Extinct Animals

The mass extinction at the end of the Permian was by far the most severe crisis in the history of life: more than 60% of animal families, both marine and terrestrial, disappeared.

• The mother of all mass extinctions.
• Perhaps as few as 10% of species survived.

While the project is progressing well, there are still those who have certain reservations or are outright against the project.

It has been argued that there might have been other non-morphological, genetically-coded features (such as habitat adaptations) unique to the Quagga and that therefore, any animal produced by a selective breeding programme would not be a genuine Quagga. Since there is no direct evidence for such characters and since it would be impossible now to demonstrate such characters were they to exist, the argument is spurious. The definition of the Quagga can only rest on its well-described morphological characteristics and, if an animal is obtained that possesses these characters, then by definition, it will be a Quagga.

The genetic basis of the Quagga Breeding Project, relies on the demonstration by Higuchi et al (1987) (Mitochondrial DNA of the Extinct Quagga: Relatedness and Extent of Postmortem Change. Journel of Molecular Evolution 25:283-287) that the mitochondrial DNA of the Quagga is identical to that of other Plains Zebras. Therefore the Quagga and other Plains Zebras belong to the same species and consequently the Quagga should be considered merely a different population (or deme), of the Plains Zebra.

The only characters that have been used to identify the Quagga are its coat-pattern characters. Therefore if, within a few generations of selective breeding, an animal demonstrating these characters is obtained, it can with full justification be claimed to be a Quagga, since it would possess the same assemblage of coat-pattern genes as the original Quagga. It would not be a "look-alike".

Futhermore, since the indigenous grasses in the original habitat of the Quagga are not significantly different from those areas occupied by extant Plains Zebras, and since extant Plains Zebras occupy habitats of similar degree of aridity to those of the Quagga, there is no sound reason for proposing significant adaptive features of the Quagga to its original habitat, and no reason to believe that animals produced in the selective breeding programme would not survive successfully in the region formerly occupied by the Quagga.

There are a number of conditions that must apply. Notable are suitable preservation environment, and stability.

If the animal has been preserved in ice and stayed frozen until now such as some cases of the Woolly Mammoth, they have the best chances. Their DNA is relatively easy to extract, although it had major problems with contamination from modern and ancient bacteria. This bacterial DNA massively outweighed the Mammoths' DNA, requiring massive use of computers to search the DNA as it was sequenced comparing it to known bacterial samples vs. Elephant DNA.

There are examples where extinct animal DNA has been found where it is a relatively bad environment, but a stably bad environment. For instance giant ground sloth bones were found in caves in deserts that were technically too hot for good preservation, but because the caves had little change in temperature or humidity there was still DNA to extract.

It is extremely rare to find DNA in fossilized animals. However, in a case discovered in the US, a 67 million year old Tyrannosaurus Rex was found with viable protein which could be use for comparing relation of species, but never cloning. The paleontologists found the preserved tissue inside bones fossilized with large amounts of iron and managed to extract small traces of protein. In this case the large amount of iron worked out as a preservative.

Often only Mitochondrial DNA is preserved. This is because most cells have several, or in some cases many mitochondria, and mitochondria additionally have an extra layer of protection. Mitochondrial DNA has been extracted from a very large number of relatively recently extinct animals that were poorly preserved.

Because the amounts of preserved ancient DNA in fossils is so tiny, very careful steps must be taken. Touching the remains bare handed, or even in some cases breathing on them can produce such massive contamination that the ancient DNA is a drop in the ocean. The remains, or more usually pieces of remains, are very carefully cleaned to try to remove as much outside contamination as possible. Samples are taken and put into a PCR (Polymerase Chain Reactioin), which causes the DNA to reproduce itself again and again and again, as much as possible.

Once results start to come in, it's off to the computers. Since the vast majority of DNA is contamination, specifically bacteria, computers are used to identify the chunks of bacterial DNA and mark them for exclusion as fast as possible. Once this gives an idea of what kind of original DNA is in the sample, it's possible to modify the PCR process to target the original DNA and ignore the contaminant DNA.

This is done until there are enough pieces read in to start assembling them, often by matching them to what's thought to be the closest living relative.

The Thylacine was, of course, discovered by indigenous Australians centuries ago. This is known through ancient cave paintings.

In 1642 Abel Tasman became the first to make note of the Thylacine. He recorded that crewman Jacobszoon had found "footprints not ill-resembling the claws of a [tyger]" on the shores of Van Diemen's Land.

The first actual sighting occurred in 1772, when French ship the Mascarin arrived in Tasmania. Explorer Marc-Joseph Marion du Fresne claimed he saw a "tiger cat", but it is possible this was the spotted tiger quoll. Then, on 13 May 1792, French naturalist Jacques-Julien Houtou de Labillardière made what is considered to be the first definitive sighting of the Tasmanian tiger.

In April 1805 William Paterson, the Lieutenant Governor of Tasmania, sent a detailed description of the Thylacine for publication in the Sydney Gazette after an animal had been killed by dogs.