The humerus and stratigraphic range of Palaeospheniscus (Aves, Sphenisciformes)

Document title: The humerus and stratigraphic range of Palaeospheniscus (Aves, Sphenisciformes)
Journal: Ameghiniana
System number: 000376464
ISSN: 0002-7014
Authors: 1
Institutions: 1University of Bristol, School of Earth Sciences, Bristol, Avon. Reino Unido
Season: Jun
Volumen: 51
Number: 3
Pages: 159-172
Country: Argentina
Language: Inglés
Document type: Artículo
Approach: Taxonómico
English abstract A comparison between the Paleogene and Neogene marine assemblages in South America suggests a major turnover among penguins by the late Miocene, with the disappearance of the stem Sphenisciformes and the rise of the modern penguins. However, isolated specimens attributed to Palaeospheniscus from the late Miocene of Chile suggest that stem and crown taxa coexisted until the end of the Miocene. To clarify the stratigraphic range of Palaeospheniscus and determine how long the stem Sphenisciformes persisted in South America, the present study offers a revision of its putative records in Chile (Bahía Inglesa and Coquimbo formations), Peru (Chilcatay Formation), and South Africa (Ysterplaats site). In order to reliably discriminate isolated humeri of Palaeospheniscus from Spheniscus, twelve potential discriminating characters were identified and evaluated. Despite the existence of a wide range of variability and overlap, these humeri can be discriminated using large sets of characters, such as a transverse ligament sulcus connected with the capital incisure by a sulcus, or the lack of the proximal ligament pit in Palaeospheniscus. The putative record of Palaeospheniscus in the late Miocene–Pliocene of Chile and early Pliocene of South Africa is discarded, restricting its stratigraphic range to the early and middle Miocene of Argentina and the middle Miocene of Peru. This reduces the biochron of the genus from 18 Ma to a maximum of 11 Ma and suggests that the middle Miocene was a crucial time for the establishment of modern seabirds communities in general and penguins in particular
Disciplines: Biología
Keyword: Anatomía e histología,
Aves marinas,
Claves de identificación,
Variación intraespecífica,
Keyword: Biology,
Anatomy and histology,
Marine birds,
Identification keys,
Intraspecific variation,
Document request
Note: The document is shipping cost.

Original documents can be consulted at the Departamento de Información y Servicios Documentales, located in the Annex to the General Directorate of Libraries (DGB), circuito de la Investigación Científica across from the Auditorium Nabor Carrillo, located between the Institutes of Physics and Astronomy. Ciudad Universitaria UNAM. Show map
For more information: Departamento de Información y Servicios Documentales, Tels. (5255) 5622-3960, 5622-3964. E-mail: . Monday to Friday from (8 to 16 hrs).