A century on and the adventure continues in hunt for the giant sloth Now, a century later, Prichard's great-grandson Charlie Jacoby is planning to retrace his ancestor's journey A hundred years ago Cyril Arthur Pearson decided to launch a new national newspaper - that paper was the Daily Express. At the same time, reports were reaching Britain of a huge red-haired creature roaming the forests of Patagonia in South America. Scientists believed the creature could be the giant ground sloth, thought to be extinct. Pearson commissioned Hesketh Prichard to track down the sloth. Readers were gripped as he sent back a diary of his epic 3,000-mile trek. Now, a century later, Prichard's great-grandson Charlie Jacoby is planning to retrace his ancestor's journey and the Daily Express will once more be first with the news At some stage in his early years, every young boy dreams of being an intrepid explorer. Whether it's tales of Shackleton battling to reach the Pole, or simply the fascination of watching Harrison Ford's Indiana Jones. For me, my hero was much closer to home - my great-grandfather. Hesketh Prichard was just 20 when he was approached by Cyril Pearson in 1897 and asked to write ghost stories for Pearson's Magazine. He had already lived an extraordinary life. In a Victorian tradition which went into overdrive during the Edwardian days before the First World War, he went from writing stories to being an explorer, cricketer, naturalist, journalist, author and big-game hunter. So when Pearson needed someone to travel to Patagonia in search of the giant ground sloth or "mylodon" for the Daily Express, it was Prichard he summoned. Patagonia is a vast area of land spanning parts of Argentina and Chile. Nearly 1,500 miles long and 500 miles at its widest point, it ranges from the Atlantic coast, where killer whales breed, up to the forests of the high Andes where condors fly. By 1900, stories were coming back from the region that the giant sloth was not extinct at all. In the 1890s an Argentinian geographer, Ramon Lista, was hunting there when a large, unknown creature covered with long red hair trotted past the party. To Lista the creature looked like a gigantic armadillo. Members of the party shot at the beast but the bullets seemed to have no effect. Professor Florentino Ameghino, a paleontologist in Argentina, heard the Lista story and began to wonder if the strange beast was a giant sloth which had survived from the Pleistocene era - a time which included the ice age and the appearance of humans. The largest of the ground sloths was megatherium - on its hind legs it stood 20ft tall and weighed up to four tons. It had a short flat head, powerful jaws and blunt teeth, its fur was thick and it used its sturdy tail to balance itself when standing upright. Lista's tale reminded Ameghino of legends he'd collected from Indians in Patagonia about hunting the "iemisch" or "mapinguari", a creature which lived in the mountains and so terrified them they refused to go there. The animal in the Indian stories was big, about the size of an ox, with short legs. It had reddish fur, a soul-wrenching scream and it stank. It was nocturnal and slept during the day in burrows. The Indians found it difficult to penetrate the animal's skin with their arrows. Professor Ameghino also had a piece of physical evidence. A small section of apparently fresh hide found by a rancher named Eberhardt in a cave in 1895. It was discovered near human remains, suggesting that it had been hunted by man. The hide was studded with bony nodules and would have been impervious to the teeth of Pleistocene predators. It seemed likely that it would have also resisted Indian arrows and Lista's bullets. Prichard was sceptical about these stories but the adventure of the trip appealed to him. He agreed to do it and spent a year there, starting in 1900, leading a 3,000-mile expedition into the interior and the Andes to Lake Buenos Aires and Lake Argentino. To my family, Prichard was both a family hero and a hard act to follow. His trip to South America required eight men, 60 horses, a wagon and a leaky boat. Prichard described his journey across Lake Argentina, between icebergs, on his way to discover Lake Pearson as "perhaps the most heartbreaking moments we experienced throughout the whole trip". A storm stranded him and another man for two nights with only berries and the remains of a Rhea (a large flightless bird) to eat. But he survived his ordeal to observe: "Things rarely fulfil their promise of disagreeableness - things of this kind anyway." Prichard set out to find the giant sloth with the hope that there must be some grains of truth behind the local legends. Disappointingly for Pearson, my great-grandfather could find no trace of such a mammal. "I wanted to find a substratum of fact below these fancies," he wrote. "After thorough examination, however, I am obliged to say that I found none. The Indians not only never enter the Cordillera but avoid the very neighbourhood of the mountains. The rumours of the Iemisch and the stories concerning it, which, in print, had assumed a fairly definite form, I found nebulous in the extreme when investigated on the spot. Finally, after much investigation I came to the conclusion that the Indian legends in all probability refer to some large species of otter." The otter theory is widely believed as the Brazilian river otter grows to nearly six-feet long. However, Prichard's journey was not entirely in vain - he uncovered a new subspecies of puma which, like Lake Pearson, he named after his sponsor. Prichard's suspicions were confirmed later in the 20th century. With the development of Carbon-14 dating, the age of mylodon remains in Eberhardt's cave was settled. Dung found in the cave was more than 10,000 years old. The skin was estimated to be 5,000 years old. Conditions in the caves may have preserved it. Yet, some scientists still believe that these giant sloths exist. Their cousins, the tree sloths, still thrive and there is no scientific reason why their ground cousins should have become extinct: when North and South America were joined, the invasion of species from the north drove many southern species to extinction. However, the sloths survived and fossil remains have been found from Antarctica to Canada. In 1975, mine worker Mário Pereira de Souza claims he came face to face with a giant sloth near the Jamauchim River in Brazil. He heard a scream, he looked and saw the creature coming towards him on its hind legs. The animal seemed very unsteady and emitted a terrible stench. An American zoologist, David Oren, has since led six expeditions in search of the creature since 1994. He has videotaped clawed trees, taped minute-long screams he believes are the giant sloth's call and cast some big tracks that had backwards-facing claws. It is this new evidence that has persuaded me to travel to Patagonia 100 years after my great-grandfather and retrace his steps. Even if my quest to find the giant sloth is unsuccessful, Pearson's dream could yet become reality. Giant sloths might once again roam the forests -but this time in Germany. The Max Planck Institute in Munich has identified DNA from giant sloth droppings found in a cave in Nevada. And scientists are confident of breeding extinct species as long as they have the DNA. But if science outwits natural extinction and the sloth - and other lost species - becomes as common as a kangaroo in Australia, there would be little left to explore. Another ancient animal - the intrepid explorer - would itself die out and take with it the childhood fantasies of thousands of little boys. And where's the adventure in that? THE ONES THAT ALMOST GOT AWAY There's still a chance the giant sloth will be found. After all, plenty of other beasts have slipped through science's net A 100lb wild pig, the Chacoan peccary, thought to have become extinct several hundred years ago, was discovered in 1972 in South America. In 1982 in Tasmania, wildlife officer Hans Naarding spotted a Thylacine. The creature, the largest known marsupial carnivore and dog-like in appearance, had been declared "probably extinct" in 1936. Coelacanths were ancient fish-like vertebrates thought to have disappeared 70 million years ago. In 1938, however, fishermen working off South Africa caught a living coelacanth. Since then more than 200 species have been found. Scientists visiting a remote region of Cambodia this year came across large numbers of Siamese crocodiles, thought to have been extinct.