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''Remingtonocetus'' is an extinct
named ''
''Remingtonocetus'' was a small cetacean with ''R. harudiensis'' weighing . interpreted ''R. domandaensis'' as an older and more generalized species than ''R. harudiensis''. Based on a morphological analysis, they concluded that the hindlimbs of ''Remingtonocetus'' were probably not weight-bearing, and that (1) the fused sacrum indicates a limitation in tail-powered locomotion, and (2) the presence of powerful hip extensors and femoral adductors indicates that ''Remingtonocetus'' was an efficient and specialized foot-powered swimmer.
''Remingtonocetus'' had four working and usable limbs, a slender
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of early cetacea
Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...
n freshwater aquatic mammal
Aquatic and semiaquatic mammals are a diverse group of mammals that dwell partly or entirely in bodies of water. They include the various marine mammals who dwell in oceans, as well as various freshwater species, such as the European otter. Th ...
s of the family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Remingtonocetidae
Remingtonocetidae is a diverse family of early aquatic mammals of the order Cetacea. The family is named after paleocetologist Remington Kellogg.
Description
Remingtonocetids have long and narrow skulls with the external nare openings located ...
endemic to the coastline of the ancient Tethys Ocean
The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean that covered most of the Earth during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents ...
during the Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
. It was named after naturalist Remington Kellogg
Arthur Remington Kellogg (5 October 1892 – 8 May 1969) was an American naturalist and a director of the United States National Museum. His work focused on marine mammals.
Early life and career
Kellogg was born in Davenport, Iowa, and quick ...
.
History of discovery
named ''Protocetus
''Protocetus atavus'' ("first whale") is an extinct species of primitive cetacean from Egypt. It lived during the middle Eocene period 45 million years ago. The first discovered protocetid, ''Protocetus atavus'' was described by based on a cran ...
harudiensis'' based on a partial skeleton, the type specimen found in the Lutetian
The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Midd ...
shallow subtidal
The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth.
From the point of view of marine biology it forms a relatively stable and well-illuminated ...
mudstone in the Harudi Formation, India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
. renamed it ''Remingtononocetus harudiensis'' due to morphological differences from protocetus.
''Remingtonocetus domandaensis'' was named by based on a partial skeleton found in a Lutetian coastal shale in the Domanda Formation of Pakistan
Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
.
''Remingtonocetus'' is larger, has a broader rostrum
Rostrum may refer to:
* Any kind of a platform for a speaker:
**dais
**pulpit
* Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects
* Rostrum (ship), a form of bow on naval ships
* Ros ...
, and longer premolar
The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...
s than ''Andrewsiphius
''Andrewsiphius'' is an extinct remingtonocetid early whale known from the Eocene (Lutetian, ) of Gujarat and Kutch, India and Balochistan, Pakistan.
Discovery and naming
The first specimen was collected by who described it as mandibular f ...
''. It is smaller than, has more gracile premolars and molars than ''Dalanistes
''Dalanistes'' is an extinct genus of remingtonocetid early whale known from the late early Eocene (Lutetian, ) of Kutch, India and Punjab and Balochistan, Pakistan. ''Dalanistes'' is closely related to '' Remingtonocetus'' (the type genus ...
''. ''R. harudiensis'' differs from ''R. domandaensis'' in molar morphology.
Description
''Remingtonocetus'' was a small cetacean with ''R. harudiensis'' weighing . interpreted ''R. domandaensis'' as an older and more generalized species than ''R. harudiensis''. Based on a morphological analysis, they concluded that the hindlimbs of ''Remingtonocetus'' were probably not weight-bearing, and that (1) the fused sacrum indicates a limitation in tail-powered locomotion, and (2) the presence of powerful hip extensors and femoral adductors indicates that ''Remingtonocetus'' was an efficient and specialized foot-powered swimmer.
''Remingtonocetus'' had four working and usable limbs, a slender whale
Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...
-like body with long tail and slender, hydrodynamic
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and ...
head.
Taxonomy
''Remingtonocetus'' was named by . Its type is ''Protocetus harudiensis''. It was consideredmonophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
by . It was assigned to Cetacea by . To ''Remingtonocetidae'' by , , , , , , , , , and .
See also
*Evolution of cetaceans
The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. Cetaceans are fully aquatic marine mammals bel ...
Notes
References
* * * * * * * * * * * * * * {{Taxonbar, from=Q3268443 Remingtonocetidae Eocene mammals of Asia Fossil taxa described in 1986 Prehistoric cetacean genera