Phylogenetic interpretation of eggs and eggshells: implications for phylogeny of Palaeognathae

Abstract

This oological analysis supports Palaeognathae monophyly, and places Dromornithidae within Neognathae, the sister clade of Paleognathae. This Dromornithidae relationship is congruent with a recent phylogenetic hypothesis, based on cranial characters, that differs from the original assignment of this group of extinct birds to the Palaeognathae. Minor differences exist between previous palaeognath phylogenetic hypotheses and that obtained from this research. Some of the topological disparities might be influenced solely by inclusion of more fossil taxa in this analysis compared with those considering either molecular or skeletal characters. Surprisingly, oological data differentiate the Australasian palaeognath taxa from those of Africa and South America; this phylogenetic topology conforms to the paleognath geographic distribution. Regardless of the issues related to Paleognathae, results show that oological characters permit the differentiation of groups at a generic level, thus validating the use of eggs and eggshells as a source of evolutionary characters.