Morphology, Paleontology, and Placental Mammal Phylogeny

Placental mammals constitute the most intensively studied large clade of organisms. Deciphering their relationships has important implications not only to understand evolutionary processes Springer et al. (2007) have recently discussed limitations of morphological analysis of placental phylogeny compared with reconstructions based on molecular data. They presented a pessimistic view of the potential of morphological characters for use in high-level placental mammal phylogeny reconstruction, as the morphological data set they scrutinized (from Asher et al., 2003) does not recover the four major clades of mammals (Afrotheria, Xenarthra, Laurasiatheria, and Euarchontoglires) that these authors regard as overwhelmingly supported.