I checked on the Ashfall web site. They are still listing the one-toed horse as Pliohippus pernix. I thought it might be Dinohippus, but I guess not.
Below I’m pasting your email, so as to start a topic thread within this forum:
From: David Butler
Sent: Sunday, November 8, 2015 8:16 AM
To: MacFadden,Bruce J
Perhaps you can help me. I’m an amateur interested in equine evolution, and in researching this, I ran across a 1981 National Geographic article about the Nebraska Ashfall site (attached starting on Pg.66 of the issue) in which there’s a photo of a Pliohippus fossil and an unnamed hoofed fossil. I have attached that photo itself to this text also.
Some sources suggest that this unnamed photo might be a Dinohippus, but I’m trying to nail down the real answer. There’s some hint that the top photo is simply another (later) version of Pliohippus, but there’s just nothing for me to go on. I cannot find any records that Dinohippus was found at the Ashfall site.
At any rate, if you can spare any time and perhaps at least point me to where I might get an answer to this, I’d appreciate it.
Thanks Bruce. Here is an email from the superintendent of Ashfall:
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.