Pick from the Past
Natural History, May 1939

A Fossil Comes to Life

One of the most important zoological discoveries of the present century
gives us a glimpse at the closest living relative of our fish-like ancestors.

N the twenty-second of last December a trawler dredging in shallow waters off the tip of South Africa brought up in its net a large threshing, biting fish which, because of its size and its unusual appearance, at once attracted the animated and rather cautious attention of the fishing crew. Looking at their curious find with speculative wonder, the fishermen hardly realized their inadvertent discovery of this fish was no less important than if some heat-plagued explorer, fighting his way through an unknown tropical jungle, had suddenly come face to face with a live dinosaur.

Ceolacanth

The modern coelacanth (Latimeria chalumnae), the closest living relative of our fish-like ancestors

This fish was big—over five feet in length, with a weight of 127 pounds; and it was vicious, and, above all, it was quite unlike anything the fishermen had ever seen before. So they took it into East London when they returned to port and presented it as a rather noisome gift to the local Museum. Of course, by the time the fish reached the Museum in East London it was very much defunct, so that the curator, Miss Courtenay-Latimer, had a weighty problem on her hands as to how to preserve such a large zoological specimen with limited facilities.

She sent a communication post-haste to Dr. J. L. B. Smith, a leading South African authority on fishes, asking him to come to see the new animal as soon as possible. But before Doctor Smith could reach East London, the fish was becoming decidedly odoriferous, so Miss Latimer had it skinned, had the skin mounted, saved the skull and disposed of the body.

When Doctor Smith saw the skin, he recognized at once that one of the greatest zoölogical discoveries of the present century lay before him. For what he saw was a living member of a great group of fishes which hitherto had been thought to have become extinct some 60 million years ago. Not only that, this fish belonged to a special group or subclass of the very ancient fishes which included the direct ancestors of all the amphibians, reptiles, birds and mammals. In other words, here was the great-grandchild, to the nth generation, of the brother of our own forebears.

To many people, fishes are fishes and pretty much alike.

To many people, fishes are fishes and pretty much alike. So that the finding of a specimen so unusual as this new fish from South Africa will not catch the public imagination as much as would a more spectacular and perhaps a more familiar discovery—even of much lesser importance. Yet to those acquainted with fishes, this new find is one of the events of a lifetime—and justly so. For it is a living coelacanth fish (pronounced seé-la-kanth), the likes of which were supposed to have passed from an earthly existence at the time the dinosaurs became extinct.

What are the coelacanth fishes? These are fishes quite distinct from the "ordinary" bony fishes and sharks with which most of us are acquainted. They belong to a separate group or subclass known as the Crossopterygia, or lobe-finned fish, which passed the heyday of their evolutionary history many millions of years ago. The crossopts are distinguished, in short, by a deep body and skull, the skull having a steep "humped" forehead, by two dorsal fins (in contrast with the single dorsal fin of typical fishes), by lobed paired fins, in which the bones show the same positions and relationships as do the bones in the legs and feet of land-living vertebrates, including man himself, and are quite different in structure from the fins of ordinary fish. The coelacanths are also distinguished by a tail having the long axis or backbone running to its tip, by a reduced gill cover or operculum, and by large, heavy scales, the surfaces of which are rugose and covered with enamel. In the extinct coelacanths there was a calcified or partially ossified air-bladder or lung.

A report gained wide acceptance that the fish oozed oil until 20 gallons had escaped, a quantity which would weigh more than the fish itself.

It is unfortunate that the body of this new fish could not be saved, because certain problems as to it internal anatomy, such as the presence of the large lung-like air-bladder, must remain unknown until another specimen can be procured. Meanwhile a false impression should be corrected regarding its capacity for storing oil. A report gained wide acceptance that the fish oozed oil until 20 gallons had escaped, a quantity which would weigh more than the fish itself. The fish exuded 20 ounces of oil, not 20 gallons.

Until this discovery in South Africa upset all our man-made definitions, the span of the coelacanths on earth was thought to have ended with the Mesozoic Era, the time during which dinosaurs ruled the land. Yet even at that far distant period in earth history they were already the long-persistent survivors of much earlier ancestors, for their crossopterygian relatives lived far back in Devonian times, some 300 million years ago—long before the dinosaurs began, before there were any such things as land-living vertebrates. And it was these Devonian crossopterygians with their lobed fins, so prophetic of the limbs of later vertebrates, that were the direct ancestors not only of their little-changed descendants, the coelacanths, but also of the first amphibians, which were the first vertebrates to venture out of the water for a new life on the land. They in turn were the ancestors of the reptiles, birds and finally the mammals, including man. So it is that by looking at this living coelacanth we can see approximately what the ancient crossopterygians of 300 million years ago might have looked like, and we are thus enabled by the discovery of this living "flash-back" to get some idea as to how our own fish ancestors appeared in flesh and blood.

