A cladistic analysis of 19 characters was used to investigate the phylogeny of the Schzjornis group, a monophyletic assemblage of six genera of suboscine passerines which are currently placed in three different tyrannoid families: Schzfirnis (Pipridae, manakins), Laniisoma, Zodopleura (Cotingidae, cotingas), Laniocera, Xenopsaris, and Pachyramphus (Tyrannidae, tyrant flycatchers). The character systems analyzed include syringeal and cranial morphology, plumage, and nest architecture. Monophyly of the Schijornis group was supported by two syringeal synapomorphies. Within the group, the phylogenetic relationships of five of the six genera were resolved; Schzfirnis is the sister group to Laniisoma and Laniocera, and Xenopsaris is the sister group of Pachyramphus. The relationship of Zodopleura to these two corroborated clades was not resolved. The higher-level relationships of the Schzjornis group to other tyrannoids was not resolved. Results of two previous biochemical phylogenies of tyrannoids both corroborate and conflict with this morphological hypothesis. Comparative analysis of the evolution of breeding systems in tyrannoids indicates that polygyny may have developed independently within the group, resulting in the evolution of a novel form a male advertisement behavior without conspicuous sexual dimorphism and a distinct type of spatial dispersion of male territories.Resumen. Un analisis cladistico de 19 caracteristicas se emplea para investigar las relacidnes filogeneticas de1 grupo Schzfirnis, un conjunto monofilttico de seis generos, 10s cuales se ubican ahora en tres familias diferentes en la superfamilia Tyrannoidea: Schzfirnis (Pipridae), Laniisoma, Zodopleura (Cotingidae), Laniocera, Xenopsaris, y Pachyramphus (Tyrannidae). Las caracteristicas empleadas incluyen la morfologia de la siringe y de1 craneo, el plumaje, y la estructura de1 nido. La posici6n de1 grupo Schzjornis en Tyrannoidea no se ha determinado. Dentro de1 grupo, las relaciones de cinco de 10s seis gtneros fueron resueltas por la hipBtesis filogenetica mas parsimoniosa, es decir, aquella que requiere el menor numero de caracteristicas derivados. Schzfirnis es m&s cercano a un linaje que consiste de Laniisoma y Laniocera; y Xenopsaris es m8s cercano a Pachyramphus. Las relaciones de Zodopleura no eran resolvado. La comparaci6n de estos resultados con dos hip6teses filogeneticas bioquimicas resulta similitudes y conflictos. Un analisis comparative de la evoluci6n de 10s comportamientos reproductivos en Tyrannoidea indica que polyginia se ha desarollado independientemente en el grupo Schzfirnis. TambiCn en el group0 Schiffornis, se han desarollado nuevos tipos de dispersion territorial y anuncio nuptial de 10s machos sin dimorfismo sexual.
