Mimetismo em aves

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Volume 49(21):257‑275, 2009

Osteologia craniana de Nyctibiidae (Aves, Caprimulgiformes)
Thiago Vernaschi Vieira da Costa1 Reginaldo José Donatelli2
AbsTRACT The Potoos form an exclusively neotropical family of nocturnal birds distributed throughout Central and South America, except Chile, and reaching their highest diversity in the Amazon region. The seven currently recognized species arecertainly among the most poorly known birds of this region. They are characterized by a distinctive mimicry of vegetal trunks, where they remain almost motionless during daytime. For this reason, their nocturnal and cryptic habits make them exceedingly difficult to study. Published accounts on behavior and natural history of the family are scarce and contributions regarding its anatomy are rare.Here we sample six of the seven currently recognized species of Nyctibiidae, including Nyctibius grandis, N. aethereus, N. griseus, N. jamaicensis, N. leucopterus and N. bracteatus, in order to conduct a detailed and illustrated description of the skull and jaw osteology. High interspecific variation in skull osteology was observed in the family. Species of this family possess a highly modifiedskull, adapted to their life habits, which shelters their well developed eyes and permits a large mouth opening. The bones that form the palate structure exhibit a dorsoventral flattening, particularly in the pterigoid and parasphenoid bones, with the palatine bone being a broadly developed, wing-shaped structure. In the maxilar region, near the jugal arch, there is a “tooth-like” projection, uniqueamong birds, which may assist in the retention of prey upon capture. The vomer bone is highly variable within the family, showing varying numbers of rostral projections amongst species. The broad occipital region exhibits large spacing between the quadrate bones, which are vertically disposed and possess a reduced processus orbitalis. The mandible, which is flexible and elastic, has an extremelyshort symphyseal region and sindesmotic joints in both mandibular rami. As a family, potoos possess a highly specialized skull which provides insight into the relationship between the form of the structures and the feeding habits of the species. Furthermore, the large interspecific variation in skull morphology emphasizes the needs for taxonomic revision within the family, which at present is lumpedinto a single genus. Keywords: Osteology; Skull; Potoos; Nyctibiidae, Caprimulgiformes.
1. Pós-Graduação em Ciências Biológicas (Zoologia), Universidade Estadual Paulista (UNESP), Instituto de Biociências de Botucatu, CEP 18618-100, Rubião Júnior, Botucatu, São Paulo, Brasil. Endereço atual: Instituto Nacional de Pesquisas da Amazônia (INPA), Coleções Zoológicas, Coleção de Aves, Caixa Postal478, Manaus, Amazonas, Brasil. E-mail: thiagobio@hotmail.com 2. Universidade Estadual Paulista (UNESP), Faculdade de Ciências, Departamento de Ciências Biológicas, Campus de Bauru, Caixa Postal 473, CEP 17001-970, Bauru, São Paulo, Brasil. E-mail: rjdonat@yahoo.com.br


Costa, T.V.V. & Donatelli, R.J.: Osteologia craniana de Nyctibiidae

INTRODuçãO A família Nyctibiidae (urutaus oumães-da-lua) pertence à ordem Caprimulgiformes, a qual é tradicionalmente composta ainda pelas famílias Steatornithidae, Caprimulgidae, Aegothelidae e Podargidae. A família é composta por sete espécies incluídas em um único gênero Nyctibius Viellot, 1816: N. grandis (Gmelin, 1789), N. aethereus (Wied, 1920), N. griseus (Gmelin, 1789), jamaicensis (Gmelin, 1789), N. maculosus Rigway, 1912, N. leucopterus(Wied, 1921) e N. bracteatus Gould, 1846, distribuídas desde o México até a América do Sul, exceto Chile, e alcançando sua maior diversidade na região amazônica (Cohn-Haft, 1999). O mais antigo fóssil atribuído aos Nyctibiidae, Euronyctibius kurochkini Mourer-Chauviré 1988, data do período entre o Eoceno Superior e o Oligoceno Superior da França, com idade aproximada de pelo menos 25 milhões de...