Changes in Flora at K-T Boundary

(from Vajda et al. 2001. Science 294, pp 1700-1702 and Flannery, 2001. Science 294, pp 1668-1669).

I) Evidence of Global devestation after K-T boundary impact.

II) Palynological study shows a "spike" in fern spores at K-T boundary w/ a reduction in gymnosperms and disappearance of angiosperms forests in New Zealand; similar to what is known for North America.

III) Recognize 5 phases of floral succession:

1) Abrupt excinction due to prolonged darkness, freezing, acid rain and wildfires (?)

2) Colonization of waterlogged, acidic cool areas by moss and ground ferns

3) Expansion of tree ferns indication regional change to warmer, humid condition after intial cooling

4) Decline in tree ferns before a longerm rise in cool-temperate gymnosperms

5) Recovery of angiosperms related to warming in late Paleocene.

IV) Data may indicate a pattern of long-term environmental disruption that may relate to massive injection of CO2 into atmosphere.

V) Data suggest it may take long time for CO2 levels to return to equilibrium

VI) Took several million years for angiosperms to regain pre-impact prominence.