Origin of Whales from Early Artiodactyls: Hands and Feet of Eocene Protocetidae from Pakistan

Gingerich, Philip D.; Haq, Munir ul; Zalmout, Iyad S.; Khan, Intizar H.; Malkani, Muhammad Sadiq

doi:10.1126/science.1063902

Cited by 275 publications

(246 citation statements)

References 36 publications

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“…4). Therefore, although this may contribute to the frequent parallel and convergent evolution of tooth cusps (35) and substantiates inferences stemming from recent phylogenetic studies (36)(37)(38), genetic changes can differ in the evolution of similar tooth shapes. This result is also consistent with the general finding that the same phenotypic effects can be found in mutations of diverse molecular nature (39)(40)(41)(42)(43).…”

Section: Resultssupporting

confidence: 77%

A gene network model accounting for development and evolution of mammalian teeth

Salazar‐Ciudad

Jernvall

2002

Proc. Natl. Acad. Sci. U.S.A.

354

294

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Generation of morphological diversity remains a challenge for evolutionary biologists because it is unclear how an ultimately finite number of genes involved in initial pattern formation integrates with morphogenesis. Ideally, models used to search for the simplest developmental principles on how genes produce form should account for both developmental process and evolutionary change. Here we present a model reproducing the morphology of mammalian teeth by integrating experimental data on gene interactions and growth into a morphodynamic mechanism in which developing morphology has a causal role in patterning. The model predicts the course of tooth-shape development in different mammalian species and also reproduces key transitions in evolution. Furthermore, we reproduce the known expression patterns of several genes involved in tooth development and their dynamics over developmental time. Large morphological effects frequently can be achieved by small changes, according to this model, and similar morphologies can be produced by different changes. This finding may be consistent with why predicting the morphological outcomes of molecular experiments is challenging. Nevertheless, models incorporating morphology and gene activity show promise for linking genotypes to phenotypes.

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Section: Resultssupporting

confidence: 77%

A gene network model accounting for development and evolution of mammalian teeth

Salazar‐Ciudad

Jernvall

2002

Proc. Natl. Acad. Sci. U.S.A.

354

294

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“…Phalanx number does not exceed 2-3-3-3-3 in any mammal in this phylogeny with the exception of the dolphin (a species chosen here to represent hyperphalangy in cetaceans). This species shows hyperphalangy relative to the basal cetacean Rodhocetus balochistanesis (Gingerich et al, 2001). Instances of hyperphalangy are also seen among extinct aquatic reptiles (mosasaurs, plesiosaurs and ichthyosaurs in Fig.…”

Section: The Phylogenetic Distribution Of Transformations Leading To mentioning

confidence: 82%

“…(2) Otarids have cartilaginous extensions on the tips of the phalanges and there is elongation of the digit I, but in general the pinniped flipper is relatively short (King,'83: 158). (3) Rodhocetus balochistanensis was possibly amphibious, with a webbed manus, and may have swum by pelvic paddling and caudal undulation; the forelimbs may have been folded back during active swimming (Gingerich et al, 2001). (4) Motani et al ('98) suggest that this species had eel-like swimming, whereas Sander (2000: 12) suggests that tail propulsion might have been important.…”

Section: -3-4-5-3mentioning

confidence: 99%

Developmental constraints in a comparative framework: A test case using variations in phalanx number during amniote evolution

Richardson

Chipman

2003

J Exp Zool Pt B

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Constraints are factors that limit evolutionary change. A subset of constraints is developmental, and acts during embryonic development. There is some uncertainty about how to define developmental constraints, and how to formulate them as testable hypotheses. Furthermore, concepts such as constraint-breaking, universal constraints, and forbidden morphologies present some conceptual difficulties. One of our aims is to clarify these issues. After briefly reviewing current classifications of constraint, we define developmental constraints as those affecting morphogenetic processes in ontogeny. They may be generative or selective, although a clear distinction cannot always be drawn. We support the idea that statements about constraints are in fact statements about the relative frequency of particular transformations (where 'transformation' indicates a change from the ancestral condition). An important consequence of this is that the same transformation may be constrained in one developmental or phylogenetic context, but evolutionarily plastic in another. In this paper, we analyse developmental constraints within a phylogenetic framework, building on similar work by previous authors. Our approach is based on the following assumptions from the literature: (1) constraints are identified when there is a discrepancy between the observed frequency of a transformation, and its expected frequency; (2) the 'expected' distribution is derived by examining the phylogenetic distribution of the transformation and its associated selection pressures. Thus, by looking for congruence between these various phylogenetic distribution patterns, we can test hypotheses about constraint. We critically examine this approach using a test case: variation in phalanx-number in the amniote limb.

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“…Throughout the 1990s, aspects of this topology [25] were challenged through new fossil finds and phylogenetic analyses: for example, Beard [30] suggested a closer affinity of Dermoptera (e.g. colugos) with Primates than bats, and the finding of Eocene whale fossils (Artiocetus, Rodhocetus) with diagnostic ankle bones suggested derivation of Cetacea from Artiodactyla rather than from Mesonychia [31]. Nevertheless, a recent cladistic analysis of the largest morphological dataset to date, which includes approximately 4500 characters [8], has many features in common with Novacek's [25] morphological tree and still supports numerous polyphyletic groups including an 'insectivore' group, a 'spiny hedgehog' group, an 'ant and termite eating' group, a 'tree-dwelling' group and an 'ungulate' group [9] (table 1).…”

Section: Shaking the Morphological Treementioning

confidence: 99%

Mammal madness: is the mammal tree of life not yet resolved?

Foley

Springer

Teeling

2016

Phil. Trans. R. Soc. B

215

195

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One contribution of 15 to a discussion meeting issue 'Dating species divergences using rocks and clocks'. Most molecular phylogenetic studies place all placental mammals into four superordinal groups, Laurasiatheria (e.g. dogs, bats, whales), Euarchontoglires (e.g. humans, rodents, colugos), Xenarthra (e.g. armadillos, anteaters) and Afrotheria (e.g. elephants, sea cows, tenrecs), and estimate that these clades last shared a common ancestor 90-110 million years ago. This phylogeny has provided a framework for numerous functional and comparative studies. Despite the high level of congruence among most molecular studies, questions still remain regarding the position and divergence time of the root of placental mammals, and certain 'hard nodes' such as the Laurasiatheria polytomy and Paenungulata that seem impossible to resolve. Here, we explore recent consensus and conflict among mammalian phylogenetic studies and explore the reasons for the remaining conflicts. The question of whether the mammal tree of life is or can be ever resolved is also addressed.This article is part of the themed issue 'Dating species divergences using rocks and clocks'.

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Origin of Whales from Early Artiodactyls: Hands and Feet of Eocene Protocetidae from Pakistan

Cited by 275 publications

References 36 publications

A gene network model accounting for development and evolution of mammalian teeth

A gene network model accounting for development and evolution of mammalian teeth

Developmental constraints in a comparative framework: A test case using variations in phalanx number during amniote evolution

Mammal madness: is the mammal tree of life not yet resolved?

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