I finally figured out what topic I'd use for a thesis if I went back to finish my education, and, of course, what my major would be. The latter: paleobiology, with a minor in paleontology. The topic: evidence of paleofires (natural fire) as indicators of the possible contemporary presence of amphibian fossils.

The region of study would cover Gondwanaland, one of two paleosupercontinents (the other was Laurasia, making up the modern supercontinent of Eurasia) making up the hyperpaleocontinent of Pangaea. The time would be the Permo-Triassic boundary, at the time of the greatest mass extinction Earth has ever known. As for why paleoamphibians and paleofires, the answer is as follows:

Amphibians first emerged during the late Devonian, around 400 million years ago. They have survived every single mass extinction event since. The question is, how? Of all terrestrial vertebrates, amphibians are the most vulnerable to certain adverse environmental conditions, for they must lay their eggs in freshwater, and live near a source of relatively clean freshwater in order to keep their skins moist at all times. If the water sources available to them are too toxic, too warm, too cold, etc., and air quality is low, their tadpoles will die or simply never hatch, and adult amphibians will struggle and then succumb to one or another environmental insult. Amphibia usually don't have long lifetimes, and they reproduce every year, so if environmental insults persist over a period of more than a year or two, they will become extinct in that area.

During the End-Permian crisis, 250 million years ago, the oxygen content of Earth's atmosphere dropped to very low levels. It was extremely hot throughout the world, much hotter than our world today. The center of Gondwanaland dried out almost completely due to receiving almost no rainfall -- far from coastlines, it was starved of life-giving ocean rains, and the increasing heat of that world baked everything dry in the endless drought. The coasts were no better, but for a different reason: the oceanic shallows had become Canfield Oceans filled with sulfur-emitting purple and methanogenic green bacteria, and the vast tonnages of hydrogen sulfide released by the purple bacteria filled the coastal air, killing off virtually everything nearby. Amphibians couldn't persist near the coasts -- they needed freshwater, and saltwater would have killed them and their eggs, as would all that hydrogen sulfide. But the ten-thousand year drought at the center of Gondwanaland meant that there was nothing for them there, either. So where did they survive in that deadly world? (As for Laurasia, it was busy being covered over with vast flood basalts erupting from an area that is now Siberia, the air above it so filled with toxic volcanic gases that between those gases, the greenhouse effect they generated, and volcanic heat, amphibians couldn't have done very well there, either.)

Obviously those ancient amphibia survived somewhere in that hellish world -- their descendants are with us today. So, where?

There was another sort of creature back then that could only survive in an environment where amphibia would at least have had a chance: fire. That was, of course, lightning-caused fire, or the rarer fires started by molten lava outpoured from volcanoes that encountered brush or forests on their way downhill. Fires leave traces in the form of charcoal and damaged fossil sites, traces that can be dated using modern radiodating techniques. Like living creatures of the normal sort, fire requires certain things to exist: oxygen, an absence of water (try starting a normal fire underwater with a match!), and plenty of organic material in the form of, e.g., brush, trees, herbs and forbs, petroleum, natural gas, coal, animal fats, animal carcasses, and so on. In turn, that organic material requires water for its creation -- trees and brush die without it, petroleum came from the tissues of once-living creatures that required water for life, and so on. And that means that you aren't likely to find the fossils of amphibia or just about any other animal in areas where there never were any fires. Of course, even where there is fire, that doesn't automatically mean that there were any animals there at the same time, amphibians or any others. But where fire can't live, for lack of water, animals can't, either. Conversely, in an area where fire struck relatively frequently, there had to be plenty of water to feed the plants and other creatures that provided the fire-fodder. Among such sites is where fossils of amphibians can be found -- not in all, probably not even in most, but their fossils will only be found in areas where fire was nurtured by plants bathed in fresh water. Plants don't do all the well in an atmosphere replete with hydrogen sulfide and/or methane, either, so sites where such atmospheric conditions held would not be likely to show fossil traces of paleofires -- or those of animals, especially amphibia.

Thus by looking at transits -- lines or areas of study taken over this or that site -- for places where traces of paleofire can be found, one is likely to find that at least some of those transits also include fossils of amphibians. The biomarkers that indicate paleofire should be indicative of areas where fossils of amphibia would be more likely to be found than other places. Draw a line from the heart of Gondwanaland to a point on any of its coastlines at time tvx and start hunting for traces of paleofires. Where you find those, start looking for the fossils of amphibians. Then draw another such line, and try there. Shift the time interval of a transit by a thousand or ten thousand years one way or the other and look again. Hypothesis: where there are traces of paleofires during any given slice of time, among such sites are places where fossils of amphibians will be found. Proving that out would be a long tedious process, of course, and it might turn out to be entirely wrong, but it's the proposal of a thesis topic and the proving out that's important, and the results are icing on the cake.

Why is this important? Well, mass extinctions involving radical global warming events, such as the Permo-Triassic crisis, took place over the whole of the Earth. If something survived them, it did so by luck -- you can't adapt to such an event, because life adjusts to the long predictable haul, not the extreme and short, conditions that can't be predicted in advance. So you either have a bolt-hole to hide in successfully from whatever horrors are taking place elsewhere, or you are a victim of those same horrors. And that applies to species and higher taxa as well as to individuals. And because amphibia are so vulnerable to environmental conditions, if they could survive such an event, which lasted anywhere from ten thousand to a million years, so could many other creatures that weren't nearly as vulnerable. So where and how did they survive to help repopulate the Earth? Looking for traces of paleofires just might go a long way to help answer that question.