This paper isn’t quite out yet, but it’s showing in google scholar, so I guess it’s worth putting up on my [non-promoted] blog.
Matthew Bennett, at the University of Bournemouth led on this one, in which we describe possible hippo swim tracks from the Koobi Fora footprint site in Kenya (site of ancient hominid tracks).
Paper is available here:
http://www.sciencedirect.com/science/article/pii/S0031018214002193 though a) it’s stlll in Press, and b) it’s behind a paywall if you don’t have access to palaeo3. When it’s assigned an issue number, and the final PDF is available, you’re welcome to drop me an email for it, or find it on my academia.edu page or ResearchGate. (Check the publications tab up top for links).