Peterson - p. 5 
The glenoid is turned far laterally but muscular adaptation is again equivocal. 
4, Trunk-small trunk-crown behavior (A. stratulus, A, distichus, A, 
opalinus): This ecomorph uses a very fast walk or trotting “gait a 
consistently. Moermond reports that distichus rarely moves slowly and this 
is certainly true in the film sequences, The combination of cycles is quite 
distinctive. There are five to six cycles followed by a dead stop and then 
repeat, They appear to skitter. Moermond reports that distichus at least 
leaps for about a third of its moves, but they appear remarkably unacrobatic 
compared to cybotes or the grass anoles. The behavioral repertoire in terms 
of gaits, variation in limb position, etc. is the narrowest among the anoles 
observed, 
Morpholo (A. distichus): The morphology of distichus strongly 
suggests secondary adaptation to reduce both girdle and glenohumeral mobility 
in favor of joint stability and muscle leverage, There is probably very 
little girdle movement because 1) a ligament connection is shifted close to 
the main articulation between the body wall and girdle, 2) the ventral 
clavicular articulation lies just anterior and in the plane the girdle would 
have to occupy if it shifted anteriorly, and 3) the girdle muscles poorly 
discriminate the clavicular articulations; they may act on both sides of the 
joint with consequent ineffective action. The glenohumeral articulation 
faces entirely laterally but is more closed and cuplike with very robust 
ligaments. The humeral head is reflected at an angle to the shaft (like the 
human femur), The major protracting muscle originates so that it can effect 
little more than 90° of protraction (abduction). Th mode of origin is also 
seen in Agama but apparently in no other lizards. 
5, Trunk-ground behavior (A. cristatellus, A. cybotes, A. lineatopus); 
Like the trunk ecomorph these species have a fast or running walk gait. But, 
unlike the trunk forms they are quite spectacular leapers and more frequently 
use acrobatic postures and maneuvers, The latter permits them to use rela- 
tively small diameter perches (1/2-1/4 inch). The plane of forelimb action 
is usually erect or semi-erect, This is partially due to the proportional 
disparity between the fore and hind limbs, 
Morphology (A. cybotes): The girdle is set at a relatively high angle 
to the sagittal plane (44%). In spite of this, films indicate that at least 
35° of girdle rotation is used during fast baling. This rotation occurs 
entirely during the cycle phases when the limb is anterior to the transverse 
plane of the shoulder. The clavicular locking mechanism is most well 
developed in cybotes and stops girdle displacement as the limb ts extended, 
The girdle and glenohumeral musculature is very highly specialized. The 
bellies are generally placed to provide for maximum limb and girdle excursion 
frequently at the expense of leverage, but there are architectural adapt- 
ations of the bellies which permit many more muscle fibers to be packed into 
the belly. Conflicting selection for mobility and stability is nowhere more 
evident than in cybotes. 
