When did platypus appear?

According to a new fossil research project, Australia's platypus may have appeared longer than people thought. The origin of this species may stem from the period of dinosaur survival.

The platypus and its closest evolutionary relative, the porcupine fur, are thought to evolve from the same ancestor 17 to 65 million years ago. But the fossils of a species of distant relatives of both species belong to the group of the first platypus on Earth. This is the conclusion of scientists who have conducted X-ray examination of a jaw of a Teinolophos.

The discovery synonymous with the two species must be separated from the date of the fossil - at least 112 million years ago.

Live longer than dinosaurs

The international team led by Timothy Rowe, of the University of Texas, Austin, uses specially modified tomography to capture high-resolution images of the internal structure of the jaw of the aged fossil. Life 112.5 to 122 million years old, discovered in southeastern Australia.

Scientists found that in the Teinolophos species, the characteristics of the current platypus appeared, including an electric induction beak for hunting underwater. The discovery has pushed the platypus appearance back to the KT period, close to the mass extinction that killed dinosaurs 65 million years ago. Rowe said: 'It seems that the platypus has survived this stage without any difficulty.'

The study was published in the magazine version of the National Academy of Sciences Meeting Minutes.

Jawbone unique

Platypus beak is a complex sensitive part equipped with electrical sensors. In the cloudy waters, platypus hunt by hunting for weak currents produced by the muscle activity of fish and other prey.

The Teinolophos species also has an electric induction mine, scientists have drawn this conclusion after the photo shows a tube throughout the lower jaw bone. All mammals have such a tube to guide nerves to their teeth. But in platypus, this pipe is particularly large to contain a giant network to transmit information from the mine. The declaration of Teinolophos is an ancient platypus species based mainly on this characteristic. Rowe said: 'There are no species except this giant platypus.'

But Matt Phillips, of the Australian National University in Canberra, said more evidence is needed.'This study cannot confirm that platypus and porcupine fur have been different from 112 million years ago.' Phillips offers another explanation for this new finding: An ancestor of both species may have large tubes in the jawbone, which remains in platypus but loses in the process of porcupine evolution. In isolated conditions these two species may have only recently taken place.

Rowe argued that the evidence of this event was not strong enough, he believed that the hypothesis of a wide tube is a characteristic of platypus descendants would be much more reasonable.

Fossilized tomography of the jaw of an organism thought to be an ancestor of platypus and neighboring species, exposing a fairly wide pipeline.Scientists believe the wide jaw indicates that fossils belong to a platypus.This discovery caused the time-lapse of these mammals to fall back 10 million years compared to those who thought.(Photo: Timothy Rowe)

Molecular clock

Because fossils of platypus and porcupine fur are quite rare, knowledge of these two species is based more on molecular analysis than fossil studies.

The gradual accumulation of DNA changes in neighboring species provides a kind of ' molecular clock ' that biologists use to estimate the time when species grow apart. However, changes in DNA do not occur at the same pace in different animals. This watch must be checked by other evidence such as fossils.

Rowe also said that the study of the origin of platypus uses molecular clocks combined with information from marsupials and other mammals and not platypus and porcupine.

Scientists claim that the molecular evolution of these two species is much slower than other mammals.

Rowe said: 'None of the molecular research projects predicting we will find a platypus that has this longevity. Another finding is that 'slow' monogamous animals are in many ways. '

These two species are the only monogamous animals that still exist, ie mammals that lay eggs.'The process of energy metabolism and respiratory rate is slower, body temperature is lower, and it is possible that the strain of monoculture evolved quite slowly.'