Thanks Bruce. Here is an email from the superintendent of Ashfall:
David,
Both photos are feet of Pliohippus skeletons from the Ashfall site – just different individuals. There is variation in the three-toedness of the individuals within Pliohippus pernix indicating a transition from a three-toed stance to a single-toed stance at this point in time.
Thank you for your interest in the Ashfall Fossil Site.
Rick Otto
Superintendent
Ashfall Fossil Beds SHP