Comparative Functional Analysis of the Anatomy of the appendicular skeleton in two reptilian species

Abstract

Aim of the work: the present study aimed to illustrate the osteological characters of the appendicular skeleton of two Egyptian lizard species, Acanthodactylus boskianus and Ptyodactylus guttatus and clarify the relationship between characteristics of the appendicular skeleton and mode of their locomotion of the two species. A. boskianus is diurnal insectivorous lizard forage in open area and it is a generalized ground-dwelling species and P. guttatus is a diurno-nocturnal omnivorous gecko which is a highly specialized climbing on vertical substrates. Material and methods: in the present study we used Alizarin red and Alcian blue as double skeletal staining to investigate the the bony and cartilaginous pattern of limbs and girdles of A. boskianus and P. guttatus. Results: in P. guttatus, the pectoral girdle was characterized by the presence of the interclavicles was dagger in shape and partially fused with clavicles, while it was cruciform and completely fused with the clavicles in A. boskianus. In P. guttatus, the epicoraoid was well developed, broad bony plates and fused with the interclavicles, while in A. boskianus it was narrow cartilaginous, plates and overlap in the mid-line. Moreover, in P. gutattus two fenestrae were appeared within coracoid and scapula with un-fenestrated cartilaginous sternum, while one fenestra appeared in both coracoid and sternum of A. boskianus. On other hand, the pelvic girdle of P. guttatus had complete fusions between the pubis, ischium and ilium, while in A. boskianus the pubis articulated poster-omedially with the ischium. In both P. gutattus and A. boskianus, the forelimbs posture was in horizontal plane, while the hind limbs were in vertical plane. In P. gutattus both the fore and hind limbs were relatively equal in length, while the fore limb in A. boskianus was greatly shorter than the hind limb. Conclusion: the P. gutattus is considered as a one of climbers species which have stout appendicular skeleton to support the climbing process on the vertical surface with relatively short limbs, while A. Boskianus is ground-dwellers and also good climbers and use their claws to walk and climbing on rocky areas and these abilities of locomotion depend on the flexibility of skeletal elements of its appendicular skeleton.