Carboniferous Rainforest Collapse

[Stocksdale]

Hello Everyone,

I'm interested in info and thoughts on the Carboniferous Rainforest Collapse. It is an extinction event that they think occurred between the Moscovian and Kasimovian stages of late Carboniferous.

Here's a wikipedia article about it. Carboniferous Rainforest Collapse .

In my opinion this wikipedia page NEEDS some help. I think some info is incorrect and a little misleading

It would appear to me that there may be evidence for the event but recovery happened pretty quickly with a return of most of the species but in a different overall balance.

I may be wrong on this and would be glad to be corrected.

Anyway, give me your opinions or articles or info or data on the subject..... if you'd like.

Edited July 12, 2014 by Stocksdale

[siteseer]

Stocksdale,

I haven't read a lot about the Pennsylvanian Period (Late Carboniferous) other than what has been summarized in a textbook or generalized in a popular science book. Maybe you have read the same sorts of books and have a similar impression of that time which goes something like this:

The Late Carboniferous was an interval that continued a general cooling and drying climatic trend. Evidence of this climate change is shown in the appearance of gymnosperms, cone-bearing plants that could live less water and could replace areas of shrinking rainforest as well as invade places that had been too dry for jungle. This cooling/drying was also bad for amphibians and good for reptiles (amniotes) leaving the former less diverse by the end of the period and the latter more diverse. The first synapsids, the lineage represented today by mammals, appear during the Pennsylvanian as well as the first herbivorous vertebrates.

It was a time of ice ages with glaciers advancing and retreating from the South Pole with falls and rises of sea level. Yet, it was also a time known for a vast tropical environment that covered much of equatorial Euramerica, a continent composed of large parts of North America and Europe. In fact the continents had all nearly drifted into each other to form Pangaea by then. Part of Siberia and part of southeast Asia were still islands on the way to that union. The tropical environment is indicated by fossils known from the Mazon Creek flora and fauna as well as those from France and England.

Of course, the Carboniferous was named for the extensive coal deposits that formed from the tropical environment especially in the late part of the period. However, it is a little misleading to say that because even as climates became cooler and drier, coal-forming continued. It was just composed of a different percentage of plant types, leaning more toward those that thrived under cooler and drier conditions.

It has been said that the Pennsylvanian/Carboniferous ended without a mass extinction. I don't really know what marks the end but it is apparently seen clearly in the nonmarine rocks in Perm, Russia, from which the Permian gets its name. I assume it's a noticeable drop in coal content.

The other thing said about the Carboniferous especially recently is that it was a time of high oxygen levels in the atmosphere perhaps reaching 35% by the end of the period. This significantly higher than the level of 21% we live with now. The higher oxygen levels are said to explain the unusually-large land arthropods of the time (seagull-sized dragonflies, baseball mitt-sized spiders, and human-sized millipedes).

- end of Pennsylvanian Period summary

I read that Wikipedia page. It is different from what I've read in that it notes an extinction event within the Late Carboniferous that is significant but not severe enough to be considered a mass extinction, a "collapse" being the term evidently. Previously, the climatic shift from warmer/wetter to cooler/drier was stated as step-by-step though that was always qualified by words to the effect of "pending further analysis." It appears recent research over the past 5-10 years has produced more detailed information about the shift that would culminate with the mass extinction at the end of the Permian.

Having said that, it seems like that page was written by one Wikipedia editor and would be therefore one opinion expressed. Someone reading all those cited articles might draw a somewhat different conclusion of the "collapse." We would have to read it all and then see what else has been written on the subject.

It would be interesting if someone wrote a book just about the Carboniferous. It should be geared to the mainstream but still have enough detail to be useful to students. It would discuss how our understanding of the time developed and what the prevailing opinions are now plus what the critics point out. It would also talk about the stages of evolution of the various groups of organisms as well as the positions of the continents. It would be an education for those who collect fossils of that time anywhere in the world and perhaps even help those who collect Permian fossils to some extent or those who wonder about how the world ramped up to the Permian mass extinction.

Jess

[Auspex]

Coal formation has continued through the ages, but the massive, extensive coal beds that formed from the luxuriant Carboniferous forests are never again equaled. This may be due in part to lower production of plant matter overall, and in part due to less of it being buried rapidly, but I think that a major reason was the evolution of organisms capable of breaking down lignin. This also profoundly altered the carbon cycle, with much more being cycled back into the atmosphere through the activity of the new microbes. The traces of these events can be correlated, globally, and within the time frame.

[FossilDAWG]

Coal formation has continued through the ages, but the massive, extensive coal beds that formed from the luxuriant Carboniferous forests are never again equaled. This may be due in part to lower production of plant matter overall, and in part due to less of it being buried rapidly, but I think that a major reason was the evolution of organisms capable of breaking down lignin. This also profoundly altered the carbon cycle, with much more being cycled back into the atmosphere through the activity of the new microbes. The traces of these events can be correlated, globally, and within the time frame.

Indeed, the end of the Carboniferous has been found to coincide with the evolution of "white rot fungi" with the ability to degrade lignin. Up to that point, woody material accumulated faster than existing decay processes could remove it, and large coal beds resulted. After white rot fungi evolved lignin-degrading enzymes, wood would rot except in special circumstances where it was buried quickly, so coal deposits became much less frequent.

Don

[Missourian]

In my corner of the Pennsylvanian world, at least, the decline of coal deposits seems to coincide with an increase in marine limestone (Moscovian-Kasimovian transition). I've figured these changes were due to a long-term trend in sea level rise caused by a warming climate (less glaciation in Gondwana) leaving less 'real estate' on the platform for forests to have a chance to become established. But as hinted in the posts above, the amount of coal is not necessarily proportional to the extent of forests. Depending on the circumstances of climate, sedimentation and erosion (and biology?), forests could have spread, flourished, died off and had all traces removed before they had a chance to be preserved.

Edited July 14, 2014 by Missourian

[Stocksdale]

Thanks for the info. I think one problem with the wikipedia page is that it didn't distinguish between a short event at about 305 mya and the larger Carboniferous/Permian transition that occurred from 309 mya to early Permian 295 mya or so.

I tweaked the intro to the wikipedia article to clarify that a little.

Edited July 14, 2014 by Stocksdale

[siteseer]

There are huge Paleocene coal deposits in just the Powder River Basin of Wyoming, reported to exceed even the coal resources of Illinois. During the Paleocene and into the Early Eocene, dense forests covered much of North America (from New Mexico to Alaska and northernmost Canada) and Eurasia. The western beds are often many times thicker (70-225 feet thick), closer to the surface, and lower in sulfur (cleaner-burning). There are also significant Late Cretaceous coal beds in Utah, Colorado, and New Mexico. Alaska's potential was still under study the last time I read about it. It has Pennsylvanian coal as well but most of its deposits range from Late Cretaceous to Early Cenozoic.

Coal mining around Price, Utah has uncovered tyrannosaur tracks. There is a nice little museum in town that includes an unexpected exhibit of tar pit fossils from Los Angeles.

Jess

Coal formation has continued through the ages, but the massive, extensive coal beds that formed from the luxuriant Carboniferous forests are never again equaled. This may be due in part to lower production of plant matter overall, and in part due to less of it being buried rapidly, but I think that a major reason was the evolution of organisms capable of breaking down lignin. This also profoundly altered the carbon cycle, with much more being cycled back into the atmosphere through the activity of the new microbes. The traces of these events can be correlated, globally, and within the time frame.