Ribs, fins and flanges lined the hips of the beast- it was just about possible to clamber along.
The enormous shark had an exterior set of ribs, 5 fins and flanges lining its hips. 
mnli hypothesis: The enormous shark had an exterior set of ribs, 5 fins and flanges lining its hips.  premise: Ribs, fins and flanges lined the hips of the beast- it was just about possible to clamber along.