Extinction of Dinosaurs take X

[bombus]

Please define this and give us some sources, as well as a description of how this causes extinction, especially of widely distributed species or groups of species.

 

Hewzulla, D., Boulter, M.C.,Benton, M.J. & Halley J.M., 'Evolutionary patterns from mass originations and mass extinctions', Philisophical Transactions of the Royal Society B (1999)

 

Bak, P. How nature works: the science of self-organized criticality. New York. Copernicus 1996.

 

Basically, the theory says that SOC causes extinctions because species evolve into new species exponentially, filling in niches, creating new niches, which then get filled ad infinitum. When the rate of speciation reaches a certain steepness there tends to be a collapse (extinction). There are many small extinctions and fewer larger ones (mass extinctions) as the system follows a Power Law: variables that plot as a straight line from any organized system.

 

The extinctions come from within the system itself. Examples could include the evolution of oxygen producing organisms causing the extinction of many of the early anaerobic life forms, the evolution of dinosaurs causing the extinction of many of the large amphibians, evolution of placentals causing the exintinction of most the marsupials, evolution of humans causing the extinction of mammoths, sabre toothed tigers, chinese river dolphins, humans!

 

As the Earth system includes every natural process on Earth I suppose it might also include the effects of plate tectonics, vulcanism etc, but that could be pushing it. There is also the effects of meteorite impacts to consider which add a bit of randomness to the system.

 

It's got my vote anyway.

 

They do. Population genetics is the mathematics of natural selection. However, biology/ecology/evolution also incorporate contingency. Because events outside biology can profoundly influence biology (such as solar input or plate tectonics), biology/evolution can never be as deterministic as classical physics. Also, since individuals vary, this also forbids biology/evolution from being strictly deterministic, but instead being probabilistic.

 

I agree with that. I would describe the system as being fundamentally deterministic, but with a high degree of variability/randomness due to the factors you mention.