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

Gingerich, Philip D.; Raza, S. Mahmood; Arif, Muhammad; Anwar, Mohammad; Zhou, Xiaoyuan

doi:10.1038/368844a0

Cited by 145 publications

(99 citation statements)

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“…6) as well as a rod-shaped mesosternal element. The manubrium is similar to those of Rodhocetus (personal observation; Gingerich et al, 1994), Eocetus (Uhen, 2001) and Georgiacetus (personal observation), in contrast to the thick and broad sternal elements of the Basilosauridae (Kellogg, 1936;Uhen, 2004), indicating a retention of this protocetid characteristic. The mesosternal element is more similar to those of Rodhocetus, but differs from those of Eocetus which are more broad and flat (Uhen, 2001).…”

Section: Supayacetus Muizoni New Speciesmentioning

confidence: 95%

New Middle Eocene Whales from the Pisco Basin of Peru

Uhen

Pyenson

DeVries

et al. 2011

Journal of Paleontology

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Section: Supayacetus Muizoni New Speciesmentioning

confidence: 95%

New Middle Eocene Whales from the Pisco Basin of Peru

Uhen

Pyenson

DeVries

et al. 2011

Journal of Paleontology

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“…Slightly younger cetaceans such as the early protocetid Rodhocetus (Gingerich et al, 1994b show a further development of the adaptations seen in pakicetids, with more changes apparent in the appendicular and axial skeletons. In Rodhocetus, the teeth have a similar arrangement as in Pakicetus, but the cusp patterns are becoming more simplified on the cheek teeth.…”

Section: Cetacean Evolutionary Historymentioning

confidence: 99%

“…This finding also increased the ability to hear directionally under water. While Rodhocetus still has hind limbs that function on land, they are reduced in size when compared with terrestrial mammals (Gingerich et al, 1994b). Rodhocetus also has sacral vertebrae that articulate with the pelves and each other, but they are not fused to one another (Gingerich et al, 1994b).…”

Section: Cetacean Evolutionary Historymentioning

confidence: 99%

Evolution of marine mammals: Back to the sea after 300 million years

Uhen

2007

The Anatomical Record

162

113

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The fossil record demonstrates that mammals re-entered the marine realm on at least seven separate occasions. Five of these clades are still extant, whereas two are extinct. This review presents a brief introduction to the phylogeny of each group of marine mammals, based on the latest studies using both morphological and molecular data. Evolutionary highlights are presented, focusing on changes affecting the sensory systems, locomotion, breathing, feeding, and reproduction in Cetacea, Sirenia, Desmostylia, and Pinnipedia. Aquatic adaptations are specifically cited, supported by data from morphological and geochemical studies. For example, analysis of oxygen isotopes incorporated into fossil tooth enamel indicates whether these mammals foraged in (and, therefore, ingested) fresh water or sea water. Comparisons between groups are made to see if there are any common patterns, particularly relating to adaptations to aquatic life. Results show that aquatic characteristics evolved in mosaic patterns and that different morphological solutions to aquatic conditions were achieved separately in each of these groups. Changes in the axial and appendicular skeleton assist with locomotion for aquatic foraging. Nostril and eye placement modifications accommodate wading versus underwater foraging needs. All groups exhibit aquatic adaptations directly related to feeding, particularly changes in the dentition and rostrum. The earliest representatives of these clades all show morphological features that indicate they were feeding while in the water, suggesting that feeding ecology is a key factor in the evolution of marine mammals.Anat Rec 290:514-522, 2007.2007 Wiley-Liss, Inc.Key words: cetacea; sirenia; pinnipedia; carnirora; desmostylia; feeding ecology; aquatic adaptation A recurrent theme in tetrapod evolution is a return to an aquatic habitat. Whereas amphibians never quite parted with the water, all other tetrapod groups (reptiles, birds, and mammals) have several representatives that have returned to the water for at least an amphibious lifestyle of some degree, if not a fully aquatic existence. Mammals in particular have returned to the water in at least seven separate lineages (Cetacea, Sirenia, Desmostylia, Pinnipedia, Ursus maritimus [polar bear], Enhydra lutris [sea otter], and Thalassocnus spp. [aquatic sloths]). Some of these lineages have retained most of their terrestrial form while spending a great deal of time in the water, whereas others have changed their morphology dramatically and spend almost all, if not all, of their time in the water.Before exploring how the anatomical changes for life in water came about, one must know how marine mammals are related to one another, and particularly to their terrestrial relatives. A brief introduction to the phylogeny of each group of marine mammals is presented here, based on the latest studies using both morphological and molecular data. CETACEAN PHYLOGENYThe relationships of cetaceans to terrestrial mammals and other marine mammals was a great mystery for many

