A new condor (Ciconiiformes, Vulturidae) from the late Miocene/early Pliocene Pisco Formation, Peru

We report the oldest fossil condor (Vulturidae) from South America and the first from the Pisco Formation (14.0–2.0 Ma) of Peru, described herein as Perugyps diazi new genus and species. The Pisco Formation, exposed on the southern coast of Peru, has produced well-preserved and abundant marine and terrestrial vertebrate fossils from the late Miocene/early Pliocene (6.0–4.5 Ma) Montemar and Sacaco Sur localities, from where P. diazi was recovered. The new condor adds to our knowledge on the evolution and biogeographic distribution of New World vultures. The age of this new species supports the hypothesis that condors probably evolved in North America and entered South America by the late Miocene/early Pliocene. We believe it is likely that the first condors to reach South America probably did so via a coastal corridor along the western side of the Andes where they became part of the diverse coastal fauna in southern Peru.

Key words: condor, Miocene, Peru, Perugyps diazi, Pisco Formation, Pliocene, Vulturidae.

Un Nuevo Cóndor (Ciconiiformes, Vulturidae) del Mioceno Tardío-Plioceno Temprano de la Formación Pisco, Perú.

Resumen. Se reporta el cóndor más antiguo de América del Sur y el primero para la Formación Pisco (14–2 Ma), y se describe como Perugyps diazi. De esta formación, situada en la costa sur del Perú, provienen gran cantidad de aves marinas en muy buen estado de conservación, en especial de los niveles Montemar y Sacaco Sur (Mioceno tardío/Plioceno temprano, 6.0–4.5 Ma), justamente de donde procede Perugyps. Este nuevo cóndor añade importante información sobre la evolución y distribución biogeográfica de estas aves, pues su edad apoya la hipótesis de que los cóndores probablemente evolucionaron en América del Norte y entraron a América del Sur entre el Mioceno tardío y el Plioceno temprano. Sugerimos que su llegada pudo realizarse por el corredor costero del lado occidental de los Andes, en donde pasaron a formar parte de la diversa fauna del sur del Perú.

INTRODUCTION

The oldest record of the family Vulturidae in the Americas is the early Oligocene genus Phasmagyps Wetmore 1927 from the United States (see Emslie 1988a), though the validity of this taxon has been questioned (Olson 1985). New World vultures appeared in South America by the late Oligocene/early Miocene in Brazil with Brasilogyps Alvarenga 1985, a species very similar in size and features to the living Coragyps (Emslie 1988a). In Peru, fossils of five modern genera (Vultur, Gymnogyps, Sarcoramphus, Coragyps, and Cathartes) and one extinct genus (Geronogyps Campbell 1979) have been identified and described, all from late Pleistocene tar seeps at Talara on the northern coast (Campbell 1979). Recently, eight disassociated bones of a new species of condor were found in deposits of the Montemar (6–4.5 Ma) and Sacaco Sur (5 Ma), vertebrate-bearing levels of the Pisco Formation on the south-central coast of Peru (Fig. 1). These fossils are assumed to represent a single genus and species of condor described herein.

METHODS

All fossils were compared with skeletal material of living genera of condors and vultures (Vultur Linnaeus 1758, Sarcoramphus Duméril 1806, Cathartes Illiger 1811, Gymnogyps Lesson 1842, Coragyps Saint-Hilaire 1853) at the U. S. National Museum of Natural History, Smithsonian Institution (USNM), and the Field Museum of Natural History (FMNH), Chicago. Because current Peruvian law does not allow the removal of original fossil material from the country, nor could casts be made due to the fragile nature of the bones, all comparisons outside of Peru were completed with high-quality digital photographs (SONY Cyber-shot DSc-P92, 5.0 megapixels) of the fossils, in 2–3 views per element, as well as with 360º digital videos of each specimen, with modern skeletal material. Thus, we are confident that all characters that distinguish the new fossil species could be discerned from these comparisons.

Comparisons to other fossil taxa were completed using published illustrations and descriptions, and casts of Royal Ontario Museum fossils (ROM 12991, 12992, 12993, 13007) of Geronogyps reliquus Campbell 1979. Terminology follows that of Howard (1929) and Baumel (1993); measurements were completed with vernier calipers to the nearest 0.1 mm. All fossils described here are housed at the Departamento de Paleontología de Vertebrados, Museo de Historia Natural, Universidad Nacional Mayor de San Marcos (MUSM), Lima, Peru, and are catalogued with MUSM numbers.

FIGURE 1. Map of the Pisco Formation in Peru showing the location of the Montemar and Sacaco Sur localities where fossils of Perugyps diazi new genus and species were recovered (after de Muizon and DeVries 1985). Inset map depicts the location of the Pisco Formation in relation to Lima, the capital of Peru.

FIGURE 2. (A) Holotype right carpometacarpus (MUSM 213) of Perugyps diazi new genus and species in internal (left) and external (right) views. (B) Proximal right carpometacarpus (MUSM 206) of Perugyps diazi new genus and species in internal view. (C) Distal left ulna (MUSM 423) of Perugyps diazi new genus and species in internal view. Scale bar = 2 cm.

RESULTS

SYSTEMATIC PALEONTOLOGY