Old and New Hypotheses About the Homology of the Compound Bones From the Cheek and Otico-occipital Regions of the Anuran Skull

ALCALDE, L.; BASSO, N. G.

ZOOLOGY

ELSEVIER GMBH

Año: 2013 vol. 116 p. 232 - 245

0944-2006

tWe studied the larval development of compound bones from the otico-occipital and cheek regions inspecies of the neobatrachian genera Batrachyla, Hylorina, Leptodactylus, Odontophrynus and Pleurodema.Comparisons were made using a set of Ambystoma spp. (Caudata) and Ceratophrys ornata (Anura; Cer-atophryidae) larvae. As suggested by previous studies, we verified the compound nature of the exoccipital(two centers, anurans only), frontoparietal (one center, most anurans and Ambystoma; three centers, someanurans), and squamosal (two centers, all anurans and Ambystoma) bones. We discuss old and new homol-ogy hypotheses for each of the compound bone centers in the context of the most widely accepted scenarioof lissamphibian origins and relationships, i.e., monophyletic Lissamphibia that includes the clade Batra-chia (Caudata + Anura) and the most divergent Gymnophiona. Our findings have a direct impact on ourunderstanding of the composition of the skull in Lissamphibia. We recognized the presence of the fol-lowing bones: (i) opisthotic (fused to the exoccipital) and tabular (fused to the squamosal) in Batrachia(Anura + Caudata) and (ii) supratemporal (fused to the parietal portion of the frontoparietal) in Anura.Separate centers of the parietal were found only in Pleurodema.We studied the larval development of compound bones from the otico-occipital and cheek regions inspecies of the neobatrachian genera Batrachyla, Hylorina, Leptodactylus, Odontophrynus and Pleurodema.Comparisons were made using a set of Ambystoma spp. (Caudata) and Ceratophrys ornata (Anura; Cer-atophryidae) larvae. As suggested by previous studies, we verified the compound nature of the exoccipital(two centers, anurans only), frontoparietal (one center, most anurans and Ambystoma; three centers, someanurans), and squamosal (two centers, all anurans and Ambystoma) bones. We discuss old and new homol-ogy hypotheses for each of the compound bone centers in the context of the most widely accepted scenarioof lissamphibian origins and relationships, i.e., monophyletic Lissamphibia that includes the clade Batra-chia (Caudata + Anura) and the most divergent Gymnophiona. Our findings have a direct impact on ourunderstanding of the composition of the skull in Lissamphibia. We recognized the presence of the fol-lowing bones: (i) opisthotic (fused to the exoccipital) and tabular (fused to the squamosal) in Batrachia(Anura + Caudata) and (ii) supratemporal (fused to the parietal portion of the frontoparietal) in Anura.Separate centers of the parietal were found only in Pleurodema.