Ritualistic Behavior Lizards 
261 
tion toward their adversary, usually facing 
in the opposite direction (Fig. 9). I call this 
the faceoff (a term borrowed from ice 
hockey). The aggressive, challenging male 
postures by compressing his trunk laterally 
(lateral compression) and extending his dew- 
lap. In many iguanids (i.e., most sceloporine 
genera — Sceloporus, Uma, Holbrookia, Uro- 
saurus) this postural change enhances the 
appearance of usually sexually dimorphic 
colors or patterns present ventrolaterally and 
on the dewlap of the male. The total effect is 
to increase the laterally viewed size, color, 
and pattern of the male. In some species 
(Anolis) a roach or crest may also be erected 
along the mid-dorsal line, enhancing the lat- 
erally viewed size. The crest may also show 
contrasting color {Amblyrhynchus cristatus 
from Hood Island in the Galapagos Islands). 
Size increases may also be effected by inflat- 
ing the trunk region (Conolophits, some 
Tropidurus) or by arching the back {Cro- 
taphytus) (Fig. 10). The manner or degree 
of posturing may in some way relate to the 
ecological niche or the display site used by a 
species. 
The type of movements and the parts 
which are moved may at first seem to be the 
same, but in light of what I shall describe 
below, considering them in more detail may 
be very useful. 
Some movements may involve no more 
than the head and neck while others bring 
the whole or the entire body into play, in- 
cluding the tail. The most common type of 
movement in small- to medium-sized iguanids 
Figure 9. An encounter between two challenging 
male Sceloporiis siniferus (Iguanidae) from Mex- 
ico. Posturing, they present laterally toward one 
another (face-off) while intermittently display- 
ing and charging, biting or tail-lashing one 
another. 
and agamids is the pushup effected by leg 
extension and flexion (Fig. 11). This type 
of movement is seen in the many species of 
the iguanid genera Sceloporus and Tropi- 
durus. In the genus Sceloporus there are 
forms which perform the pushup display 
primarily with the front legs only — two- 
legged pushups e.g., Sceloporus undulatus 
and S. occidentalis) , whereas others engage 
in four-legged pushups (e.g., Sceloporus 
jalapae, Sceloporus merriami). Purdue and 
Carpenter (1972) showed that there is a 
general relationship between size and leg 
Figure 10. The male Collared Lizard (Crotaphytus 
collaris — Iguanidae) from Oklahoma arches his 
back and bounces on his front feet while posturing 
during his aggressive display. 
Figure 11. A diagramatic representation indicat- 
ing the change in amplitude during the front-leg 
pushup of a displaying male Netted Dragon 
(Amphibolums reticulatiLs — Agamidae) from 
Australia. 
