It is interesting that the 26 million year periodicity motivated other scientists to statistically scrutinise terrestrial impact structures, which supposedly ‘verified’ the 26 million year cycle.
Many scientists now dispute the 26 million year periodicity, revealing in the process questionable assumptions in taxonomic analysis: ‘Patterson and Smith’s analysis produced the unexpected result that only a quarter of the families and family distributions recognised by Raup and Sepkoski are valid.
The gravity of this End Permian event varies, depending upon the scientist doing the analysis and upon whether the datum is at the species, genus, or family level.
Referring to Table 1, this extinction is attributed to cooling from an ‘ice age’ in combination with a marine regression.
However, according to the uniformitarian paradigm the late Carboniferous and early Permian ‘ice age’ had ended millions of years before and should have caused a marine transgression due to melting ice, at least up until mid Permian time.
Dinosaur extinction is still a major enigma of earth history.
In this review article, extinctions in the geological record will be briefly mentioned.
Despite all these eggs, embryos within the eggs are very rare.
Why did the dinosaurs, as well as the marine reptiles and the flying reptiles, vanish from off the face of the earth? Although many dinosaurs became extinct well before the End Cretaceous, nevertheless Zhao Zi-Kui indicates that dinosaur extinction still remains a major enigma of earth history, despite two promising theories: ‘Thus, the dinosaurs could quickly make use of the available ecological and evolutionary opportunities.
Not everything over there is fully functional yet, and the internal links still point to this blog, and will for the indefinite future.
So all the old material will be left here for archival purposes, with comments turned off.
Most of those that were fossilised go unrecognised by the untrained eye.