Eschrichtiidae

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Eschrichtiidae
Temporal range: Late Miocene–Recent
Graywhale MMC.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Parvorder: Mysticeti
Family: Eschrichtiidae
Ellerman & Morrison-Scott 1951
Genera
Synonyms

Eschrichtiidae or the gray whales is a family of baleen whale (Parvorder Mysticeti) with a single extant species, the gray whale (Eschrichtius robustus), as well as four described fossil genera: Archaeschrichtius (Miocene), Glaucobalaena and Eschrichtioides (Pliocene) from Italy, [1] [2] and Gricetoides from the Pliocene of North Carolina. [3] Some phylogenetic studies have found this family to be invalid, with its members nesting inside of the clade Balaenopteridae. [4] [5] The names of the extant genus and the family honours Danish zoologist Daniel Eschricht. [6]

Contents

Taxonomy

In his morphological analysis, Bisconti 2008 found that eschrichtiids and Cetotheriidae ( Cetotherium , Mixocetus and Metopocetus ) form a monophyletic sister group of Balaenopteridae. [7]

A specimen from the Late Pliocene of Northern Italy, named "Cetotherium" gastaldii by Strobel 1875 [8] and renamed "Balaenoptera" gastaldii by Portis 1885, was identified as a basal eschrichtiid by Bisconti 2008 who recombined it to Eschrichtioides gastaldii . [9] [10]

Steeman et al. 2009 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. [11] In contrast, multiple later studies found the gray whale to fall within the family Balaenopteridae, being more derived than the minke whales but basal to all other members in the family, and reclassified it in Balaenopteridae; the American Society of Mammalogists has followed this classification. [4] [5] [12]

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. [9] 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. [13]

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, Japan, referred to Eschrichtius sp. is estimated to be 2.6 to 3.9 Mya and a similar unnamed fossil has been reported from California. [9]

In their description of Archaeschrichtius ruggieroi from the late Miocene of Italy, Bisconti & Varola 2006 argued that eschrichtiids most likely originated in the Mediterranean Basin about 10  million years ago and remained there, either permanently or intermittently, at least until the Early Pliocene (5–3 Mya), [14] (but see Messinian salinity crisis.)

Related Research Articles

<span class="mw-page-title-main">Rorqual</span> Family of cetacean mammals

Rorquals are the largest group of baleen whales, comprising the family Balaenopteridae, which contains nine extant species in two genera. They include the largest known animal that has ever lived, the blue whale, which can reach 180 tonnes, and the fin whale, which reaches 120 tonnes ; even the smallest of the group, the northern minke whale, reaches 9 tonnes.

<span class="mw-page-title-main">Baleen whale</span> Whales that strain food from the water using baleen

Baleen whales, also known as whalebone whales, are marine mammals of the parvorder Mysticeti in the infraorder Cetacea, which use keratinaceous baleen plates in their mouths to sieve planktonic creatures from the water. Mysticeti comprises the families Balaenidae, Balaenopteridae (rorquals), Eschrichtiidae and Cetotheriidae. There are currently 16 species of baleen whales. While cetaceans were historically thought to have descended from mesonychians, molecular evidence instead supports them as a clade of even-toed ungulates (Artiodactyla). Baleen whales split from toothed whales (Odontoceti) around 34 million years ago.

<span class="mw-page-title-main">Balaenidae</span> Family of mammals

Balaenidae is a family of whales of the parvorder Mysticeti that contains mostly fossil taxa and two living genera: the right whale, and the closely related bowhead whale.

<span class="mw-page-title-main">Neobalaenidae</span> Family of mammals

Neobalaenidae is a family of baleen whales including the extant pygmy right whale. Although traditionally considered related to balaenids, recent studies by Fordyce and Marx (2013) and Ludovic Dutoit and colleagues (2023) have recovered the living pygmy right whale as a member of Cetotheriidae, making it the only extant cetotheriid. Not all authors agree with this placement.

<span class="mw-page-title-main">Pygmy right whale</span> Species of mammal

The pygmy right whale is a species of baleen whale. It may be a member of the cetotheres, a family of baleen whales which until 2012 were thought to be extinct; C. marginata has otherwise been considered the sole member of the family Neobalaenidae and is the only member of the genus Caperea. First described by John Edward Gray in 1846, it is the smallest of the baleen whales, ranging between 6 and 6.5 metres in length and 3,000 and 3,500 kilograms in mass. Despite its name, the pygmy right whale may have more in common with the gray whale and rorquals than the bowhead and right whales.

<i>Balaenoptera</i> Genus of mammals

Balaenoptera is a genus of rorquals containing eight extant species. Balaenoptera comprises all but two of the extant species in its family ; the genus is currently polyphyletic, with the two aforementioned species being phylogenetically nested within it.

<i>Eobalaenoptera</i> Extinct genus of mammals

Eobalaenoptera is an extinct genus of baleen whale belonging to Balaenopteroidea.

