Department of Biology, University of California, Riverside, CA 92521, USA.
Science. 2013 Aug 9;341(6146):613. doi: 10.1126/science.1238025.
O'Leary et al. (Research Article, 8 February 2013, p. 662) examined mammalian relationships and divergence times and concluded that a single placental ancestor crossed the Cretaceous-Paleogene (K-Pg) boundary. This conclusion relies on phylogenetic analyses that fail to discriminate between homology and homoplasy and further implies virus-like rates of nucleotide substitution in early Paleocene placentals.
奥利里等人（研究文章，2013 年 2 月 8 日，第 662 页）研究了哺乳动物的亲缘关系和分化时间，并得出结论，认为一个单一的胎盘祖先跨越了白垩纪-古近纪（K-Pg）边界。这一结论依赖于未能区分同源性和同型性的系统发育分析，进一步意味着在早古新世胎盘动物中病毒样的核苷酸替换率。
