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Mammal



Molecular studies based on DNA analysis have suggested new relationships among mammal families over the last few years. Most of these findings have been independently validated by Retrotransposon presence/absence data. The most recent classification systems based on molecular studies have proposed four groups or lineages of placental mammals. Molecular clocks suggest that these clades diverged from early common ancestors in the Cretaceous, but fossils have not been found to corroborate this hypothesis. These molecular findings are consistent with mammal zoogeography:

Following molecular DNA sequence analyses, the first divergence was that of the Afrotheria 110–100 million years ago. The Afrotheria proceeded to evolve and diversify in the isolation of the African-Arabian continent. The Xenarthra, isolated in South America, diverged from the Boreoeutheria approximately 100–95 million years ago. According to an alternative view, the Xenarthra has the Afrotheria as closest allies, forming the Atlantogenata as sistergroup to Boreoeutheria. The Boreoeutheria split into the Laurasiatheria and Euarchontoglires between 95 and 85 mya; both of these groups evolved on the northern continent of Laurasia. After tens of millions of years of relative isolation, Africa-Arabia collided with Eurasia, exchanging Afrotheria and Boreoeutheria. The formation of the Isthmus of Panama linked South America and North America, which facilitated the exchange of mammal species in the Great American Interchange. The traditional view that no placental mammals reached Australasia until about 5 million years ago when bats and murine rodents arrived has been challenged by recent evidence and may need to be reassessed. These molecular results are still controversial because they are not reflected by morphological data, and thus not accepted by many systematists. Further there is some indication from Retrotransposon presence/absence data that the traditional Epitheria hypothesis, suggesting Xenarthra as the first divergence, might be true.

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See also

Mammals Portal

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References

  1. ^ (2005-11-16) in Wilson, D. E., and Reeder, D. M. (eds): Mammal Species of the World, 3rd edition, Johns Hopkins University Press. ISBN 0-801-88221-4. 
  2. ^ a b (2001) in Don E. Wilson & David Burnie: Animal: The Definitive Visual Guide to the World's Wildlife, 1st edition, DK Publishing, 86–89. ISBN 978-0789477644. 
  3. ^ a b c d e "mammal." Encyclopædia Britannica. Standard Edition. Chicago: Encyclopædia Britannica, 2007.
  4. ^ Amniota - Palaeos.
  5. ^ Synapsida overview - Palaeos.
  6. ^ Therapsida - Palaeos.
  7. ^ Kermack (1984). The evolution of mammalian characters. Croom Helm. 
  8. ^ Cynodontia: Overview - Palaeos.
  9. ^ Symmetrodonta - Palaeos.
  10. ^ Oldest Marsupial Fossil Found in China. National Geographic News (December 15, 2003).
  11. ^ Eomaia scansoria: discovery of oldest known placental mammal.
  12. ^ Dinosaur Extinction Spurred Rise of Modern Mammals
  13. ^ Jurassic "Beaver" Found; Rewrites History of Mammals.
  14. ^ Rogue finger gene got bats airborne
  15. ^ Bininda-Emonds, O.R.P. (2007). "The delayed rise of present-day mammals". Nature (446): 507–511. 
  16. ^ Dinosaur Extinction Spurred Rise of Modern Mammals
  17. ^ Oftedal, O.T. (2002). "The mammary gland and its origin during synapsid evolution". Journal of Mammary Gland Biology and Neoplasia 7 (3): 225–252. 
  18. ^ Oftedal, O.T. (2002). "The origin of lactation as a water source for parchment-shelled eggs=Journal of Mammary Gland Biology and Neoplasia" 7 (3): 253–266. 
  19. ^ Lactating on Eggs
  20. ^ Brink, A.S. (1955). "A study on the skeleton of Diademodon". Palaeontologia Africana 3: 3–39. 
  21. ^ Kemp, T.S. (1982). Mammal-like reptiles and the origin of mammals. London: Academic Press, 363. 
  22. ^ Bennett, A. F. and Ruben, J. A. (1986) "The metabolic and thermoregulatory status of therapsids"; pp. 207–218 in N. Hotton III, P. D. MacLean, J. J. Roth and E. C. Roth (eds), "The ecology and biology of mammal-like reptiles", Smithsonian Institution Press, Washington.
  23. ^ Estes, R. (1961). "Cranial anatomy of the cynodont reptile Thrinaxodon liorhinus". Bulletin of the Museum of Comparative Zoology: 165–180. 
  24. ^ Kielan−Jaworowska, Z. (2006). "Limb posture in early mammals: Sprawling or parasagittal". Acta Palaeontologica Polonica 51 (3): 10237–10239. 
  25. ^ Paul, G.S. (1988). Predatory Dinosaurs of the World. New York: Simon and Schuster, 464. 

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Bibliography

  • McKenna, Malcolm C., and Bell, Susan K. 1997. Classification of Mammals Above the Species Level. Columbia University Press, New York, 631 pp. ISBN 0-231-11013-8
  • Nowak, Ronald M. 1999. Walker's Mammals of the World, 6th edition. Johns Hopkins University Press, 1936 pp. ISBN 0-8018-5789-9
  • Simpson, George Gaylord. 1945. "The principles of classification and a classification of mammals". Bulletin of the American Museum of Natural History, 85:1–350.
  • William J. Murphy, Eduardo Eizirik, Mark S. Springer et al., Resolution of the Early Placental Mammal Radiation Using Bayesian Phylogenetics,Science, Vol 294, Issue 5550, 2348–2351 , 14 December 2001.
  • Springer, Mark S., Michael J. Stanhope, Ole Madsen, and Wilfried W. de Jong. 2004. "Molecules consolidate the placental mammal tree". Trends in Ecology and Evolution, 19:430–438. (PDF version)
  • Vaughan, Terry A., James M. Ryan, and Nicholas J. Capzaplewski. 2000. Mammalogy: Fourth Edition. Saunders College Publishing, 565 pp. ISBN 0-03-025034-X (Brooks Cole, 1999)
  • Jan Ole Kriegs, Gennady Churakov, Martin Kiefmann, Ursula Jordan, Juergen Brosius, Juergen Schmitz. (2006) Retroposed Elements as Archives for the Evolutionary History of Placental Mammals. PLoS Biol 4(4): e91.[1]
  • David MacDonald, Sasha Norris. 2006. The Encyclopedia of Mammals, 3rd edition. Printed in China, 930 pp. ISBN 0-681-45659-0.

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v • d • e
Extant Chordata classes by subphylum
Kingdom: Animalia · Subkingdom: Eumetazoa · (unranked): Bilateria · Superphylum: Deuterostomia
Urochordata
Cephalochordata
Leptocardii
Craniata
v • d • e
Extant mammal orders by infraclass
Kingdom: Animalia · Phylum: Chordata · Subphylum: Vertebrata · (unranked): Amniota
Australosphenida
Metatheria
Eutheria




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