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Post KT: Fungi Ruled The World



This says the research is from the Swedish Research Council, but that
site's in Swedish so I can't reference the original news release...
This is almost a spooky scenario.


http://www.astrobiology.com/news/viewpr.html?pid=13787

The catastrophe that extinguished the dinosaurs and other animal species,
65 million years ago also brought dramatic changes to the vegetation. In a
study presented in latest issue of the journal Science, the
paleontologists Vivi Vajda from the University of Lund, Sweden and Stephen
McLoughlin from the Queensland University of Technology, Australia have
described what happened to the vegetation month by month. They depict a
world in darkness where the fungi had taken over.

Its known that an asteroid hit the Yucatan peninsula in Mexico at the end
of the Cretaceous Period. It left a 180 km wide crater and from the impact
site tsunamis developed and the Caribbean region was buried in ash and
other debris. The consequences of the asteroid impact were global. Vajda
and her colleagues have previously studied the broad-scale changes in the
New Zealand vegetation following the impact, but now they have
dramatically improved our view of the timing of events.

At the end of the Cretaceous the vegetation on New Zealand was dominated
by conifers and flowering plants. Many of these species disappeared
suddenly at the end of the Period and were instead replaced by fungal
spores and fungal threads preserved in a four millimeter thick layer of
coal. The layer coincides with fallout of iridium, an element rare in
Earth's crust but which abounds in asteroids.

"We have managed to reconstruct the event month by month, with a very high
time resolution", says Vivi Vajda. During a very short period - from
between a few months to a couple of years - the fungi and other
saprophytes which live on dead organisms must have been the dominating
life form on Earth. Atmospheric dust blocked the sunlight and led to the
death of plants that are dependent on photosynthesis. 

The layer of fossil fungi is followed by a 60 cm thick interval containing
traces of the recovery flora, which re-established relatively quickly,
ground ferns at first, followed after decades to hundreds of years by more
diverse, woody vegetation.

A similar layer of fungi and algae is known from a previous catastrophe
which happened 251 million years ago at the Permian-Triassic boundary.
This was an even greater mass extinction: about 90% of the existing
species disappeared. Research will now focus on whether the similar
biological signatures at these mass extinctions reflect similar causal
mechanisms.