I was riding the California Zephyr eastbound in May of 2018. We were running late and approaching Winnemucca, NV, in deep twilight. I was in a lower level sleeper and had my scanner on and could hear the crew. Suddenly there was a clattering noise of something bouncing around underneath the train and a moment later the emergency brakes set. The engineer immediately queried the conductor "Who set the emergency brakes?"
The long and the short of it was that we hit something and in the process of it bouncing around underneath the train it took out half a dozen air hoses, which is what set the brakes.
It took about 40 minutes and some trial and error to locate all the damaged air connections and replace the hoses. The conductor said he just about ran out of spares and, at one point, commented to the engineer "I hope you like Bar-B-Q because we have an awful lot of hamburger back here." The engineer asked what it was and the conductor said he honestly couldn't say.
Since the engineer never saw it in front of him (the locomotive didn't hit it), whatever it was ran under the train in the dark after the brightly lit locomotive passed.
When I got off the train in Chicago I looked at the side of the cars and realized only something rather small could actually run under the train. Anything large wouldn't clear and would have bounced off. There aren't too many possibilities; I think a coyote would be too smart to do something like this. Since we were in open range, my best guess is that the train separated a calf from its mother. After having been blinded by the locomotive lights, it made a good effort to rejoin its mother once the lights and loud noise passed. Unfortunately, the rest of the train was still there passing by in the dark and it just ran underneath.
Or maybe it was Bigfoot...
Rob