This isn't a Maya animation; it's a .gr2 animation format that was exported from Maya.
You can view it in the Granny Viewer program.
You can export this type of animation from Maya 6.0 using a plugin for exporting .gr2 files.
However, no one currently knows how to open this type of animation for editing. (A long time ago, I did this using plugins for 3ds Max, but I've since lost them. However, in theory, it is possible).
Added 2 minutes later
Perhaps you can find working plugins for opening .GR2 animations in the files that the source collected.
https://yadi.sk/d/cGm__9Au3YBcz8
There are many plugins for different versions of Max and Maya, but I don't have time to check if they work yet.