2/16/2024 0 Comments Secret world digging deeper bug![]() Their massive bodies might have made them more powerful fighters, or made them too big to be considered feasible prey. For example, some insect biologists favor the idea that giant Paleozoic insects were successful because they were less likely to be eaten. Ecological factors also could explain the pattern of prehistoric gigantism. If so, giant species could have maximized their ability to breathe even in low oxygen environments. Paleozoic insects may have been able to use other mechanisms, such as respiratory pumps, to increase airflow in their tracheae. “Obviously, there are other environmental or ecological reasons for gigantism and gigantism gone extinct,” he adds. In these groups, evolution has not been linked to atmospheric oxygen levels, Harrison explains. Some well-known examples are the dinosaurs and the elephant-like mastodons of the Pleistocene era. “There has been a lot of ‘gigantism gone extinct’ in other groups,” he explains. But until he and others produce the necessary data, Harrison’s good scientific sense requires him to consider other possible explanations. “Our work is important because it is the first research I am aware of to experimentally test this hypothesis,” he says. Harrison and his students are contributing to the effort. The image in the upper right is the size of a modern day dragonfly. This insect genus lived 300 million years ago and could have wingspans up to 2 feet. Scientists have found fossil records of giant insects related to dragonflies. A convincing test of the oxygen pulse hypothesis will depend on evidence from studies on many of these insects. As a result, biologists are forced to study the next best thing: related insects still alive and crawling and flying today. There are no living giant insects, or fossils of their tracheae. Harrison points out that while there is good evidence to support the hypothesis that a prehistoric pulse in oxygen caused evolution of giant insect, there is no direct evidence. Scientists often consider several explanations for a puzzling observation like super-sized insects. What Else Could Explain the Missing Giants? The extinction of winged monsters and ginormous beetles after 100 million years may also be the result of decreased levels of oxygen that happened at the same time. They hypothesize that high oxygen levels could explain the existence of giant species. Harrison and other biologists propose that this was more than just coincidence. Interestingly, the rise and fall of atmospheric oxygen also coincided with the evolution and extinction of giant insects. During this period, the oxygen concentration in the air reached 35 percent, almost double the present level of 21 percent. In other words, there was much more oxygen in the atmosphere 300 million years ago than there is today. Recent geologic findings indicate that there was a “pulse” in the concentration of environmental oxygen during the Paleozoic era. Soon after the giant insects disappeared.īefore the dinosaurs, giant insects ruled the world more than 300 million years ago. All of this was happening just when the first dinosaurs appeared. Hundreds of different huge species evolved during the late Paleozoic era. At the same time, mammoth millipedes longer than a human leg skittered across prehistoric soil. Scientists know that dragonflies with wing spans as wide as a hawk’s and cockroaches big enough to take on house cats lived during the Paleozoic era (245-570 million years ago). How do we know?įossils hold the evidence. They were not as big as dump trucks, but some were many times greater in size than those of their modern relatives. However, insects of giant proportions really did exist 300 million years ago. These enormous insects depicted in bad B movies exist mostly in the realm of science fiction. Is this a fantastic headline, or could we see giant insects today? It's not likely, but for years movies have used these mythical images to scare and entertain millions. Bloodthirsty cockroaches plot to destroy humans! Scientists use fossil DNA to build gigantic man-eating ants! Super-sized alien flies invade Earth!
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