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What I was proposing
was that perhaps an early synapsid type, with development of endothermy already
underway, might have become arboreal, and, being of small size, would have
needed the endothermic condition as well as an insulative covering (fuzzy
scales) to survive a colder micro-enviorn in the treetops. As to why there exist
diapsids today that are not endotherms (ie.squamosa), I can only figure
them to be secondarily ectothermic. I see evidence for this in the partial
separation of the ventricle. Why any separation at all in a cold blooded type
unless the remnants of a once four chambered heart? I think that early
diapsid development took place in the trees, where they were isolated from
competing synapsids, and where they eventually developed into birds, (with dino
descendants along the way).
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