Awesome indeed! I appreciate your sharing that! The rapidity of the sequence of "steps" themselves and the intervals between each sequence... remind me very much of the sound of.... the sequence/intervals of a full-galloping horse - the absence of the 'percussive' timbre associated with hooves, claws, nails or other hard objects that would be striking the surface of that bridge, IMO, eliminates any familiar quaduped that has such....(which you point out). I would think the closest I could imagine would be a creature with pads like a cat or with tissue/flesh of knuckles or 'fingertips' and foot pads or 'toes' like we humans have - (not unreasonable to imagine that 'hair' would also be a factor in softening the sound some). A large 'cat' of some sort? I think not, unless, maybe, it was a cheetah...because, if I'm not mistaken,...most, if not all, cats don't gallop "like a horse"...with the exception, of maybe a cheetah at times. Gorillas and Chimpanzees can 'lumber' along at a sort of gallop,...but I don't believe they can do so for extended periods and I doubt that it would be at the same speed as what we hear on this recording.
Without any definite idea of distance between the microphone and the area of activity,...(especially when/where the 'breathing' is first heard)...it's hard to imagine just how large the runner is/was....but I'm thinking that because we hear its rapid breathing (while galloping) a few moments before it apparently jumps/lands on the bridge in stride and records the simultaneous continuous breathing pattern and the 'softened' or almost 'muffled' sound of the galloping, as it passes by ; I have to imagine that the runner had to be large/powerful enough to project the sound of its rapid breaths prior to its approach to the bridge - (without any prior, apparent sound of galloping, I might add)...AND the pattern of rapid breaths can be heard for several seconds after it apparently leaves the bridge...almost seems as though it may have paused at some point after passing the bridge area...because it seems like the sound of breathing is faintly detected....or I'm imagining things...tell me if you think I am. The deeper tones of its 'breathes' causes me to think of a large chest cavity - similar to that of a bear or horse. I have a fair number of early to recent newspaper accounts from N. American regions that describe strange, hairy, wild creatures that "resemble a man" or "resemble a gorilla" (after the mid to late 1800's)...that evade pursuit by dropping to "all fours" to outrun dogs and/or humans on horseback.....(interestingly,...quite a few accounts of these same 'creatures' being predacious - against dogs and horses, as well as any other domestic animals - easy pickings)
Thanks, again!!