"Howdy Fabio,
When I say that the animal was running, I mean that the animal was moving at twice normal walking speed. On the same block, we observe hind tracks that fall heel to toe. This should help you to triangulate where to put the hind feet. If our downscaling of adult apatosaurs does in fact provide us with a good model for what the infants looked like, these tracks suggest that the animal had both feet barely off the ground at the same time, or, just about had both feet in the air at the same time.
The running apatosaur should not be hard. Remember that these animals concentrated mass and power at the hips, hind limbs, and tail base. In many ways, these dinosaurs are functionally bipedal: the forelimb is utilized to take the strain of that elongated neck off the back and hindlimbs.
I would suggest two potential poses for the forelimbs - folded and held close to the body and hovering just above the ground.
I also find two possible positions for the neck - curled back toward the hips to move the center of gravity toward the hips, or sticking straight out. Compared to the rest of the body, there is not much mass to the neck.
No tail drag mark exists with these running tracks, so, the tail must be depicted in the air.
If the animal was running at top speed, perhaps the neck would curl back and the forelimbs would fold under the body. If the baby dinosaur was starting or stopping the run, the neck would be horizontal and arms, perhaps, not quite as tucked in toward the body".
Sincerely,
Matt
Matthew T. Mossbrucker
Director and Chief Curator
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Morrison Natural History Museum
