The event proved to be catastrophic to plants, and rainforests began to disappear. What happened to animals has been debated for many decades.
A prevailing theory has been that tetrapod diversity reduced markedly before endemism occurred. Endemism refers to species evolving in defined geographic locations, such as on an island, in a particular country, or in some other defined zone. In short, the species are basically confined to a certain place where they evolve to live.
The fossil data that Dunne and her team compiled and obtained from the massive Paleontology Database, however, counters that long-held theory.
"Instead of tetrapod communities of species becoming more isolated (endemism), we found that they became even more well connected, a pattern called cosmopolitanism," Dunne said. "These better-connected communities suggest that species were more able to move around between different areas."
At first the findings surprised Dunne and her team.
"But when coupled with the diversity decrease, these results make a lot of sense," she said.
The Carboniferous rainforest collapse was one of two mass extinctions recorded in the fossil record for plants. The other one occurred in the mid-late Permian (299–252 million years ago).
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Once tetrapods recovered from the changes, the Permian led to some of the most interesting animals ever to walk the earth. Amphibians and reptiles known as anapsids, diapsids, and synapsids grew to tremendous sizes.
Particularly flashy were pelycosaurs like the predator Dimetrodon, which was adorned with a line of long, bony spines along its back that supported a sail-like crest. Dinosaurs later evolved similar features.
While the dramatic climate change at the end of the Carboniferous was devastating to plants, animals seemed to recover pretty well over time. One might then wonder what lessons might be learned that could apply to today's environmental conditions.
It appears that animals highly evolved for survival in a specific habitat do not fare well during times of profound change, since they lack the flexibility to quickly adapt to new climates and environments.
"I think it's generally considered the case that species with broader niches do better in environmental crises, and there is potential to use the fossil record to test hypotheses like these, and therefore inform current environmental work," Dunne said.
"However," she quickly added, "I think we would want to be careful about using data from ecosystems like those of the Carboniferous that are so fundamentally different to today. It's probably more useful to look at the much more recent fossil record."
Dunne and many others believe that conservation of today's remaining rainforests is critical. "Rainforests today are incredible hotspots of both animal and plant diversity,” she said, “and it is very important to protect them, and indeed other threatened habitats."