The study of c. 100 skulls of the dipnoan Scaumenacia curta (Whiteaves), allows to evaluate patterns of intraspecific variation. The different types of intraspecific variation in the skull roof of Scaumenacia could be classified into the following categories: (1) change of proportions, (2) spatial competition (minor and major), (3) plasticity in the pattern of pit-lines, (4) fusion, and (5) presence of anamestic bones. Trajectories of the middle and posterior pit-lines as well as the fusion among bones of the lateral series (bones L1 to N) are the two most variable qualitative features. Fusions among elements belonging to a longitudinal series (median and lateral series) are more frequent than those in adjacent series, and occur principally along the trajectory of the main sensory canals. Bivariate statistics and principal component analysis were used to identify shape variation related to size (allometry) and fluctuating bilateral asymmetry among bones of the mesial series. Cranial patterns of variation of Scaumenacia are compared with those of other taxa.
Dipnoans, morphometry, allometry, intraspecific variation, skull, Upper Devonian