''Remingtonocetus'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of early

cetacea Cetacea (; , ) is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively c ...

n freshwater

aquatic mammal Aquatic mammals and semiaquatic mammals are a diverse group of mammals that dwell partly or entirely in body of water, bodies of water. They include the various ''marine mammals'' who dwell in oceans, as well as various freshwater species, such a ...

s of the

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 ...

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 o ...

endemic to the coastline of the ancient

Tethys Ocean The Tethys Ocean ( ; ), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era. It was the predecessor to the modern Indian Ocean, the Mediterranean Sea, and the Eurasia ...

during the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

. 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 quickly ...

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 In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

found in the

Lutetian The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), 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 ...

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-illuminate ...

mudstone in the Harudi Formation,

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

. 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, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...

. ''Remingtonocetus'' is larger, has a broader

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * 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 ...

, and longer

premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

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 fr ...

''. It is smaller than, has more gracile premolars and molars than ''

Dalanistes ''Dalanistes'' is an extinct genus of Remingtonocetidae, remingtonocetid Archaeoceti, early whale known from the late-early Eocene (Lutetian, ) of Kutch, India and Punjab, Pakistan, Punjab and Balochistan, Pakistan. ''Dalanistes'' is closely re ...

''. ''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 animal, aquatic placental mammal, placental marine mammals. As an informal and Colloquialism, colloquial grouping, they correspond to large members of the infraorder Cetacea ...

-like body with long tail and slender,

hydrodynamic In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in moti ...

head.

Taxonomy

''Remingtonocetus'' was named by . Its type is ''Protocetus harudiensis''. It was considered

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

by . It was assigned to Cetacea by . To ''Remingtonocetidae'' by , , , , , , , , , and .

Notes

References

* * * * * * * * * * * * * * {{Taxonbar, from=Q3268443 Remingtonocetidae Eocene mammals of Asia Fossil taxa described in 1986 Prehistoric cetacean genera

History of discovery

Description

Taxonomy

See also

Notes

References