Editing Rodhocetus (section)

==Description==
[[File:Rodhocetus.jpg|thumb|left|An artist's rendering of ''Rodhocetus'']]
[[file:Rodhocetus size.png|thumb|left|Size of ''Rodhocetus'' relative to a human.]]
[[File:Rodhocetus sp pelvis hind limb.jpg|thumb|Pelvis, vertebrae, and hind limb of ''Rodhocetus''.]]
''Rodhocetus'' was a small whale measuring {{cvt|2|-|3|m|ft}} long.<ref>{{cite journal |vauthors=Gingerich PD, Ul-Haq M, von Koenigswald W, Sanders WJ, Smith BH, Zalmout IS |title=New protocetid whale from the middle eocene of pakistan: birth on land, precocial development, and sexual dimorphism |journal=PLOS ONE |volume=4 |issue=2 |pages=e4366 |year=2009 |pmid=19194487 |pmc=2629576 |doi=10.1371/journal.pone.0004366 |bibcode=2009PLoSO...4.4366G |doi-access=free }}</ref> Throughout the 1990s, a close relationship between cetaceans and [[Mesonychia|mesonychians]], an extinct group of cursorial, wolf-like ungulates, was generally accepted based on morphological analyses. In the late 1990s, however, cladistic analyses based on molecular data clearly placed Cetacea within the Artiodactyla near the hippopotamus. One of the diagnostic characteristics of artiodactyls is the double-pulley [[Talus bone|astragalus]] (ankle bone), and palaeontologists, unconvinced by the data from the labs, set themselves out to find archaeocete single-pulley heel bones. Hind legs from three archaeocete species were recovered within a few years, among them those of ''Rodhocetus balochistanensis'', and all three had double-pulley heel bones, thus settling the cladistic controversy.<ref>{{Harvnb|Rice|2008|p=236}}</ref>

Through a [[principal components analysis]] {{Harvnb|Gingerich|2003}} demonstrated that ''Rodhocetus'' had trunk and limb proportions similar to the [[Russian desman]], a foot-powered swimmer using its tail mainly as a rudder. From this Gingerich concluded that ''Rodhocetus'' was swimming mostly at the surface by alternate strokes of its hind feet, and that it was insulated by fur rather than blubber, as are ''[[Dorudon]]'' and modern cetaceans, which made it buoyant and incapable of deep diving.<ref>{{Harvnb|Gingerich|2003|pp=448, 449}}</ref>

===''R. kasrani''===
The [[holotype]] of ''R. kasrani'', [[Geological Survey of Pakistan|GSP]]-[[University of Michigan|UM]]&nbsp;3012 found in 1992, was described by {{Harvnb|Gingerich|Raza|Arif|Anwar|1994}}: a cranium with two dentaries, most of the vertebral column as far as the anterior tail (C2–C7; T1–13; L1–6, S1–4, Ca1–4), most ribs, parts of the sternum, both hip bones, and a left femur. Gingerich et al. 1994 referred a specimen collected in 1981, GSP-UM&nbsp;1852 two dentaries with teeth, to ''R. kasrani''.<ref name="Gingetal-1994-844" /> The body mass of the holotype has been estimated between {{cvt|340|and|590|kg|lbs}} based on different techniques.<ref>{{cite journal|last1=Waugh|first1=D.A.|last2=Thewissen|first2=J.G.M.|title=The pattern of brain-size change in the early evolution of cetaceans|journal=PLOS ONE|volume=16|issue=9|at=e0257803|year=2021|doi=10.1371/journal.pone.0257803|doi-access=free|pmid=34582492 |pmc=8478358|bibcode=2021PLoSO..1657803W }}</ref>

[[Synapomorphy|Derived]] traits in ''R. kasrani'', relative to older archaeocetes such as ''Pakicetus'', include high-crowned cheek teeth, larger auditory bullae, larger mandibular foramen, and mandibular canals. The higher neural spines and shorter femur (60–70%) distinguish ''Rodhocetus'' from the more primitive ''Ambulocetus''. The convex posterior surface of the exoccipital, shorter cervical vertebrae, and unfused sacral vertebrae distinguishes ''R. kasrani'' from ''Indocetus''. In contrast to later archaeocetes such as ''Protocetus'' and later cetaceans, ''Rodhocetus'' [[Primitive (phylogenetics)|retains]] external nares above upper canines, high neural spines on anterior thoracic vertebrae, and four sacral vertebrae with sacroiliac joints similar to those in land-mammals (suggesting a hip joint that could support the body weight.)<ref name="Gingetal-1994-846">{{Harvnb|Gingerich|Raza|Arif|Anwar|1994|pp=846, 847}}</ref>

