lundi 3 novembre 2008


The Marsupials like the Kangaroos are Mammals caring in a maternal pouch (called marsupium ) their babies, born at a very early, nearly embryonic, stade; only Monotremes laying eggs, like the Platypus, are more primitive Mammals.
Appeared on Earth at the end of Dinosaurs' reign, at the same time as the ancestors of the more modern Mammals ( these latest ones known as Placenterians ), the Marsupials spreaded in worldwide before to be overhelmed by their
conccurents, excepted in the most isolated areas.

For this reason, they could maintain on the top of the food chain in South America until the invasion of the Saber-toothed tigers. In the New world today are still living some species of little Marsupials, like the Opossum. In Indonesia, some other species can be also found, like the Cuscus. But it's in Oceania, in spite of the presence at first of a long time extinct more modern Mammal, a little beast called Tingamarra, than Marsupials could really prospere.

When first humans came in Australia few dozens of thousand years ago, Marsupials were dominant lifeforms, with some big carnivorous Reptiles. One of these Marsupials was probably a terrific predator, and a vegetarian one could weigh 3 tons. These different creatures vanished after the installation of Australia aboriginal people.

Very more recently, European people changed the australian environnement too, and, after the Dingo, an asian Dog brought by Aboriginal people, they put with them new domestic animals, cause to new extinctions, this time among little Marsupial species. The
latest big carnivorous Marsupial, the Thylacine also known as Marsupial Wolf, that was already in concurrence with the Dingo, was completely exterminated in the middle of 1930 years by settlers because it hunted sheeps.

Nowdays, some Australian citizens become conscious that their debt is to protect the relict of this unique fauna, but a mysterious illness kills the Tasmania Devils, the biggest Marsupial alive, beast of dog-size, surviving only on Tasmania island. The members of this species, equivalent of the North America's Wolverine in the food chain, suffer and dy of big cancerous tumors, bearing some likeness with the poor mutant bearse of the movie PROPHECY, indirectly inspired by the mercury contamination of Minamata catastroph. It appears than the problem could come from some malevolent cells, transmitted by bites between Tamania devils, the population being rather restricted in a limited space to become so homogenic than there is anymore immunate differences. Even it can happen, as showed by the drama of the mad cow disease, than abnormal components of an organism would be able to infect not only other individuals, but also to travel across the genetic barrier between species, the risk upon the Tasmanian Devil recalls the difficulties to try to preserve an endangerous species when it survives only within a rather few number of animals in some protected areas, and as result there would be no more diversity in the genetic pool, able to produce some specific immunate answers versus attacking germs. This is very discouraging if you think than a lot of animal species in the world exist only at a very light quantity : there would be only a thousand and half of giant pandas, and a few hundred of Gavials ( indian fish-eater Crocodilian with a very thin snout ), and of soft-water long-beak Dolphins ( in India and Amazonia ), after the extinction of the chinese genus Lipotes in 2006 because Yangtse Kyang barrage's edification.

Without an appropriate vaccin, the Tasmania Devils, become rather famous across a Warner Bros cartoon character, could be survive only in zoos, and we would have to hope than these ones would do a best job with this species than it was done with the Marsupial Wolf : in 75 years, 18 Thylacines lived in the London zoo, but this creature extincted simultanly in captivity and in the nature.

More, the Koalas, already endangerous because their very specific food, some Eucalyptus leaves, a tree victim of human developpement and also of dryness, caused by local traditional climate and by global warming too, are attacked like Tasmania Devils by a mysterious Virus giving cancer. It seems that this Virus was became active recently, coming in the worst moment to strike this species menaced by natural space reduction.

These two dramatic events could be the final episode of the Marsupials story, and it's a cruel irony than for one time, humans seems to have nothing to do with them. It's like if, after to have to let their place to Placentarian Mammals excepted in Oceania, the latest alive Marsupials were claimed by the evolution march, as Faust waited by the Devil when his time is passed away. These two facts, even it could be a simple coincidence, are surprising for people - I think like them - who are not convincing by Pandemic theory ( even I wrote long time ago a very short story on this theme ) trying to explain the extinction of the most big Mammals after the late ice age by a very powerful epidemy. When the Nature gives a hand to human destruction, how do not be anxious about the survival of the diversity of life on our planet?

Aucun commentaire: