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100 Million Year Old Amber Tells the Story of a Unique Hunting Method

During evolution, predatory animal species developed various mechanisms used for hunting and processing the prey. Our biologist Petr Kočárek from the Faculty of Sciences of the University of Ostrava discovered and described a unique method of hunting for prey developed in an extinct insect species that lived a hundred million years ago.

A surprising discovery took place this year. An international team of scientists discovered the unknown bizarre-looking extinct insect species, Caputoraptor elegans, which is one of the least known and most mysterious insect order – Alienoptera. This order was first described in 2016 and only three species are known so far, all based on a description of fossils from 98.8 million years old Burmese amber. It is an insect allied to the praying mantises and cockroaches that became extinct at the end of the Mesozoic Period.

The team of authors that described Caputoraptor elegans discovered and described a special apparatus that consists of a cephalo-thoracic serrated part that falls into place. The authors suggested several theories about the possible meaning of this apparatus and they state that the most likely explanation is for grabbing the male’s back during copulation. However, our biologist Petr Kočárek reached a different conclusion based on the finding of the male and studying this special cephalo-thoracic apparatus in detail, which he published in the August edition of Current Biology.

“As the apparatus is found in both sexes and also in nymphs, its originally proposed function is highly unlikely. However, the other newly described structures on the head, chest and legs might have been used for holding the prey which was locked in and clamped. The serrated parts of the chest caused deep wounds, out of which hemolymph poured out. It was probably captured by the hairy parts of the legs and led to the underdeveloped mandibles, not capable of crushing the prey, through the groove-like cavities in the bottom part of the head. The prey was probably other small insect, most likely the nymphs of some herbivore insect, or aphids, but we can only speculate about that,” Petr Kočárek describes the results of his research, within which he proposed and documented the likely method of hunting in this extinct species. And he adds: “The cephalo-thoracic catching apparatus of Caputoraptor elegans was probably a blind branch of evolution. We do not know what prey it used to catch and we won’t probably find that out, but it was definitely a highly specialised hunting method, probably of a special type of prey. Exclusive specialisation usually works well and can even be highly successful, but only in a stable environment and under the given circumstances. When the conditions change, exclusive specialisation usually leads to extinction because the “over-specialised” organs have low adaptability.”

If it weren’t for the few individuals caught up in the sticky resin, out of which amber was created after millions of years of fossilisation, we would have never learned of this interesting hunting method. However, the story of Caputoraptor did not last long. “It was one of the many “trials” of evolution that dealt with the challenge in the form of a new prey in an original way. This unique mechanism was most likely successful for some time, until it was driven out by more functional and simpler methods,” Petr Kočárek concludes this story of an unsuccessful evolutionary experiment.

Updated: 27. 09. 2018

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