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First mammal-like creatures rose in Permian, 286-248 million years ago?

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cynodont Galesaurus planiceps/Smith, Iziko Museums

Recently, we noted new findings on the ways in which asexuality can lead to extinction. Even mass extinctions, however, have not been—as this recent story suggests—the “end of the world.” What often happens is that they open up niches for species that were there already or somewhere already, who just increase in numbers and range to fill the gap. These researchers argue that mammals arose at the end of the Permian, not in the Triassic, due to the departure of dominant land species:

However, new research suggests that this array of unique features arose gradually over a long span of time, and that the first mammals may have arisen as a result of the end-Permian mass extinction — which wiped out 90 per cent of marine organisms and 70 per cent of terrestrial species.

The researchers concluded that cynodont diversity rose steadily during the recovery of life following the mass extinction, with their range of form rising rapidly at first before hitting a plateau. This suggests there is no particular difference in morphological diversity between the very first mammals and their immediate cynodont predecessors.

In short, they are not quite saying that mammals arose at the end of the Permian, but it sure sounds like it for all practical purposes. And if so, this is another one for the “earlier than thought” files.

ok, but when did the first Mung-like creature appear? Mung
from "Earth's Catastrophic Past" Snelling: Vol.2 p.541 "The Triassic Mont San Giorgio Basin, Italy-Switzerland The shales of Mont San Giorgio are in a basin that is estimated to have been from 6 to 10 kilometers in diameter and only approximately 100 meters deep. Yet thousands of well-preserved fossils in a diverse assemblage of fish and reptiles have been found in these bituminous shales. Once buried in the fine-grained muds, compression flattened the animal skeletons as they petrified. In some instances, the force of the compression crushed the skeleton so severely that interpretation of fine anatomical detail is difficult, if not impossible. However, most of the fossils are well preserved, so that delicate bones and fine details, such as tiny spines and scales, are still distinctly visible. It is readily apparent that a wide variety of animal species were buried and preserved in this basin. In terms of fish diversity alone, the fossil assemblage in these shales is analogous to a modern coral reef.... Sharks, lobe-finned fish, ray-finned fish... Most abundant and perhaps best studied of the reptile fossils are the amphibious nothosaurs... 400 specimens representing each stage of the life cycle... Placodonts: short, stout marine reptiles... as well as archosauromorphs are well represented. The most bizarre of these fossil reptiles is a 4.5 meter giraffe-necked saurian, Tanystropheus, which has an absurdly long neck more than twice the length of its trunk. Only one true archosaur has been found in this fossil graveyard... The animal, which was about 2.5 meters long, is believed to have been a ferocious terrestrial carnivore. Thalattosaurs, Icthyosaurs: marine reptiles... As for how this great diversity of vertebrates came to be fossilized together, it is conventionally suggested: ""The bottom of the San Giorgio basin consisted of fine-grained mud, and when the animals that lived in the basin died they sank to the bottom. There conditions were anoxic (without oxygen), so their remains, which would normally be broken down by aerobic bacteria and other scavengers, were protected from decay, thus exquisitely preserving even fine details. (Burgen et al, 1989, 52)"" However, fish, like so many other creatures, do not naturally become entombed like this, but are usually devoured by other fish or scavengers after dying. Furthermore, when most fish die their bodies float. In the fossil assemblage at Mont San Giorgio are some indisputable terrestrial reptiles among the marine reptiles and fishes. Thus, to fossilize all those fish with the large marine and terrestrial reptiles, so that they are all exquisitely preserved, would have required a catastrophic water flow to sweep all these animals together and bury them in fine-grained mud." lifepsy
semi-related: Out of the oil emerges Venezuela's 'Jurassic Park' (Update, w/ Images) - Sept. 5, 2013 Excerpt: Under the rich Venezuelan soil, paleontologists have found treasures rivaling the bountiful oil: a giant armadillo the size of a Volkswagen, a crocodile bigger than a bus and a saber-toothed tiger. Oil companies' surveys of the soil have uncovered a trove of fossils dating from 14,000 to 370 million years ago.,,, The fossils found during the surveys include a featherless chicken that looked like an iguana, a three-meter (10-foot) pelican and giant sloths that lived on land 12 million year ago, unlike their modern relatives living in the trees. http://phys.org/news/2013-09-oil-emerges-venezuela-jurassic.html bornagain77

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