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FW: Microraptor hanqingi, new species from China.



I, for one, think that basal paravians and avialans were not highly arboreal. 
But there are at least three features that suggest that something other than 
running fast on the ground had become a new priority in the biology of basal 
paravians.

One is the very long leg wings, which Xu hypothesized were in conflict with 
fast running. This is hard to test.

Two are the longer penultimate phalanges, seen also, I believe, in Xiaotingia.

Three is the evolution of the reversed hallux. It is at least slightly reversed 
by Jeholornis and  more so, as well as longer and stronger, by Changchengornis. 
I do assume that this indicates that being good at gripping branches became 
important to their survival early in the evolution of the modern flight 
apparatus.

I guess then a testable prediction is that, if the forms in which incipient 
flight evolved were not using tree habitats at all (if strict ground up is 
correct), the 1st digit should begin its long sequence of adaptations AFTER the 
flight apparatus is assembled.

Instead I interpret the descent of the hallux to lie close to the other toes in 
Microraptor, and more so in Epidendrosaurus and Xiaotingia to possibly indicate 
the first steps of selection for branch walking. After these incipient stages 
there is a long and complex radiation of avialans with increasing rotation of 
the hallux.

The small body size, large wings, showy tails, feathered legs, long penultimate 
phalanges, and descending hallux of basal paravians could be seen as consistent 
with animals that were using tree habitats some of the time and adapting to 
those habitats. If the descending hallux and penultimate phalanges have nothing 
to do with branches, and small animals can run just fine with long wings on 
their legs, then this is not evidence for branch walking at all. But maybe then 
the burden lies with others to explain the very long and diverse series of 
morphological changes in Mt I.