Observations on the cranial anatomy of Anniella, and a comparison with that of other burrowing lizards
Article first published online: 20 AUG 2009
1950 The Zoological Society of London
Proceedings of the Zoological Society of London
Volume 119, Issue 4, pages 887–904, February 1950
How to Cite
Bellairs, A. d'A. (1950), Observations on the cranial anatomy of Anniella, and a comparison with that of other burrowing lizards. Proceedings of the Zoological Society of London, 119: 887–904. doi: 10.1111/j.1096-3642.1950.tb00915.x
- Issue published online: 30 OCT 2009
- Article first published online: 20 AUG 2009
- Received April 4, 1949.
- 1Some features of the cranial anatomy, including the chondrocranium, of the burrowing lizard Anniella pulchra are described, mainly from serial sections.
- 2The skull shows marked elongation of the temporal region, reduction of the orbits, loss of the temporal arcades and obliteration of the parieto-occipital angle, so that the skull contours are streamlined.
- 3The cranial kinesis is thought to be mainly of the mesokinetic type.
- 4Basitrabecular processes, menisci and small epipterygoids are present. The parietal bones possess extensive downgrowths which partly enclose the cranial cavity on either side.
- 5The chondrocranium shows great reduction in the orbito-temporal region. A low interorbital septum, narrow planum supraseptale and taeniae marginales are present. There are no pila metoptica or pila accessoria and the taeniae mediales are represented only by embryonic rudiments. There are no discrete optic foramina, the optic nerves passing back to the chiasma above the trabecula communis.
- 6The eyes are small but can hardly be regarded as degenerate; eyelids, nictitating membrane, lachrymal canaliculi and retractor bulbi muscles are present.
- 7The tympanic membrane, tympanic cavity and Eustachian tubes are absent. The columella is massive with a small extra-columella.
- 8Conditions in Anniella are compared with those in other burrowing lizards, especially with Anguis fragilis, the skinks Nessia sp., and Acontias meleagris, and amphisbaenids. The main structural features associated with burrowing adaptation in lizards are described.
- 9In spite of marked burrowing specialization, the cranial anatomy of Anniella resembles that of more typical Sauria in many important respects, and lacks aberrant features such as are present in amphisbaenids.