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.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjx8UVSDmWYueK6q40AMVX3twUj_dgGdWyhReqHsuNxy6Y0oHe8aSaIkFWYKPWUaVBklpL5MyDfC-ZycqrkWxMDMfpV9DEU8-0ZYG5sVsVFe30F6ydarBXis2JC8dWlDyp76Jtw6dnqI8gF/s320/007.JPG) |
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.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBObjpg6LaK7loegjmSFy-cFShP3kxJfGYBC2EEiEwpacxBLpTkRsEH8wzvXJCwEIYqUmOidz60Ah3MVhZ-ILA3lmKreFyCQwZzwsobGU-kzBIa6P_-DG-sMKd7VMr4eYh0GTD1J5Z5-T5/s320/010.JPG) |
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.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIe4vTIjvKEa-Pxbjj5iY6BcjIoa3C8wOh8dMSmnGvO6YaNpFjnefiBjVYdUaAtXQLQpcjVEcMTbFBa3mqRglSknBmZon0cTkFwlSHsHVi815SNKxBz7foo96SuMPYrIMUw5S1IbGOBsTg/s320/012.JPG) |
3 verts become one |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJPU7oForKwRKvgd5qRo8DhN5BxZ2zyGOOljBkRvegNdm895nLYjssDbxOQcD8s02ADAPsro4GXzjZ981vZvdVeYbmGVUBnD7HL9CyOd9xjVly5eO0iymQ0jvzKTUr-aR8imARs9LuTvQu/s320/011.JPG) |
Fused verts, and centra with vertical scars |
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