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Re-examination of Psilopterus lemoinei (Aves, Phorusrhacidae), a late early Miocene little terror bird from Patagonia (Argentina)

2011; Taylor & Francis; Volume: 31; Issue: 5 Linguagem: Inglês

10.1080/02724634.2011.595466

1937-2809

Federico J. Degrange, Claudia P. Tambussi,

Ichthyology and Marine Biology

ABSTRACT ABSTRACT Psilopterus lemoinei, the largest species in this genus, was a small terror bird weighing 8–9 kg, and was a ground bird with functionally tridactyl feet. New remains of this phorusrhacid, including an exceptionally preserved anterior part of a skull recovered from the Patagonian Killik Aike Norte locality (Santa Cruz Formation, late early Miocene), is now available for study. The main purpose of this paper is to provide a detailed morphological description of Psilopterus lemoinei. The new fossils show for the first time that the internal structure of the beak is hollow and reinforced with thin-walled trabeculae. The absence of zona flexoria palatina and zona flexoria arcus jugalis are key features related to the evolution of cranial akinesis. Homologies of the narial and fenestra antorbitalis boundaries have been clarified. Our re-examination allows the establishment of primary osteological homologies useful in comparative anatomy, functional morphology, and phylogenetic studies. ACKNOWLEDGMENTS M. Tejedor, L. Gonzalez, S. Vincon, A. Tauber, M. Perkins, K. Jones, and A. Rosemberger are thanked for their assistance during fieldwork. L. Acosta prepared most of the skull with his customary skill. L. Chiappe and K. P. Johnson (Natural History Museum of Los Angeles County), J. Holstein (Field Museum of Natural History), D. Brinkman, C. Norris, and M. Fox (Yale Peabody Museum), C. Mehling (American Museum of Natural History), M. Reguero (Museo de La Plata), J. I. Noriega (CICYTTP), A. Tauber and S. Mirelman (Museo Padre Molina), and A. Kramarz (Museo Argentino de Ciencias Naturales 'Bernardino Rivadavia') are thanked for allowing access to collections under their care. G. Mayr gave useful data about Otididae and Psophidae. A. Martinez helped us with the images. M. Bell improved substantially our English. Thanks to L. Witmer and D. Defeau who enriched the discussion of some features. We are deeply indebted to M. Manceñido for his assistance in systematic aspects. Thanks to the editor T. Worthy and J. Noriega, K. Campbell, and an additional anonymous reviewer for their helpful comments. This research was supported by PICT 32617. Handling editor: Trevor Worthy