Annihilation of ecosystems by large asteroid impacts on the early Earth.
Large asteroid impacts produced globally lethal conditions by evaporating large volumes of ocean water on the early Earth.  The Earth may have been continuously habitable by ecosystems that did not depend on photosynthesis as early as 4.44 Gyr BP (before present).  Only a brief interval after 3.8 Gyr exists between the time when obligate photosynthetic organisms could continuously evolve and the time when the palaeontological record indicates highly evolved photosynthetic ecosystems.
Sleep
N H
NH
Department of Geophysics, Stanford University, California 94305, USA.
Zahnle
K J
KJ
Kasting
J F
JF
Morowitz
H J
HJ
D005075:Biological Evolution; D018534:Earth, Planet; D017753:Ecosystem; D055593:Geological Phenomena; D005844:Geology; D018543:Minor Planets; D009792:Oceans and Seas; D010163:Paleontology; D010788:Photosynthesis; D013997:Time Factors