Ceolacanth Fossil

If the ancient fossil coelacanth (Undina) could come to life, the living coelacanth might well swim toward it with all the signs of recognition it would exhibit for its own species. It cannot be said, of course, that the two could interbreed, but the living coelacanth possesses in its germ plasm, hereditary factors supposed have long since vanished from the earth, controlling among many other things the flipper-like lobed fin which was the predecessor of the mammalian hand and foot.

Until the living coelacanth was discovered, all the coelacanth fish and all the ancient crossopterygians (in which the coelacanth group is included) were known only from fossil forms; hence any restorations of these fishes as they might have appeared in life were based on remains of their bodies preserved in the rocks for 60 million years or more. Now that a "living fossil" has swum into our ken, so to speak, it is possible to see how nearly right were the scientific studies on the fossil specimens. Surprisingly enough, we see that the living fish is just what we thought it should be—in other words, the restorations based on fossils are now corroborated. Two of the reconstructed fossil coelacanths in particular, forms know as Macropoma and Undina, are closely approximated by the living fish. In the accompanying illustrations you can note the truly remarkable similarity between Macropoma as restored and the modern fish as it appears without benefit of human fallibilities and opinions. "Shall these bones speak?" Perhaps not, but the men who studied the bones spoke and drew pictures too, and now that the fossil has come to life it shows that the words and pictures were essentially correct.

To get back to the main story of the discovery of this fish—when Doctor Smith saw what a magnificent thing he had he promptly sent word to London, where, of course, there were not a few lifted eyebrows, for the dyed-in-the-wool scientist is sometimes a skeptical individual, especially when confronted with anything so astonishing as a resurrected crossopterygian fish. But Doctor Smith wrote a brief description wherein he gave a name to the new form, Latimeria chalumnae (in honor of Miss Latimer, who first recognized that this was an unusual specimen) and sent this to London with pictures of the fish. Then things began to happen.


There were not a few lifted eyebrows, for the dyed-in-the-wool scientist is sometimes a skeptical individual, especially when confronted with anything so astonishing as a resurrected crossopterygian fish.

There was a meeting of the Linnaean Society at Burlington House, at which some of the foremost experts on recent and fossil fishes were present. An examination of the pictures and of the description convinced these men—Sir Arthur Smith Woodward, formerly the head of the Department of Geology at the British Museum and one of the great authorities on fossil fishes, Professor D.M.S. Watson of University College, London, an outstanding worker on primitive land vertebrates and their immediate ancestors, Dr. E.I. White, in charge of fossil fishes at the British Museum, and Mr. J.R. Norman, in charge of recent fishes at the same institution. Their blessing was given to the discovery, the description was published, and soon it became a zoölogical sensation throughout the world, to be discussed and studied in classrooms and laboratories from New York to New Zealand.

Now there comes this question: Why wasn't Latimeria, the new coelacanth crossopterygian, discovered long before this? Several answers are possible. In the first place, it is quite possible that this fish has been caught before by fishing trawlers but was thrown back by incurious or indifferent men as "another catfish." That it may have come to the attention
Fin Illustration

A: (FISH) A lobe fin of approximately 300 million years ago (essentially Eusthenopteron)

B: (INTERMEDIATE) hypothetical

C: (AMPHIBIAN) A primitive foot of some 200 million years ago. (Erypos)
of men before is made probable by the statement of one resident of East London, who claims he saw one of these animals cast up on the beach some five years ago, but before he could get help to pull it in, it was washed away by the tide. Perhaps this is a deep-sea form that only on rare occasions wanders into shallow water where it will fall prey to the sweeping net of the trawler. Or what is more probable, it may be that Latimeria lives among the rocks and crannies of the ocean floor, so that even in shallow water it is ordinarily below the range of the net.

Whatever may be the explanation, it is a safe guess that there is going to be some intensive fishing and some excited fishermen off the South African coast during the next few years.

The fin of the living coelacanth is believed to resemble the ancient type shown in the first drawing above, possessed in essential characteristics by the ancient fish Eusthenopteron of about 300 million years ago. This series of three drawings, based on the data and conclusions of several well-known scientists, shows the probable evolution of the amphibian foot, on the direct evolutionary line to all the great animals that walk the earth today. But long after the passably good foot C was evolved 200 million years ago, the coelacanths clung to their backward form, so that today the living fish has something of the out-moded appearance of one of the first horseless carriages on a four-lane highway.

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