Abstract

Proboscidean ontogeny has been previously studied, but typically only a single type of growth character at a time is studied, or methods unable to recover a high-resolution growth series are used. This study seeks to identify ontogenetic growth series for three living proboscidean taxa (Loxodonta africana, L. cyclotis, and Elephas maximus) and five extinct proboscidean taxa (Mammuthus primigenius, M. columbi, M. trogontherii, Palaeoloxodon antiquus, and Mammut americanum) through a quantitative cladistic analysis and test results with previous research on ontogeny, sexual dimorphism, and phylogeny. Fourteen growth series were recovered, eight for species as a whole and six sex-based growth series that only include specimens of a single sex. The growth series generally align with previous estimations of age, are congruent with previous work on epiphyseal fusion, and show evidence for sexual dimorphism in L. africana. Growth series were combined with previous research using shared congruent sequences and inferences on the timing of growth characters not found in both this study to improve resolution, and were combined with each other to recover the growth series of the common ancestor of Elephantidae with fifteen stages and eighteen characters. The growth series of the common ancestor of Elephantidae was compared with published data on epiphyseal fusion in Mammalia. Growth character sequences were identified as synapomorphies of Mammalia, Theria, Eutheria, Metatheria, Atlantogenata, Primates, Rodentia, Paenungulata, Hyracoidea, and Elephantidae.