<span class="mw-page-title-main">Evolution of cetaceans</span>

The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates (Artiodactyla) 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. Cetaceans are fully aquatic marine mammals belonging to the order Artiodactyla and branched off from other artiodactyls around 50 mya. Cetaceans are thought to have evolved during the Eocene, the second epoch of the present-extending Cenozoic Era. Molecular and morphological analyses suggest Cetacea share a relatively recent closest common ancestor with hippopotami and that they are sister groups. Being mammals, they surface to breathe air; they have five finger bones (even-toed) in their fins; they nurse their young; and, despite their fully aquatic life style, they retain many skeletal features from their terrestrial ancestors. Research conducted in the late 1970s in Pakistan revealed several stages in the transition of cetaceans from land to sea.

<i>Cetotherium</i> Extinct genus of mammals

Cetotherium is an extinct genus of baleen whales from the family Cetotheriidae.

<span class="mw-page-title-main">Cetotheriidae</span> Family of mammals

Cetotheriidae is a family of baleen whales. The family is known to have existed from the Late Oligocene to the Early Pleistocene before going extinct. Although some phylogenetic studies conducted by Fordyce & Marx 2013 recovered the living pygmy right whale as a member of Cetotheriidae, making the pygmy right whale the only living cetotheriid, other authors either dispute this placement or recover Neobalaenidae as a sister group to Cetotheriidae.

<i>Parietobalaena</i>

Parietobalaena is an extinct genus of baleen whale, belonging to the family Pelocetidae. Fossils are found in Miocene-aged marine strata in North America, Europe, Australia, and Japan, including the Temblor and Itahashi formations. Based on previous estimates of juvenile specimens, Tsai (2017) suggested a body size of 12-15 m for P. yamaokai, akin to that of the gray whale.

<i>Protororqualus</i> Extinct genus of mammals

Protororqualus is a genus of extinct rorqual from the late Pliocene of Mount Pulgnasco, Italy.

<i>Archaebalaenoptera</i> Extinct genus of mammals

Archaebalaenoptera is a genus of extinct rorqual known from late Miocene to Pliocene-age marine deposits of the Netherlands, Northern Italy, and Peru.

Plesiocetus is a genus of extinct rorquals found worldwide. It has had a chequered taxonomic history, having served as a wastebasket genus for a handful of mysticete species.

<i>Eschrichtioides</i> Extinct genus of mammals

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, before being finally recognized as a relative of the gray whale.

<i>Aglaocetus</i> Extinct genus of mammals

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.

<span class="mw-page-title-main">Pisco Formation</span> Geologic formation in Peru

The Pisco Formation is a geologic formation located in Peru, on the southern coastal desert of Ica and Arequipa. The approximately 640 metres (2,100 ft) thick formation was deposited in the Pisco Basin, spanning an age from the Late Miocene up to the Early Pliocene, roughly from 9.6 to 4.5 Ma. The tuffaceous sandstones, diatomaceous siltstones, conglomerates and dolomites were deposited in a lagoonal to near-shore environment, in bays similar to other Pacific South American formations as the Bahía Inglesa and Coquimbo Formations of Chile.

Isocetus is an extinct genus of baleen whale belonging to the clade Thalassotherii. Remains have been found in middle Miocene marine deposits in Belgium.

Fragilicetus is an extinct genus of rorqual from Early Pliocene deposits in Belgium.

References

Notes

  1. ↑ Bisconti 2008
  2. ↑ Bisconti, Michelangelo; Damarco, Piero; Marengo, Lorenza; Macagno, Mattia; Daniello, Riccardo; Pavia, Marco; Carnevale, Giorgio (2024-09-05). "Anatomy and Relationships of a New Gray Whale from the Pliocene of Piedmont, Northwestern Italy". Diversity. 16 (9): 547. doi: 10.3390/d16090547 . ISSN   1424-2818.
  3. ↑ Pyenson & Lindberg 2011
  4. 1 2 McGowen, Michael R; Tsagkogeorga, Georgia; Álvarez-Carretero, Sandra; dos Reis, Mario; Struebig, Monika; Deaville, Robert; Jepson, Paul D; Jarman, Simon; Polanowski, Andrea; Morin, Phillip A; Rossiter, Stephen J (2019-10-21). "Phylogenomic Resolution of the Cetacean Tree of Life Using Target Sequence Capture". Systematic Biology. 69 (3): 479–501. doi:10.1093/sysbio/syz068. ISSN   1063-5157. PMC   7164366 . PMID   31633766.
  5. 1 2 "Explore the Database". www.mammaldiversity.org. Retrieved 2021-08-20.
  6. ↑ Jones & Swartz 2008 , p. 503
  7. ↑ Bisconti 2008 , Results, pp. 173–174
  8. ↑ Strobel 1875 , p. 136
  9. 1 2 3 Pyenson & Lindberg 2011 , Fossil record of gray whales
  10. ↑ Deméré, Berta & McGowen 2005 , pp. 119–120
  11. ↑ Steeman et al. 2009 , p. 580
  12. ↑ Árnason, Úlfur; Lammers, Fritjof; Kumar, Vikas; Nilsson, Maria A.; Janke, Axel (2018). "Whole-genome sequencing of the blue whale and other rorquals finds signatures for introgressive gene flow". Science Advances . 4 (4): eaap9873. Bibcode:2018SciA....4.9873A. doi:10.1126/sciadv.aap9873. PMC   5884691 . PMID   29632892.
  13. ↑ Bisconti & Varola 2006 , p. 450
  14. ↑ Bisconti & Varola 2006 , Implications for eschrichtiid fossil record and paleobiogeography, p. 454

Sources

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