Wow, link for that?

I can't vouch for dolphin sonar resolving fine anatomical detail /in vivo/, but dolphins can recognize visually obscured objects using the ability [0].

[0] http://www.dolphin-institute.org/our_research/dolphin_resear...

There's a link with some stuff here

http://www.livescience.com/38087-can-dolphins-detect-pregnan...