Two Mosasaur caudal vertebrae

Two Mosasaur caudal vertebrae

Campanian

Texas

These two caudal vertebrae, found in the same stream, demonstrate some of the size variation seen in mosasaurs. Notice the two pits of the bottom vert - those are for the haemal arches, and with no other bony attachments except for the base of the neural spine (on the other side), we can infer that this vert came from close to the end of the tail, probably putting its owner in the 30+ foot range. Alternatively, though very worn, it seems that the smaller vert came from a position closer to the pelvis (though still caudal). Likely from a juvenile of what had to already have been a different, very small species.