Posted on 05/05/2011 4:28:50 PM PDT by decimon
The end-Permian extinction, by far the most dramatic biological crisis to affect life on Earth, may not have been as catastrophic for some creatures as previously thought, according to a new study led by the University of Bristol.
An international team of researchers studied the parareptiles, a diverse group of bizarre-looking terrestrial vertebrates which varied in shape and size. Some were small, slender, agile and lizard-like creatures, while others attained the size of rhinos; many had knobbly ornaments, fringes, and bony spikes on their skulls.
The researchers found that, surprisingly, parareptiles were not hit much harder by the end-Permian extinction than at any other point in their 90 million-year history. Furthermore, the group as a whole declined and diversified time and time again throughout its history, and it was not until about 50 million years after the end-Permian crisis that the parareptiles finally disappeared.
During the end-Permian extinction, some 250 million years ago, entire groups of animals and plants either vanished altogether or decreased significantly in numbers, and the recovery of the survivors was at times slow and prolonged before new radiations took place.
By studying the fossil record, palaeontologists can examine how individual groups of organisms responded to the end-Permian event and assess just how dramatic it was. However, as the quality and completeness of the fossil record varies considerably, both geographically and stratigraphically, palaeontologists need to find a way to ‘join the dots’ and piece together the fragments of a complex mosaic to give a more satisfactory and better picture of ancient life’s diversity.
(Excerpt) Read more at bris.ac.uk ...
Ping
Sounds as if they're using statistics and imagination rather than real fossil data.
Some combination, I think.
Endogenous Proteins Found in a 70-Million-Year- Old Giant Marine Lizard
Lund University | May 2, 2011 | Unknown
Posted on 05/02/2011 7:58:24 AM PDT by decimon
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Were the parareptiles the same as the therapsids? My understanding was that the therapsids, which were a strong protomammalian group before the great Permian extinction, died out but were the precursors of the small mammals that persisted throughout the reign of the dinosaurs, which then flourished after the dinosaur extinction 65 mya.
Jean-Luc’s evil twin from another dimension. Boy, I hate that guy.
Parareptiles -- Figure: The phylogeny of the parareptiles.*and*
Known from the Late Devonian to the Early Triassic, the Anthracosauria probably had a very short amphibian stage of their evolution and gave rise appearently to all groups of reptiles.
Phylogeny of Therapsida -- Steven M. Carr(I used a width= tag to avoid putting the whammy on your pings screen, and for that matter this topic, try right-click open in new window to view the lower image)
Plesiomorphic characters in blue; apomorphic characters of three extant Therian lineages in red. Evolution of the characteristic Dentary-Squamosal jaw occurs gradually in Cynodont lineage.
That explains a lot.
That has to be the ugliest white man I’ve ever seen!
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