tailieunhanh - Báo cáo sinh học: "Colugos: obscure mammals glide into the evolutionary limeligh"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Colugos: obscure mammals glide into the evolutionary limelight. | Journal of Biology BioMed Central Minireview Colugos obscure mammals glide into the evolutionary limelight Robert D Martin Address Department of Anthropology The Field Museum Chicago IL 60605-2496 USA. Email rdmartin@ Published I May 2008 Journal of Biology 2008 7 13 doi jbiol74 The electronic version of this article is the complete one and can be found online at http content 7 4 13 2008 BioMed Central Ltd Abstract Substantial molecular evidence indicates that tree-shrews colugos and primates cluster together on the mammalian phylogenetic tree. Previously a sister-group relationship between colugos and primates seemed likely. A new study of colugo chromosomes indicates instead an affinity between colugos and tree-shrews. Colugos constituting the obscure and tiny order Dermop-tera are gliding mammals confined to evergreen tropical rainforests of South-East Asia. There are two extant species now placed in separate genera Galeopterus variegatus Malayan colugo formerly known as Cynocephalus variegatus and Cynocephalus volans Philippine colugo . Their most obvious hallmark is a gliding membrane patagium surrounding almost the entire body margin. Colugos are also called flying lemurs but - as Simpson aptly noted 1 -they are not lemurs and cannot fly . They differ from other gliding mammals certain rodents and marsupials in that the patagium also extends between the hind limbs and the short tail even stretching between fingers and toes hence the name mitten-gliders . The lower incisors are unique the forward-leaning procumbent crown of each tooth is subdivided into several comb-like tines. Colugos are strict herbivores predominantly eating young leaves from many tree species and in the gastrointestinal tract the caecum is greatly enlarged. Their habits are poorly documented although a recent field study yielded valuable new information 2 . Colugos would doubtless still be languishing in obscurity but for mounting evidence indicating a .

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