New whale from the Eocene of Pakistan and the origin of cetacean swimming

@article{Gingerich1994NewWF,
  title={New whale from the Eocene of Pakistan and the origin of cetacean swimming},
  author={Philip D. Gingerich and S. Mahmood Raza and Muhammad Arif and Mohammad Anwar and Xiaoyuan Zhou},
  journal={Nature},
  year={1994},
  volume={368},
  pages={844-847}
}
MODERN whales (order Cetacea) are marine mammals that evolved from a land-mammal ancestor, probably a cursorial Palaeocene–Eocene mesonychid1–3. Living whales are streamlined, lack external hind limbs, and all swim by dorsoventral oscillation of a heavily muscled tail4,5. A steamlined rigid body minimizes resistance, while thrust is provided by a lunate horizontal fluke attached to the tail at a narrow base or pedicle6. We describe here a new 46–47-million-year-old archaeocete intermediate… 

New Protocetid Whale from the Middle Eocene of Pakistan: Birth on Land, Precocial Development, and Sexual Dimorphism

TLDR
Discovery of a near-term fetus positioned for head-first delivery provides important evidence that early protocetid whales gave birth on land and corroborates previous ideas that protocETids were amphibious.

Aegicetus gehennae, a new late Eocene protocetid (Cetacea, Archaeoceti) from Wadi Al Hitan, Egypt, and the transition to tail-powered swimming in whales

TLDR
Vertebral elongation, loss of a sacroiliac articulation, and hind limb reduction indicate that Aegicetus gehennae was more fully aquatic and less specialized as a foot-powered swimmer than earlier protocetids.

Fossils explained 46: Ancient toothed whales

  • D. Naish
  • Geography, Environmental Science
  • 2004
Archaeocetes (‘ancient whales’) were amphibious and aquatic mammals that inhabited the estuaries, seas and oceans of the Eocene. Evolving from primitive hoofed mammals, most probably during the

From Land to Water: the Origin of Whales, Dolphins, and Porpoises

TLDR
This work focuses on the evolution of cetacean organ systems, as these document the transition from land to water in detail.

The earliest known fully quadrupedal sirenian

TLDR
Eocene fossils from Jamaica are described that represent nearly the entire skeleton of a new genus and species of sirenian—the most primitive for which extensive postcranial remains are known and one of the most marked examples of morphological evolution in the vertebrate fossil record.

Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls

TLDR
Cladistic analysis of the skeletons of two early Eocene pakicetid cetaceans, the fox-sized Ichthyolestes pinfoldi, and the wolf-sized Pakicetus attocki, indicates that cetACEans are more closely related to artiodactyls than to any mesonychian, and supports monophyly of artiodACTyls.

NEW GENUS OF DORUDONTINE ARCHAEOCETE (CETACEA) FROM THE MIDDLE‐TO‐LATE EOCENE OF SOUTH CAROLINA

TLDR
The pelves resemble those of Basilosaurus, documenting a similar stage of hind limb reduction in dorudontines and suggesting that Chrysocetus was not able to support its body on land.

The Origin(s) of Whales

  • M. Uhen
  • Geography, Environmental Science
  • 2010
TLDR
This work states that modern whales originated from ancient whales at or near the Eocene/Oligocene boundary, approximately 33.7 Mya, and that whale diversity peaked in the late middle Miocene and fell thereafter toward the Recent, yielding the authors' depauperate modern whale.

New species of protocetid archaeocete whale, Eocetus wardii (Mammalia: Cetacea) from the middle Eocene of North Carolina

  • M. Uhen
  • Biology
    Journal of Paleontology
  • 1999
A new species of protocetid archaeocete, Eocetus wardii n. sp., is named based on material from the late Lutetian (middle Eocene, 43-44 Ma) Comfort Member of the Castle Hayne Formation, North

General aspects of the evolutionary history of whales and dolphins

TLDR
Recently discovered archaeocetes with large, mesonychid-like heads and dentitions and functional hind limbs reconfirm earlier ideas about the mesonychids origin of cetaceans and the amphibious nature of the earliest transitional forms.
...

References

SHOWING 1-10 OF 11 REFERENCES

Origin of Whales in Epicontinental Remnant Seas: New Evidence from the Early Eocene of Pakistan

TLDR
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.

Fossil Evidence for the Origin of Aquatic Locomotion in Archaeocete Whales

TLDR
The fossil indicates that archaic whales swam by undulating their vertebral column, thus forcing their feet up and down in a way similar to modern otters.

Hind Limbs of Eocene Basilosaurus: Evidence of Feet in Whales

New specimens of middle Eocene Basilosaurus isis from Egypt include the first functional pelvic limb and foot bones known in Cetacea. These are important in corroborating the intermediate

Origin of underwater hearing in whales

TLDR
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.

MONOPHYLY OR DIPHYLY IN THE ORIGIN OF WHALES

  • L. V. Valen
  • Biology
    Evolution; international journal of organic evolution
  • 1968
TLDR
Yablokov and Kleinenberg conclude, in agreement with several previous authors, that the Odontoceti and Mysticeti originated separately from terrestrial animals, and that much of the aquatic adaptation of the two recent suborders was evolved separately.

Dolphin swimming–a review

into dolphin swimming has historically been guided by false assumptions of 'effortless', 'high-speed' swimming. These assumptions have instigated the develop- ment of drag-reduction hypotheses but

Intramuscular morphology and tendon geometry of the epaxial swimming muscles of dolphins

TLDR
Intramuscular and tendon morphology coupled with kinematic data are used to hypothesize regionally specific functions of these muscles, and a novel interaction between its insertional tendons and the subdermal connective tissue sheath is identified.

Planktonic Foraminiferal Biostratigraphy of the Early Tertiary of the Rakhi Nala Section Sulaiman Range, West Pakistan

Of the four Formations, the Ranikot, the Dunghan, the Ghazij and the Khirthar, constituting the early Tertiary succession exposed in the Rakhi Nala, a river in the Sulaiman Range, West Pakistan, only

Simple Physical Principles and Vertebrate Aquatic Locomotion

TLDR
Numerical solutions to models estimate thrust and drag, and rates of working, which are several times greater than expected for manmade non-flexing bodies, used in prediction of optimal two-phase swimming behaviors.