Description and Labels

Paleontology has a great habit of pairing quality photographs with highly informative labels of line drawings. This happens, of course, in the best papers and less often in papers that are not as high in quality. In fact, it is the highly detailed photographs in conjunction with highly detailed text description that often make the best papers when it comes to discussion of anatomy and characteristics. We are fortunate with descriptions of Haikouichthys because many of them include detailed description, photos, and labels on line drawings. Sometimes the fossil can be adequately labelled on its own, though. Today we have an adapted image of a number of views of fossils that show different aspects of Haikouichthys. In that image we can see different views of the eyes, fins, and rostral end of the animal. The most interesting aspects of the fossil are the shape of the dorsal fin and the tail fin. Also of interest are the clearly visible myomeres, which are undifferentiated muscle bundles that are, effectively, the most primitive form of musculature an animal can possess. We do see myomeres in extant agnathan cyclostomes such as hagfish and lampreys. This level of organization is, strangely it seems, still evident therefore. That allows us to have similar, but not identical, locomotive systems in animals that are still living in aquatic environments. That type of diversity is actually quite fantastic.