A Comparison of Placental and Marsupial Evolution James

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A Comparison of Placental and Marsupial Evolution James Duke, Katie Mayer, & Stephen Ulrich

A Comparison of Placental and Marsupial Evolution James Duke, Katie Mayer, & Stephen Ulrich

Placental-Marsupial Divergence Sinodelphys szalayi The oldest known ancestor to marsupials (125 million years old)

Placental-Marsupial Divergence Sinodelphys szalayi The oldest known ancestor to marsupials (125 million years old) Eomaia scansoria The oldest known ancestor to placental mammals (125 million years old)

Convergent Evolution

Convergent Evolution

Historical Patterns of Distribution Marsupial distribution in the late Cretaceous http: //www. scotese. com/images/094.

Historical Patterns of Distribution Marsupial distribution in the late Cretaceous http: //www. scotese. com/images/094. jpg

Current Patterns of Distribution Current marsupial distribution

Current Patterns of Distribution Current marsupial distribution

Current Patterns, cont.

Current Patterns, cont.

Reproductive Differences Marsupials Placentals Multiple reproductive Single reproductive organs Short internal gestation period followed

Reproductive Differences Marsupials Placentals Multiple reproductive Single reproductive organs Short internal gestation period followed by long development in marsupium organ Long gestation period Placenta Wider pelvic openings

Benefits of Marsupial Reproduction Survival association with death during pregnancy Common birthing problems of

Benefits of Marsupial Reproduction Survival association with death during pregnancy Common birthing problems of placentals Amniotic membrane Advantages of shorter gestation period

Other Differences Brain structure Sociality Developmental focus Other, minor differences http: //brainmind. com/images/Corpus. Callosum

Other Differences Brain structure Sociality Developmental focus Other, minor differences http: //brainmind. com/images/Corpus. Callosum 222. jpg

Other Reasons for Marsupial Extinction Australia • Habitat destruction • Introduction of predators by

Other Reasons for Marsupial Extinction Australia • Habitat destruction • Introduction of predators by humans Worldwide • Smaller average body size Other • Stephen

References • Lessa, Enrique P. & Richard A. Farina. (1996). Reassessment of extinction patterns

References • 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%20651662. pdf. • Pickrell, John. (2003). Oldest Marsupial Fossil Found in China: National Geographic News. Retrieved from • http: //news. nationalgeographic. com/news/2003/12/1215_031215_oldestm arsupial. 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=d 06 Pg. Bv. L 5 l. IC&oi= fnd&pg=PA 129&dq=marsupial+evolution&ots=rongh 7 ew 3 o&sig=7 v NP_mvfq. Qhuef 5 Hrt. Etmuv. Si. F 4#v=onepage&q=marsupial%20 evolu tion&f=false. • Tyndale-Biscoe, Hugh. (2005). Life of Marsupials. CSIRO publishing. Retrieved from http: //www. publish. csiro. au/samples/LOMsample. pdf.