|
|
|
The early Cenozoic was a world in disarray. The lengthy volcanic outpourings that mantled 350,000 square miles in India over millions of years must have had a powerful influence on the world's climate, causing abnormally cold winters and summer temperatures far below normal. This was a climate already in flux due to mountain- building and the retreat of inland seas. Then, in a final insulting hammer-stroke, came the devastating asteroid impact on the Yucatan peninsula. Life in southern North America was decimated in a blast wave and fan of white hot ejecta that extended far out into the Atlantic. The mushroom cloud that towered into that Late Cretaceous sky must have dwarfed modern nuclear tests. Fire storms may have incinerated forests in Central and North America for thousands of miles around the strike zone and the European coast would have shuddered under the impact of massive tidal waves surging across the Atlantic Ocean. |
Dioon prespinulosum, tip and |
|
Drawing of modern |
The Cycadales were negatively impacted along with other life of the time. Of the Bennettitales, the tall arborescent williamsonias and the more compact Cycadeiodeae both vanished, probably due to the loss of their dinosaurian grazers and insect pollinators, for the climate of the Eocene period eventually became warm and moist. And this was yet another defining moment for the modern Cycadales. Shaped by millions of years of structural refinement, they reestablished their ranges in an empty world as denuded stumps and buried root masses regenerated and here and there isolated, long dormant seeds sprouted as temperatures began to moderate and the sun began to shine once more through a thinning mantle of clouds. In the early Cenozoic the Cycadales grew in higher latitudes. The Eocene Period was warmer than today. Cycas was represented in Europe and Asia through fossils found in Bulgaria, Britain, and in Japan. |
