Giant insects can be found in a handful of science fiction movies and many comic books, but have these ever existed? Based on paleontological findings as well as studies that have been done in the past, these human-sized insects once existed and they were the first form of life to widespread across Earth.
HeritageDaily has presented an article where they give examples of different giant insects that have once ruled the world based on discoveries of their existence. This article has refreshed the debate on how reliable this theory of giant insects actually is.
One of the more plausible scientific theories given on the existence of giant insects had been mentioned in a study from 2012 conducted by biologists from the University of New Mexico. The study focused on brilliant discoveries such as the wings of flying insects with a span as long as 28 inches (70 centimeters).
The study was not based on only one discovery, but a dataset that analyzed over 10,500 fossil insects that had an abnormal size or at least 10 times the size of present similar species. The main hypothesis of the study mentioned that giantism was at fault where the growth hormone within the organism cannot be stopped or slowed down, causing quick growth. This and also the high concentration of oxygen is needed for any organism to grow.
“Gigantism has been linked to hyperoxic conditions because oxygen concentration is a key physiological control on body size, particularly in groups like flying insects that have high metabolic oxygen demands.” (Author Matthew E. Clapham)
Most of the fossils that have been discovered of giant insects have been dated about 300 million years old. What is interesting is that not all species of insects had the issue of giantism. Based on data gathered from the fossils discovered, Dragonfly (Meganeura Monyi) was very common with a wingspan close to 30 inches.
Another insect that grew to a very large size was the Arthropleura Armata or more commonly known as the centipede. This pre-historic species grew to a length of 8 feet. Two more floor-dwelling inspects were spiders and scorpions who were growing to a scary 28 inches long.
So if we have physical evidence of the existence of such giant insects, where are they today? This is a question asked by many scientists who say that it was the evolution of predatory birds that slowly lead these giant insect species to extinction. About 150 million years ago, predatory birds within the Jurassic era started to become the perfect hunters, not only for flying insects but also for those on the ground.
It was not only birds coming into the food chain but also a major drop in the levels of oxygen that affected the growth hormones within insects. This is a process that occurred during millions of years of evolution and due to the pre-historic age of these giant insects, it is difficult to accurately name the exact cause of their extinction.
Tim Stephens from the University of California argued that it could have been the biological instinct of the insects as organisms to survive, therefore evolving to a smaller size in order to hide from predatory animals.