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A Comparison of Placental and Marsupial Evolution. James Duke, Katie Mayer, & Stephen Ulrich. Placental-Marsupial Divergence. Sinodelphys szalayi. Eomaia scansoria. The oldest known ancestor to marsupials (125 million years old). - PowerPoint PPT Presentation
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James Duke, Katie Mayer, & Stephen Ulrich
The oldest known ancestor to marsupials (125 million years old)
The oldest known ancestor to placental mammals (125 million years old)
Eomaia scansoria
Marsupial distribution in the late Cretaceous
http://www.scotese.com/images/094.jpg
Current marsupial distribution
Multiple reproductive organs
Short internal gestation period followed by long development in marsupium
Single reproductive organ
Long gestation period
PlacentaWider pelvic
openings
Placentals
Survival association with death during pregnancy
Common birthing problems of placentalsAmniotic membraneAdvantages of shorter gestation period
Brain structureSocialityDevelopmental focusOther, minor
differences
http://brainmind.com/images/CorpusCallosum222.jpg
Australia•Habitat destruction•Introduction of predators by humans
Worldwide•Smaller average body size
Other•Stephen
• Lessa, Enrique P. & Richard A. Farina. (1996). Reassessment of extinction patterns among the late Pleistocene mammals of South America. Palaeontology:Vol 39, part 3, 1996, pp 651-662. Retrieved from http://palaeontology.palass-pubs.org/pdf/Vol%2039/Pages%20651-662.pdf.
• Pickrell, John. (2003).Oldest Marsupial Fossil Found in China: National Geographic News. Retrieved from
• http://news.nationalgeographic.com/news/2003/12/1215_031215_oldestmarsupial.html
• Nowak, Ronald M. (1999). Walker's Book Of Mammals, Sixth Edition. Baltimore and London: Johns Hopkins University Press. p. 5.
• Springer, Mark S., John A.W. Kirsh, & Judd A. Case. The Chronicle of Marsupial Evolution: Molecular Evolution and Adaptive Radiation. Edited by Thomas J. Givnish & Kenneth J. Sytsma. 1997. Cambridge, United Kingdom: Cambridge University Press. Retrieved from http://books.google.com/books?hl=en&lr=&id=d06PgBvL5lIC&oi=fnd&pg=PA129&dq=marsupial+evolution&ots=rongh7ew3o&sig=7vNP_mvfqQhuef5HrtEtmuvSiF4#v=onepage&q=marsupial%20evolution&f=false.
• Tyndale-Biscoe, Hugh. (2005). Life of Marsupials. CSIRO publishing. Retrieved from http://www.publish.csiro.au/samples/LOMsample.pdf.