Re: New Article in Experimental Zoology

[Dinogeorge@aol.com]

In a message dated 8/24/02 1:27:08 PM Pacific Daylight Time, 
a_ekaterina@yahoo.com writes:

<< Better preserved fossils of forms like Scleromochlus
 would definitely help in clarifying if you hypothesis
 stands a chance. Still we have quite a few primitive
 dinosaurs and dinosauromorphs:
 Marasuchus, Lagerpeton, Lagosuchus, Eoraptor,
 Aliwalia, Staurikosaurids, Pisanosaurus. In not one of
 them do we see any special arboreal adaptations.Your
 hypothesis would demand that we see at least a few
 signs of them. >>

In my hypothesis, these are cursorial forms descended from small, scansorial 
ancestors in which arboreal features were only weakly developed if at all. 
The more strongly arboreal forms were ancestral just to theropods at and 
above the tetanuran grade. One weakly arboreal feature, for example, would be 
marked forelimb-hindlimb disparity (including as an extreme case, 
bipedality), which occurs in all dinosaurs from sauropods on up and which, 
BCF asserts, arose from the functional forelimb-hindlimb differences useful 
in a scansorial lifestyle. The reason I call them "weakly" arboreal is that 
they are the kinds of features that would show up in the descendants of 
arboreal animals but might also show up as a result of other kinds of 
lifestyles: They support BCF essentially because they do not falsify it.

BCF does not multiply hypotheses unnecessarily; it actually explains the 
mosaic appearance of numerous features in dinosaurs via a single hypothesis, 
namely, that ancestral dinosaurs were small, scansorial to arboreal animals. 
A whole lot of features that have an assortment of ad hoc disconnnected 
explanations in the conventional theory can be seen in BCF as resulting from 
arboreality, everything from the huge claws and pneumaticized skeletons of 
theropods to bipedality. See my articles in Dino Press #4-6 for a list.

Incidentally, current candidates for "ancestral" dinosaurs, such as 
Herrerasaurus, lagosuchians, and so forth, are in my opinion already pretty 
far along the theropod branch of the dinosaur family tree. The common 
ancestors of sauropods and other dinosaurs, for example, remain hidden in the 
Middle Triassic or earlier. I cannot derive sauropods and prosauropods very 
easily from theropods such as herrerasaurians and lagosuchians: the foot 
anatomy presents a major problem.