Topic
Pakicetus
About: Pakicetus is a research topic. Over the lifetime, 13 publications have been published within this topic receiving 1132 citations.
Papers
TL;DR: A 30-year renaissance in research on fossil marine mammals has brought advances on several fronts and suggests potential directions for future study.
Abstract: A 30-year renaissance in research on fossil marine mammals has brought advances on several fronts and suggests potential directions for future study Gingerich and Russell have described Pakicetus, the most primitive archaeocete cetacean Mchedlidze has described a diverse assemblage of late Oligocene/early Miocene cetaceans from the Caucasus and Georgia, SSR Barnes and Fordyce, respectively, have outlined sequences of fossil cetacean assemblages in the northeast and southwest Pacific Much remains to be done on origin and definition of cetacean suborders, diversification and systematics of families, and relationships among infra-familial taxa
New material has been recovered of the most primitive desmostylians, and other new specimens, especially ones from Japan studied by Inuzuka and others, give a relatively complete picture of their anatomy Material now exists for phylogenetic analysis
Domning has proposed a phyletic lineage of the sirenian subfamily Hydro-damalinae and has outlined patterns of Late Cenozoic manatee evolution With Morgan and Ray he reviewed Eocene sirenians in the northwest Atlantic Numerous new specimens are being actively studied in attempts to reassess relationships within the Sirenia
Mitchell and Tedford described the most primitive otariid, Enaliarctos Repenning and Tedford reviewed the otarioids The primitive taxa and their origin near or in the amphicynodontine ursids have been identified
The zoogeography of true seals, the phocids, has been analyzed recently by Repenning, Ray and Grigorescu, and by de Muizon Most taxa are based on a few fragmentary specimens, and much work needs to be done on basic descriptions, interspecific comparisons and phyletic analysis However, major progress has been made in the southern hemisphere through description of extensive new materials from Peru and South Africa
Many important phylogenetic gaps in the fossil record of marine mammals have been filled recently, and further advances continue at a rapid rate Studies of zoogeography, functional anatomy and paleoecology, in addition to phylogeny, are coming into their own and promise an exciting series of discoveries in the coming years
241 citations
TL;DR: Discovery of Pakicetus strengthens earlier inferences that whales originated from terrestrial carnivorous mammals and suggests that whales made a gradual transition from land to sea in the early Eocene, spending progressively more time feeding on planktivorous fishes in shallow seas and embayments associated with tectonic closure of eastern Tethys.
Abstract: Pakicetus inachus from the early Eocene of Pakistan is the oldest and most primitive cetacean known. The dentition of Pakicetus resembles that of carnivorous mesonychid land mammals as well as middle Eocene cetaceans. The otic region of the cranium lacks characteristic specializations of whales necessary for efficient directional hearing under water. Pakicetus occurs with a land-mammal fauna in fluvial sediments bordering epicontinental Eocene remnants of the eastern Tethys seaway. Discovery of Pakicetus strengthens earlier inferences that whales originated from terrestrial carnivorous mammals and suggests that whales made a gradual transition from land to sea in the early Eocene, spending progressively more time feeding on planktivorous fishes in shallow, highly productive seas and embayments associated with tectonic closure of eastern Tethys.
223 citations
TL;DR: A phylogenetic analysis of cetaceans, five groups of mesonychians, and five other groups of ungulates indicates that Pakicetus is the sister group to all other cetACEans, and that Cete (mesonychian and Cetacea) is a monophyletic group.
Abstract: The evolutionary steps leading up to the origin of cetaceans involved pervasive changes in the masticatory apparatus, the ear, and limb morphology. These changes bear heavily on the phylogenetic relationships of Cetacea, and are investigated here on the basis of two of its earliest members:Pakicetus andAmbulocetus. A phylogenetic analysis of cetaceans, five groups of mesonychians, and five other groups of ungulates indicates thatPakicetus is the sister group to all other cetaceans, and that Cete (mesonychians and Cetacea) is a monophyletic group.
90 citations
TL;DR: The incus and mandible of Pakicetus indicate that the path of soundwaves to its ear resembled that of land mammals, and corroborate the hypothesis that artiodactyls are the closest extant relatives of cetaceans.
Abstract: ALL described fossil and Recent cetaceans have relatively similar ear bones (malleus, incus and stapes) that strongly diverge from those of land mammals1–4. Here we report that the hearing organ of the oldest whale, Pakicetus, is the only known intermediate between that of land mammals and aquatic cetaceans (whales, dolphins and porpoises). The incus of Pakicetus is intermediate with respect to inflation, crural proportions, and position of the mallear joint. The incus and mandible of Pakicetus indicate that the path of soundwaves to its ear resembled that of land mammals. These fossils suggest that the first whale was amphibious, and corroborate the hypothesis that artiodactyls (for example, pigs, camels and ruminants) are the closest extant relatives of cetaceans.
89 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2018 | 1 |
| 2017 | 1 |
| 2013 | 1 |
| 2009 | 1 |
| 2003 | 1 |
| 2001 | 1 |