This picture kindly provided by the artist, Dan Varner, depicts Brachauchenius lucasi, a giant pliosaur about to snack on a large squid. This animal is known from fragmentary remains from Edgemont in South Dakota and dates to the late Cretaceous period. More details on this animal are available here:
http://www.oceansofkansas.com/Brachauch.html
Thanks Dan!