Coelacanth: The Living Fossil

On the 22nd of December 1938, paleontological history was made when a fishing boat in the Indian Ocean near the coast of Madagascar caught a strange fish. Miss Courtenay-Latimer, the curator of the local museum, happened to be walking in the fish market, and saw the strange animal. She purchased the specimen, and took it back to her museum, where she made a sketch of the animal, and sent it to Dr. J. L. B. Smith, an expert on fishes. On seeing the sketch, Dr. Smith is believed to have said, "I would not have been more surprised if I had seen a dinosaur walking down the street!" Dr. Smith later named the species Latimeria, after the sharp-eyed curator who spotted it.

What Miss Courtenay-Latimer had discovered at that fish market was a living specimen of a group of fishes called the coelacanths, a group that, at the time, was believed to have been extinct for 65 million years!

Ichthyologists, scientists who study fish (don't get ichthyology confused with ichnology, the study of fossil footprints! - see my previous article "Dinosaur Tracking"), divide the fish into two groups: the cartilaginous fishes and the bony fishes. The cartilaginous (or chondrichthyan) fish are represented by sharks and rays, whose skeletons are made up entirely of cartilage (that firm but squishy stuff that makes up your nose and ear lobes), except for their jaws and teeth. Cartilage does not fossilize as well as bones do, so good fossils of sharks and rays are not very common. (See my article, "The Fish, Part II--The Chondryichthyans" for more information.) The bony (or osteichthyan) fish greatly outnumber the cartilaginous fishes, in both fresh water and salt water. Their skeletons are made up of bones, and many more fossils of bony fish have been discovered. (See my article "The Fish, Part III--The Osteichthyans" for more information.)

The coelacanths first appeared in the fossil record in the middle Devonian Period (about 387 million years ago), and by the Triassic Period (230 million years ago) looked almost exactly as they do today. Their early fossils from the Devonian are found in rocks from both marine (salt water) and fresh water, but by the Triassic Period they had become almost entirely marine. At this time, they could be found all over the world.

After the Cretaceous Period (65 million years ago), however, coelacanths had disappeared from the fossil record, and paleontologists believed that they had become extinct at the same time as the dinosaurs and many other animals. When the living specimen of coelacanth was caught in 1938, it grabbed the attention of the world, a living fossil had been discovered!

Go To Page: 1 2

Articles in this Topic    Discussions in this Topic