We report a new specimen of the extinct procellariiform species Diomedeoides brodkorbi (Aves, Diomedeoididae) from the early Oligocene (Rupelian) of Rheinweiler in southwestern Germany. The well−preserved partial skeleton allows the recognition and reassessment of new osteological details that bear on the phylogenetic affinities of diomedeoidids. The presence on the coracoid of a deeply excavated, cup−like facies articularis for the scapula suggests a stem group position of the Diomedeoididae within Procellariiformes, because this trait also occurs in stem−group representatives of several avian groups, as well as in Mesozoic non−neornithine birds, and is a plesiomorphic character. We hypothesize that the similarities of Diomedeoides to extant southern storm−petrels (Oceanitinae), such as the long mandibular symphysis, the small processus supracondylaris dorsalis and the long legs are plesiomorphic for Procellariiformes.

Key words: Aves, Diomedeoididae, phylogeny, stem−group, Oligocene, Rupelian,Upper Rhine Graben, Germany.

Vanesa L. De Pietri [vanesa.depietri@nmbe.ch], Naturhistorisches Museum der Buergergemeinde Bern, Bernastrasse 15, CH-3005 Bern, Switzerland; Jean-Pierre Berger [jean-pierre.berger@unifr.ch], Claudius Pirkenseer [claudiusmarius.pirkenseer@unifr.ch], and Laureline Scherler [laureline.scherler@unifr.ch], Dept. Geosciences-Earth Sciences, Chemin du Musée 6, University Fribourg, CH-1700 Fribourg, Switzerland; Gerald Mayr [Gerald.Mayr@senckenberg.de], Forschungsinstitut Senckenberg, Sektion Ornithologie, Senckenberganlage 25, 60325 Frankfurt am Main, Germany.