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June 28, 2018 – 12:37
The "orange cave crocodile", which can measure up to 1m70, is unique in the world and has only been seen in the caves of the African country, according to Osysly archaeologist
In Gabon, known for its geological diversity and its fauna, the scientists took the great surprise of discovering orange crocodiles, unique in the world, living among bat droppings in the caves.
"When I approached with my lantern in the cave, I saw red eyes … crocodile! It was in 2008. Two years later, we released a first specimen of the cave and we realized that it was orange, "recalls Richard Oslisly, geographer (specialist in archaeological sediments).
An extraordinary double discovery that occurred while he and a team of investigators were trying to find remnants of human presence in the caves of Abanda, in southern Gabon.
The "Orange Caves Crocodile", which can measure up to 1m70, is unique in the world and has only been seen in the caves of the African country, according to Oslisly.
"At first, we thought that the color could be due to their diet, since we found that these reptiles eat bats orange," says the French researcher.
But after more careful studies, the scientists presented other hypotheses: a "depigmentation" caused by the lack of light in these caverns or the harmfulness of "guano", a substance composed of bats' droppings. mice in which these animals move their underground life.
"The urine of bats began to attack their skin and transform their color," says Olivier Testa, speleologist and member of the scientific team.
Oslisly, Testa and American researcher Matthew Shirley have been increasing scientific expeditions since 2010 to better understand these crocodiles.
When mapping the caves, they found four orange crocodiles on about 40 specimens of this species of "caveman".
Dozens of crocodiles with "normal" pigmentation live in nearby caves connected to the surface, says Testa, while orange specimens live in caves that can only be accessed through vertical shafts.
A presence of 3000 years.
"We believe that dozens of crocodiles have settled in the caves of Abanda 3000 years ago, which corresponds quite well to a period when the sea level had fallen and where this coastal area was again, "says Shirley
The orange crocodiles were probably trapped in the cave" after entering the hallways when they were little "and not being able to get out of there as they grew up , according to Oslisly.
Several more or less narrow and interconnected corridors form a network of caves in Abanda and are sometimes inundated by the rising waters of the water table.
Shirley maintains, however, that the crocodiles may have been settled in their cave by their own decision and that they may not be trapped there.
In total darkness, these animals survive with a particular diet. In the caves there are no fish or shellfish, and they feed on bats, grasshoppers and crickets. "It's a particularly demanding environment," Shirley says. According to the researchers, these specimens, whether they are orange or of normal color, belong to the group of dwarf crocodiles 'Osteolaemus tetraspis'. and are "changing".
According to Shirley, the DNA of these specimens is not sufficiently different from the surface of their dwarf cousin to make a new species, but these animals have developed their own "genetic signature".
Crocodiles in caves have, in effect, only one group of genes passed down from generation to generation, scientists have found by comparing blood samples of specimens living in caves with those of their living dwarf cousins only on the surface in Gabon.
Although the crocodile is already a protected species in Gabon, Oslisly advocates that the caves of Abanda become a "fully protected sanctuary".
"There is still much to discover in the caves of Abanda", explains the geoarchaeologist, who hopes to promote "scientific tourism".
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