Asteroid likely caused global fires, which led to extinctions

Watts Up With That? ^ | March 27, 2013 | by Anthony Watts

[SunkenCiv]

Thanks Ernest. Just the energy release from the impact (and leaving aside consideration of any other of its effects) would be sufficient to raise the global atmospheric temperature -- at first -- by degrees (somewhere in double digits). Even if nothing else happened, some species would succumb just from the temperature increase. The fires started by both the flash (over hundreds of miles in all directions) and hot ejecta (thousands of miles) did do damage, but the crud that went straight up, then out, blanketed the Earth with an opaque cloud of dust and soot in perhaps 90 minutes, and the blanketing lasted probably for years; so after the temporary increase in temperature, the lack of sunlight reaching the surface slowed the hydrologic cycle (no rain or snow for years), and the basis for the food chain (the plants) went dormant or died from lack of light and water.

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[gleeaikin]

I think another factor in the mass extinction could have been destruction of the ozone layer and radiation burning and cancer to animals without thick fur/feathers, or nocturnal or underground habits. Note that the reptile survivors were snakes, alligators, turtles, etc. which all tend to use burrows or are small and can hide. Birds and mammals, feathers, fur, live in trees or jungles, or hide in burrows or were small.

[SunkenCiv]

Burrowing species had an advantage over other land creatures because of availability of water, soil critters (insects, worms, etc) and cover (all foliage vanished); marine species were mostly selected by size.