Infected tails do it better

Sometimes you work on a fossil and just think "oooh, that had to hurt". This tail from a pretty large Clidastes from the upper Niobrara chalk is fairly boring when viewed from afar. Up close though something just doesn't look right.

Yep, pretty boring

Of the 45 bones, 23 are pathological, with 17 of them fused at the centrum in 5 separate masses. All of these bones lack transverse processes, so they come from the lower lobe of Clidastes' bifurcated tail fin: a bit of dangling flesh that might make for a tasty morsel for a predator.

I think this mass used to be 8 separate vertebrae, based on the number of chevrons

The bones, though mostly healed, show bone growth consistent with a long infection. As the tail was the primary means of locomotion/propulsion for mosasaurs, this injury must have been very painful for a very long time for this mosasaur.

3 verts become one

Fused verts, and centra with vertical scars