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Science 12 December 2003:
Vol. 302. no. 5652, pp. 1899 - 1900
DOI: 10.1126/science.1092272
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Perspectives

Also see the archival list of Science's Compass: Enhanced Perspectives

PALEONTOLOGY:
Enhanced: Marsupial Origins

Richard L. Cifelli and Brian M. Davis

The different reproductive systems of marsupial and placental mammals have profound implications for other aspects of their biology. When and where in evolutionary history did the two groups of mammals divide? In their Perspective, Cifelli and Davis discuss recent advances toward answering these questions. He highlights the report of Luo et al., who have discovered the oldest known fossil ancestor of the marsupials. The fossil provides important insights into the biology of the early marsupial ancestors and helps to define the time of divergence from placentals. Luo et al. propose a Eurasian origin for both placental and marsupial mammals, but Cifelli and Davis caution that this issue remains to be resolved.

The authors are at the Oklahoma Museum of Natural History and Department of Zoology, University of Oklahoma, Norman, OK 73072, USA. E-mail: rlc{at}ou.edu, bmdavi{at}ou.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Post-Miocene expansion, colonization, and host switching drove speciation among extant nematodes of the archaic genus Trichinella.
D. S. Zarlenga, B. M. Rosenthal, G. La Rosa, E. Pozio, and E. P. Hoberg (2006)
PNAS 103, 7354-7359
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Science. ISSN 0036-8075 (print), 1095-9203 (online)