Ontogenetic sequence reconstruction and sequence polymorphism in extinct taxa: an example using early tetrapods (Tetrapoda: Lepospondyli)

Ontogenetic sequence reconstruction is challenging particularly for extinct taxa because of when, where, and how fossils preserve. Different methods of reconstruction exist, but the effects of preservational bias, the applicability of size-independent methods, and the prevalence of sequence polymorphism (intraspecific variation) remain unexplored for paleontological data. Here I compare five different methods of ontogenetic sequence reconstruction and their effects on the detection of sequence polymorphism, using a large collection of the extinct vertebrates Microbrachis pelikani and Hyloplesion longicostatum. The postcranial ossification sequences presented here for those taxa are the first examples known for extinct lepospondyls. Sequences were reconstructed according to skull length, trunk length, increasing number of ontogenetic events, majority-rule consensus, and Ontogenetic Sequence Analysis (OSA). Results generally were in agreement, demonstrating that paleontological data may b...