JANE PETERSON (MCZ), starting from a base of detailed knowledge of 
locomotor anatomy and function in Chamaeleo, Agama, Dipsosaurus and five 
anole species, has begun analyzing locomotor behavior and structure in 
selected anole ecomorphs from Jamaica, Hispaniola and Puerto Rico, Many 
of these she has seen and filmed in the field; a large number of species 
are being studied in a facility at Harvard's Concord Field Station. 
Five anole species representing five ecomorphs demonstrate very 
significant differences in functional morphology of the shoulder region 
and locomotor behavior, The broader comparative project now underway is 
designed to explore the relationship of locomotor behavior and morphology 
with the physical and ecological aspects of locomotor habitat. Data on 
functional morphology is based on dissections of six to ten specimens, 
osteometry and manipulation of ligament preparations. For the larger 
species functional inference will be tested by cine-radiography and electro- 
myography. Locomotor behavior is being surveyed by filming each species 
on a variety of perches simulating different locomotor habitats, 
The morphological and behavioral trends exhibited by a number of 
arboreal lizards (compared to their terrestrial relatives) suggest that 
arboreality selects for increased range of movement (mobility) and for a 
greater variety of positions in which the limb can grasp the perch and 
propel the animal. A relatively stereotyped locomotor cycle ig inappropri- 
ate where the substrate is varied in orientation and diameter and is 
discontinuous so that the animal must change perches frequently. 
The limb is composed of a series of elements the most distal of which 
transfers force between the limb and substrate and must meet requirements 
for stable contact with a given substrate, Arboreal adaptation in distal 
segments, whether by adhesive, suction or prehensile devices, is reasonably 
well documented even if the mechanisms are poorly understood, Adaptation of 
the most proximal segments (girdle and humerus or femur) has the greatest 
bearing on the total arc of limb movement; selection for a greater range of 
movement should be evidenced in these regions. 
Lizards seemingly demonstrate a variety of biomechanical solutions to 
the problem of increasing the range of movement. A greater arc of movement 
at a given joint is generally bought by decreased stability in the articu- 
lation. Tissues with relatively poor stress bearing characteristics, e.g. 
groups of muscles, are substituted for elements which are adapted to resist 
stress and confine joint excursion, e.g. ligaments, cartilaginous menisci 
and bony cups or prominences. This substitution reduces overall joint 
stability and by implication limits the amount or kinds of forces that can 
be transmitted through the joint efficiently or without mechanical failure, 
Given 1) selective pressure to increase mobility with minimum cost in 
stability, 2) three linkage areas available for modification, and 3) a 
variety of behavioral and morphological "starting points" in different 
phyletic lines, biomechanical adaptations are likely to vary. Increased 
