Flipside of a dinosaur mystery: 'Bloat-and-float' explains belly-up ankylosaur fossils. Why are fossil remains of ankylosaurs -- armored 'tanks of the Cretaceaous' -- usually found belly-up? A paleontologist proposes the explanation is 'bloat-and-float', where the dead dinos would float downstream, bloat, flip upside down, and be fossilized that way. Source 9x.