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Zoology and wildlife conservation

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Abstracts » Zoology and wildlife conservation

Continental breakup and the ordinal diversification of birds and mammals

Article Abstract:

The ordinal diversification of birds and mammals may have been due to continental breakup. A comprehensive set of genes showing a constant rate of substitution provides estimates of times of divergence among avian and mammalian orders. Molecular estimates of divergent times show that the divergence occurred during Mesozoic fragmentation of emergent land areas. The classical hypothesis indicates rapid divergence of most of the orders after the Cretaceous/Tertiary extinction event that occurred 65 million years ago.

Author: Hedges, S. Blair, Kumar, Sudhir, Parker, Patrick H., Sibley, Charles Gald
Publisher: Macmillan Publishing Ltd.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
Environmental aspects, Biological diversity, Biodiversity, Continental drift

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A molecular timescale for vertebrate evolution

Article Abstract:

Molecular clocks are used to estimate divergence times of species, and the divergence of birds and mammals provides a reliable calibration based with which to anchor molecular clocks. Divergence times were estimated by two methods, using 658 genes, representing 207 vertebrate species. Molecular times for the origin of vertebrates in the Palaeozoic and early Mesozoic eras were similar to fossil records, although there were major gaps indicated in the Mesozoic fossil record.

Author: Kumar, Sudhir, Blair Hedges, S.
Publisher: Macmillan Publishing Ltd.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1998
Paleontology, Mesozoic Era, Biological rhythms, Biorhythms

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Relations of fish and tetrapods

Article Abstract:

Tetrapods have been found to be more closely related to lungfishes than to the coelacanth. Comparisons of tetrapod representatives were made against existing sarcopterygians, lungfishes and coelacanths, to establish more distinct phylogenetic relationships. Genetic analysis using mitochondrial DNA may be useful in interpreting the changes in morphology as fishes evolved into present-day tetrapods.

Author: Hedges, S. Blair, Hass, Carla Ann, Maxson, Linda R.
Publisher: Macmillan Publishing Ltd.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
Fishes, Vertebrates, Evolution (Biology)

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Subjects list: Observations
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