The comparative morphology of the head skeleton, girdles and hind limbs in the Pygopodidae
Version of Record online: 28 JUN 2008
Journal of the Linnean Society of London, Zoology
Volume 44, Issue 300, pages 627–644, April 1962
How to Cite
Stephenson, N. G. (1962), The comparative morphology of the head skeleton, girdles and hind limbs in the Pygopodidae. Journal of the Linnean Society of London, Zoology, 44: 627–644. doi: 10.1111/j.1096-3642.1962.tb01628.x
- Issue online: 23 DEC 2008
- Version of Record online: 28 JUN 2008
- Accepted for publication August 1961
- 1Apart 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 of Pygopus is the least modified, while that of Delma is very similar to it.
- 3The most extreme elongation of the pre-optic and post-optic regions of the skull occurs in Lialis. In Aprasia, differential elongation of dorsal and ventral regions of the skull anteriorly results in the mouth being ventral instead of terminal.
- 4Pletholax is 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.
- 5Lialis is unique among pygopods in lacking a jugal.
- 6Aprasia invariably lacks maxillary teeth. Furthermore, premaxillary teeth are lacking in juveniles of this genus, and also in adult females except those of A. 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 of Aprasia is 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 of Pletholax gracilis is 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, from Pygopus in which even four digits of the foot are present, to Aprasia, 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 of development.