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(Gingerich, Raza, Arif, Anwar, & Zhou, 1994). While such events are rarely predictable, they can be reliably explained by Charles Darwin's and Alfred Russel Wallace's great idea, natural selection.

…”

mentioning

confidence: 99%

Evolution, emotions, and emotional disorders.

Nesse

Ellsworth

2009

American Psychologist

302

267

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(Gingerich, Raza, Arif, Anwar, & Zhou, 1994). While such events are rarely predictable, they can be reliably explained by Charles Darwin's and Alfred Russel Wallace's great idea, natural selection. Four-legged whale ancestors that could swim better underwater had more offspring; over thousands of generations, their descendants gradually became superb aquatic athletes.Happenstance occurs in intellectual evolution as well. After finishing The Descent of Man, and Selection in Relation to Sex (Darwin, 1871), Darwin realized that materials he had long collected on emotions could be organized to refute Charles Bell's earlier claim that the elaborate musculature of the human face was evidence of Divine design. He quickly wrote The Expression of the Emotions in Man and Animals (Darwin, 1872(Darwin, /1965, emphasizing the phylogenetic consistency of emotional expressions from animals to humans. The book is, as advertised, about expression, and it says little about the selective forces that produced emotions, leaving a persisting anti-Darwinian legacy for emotions research (Fridlund, 1992).However, Darwin clearly recognized that evolution shaped not only the physical characteristics of an organism but also its mental processes and behavioral repertoires. The knowledge that natural selection shaped the brain mechanisms that mediate motivation and emotions offers a solid foundation on which a modern theory of emotions is being built.Although current psychological theories of emotion differ widely in many particulars, almost all now agree that emotions are adaptive responses that arise from mechanisms shaped by selection (Plutchik, 2003). It is now hard to imagine that just four decades ago emotions were generally seen as products of learning unrelated to natural selection. It took Ekman's, Izard's and Eibl-Eibesfeldt's studies of cross-cultural consistency in emotional expression to overthrow that view (Eibl-Eibesfeldt, 1983;Ekman & Davidson, 1994;Izard, 1991). In retrospect, it is obvious that learning cannot be the whole story and that emotions would not exist unless they were useful. Evolution is not an alternative to other theories of emotions; it is the common foundation for all. Many of its contributions are so simple that they are not always recognized. To highlight the continuing importance of Darwin's theory of natural selection for emotions, we consider its implications for several classic questions. What Emotions AreDefinitions of emotions typically describe proximate aspects such as physiology, subjective experience, or facial expression, often emphasizing one or another component (Ekman & Davidson, 1994;Izard, 2007). An evolutionary approach defines what emotions are in terms of how they came to exist. Emotions are modes of functioning, shaped by natural selection, that coordinate physiological, cognitive, motivational, behavioral, and subjective responses in patterns that increase the ability to meet the adaptive challenges of situations that have recurred over evolutionary time (Nesse, 1990). They are adapta...

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

Cited by 145 publications

References 10 publications

New Middle Eocene Whales from the Pisco Basin of Peru

New Middle Eocene Whales from the Pisco Basin of Peru

Evolution of marine mammals: Back to the sea after 300 million years

Evolution, emotions, and emotional disorders.

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