Characterization of the morphology of the anuran ilium: a geometric morphometric approach.

GOMEZ, RAUL O.; BECERRA, MARCOS G.

Capital Federal

Congreso; Reunión Anual de Comunicaciones de la Asociación Paleontológica Argentina; 2009

Asociación Paleontológica Argentina

The ilium of anurans has been widely employed in the taxonomic identification of disarticulated fossil material. The morphologyof this element has been stereotyped in familial diagnoses but many of these traditional families have resultednon-monophyletic in recent phylogenetic analyses. Hence, a reanalysis of the evidence is needed in the new phylogeneticcontext. Herein we perform a geometric morphometric analysis to characterize the iliac morphology of several anurangroupings, including ?archeobatrachians? as well as neobatrachians. Particularly, we focused our study on hyloid taxa,such as leptodactylids, cycloramphids, hylids, and bufonids. A total of 127 specimens were digitized in two dimensions,using 9 landmarks and 10 semilandmarks to capture the anatomy of the ilium. All sets of landmark configurations weresuperimposed following the procrustes analysis procedure and using the TPS software. Additionally, we conducted separateanalyses of subsets of the data for ?archeobatrachians? and hyloids in order to facilitate the interpretation of the results.The results of the relative warp analysis of the total set, as well as that of the subsets, show that several related taxatend to occupy the same areas of the morphospace. However, some taxa (e.g. bufonids) occupy large areas that widelyoverlap those of other groups and show singular deviations from the bulk of the group to which they belong. These preliminaryresults show that the iliac morphology partially reflects a phylogenetic signal and that traditionally consideredmorphotypes are oversimplifications that obscure the actual morphological diversity of the anuran ilium.