We have already known our ancient ancestors for long – these are medium-sized animals - eutherapsida (which means “real Synapsida”), they appeared at the end of the palaeozoic, approximately 270 million years ago, and continued to develop in the Age of Reptiles – the era of huge dinosaurs’ predominance. Ultimately, dinosaurs became extinct, and eutherapsida, gradually changing, turned into mammals.
However, there are blank spots on this long way, and far from all of its stages are clear once and for all. Thus, investigations by Mikhail Ivakhnenko, Doctor of Biology (Paleontological Institute, Russian Academy of Sciences), make researchers review relations between contemporary mammals and the duck bill and echidna of Australia and the New Guinea long-nosed echidna (Zaglossus). These strangely looking animals belonging to the ovipositor subclass are considered to be primitive mammals (they are also called Prototheria – “primitive animals”).
It is assumed that formerly in the Age of Mammals, they gave rise to contemporary mammals and remained till nowadays. “However, frankly speaking, they are not resembling ordinary mammals that much, says M.F. Ivakhnenko. But, on the other hand, contemporary investigations have revealed suspicious similarity between them and other extinct group of animals – eotherapcida (“ancient Synapsida”). This similarity is particularly connected with specific construction of their auditory apparatus. It looks as if eutherapcida gave origin to only marsupial and placental mammals, and the duck bill, echidna and New Guinea long-nosed echidna (Zaglossus) - are not our ancestors but the top of other branch of evolutionary tree.”
“Ancient Synapsida” had appeared much earlier than “real Synapsida” did, approximately 320 million years ago, and, as paleontologists have proved, the former cannot be the ancestors of the latter. They have a common ancestor group but their ways diverged at once. The two of them differ fundamentally in the cranium structure, or more precisely, they adapted differently the cranial cavities inherited by them from the Crossopterygii fish. “Ancient Synapsida” occupied these cavities with the jaw muscular system – and acquired strong jaws which were certainly useful. But the other way followed by “real Synapsida” turned out to be even more useful and promising. Due to these cavities they extended the cranium and enlarged the size of brain. The difference is really a fundamental one: one got jars, the other – brain.
All the Synapsida acquired hairy “fur coat” (in contrast to reptiles, which protected the body from drying up by scales), the coat preserved moisture and turned out to be useful in the cold spell conditions. By the end of the palaeozoic, they dominated among land quadrupedals and were extremely diverse: some were of a mouse size, gigantic herbivorous – of a rhinoceros size, and predators - of a tiger size. Their reign lasted for more than 150 million years. At the boundary between the palaeozoic and the Age of Reptiles a catastrophe took place, the reasons for which are still being debated by researchers. The diverse paleozoic world disappeared and the dinosaur era began.
It was assumed for a long time that “ancient Synapsida” – eotherapsida, had disappeared completely. But there emerged a new hypothesis. They did not disappear but reached to our time in the form of duck-bills and echidnas, which in that way are not our ancestors, but first cousins.
Sergey Komarov | alfa
'Y' a protein unicorn might matter in glaucoma
23.10.2017 | Georgia Institute of Technology
Microfluidics probe 'cholesterol' of the oil industry
23.10.2017 | Rice University
Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
23.10.2017 | Event News
17.10.2017 | Event News
10.10.2017 | Event News
23.10.2017 | Life Sciences
23.10.2017 | Physics and Astronomy
23.10.2017 | Health and Medicine