Last week I spent some time writing about Dimetrodon and the various functions paleontologists ascribed to its sail (from a literal sail to a sign of coming extinction). It can be easy to forget that no two sails were exactly alike, though, and paleo-artist Michael Skrepnick (see my interview with him here) was kind enough to remind me of a rather spectacular example of this point.
Just like any other bones the osteological supports for the sail of Dimetrodon would have been subject to injury and disease. This was the case with a particular specimen of Dimetrodon gigashomogenes described by Stuart Sumida and Elizabeth Rega and restored by Skrepnick. (You can see Rega’s .ppt presentation on the specimen here.) Apparently this individual had suffered some injury earlier in life that caused some of the spines supporting the sail to break. When the bones healed they did not retain their “normal” position. Instead they twisted and bent forward.
Lots of books on paleontology feature somewhat idealized versions of extinct animals, but I love learning about cases like this. It drives home the fact that fossils are the extant remains of once-living creatures which exhibited variation and are not just funny-shaped rocks. It is one thing to look at a fossil skeleton and appreciate it in its present state. It is quite another to study it in detail to understand the life of that particular animal.