Coelacanth in the museum in Oxford

Fossil coelacanth in the Teyler Museum at Haarlem (NL)

It was the sensation of the century when a lobed-finned fish (a fish with 'legs'), whose group was thought to have been extinct for 70 millions of years, was caught in 1938 in South Africa. It was a so-called Coelacanth (see-luh-kanth), the last living member of a group of fishes with bones in the fins instead of rays. Fishes from this group are probably the ancestors of the first quadrupeds (amphibians). The coelacanth is an example of a 'living fossil'. That is a name for a plant or animal that has hardly changed in the course of many millions of years. Other living fossils are the Ginkgo and the Bald-cypress (Taxodium).   Plants and animals will not change when the circumstances are very stable. Evolution is always a reaction to a changing environment. When everything is all right, if there is enough food and space, if there are no dangerous predators, then a species will stay as it is. Know more? Living fossil Swimming coelacanth

This is a wonderful fossil coelacanth in the Teyler Museum in Haarlem (NL). The length of the animal is about 1.5 m and the age is about 140 million years. The similarity with the recent coelacanth from the picture on the left is striking. The changes in species, which are reviewed till now, are relatively small. These small changes are called micro-evolution. But there are also large, radical changes. Think of the occurrence of land animals with four legs, the occurrence of wings, eyes and consciousness. This is called macro-evolution. Macro-evolution is more difficult to understand than micro-evolution. Examples of the last type are observable, like in the colour of the Peppered Moth around Manchester, in the beaks of the finches on the Galapagos and in many other cases which have been described. Hugo de Vries thought that saltations (sudden and radical mutations in the chromosomes) were responsible for the occurrence of new life forms. Indeed there are some examples of saltations but in by far the most occasions macro-evolution is the sum of an ongoing micro-evolution. Know more? What is macroevolution?

Evolution 29

Back

Stop

Next