Several cranial features identifies ''R. kasrani'' as an archaeocete: both the premaxillae and the dentaries are elongated, the frontal shield is wide, and the nuchal crest is high. The [[auditory bulla]]e are large and dense but, there are no associated [[pterygoid fossa]]e or air sinuses. The [[Mandibular foramen|mandibular foramina]] are large with a pan bone {{Convert|90|mm|abbr=on}} long and {{Convert|65|mm|abbr=on}} high.<ref name="Gingetal-1994-846" />

The specific name ''kasrani'' comes from [[Qaisrani]], the Baloch tribe inhabiting the type locality.<ref name="Gingetal-1994-844" />  The protocetid ''[[Qaisracetus]]'' is also named after them.

===''R. balochistanensis''===
The fossil remains of ''R. balochistanensis'' were found in eastern [[Balochistan, Pakistan|Balochistan]], [[Pakistan]] in 2001 by Philip Gingerich. Dating from about 47 million years ago, they are one of a series of recent discoveries, including the [[pakicetid]]s, which have thrown considerable light on the previously mysterious evolutionary origin of whales.<ref>{{Cite web|last=Gingerich|first=Philip D|title=Research on the Origin and Early Evolution of Whales (Cetacea)|url=http://www-personal.umich.edu/~gingeric/PDGwhales/Whales.htm|access-date=26 January 2013}}</ref>

The holotype of ''Rodhocetus balochistanensis'', GSP-UM&nbsp;3485, is:<ref name="Gingetal-2001-2240">{{Harvnb|Gingerich|Haq|Zalmout|Khan|2001|loc=pp. 2240–2241; Note 35}}</ref><ref>{{Harvnb|Gingerich|Haq|Zalmout|Khan|2001|loc=Suppl. mat.: Description of GSP-UM 3485, holotype of ''Rodhocetus balochistanensis''; [https://www.science.org/doi/10.1126/science.1063902 Supplemental Figure 4]}}</ref>
* A weathered braincase found at the surface next to a partial dentary with an unfused mandibular symphysis, a characteristic of protocetids.
* Large parts of the axial skeleton including cervical, thoracic and proximal caudal vertebrae, but excluding sacral vertebrae.
* Forelimb material including the left distal humerus, radius and ulna, and two virtually complete hand skeletons including all carpal bones, unfused and lacking an os centrale, and phalanges.
* Parts of the pelvis including an acetabular rim.
* Hind limb material includes the right femur, patella, tibia, and possible partial fibula; two virtually complete foot skeletons include tarsal and metatarsal bones and phalanges. The astragalus (heel bone) is characteristic of artiodactyls with a deep tibial trochlea restricting lateral movements and a large calcaneal tuber (posterior part of heel bone) providing leverage for powerful extension. The metatarsals and phalanges are very long and thin and can not have been weight-bearing, suggesting that ''Rodhocetus'' was predominantly aquatic and on land must have walked on the plantar surface of the tarsals. The shape of the metatarsal and phalanges reveal that these bones could be tightly compressed during flexion and widely separated during extension.

The five-fingered hand of ''R. balochistanensis'' is mesaxonic (i.e. has a central digit) with three weight-bearing central digits equipped with nail-like hooves, flanked by two more slender digits lacking hooves (distal phalanges preserved on first, second, and fourth digits). The four-toed foot is paraxonic (i.e. central axis passes between the two central digits), with all four digits ending in pointed nails (distal phalanges preserved on second and third digits).<ref>{{Harvnb|Gingerich|Haq|Zalmout|Khan|2001|loc=Fig. 2}}</ref>

With an estimated body weight of {{Convert|450|kg|abbr=on}}, ''R. balochistanensis'' was 13% smaller than ''R. kasrani'' ({{Convert|590|kg|abbr=on}}), but its femur is larger.<ref name="Gingetal-2001-2240" />