Conclusiones sobre la jurisprudencia del TC

Scientific name: Procoptodon goliath

Giant Short-Faced Kangaroo—The grapple-hook paws and the single hind claws of this enormous kanga-roo can clearly be seen in this illustration. (Phil Miller)

Scientific classification:

Phylum: Chordata Class: Mammalia Order: Diprotodontia Family: Macropodidae

When did it become extinct? Th is kangaroo became extinct around 40,000 years ago.

Where did it live? Th e giant short-faced kangaroo was found only in Australia.

An enduring image of the Australian wildlife has to be a kangaroo with a cute joey emerg-ing from its pouch. Kangaroos are the quintessential Australian mammals. Among the most familiar of all the marsupials, they have adapted to almost all the habitats the Australian continent has to off er, including open plains, forests, rocky outcrops, slopes, and cliff s. Th ere are even tree-dwelling Kangaroos. Th ese marsupials have a distinctive body shape: a stout body, massively enlarged hind limbs, and a long, muscular tail.

Lots of animals hop, but the kangaroos are the largest animals to use hopping as their preferred mode of locomotion. Th e kangaroo’s hop is actually a very effi cient means of get-ting around as it requires very little muscular eff ort at moderate speeds. Th e tendons that stretch down the back of the hind legs to the hugely elongated feet act like springs, and when the animal has gained momentum, these springs help supply much of the power for the hop. Like the limbs of the fl eet-footed placental mammals, for example, horses, which end in a single hoof, the digits on the hind limbs of many kangaroos are reduced, and only one of them, the fourth toe, may be in touch with the ground, thus minimizing friction. Th e large tail acts like a counterbalance at high speed and as a prop to support the body weight of the animal when it’s moving about slowly, foraging.

As well adapted as they are, the kangaroos have not escaped the devastation that has seen the extinction of numerous Australian marsupials. Of the 53 species of kangaroo and their close relatives that existed when Europeans fi rst reached Australia, six have become extinct.

If we go even further back, into the late Pleistocene, there were many more species, all of which have since died out. Th e largest living kangaroo by quite some margin is the male red kangaroo, which can stand around 1.8 m tall and weigh in the region of 90 kg. We have seen how the mammals from thousands of years ago were far larger than their extant relatives, and the kangaroos are no diff erent.

Th e giant short-faced kangaroo was a big marsupial. In life, it probably weighed in the region of 200 kg and reached a height of 2 m. Unlike the largest living kangaroos, this ex-tinct giant had a large, koalalike head with eyes that were more forward facing than those of living kangaroos and hands with long, central fi ngers, resembling grappling hooks, instead of normal paws. Th e feet of this hopping brute were reduced to a single, large fourth toe tipped with a single hoofl ike nail. With such a small surface area in contact with the ground, the animal could hop around the open forests and plains of Australia with considerable ef-fi ciency. All the large living kangaroos are dedicated herbivores, and we can safely assume a plant-based diet for the short-faced kangaroo. Its koalalike head suggests a leaf-eating habit. Perhaps it used the grappling hooks on its forepaws to bring high tree branches to within reach of its mouth to nibble the leaves. Marsupials, like all mammals, cannot digest plant matter without the help of symbiotic micro-organisms. Animals like cattle have a

chambered stomach that allows plant food to be broken down by the micro-organisms.

Kangaroos have a similar system, and most of their micro-organisms are to be found in the fi rst chamber of their complex stomach.

Although the giant kangaroo was undoubtedly a herbivore, it is diffi cult to explain why it had forward-facing eyes. Living kangaroos’ eyes are on the sides of their heads, giving them a 300 degree fi eld of view, excellent for spotting predators. Perhaps the giant kan-garoo was simply too big for the Australian predators to tackle and therefore had no need for a wide fi eld of view. Th ere were once numerous large predators in Australia, and only adult giant kangaroos may have had some protection from these animals because of their size. Forward-facing eyes gave the giant kangaroo a good degree of binocular vision and a better perception of distance than kangaroos with a wide fi eld of view. Th is could be very important for an animal that was moving at high speed through areas of open forest and tall shrubs, where there were numerous obstacles to negotiate. It may have also helped when reaching up into trees to select the most nutritious leaves. With that said, large herbivores are suited to surviving on low-quality food, and the forward-facing eyes may have given the living animal an advantage we will never fully understand.

Th e giant kangaroo bounded around the wilds of Australia for a long time. Th e oldest fos-sils of this animal are around 1.6 million years old, whereas the most recent are 40,000 years old. It seems to have died out at around the same time as the majority of the Australian mega-fauna. Unfortunately, the defi nitive explanation for the extinction of these animals is elusive.

Th ere are some scientists who believe that the fi rst human inhabitants of Australia are solely to blame, while there is another group of experts who think that climate change was respon-sible. As we have seen, prehistoric extinctions can very rarely be attributed to a single cause, unless the landmass in question is a small island. In the majority of cases, the evidence indi-cates a number of causes in combination ultimately leading to the extinction of a large number of species. Th e probable causes for the disappearance of the giant kangaroo were the spread of humans through Australia and climate change. Humans modifi ed the landscape through their use of fi re and probably hunted the giant kangaroo. Climate change made this continent more inhospitable to the large animals, which are often more sensitive to environmental change.

• The giant kangaroo was not closely related to the group that contains the large, living kangaroos. Its closet living relative is the banded hare-wallaby ( Lagostrophus fasciatus ), a small animal, barely 2 kg in weight, that is extinct on the mainland.

• The group to which the giant kangaroo and the banded hare-wallaby belong is known as the sthenurinae (Greek for “strong tails”). Th is group of marsupials diversifi ed about 2 million years ago, and it was once represented by numerous species, all of which are now extinct, apart from the banded hare-wallaby. Th e giant short-faced kangaroo was the largest, but many of the other species were also very large, far bigger than the living red kangaroo.

• The bones of the short-faced kangaroo have been found in many sites across Australia, including the Naracoorte World Heritage fossil deposits in South Australia.

Further Reading: Helgen, K. M., R. T. Wells, B. P. Kear, W. R. Gerdtz, and T. F. Flannery. “Ecological and Evolutionary Significance of Sizes of Giant Extinct Kangaroos.” Australian Journal of Zoology 54 (2006): 293–303.

Scientific name: Zaglossus hacketti Scientific classification:

Phylum: Chordata Class: Mammalia Order: Monotremata Family: Tachyglossidae

When did it become extinct? Th e giant echidna died out about 40,000 years ago.

Where did it live? Th e remains of the giant echidna have only been found in Australia, but its range may have included New Guinea.

Th e monotremes are a very odd group of mammals that have perplexed zoologists for decades. In some ways, they are unquestionably mammals as they have fur, nourish their young with milk, and are able to keep their body temperature constant by metabolizing food. However, they also have some reptilian features, that is, they lay eggs and their feces, urine, and eggs emerge from a common opening: the cloaca. Th e fi rst species of monotreme to come to the attention of European scientists was the platypus ( Ornithorhynchus anati-nus ) when the dried skins of this animal were sent to England from Australia. Th ese skins caused uproar among the zoological fraternity. Th ere were cries of fake! and sham! as many experts of the time claimed it to be nothing more than the abominable creation of a mis-chievous taxidermist. Gradually, scientists accepted that the platypus was a living, breathing animal and not the work of an imaginative taxidermist. Not long after the platypus came to the attention of Europeans, the echidna was described and named by scientists.