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The comparative morphology of the head skeleton, girdles and hind limbs in the Pygopodidae

 

作者: N. G. Stephenson,  

 

期刊: Journal of the Linnean Society of London, Zoology  (WILEY Available online 1962)
卷期: Volume 44, issue 300  

页码: 627-644

 

ISSN:0368-2935

 

年代: 1962

 

DOI:10.1111/j.1096-3642.1962.tb01628.x

 

出版商: Blackwell Publishing Ltd

 

数据来源: WILEY

 

摘要:

Summary1Apart from their elongation, the skulls of pygopods are gecko‐like in general form and in the elements present. Cranial morphology supports the views of gecko‐pygopod affinities which have been expressed by McDowell&Bogert (1954) and Underwood (1957).2Of the various pygopod genera, the skull ofPygopusis the least modified, while that ofDelmais very similar to it.3The most extreme elongation of the pre‐optic and post‐optic regions of the skull occurs inLialis.InAprasia, differential elongation of dorsal and ventral regions of the skull anteriorly results in the mouth being ventral instead of terminal.4Pletholaxis the only known genus amongst pygopods and Australian geckos in which the frontals are not fused, and is further characterized by the fact that certain bones of the head overlap.5Lialisis unique among pygopods in lacking a jugal.6Aprasiainvariably lacks maxillary teeth. Furthermore, premaxillary teeth are lacking in juveniles of this genus, and also in adult females except those ofA. striolata.7As in Australian geckos, only a single splinter‐like temporal bone may be recognized between the parietal and quadrate.8The hyobranchial apparatus is extremely gecko‐like in form.9The reduced, U‐shaped pectoral girdle ofAprasiais re‐interpreted. It is suggested that the elements present are the two cartilaginous suprascapulae, the two bony clavicles, and a median piece representing the clavicular symphysis.10The pectoral girdle ofPletholax gracilisis unique amongst known pygopods and Australian geckos in the presence of a bony interclavicle.11The three elements of the pelvic girdle, namely the pubis, ischium and ilium, are invariably present. However, different pygopod genera show various stages of hind limb reduction, fromPygopusin which even four digits of the foot are present, toAprasia, in which only one bone, the femur, is present in the hind limb rudiment.12The morphological distinctiveness of various pygopod genera is discussed in terms of heterochrony. Differences between adult species and genera, though genetically based, are subsequently related to the time of embryonic appearance of certain structures as compared with neighbouring structures, and to their varying rates

 

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