale belonging to the family Cetotheriidae. The type species is ''Metopocetus durinasus''.
Description
''Metopocetus'' is diagnosable by lateral occipital crests continuous with temporal crests tha ...
'') form a monophyletic sister group of
Balaenopteridae
Rorquals () are the largest clade, group of baleen whales, comprising the family (biology), family Balaenopteridae, which contains nine extant taxon, extant species in two genus, genera. They include the largest known animal that has ever lived, ...
.
A specimen from the
Late Pliocene
Late or LATE may refer to:
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* Tardy, or late, not being on time
* Late (or the late) may refer to a person who is dead
Music
* Late (The 77s album), ''Late'' (The 77s album), 2000
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* Late!, a pseudo ...
of
Northern Italy
Northern Italy (, , ) is a geographical and cultural region in the northern part of Italy. The Italian National Institute of Statistics defines the region as encompassing the four Northwest Italy, northwestern Regions of Italy, regions of Piedmo ...
, named ''"
Cetotherium
''Cetotherium'' ("whale beast") is an extinct genus of baleen whales from the family Cetotheriidae.
Taxonomy
The family Cetotheriidae and the genus ''Cetotherium'' (sensu lato) have been used as wastebaskets for all kinds of baleen whales, mo ...
" gastaldii'' by and renamed ''"Balaenoptera" gastaldii'' by , was identified as a basal eschrichtiid by who recombined it to '' Eschrichtioides gastaldii''.
found that the gray whale is phylogenetically distinct from rorquals and that previous morphological studies were correct in the conclusion that the evolution of gulp feeding was a single event in the rorqual lineage. In contrast, multiple later studies found the gray whale to fall within the family Balaenopteridae, being more derived than the
minke whale
The minke whale (), or lesser rorqual, is a species complex of baleen whale. The two species of minke whale are the common (or northern) minke whale and the Antarctic (or southern) minke whale. The minke whale was first described by the Danish na ...
s but basal to all other members in the family, and reclassified it in Balaenopteridae; the
American Society of Mammalogists The American Society of Mammalogists (ASM) was founded in 1919. Its primary purpose is to encourage the study of mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence ...
has followed this classification.
Evolution
Fossils of Eschrichtiidae have been found in all major oceanic basins in the Northern Hemisphere, and the family is believed το date back to the
Late Miocene
The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...
. Today, gray whales are only present in the northern Pacific, but a population was also present in the northern Atlantic before being driven to extinction by European whalers three centuries ago.
Fossil eschrichtiids from before the Holocene are rare compared to other fossil mysticetes. The only Pleistocene fossil from the Pacific referred to ''E. eschrichtius'' is a partial skeleton and an associated skull from California, estimated to be about 200 thousand years old. However, a late Pliocene fossil from
Hokkaido
is the list of islands of Japan by area, second-largest island of Japan and comprises the largest and northernmost prefectures of Japan, prefecture, making up its own list of regions of Japan, region. The Tsugaru Strait separates Hokkaidō fr ...
, Japan, referred to ''Eschrichtius'' sp. is estimated to be and a similar unnamed fossil has been reported from California.
In their description of ''Archaeschrichtius ruggieroi'' from the late Miocene of Italy, argued that eschrichtiids most likely originated in the Mediterranean Basin about and remained there, either permanently or intermittently, at least until the
Early Pliocene
Early may refer to:
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* Early, Iowa, a city
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* Early Branch, a stream in Missouri
* Early County, Georgia
* Fort Early, Georgia, an early 19th century fort
Music
* Early B, stage name of Jamaican d ...
(5–3 Mya), (but see
Messinian salinity crisis
In the Messinian salinity crisis (also referred to as the Messinian event, and in its latest stage as the Lago Mare event) the Mediterranean Sea went into a cycle of partial or nearly complete desiccation (drying-up) throughout the latter part of ...