They should take a look at Brand's work on tetrapod trackways in the
Coconino Sandstone. In his experimental work, the underwater
trackways were consistently better preserved than those in any other
environment he tested. However this would be underwater, not shallow
water where the substrate would be bearing unbuoyed weight. Brand's
study of the trackways (originally described as amphibians until McKee
made the sand subaerial, then they all mysteriously became reptilian)
led him to conclude McKee's classic study on the sand was wrong and
that the sand must have been deposited subaqueously. I will post the
relevant references tomorrow.
(I apologize if this was sent twice; I didn't receive a copy.)
Art