Our living fossils dying

On the half-submerged log of a fallen fir-tree sat a huge dragonfly that had just freed itself from its old skin, after crawling out of the swamp as a nymph. It was drying its quivering new wings that had an enormous span of almost 30cm.
Issue date: 29 August 2008

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On the half-submerged log of a fallen fir-tree sat a huge dragonfly that had just freed itself from its old skin, after crawling out of the swamp as a nymph. It was drying its quivering new wings that had an enormous span of almost 30cm. Suddenly a lithe, birdlike dinosaur with a lizard-like tail, short front and long, slender hind legs appeared from nowhere, and pounced on it.

That was about 200 million years ago and long before the Jurassic Park, when dinosaurs like Tyrannosaurus rex took control. Although increasing numbers of dinosaurs had started to compete with them, huge reptiles still ruled the earth. It was a dangerous time of huge swamps and lakes inhabited by terrifying reptilian creatures of death everywhere. Every day, elephant-sized dinosaurs came down to drink and were seized by enormous crocodiles, up to 15m long, and dragged into the watery depths. There they were torn apart, while swarms of smaller crocodile species joined in.

These giant crocodiles were the kings of the swamp and could swallow buffalo whole. he hilly landscape was clad in humid forests of fir-trees and giant ferns, and myriad primitive tropical plants surrounded the steaming swamps. The lush vegetation flourished in fertile volcanic ash-rich soil, while flooding downpours were the order of the day. These frequently caused enormous landslides that could bury entire forests, adding to the existing shallow, fossilised coal beds underlying the swamps. hose same coal beds are still here today but now, millions of years later, the landscape looks totally different.

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The land has risen and the dense, wet tropical forests have been replaced by undulating grassland on what is now the eastern highveld of South Africa. huge dinosaurs and other animals are all gone, the few fossils are all that remain of them. They have been replaced by birds and mammals that didn’t even exist back then. A lthough the great heyday of the reptile is long gone, the descendents of those crocodiles are miraculously still alive today. Due to severe winters they don’t exist on the highveld anymore.

However, in the lower reaches of the rivers that arise there, which combine to form the Olifants River system, they were until recently quite common. They are now true living fossils, much older than the coelacanth. didn’t only survive the catastrophe that wiped out the dinosaurs, but also two ice ages. To have done that they must have had something special. It’s their unique design and remarkable efficiency. With the most powerful bite of all animals, they are superbly efficient and immensely strong hunters with bodies built like tanks.

 Their whole dorsal side – and in some species even their belly – is heavily protected by a body-armour of thick interlocking bony shields, which can articulate enough to ensure the body retains an almost snake-like flexibility. They can live both in and out of water and besides excellent senses of smell and hearing they have acute vision, both above and below the water-line. Apart from intelligence they display the most dedicated parental care and the most advanced brain of all reptiles.

The crocodile is the only reptile with a true four-chambered heart – like a mammal – a powerful natural antibiotic in its blood, a highly efficient circulatory system and a heartbeat that can slow down, from 40 to only three beats per minute, to conserve oxygen. By slowing down bodily functions most crocodilians can, without breathing, stay underwater for three to five hours. Crocodiles don’t have to eat very often and can do with only two or three big meals per year, because it is one of the most energy-efficient animals alive. To a great degree it’s solar-powered and although cold blooded, with no need to waste food-calories on merely maintaining a constant body temperature, it can control its metabolism and even lower it at will in unfavourable hot, dry conditions.

 It’s clear the crocodile is an age-old marvel of creation that’s been on earth a thousand times longer than man and deserves both our admiration and respect. Our destinies are entwined as we need to drink the same water it needs to live in. At one time I was quite involved with at least some of the Olifants River’s crocodiles. It was when the Arabie Dam was built about 80km downstream of Loskop. I lived there at the time and when the dam was complete I took part in the first survey to get an idea of how many crocodiles there were. The best way was to count them from the air. It happened about 25 years ago, but I still remember that day very well.

A birds-eye view
Clouds of dust swirled around the big helicopter as it slowly lifted above tree-height, dipped its nose and headed for the Arabie Dam, about 1km away. I sat beside the pilot and had to do the counting. We knew we wouldn’t be able to get an accurate figure because of the large numbers involved, and would therefore only count those over 3m and estimate the number of smaller crocs. Although it was mid-morning and most were basking on the shoreline, the smaller ones were quite skittish and sprinted for the water when the chopper was still some distance away. It was easy to miss some before they submerged, but I estimated them at around 250 to 300. Those over 3m gave no problems and I counted 55, bringing the total to almost 350. Among them was a real monster of about 5m, despite missing 1m of its tail.

With name-changes everywhere, Arabie Dam must be holding the record. Its name has been changed about five times since it was built, but what I didn’t know at the time was that the biggest change wouldn’t be to its name, but to its crocodile population. This was confirmed by recent media reports. Following the huge fish kill of 2006, an almost total collapse of the crocodile population occurred in Loskop Dam, where there are now perhaps only five left of the hundreds that used to occur there. Later, a similar massacre occurred in Arabie Dam. First the fish died in their millions and then the crocodiles followed. Of the 350 I had counted only a small percentage is left. Unfortunately it didn’t stop there.

Beyond Arabie stretches the lowveld, where the Olifants represents one of the main freshwater arteries of the Kruger Park. There to date more than 100 crocodiles, some of them hundreds of years old, have died. They started to die in the Olifants Gorge on the border of Kruger and Mozambique and since then in the rest of the river inside the Park and even in the lower Letaba River. If one considers that many of them were the oldest of all the animals in the park and already adults before Kruger was established more than 100 years ago, then the gravity of the situation becomes clear. The exact mechanism of their death is still unclear and scientists are feverishly working to determine how they are affected, but everybody knows what the real causes are.

There’s no doubt the holocaust is directly or indirectly brought about by the massive pollution of the Olifants River and its tributaries. This pollution has many origins, but the mining industry, the Department of Minerals and Energy, the numerous industries in the catchment and the many local authorities whose sewerage purification doesn’t work, all contribute, and so does agriculture. Silt and pesticides from subsistence and commercial farms represent the final blow.

 If we can’t tolerate a true living fossil and share the habitat that belonged to them a thousand times longer than mankind has existed on earth, or are unwilling to protect the environment on which both they and our grandchildren will depend for survival, they are both doomed and our present fascination with extinct dinosaurs is meaningless. We consider ourselves highly civilised, yet can’t prevent ourselves from forcing the king of the swamps, which miraculously survived `til now, over the edge of the bottomless pit of extinction. This is proof we still only have the wisdom and mentality of cavemen. – Abré J Steyn Contact Abré J Steyn on 083 235 4822 or e-mail [email protected] |fw