(ORDO NEWS) — Cannibalism, that is, eating individuals of one’s own species, is a very ancient phenomenon, but it is not entirely clear when exactly it first arose.
Paleontologists have studied the remains of large trilobites from Australia and found that they were cannibals already 514 million years ago.
Cannibalism is not uncommon among modern animals – there are many cases, for example, among insects: praying mantises, termites, mosquitoes and more.
However, little is known about the first cannibals in the history of the Earth – after all, we can judge such eating habits mainly by indirect signs, which, moreover, should be well preserved.
Until recently, the oldest case of cannibalism was attributed to the end of the Ordovician period, about 450 million years ago.
However, a new study has shown that trilobites, who lived in the Cambrian 514 million years ago, began to eat their own kind.
The best evidence of cannibalism is found in the digestive tract of a member of the same species X. However, such finds are very rare.
At the same time, Emu Bay, a fossil-rich location on Australia’s Kangaroo Island, has evidence of a different sort of cannibalism.
Many well-preserved trilobites were found here, which allowed scientists to figure out who and whom they ate at the beginning of the Paleozoic era.
Recall: trilobites are a vast class of arthropods that flooded the seas in the Paleozoic era and completely died out at its end. These creatures look a bit like wood lice, as they also had a segmented hard exoskeleton.
If predators attacked the ancient trilobite, but managed to escape from them, then bite marks and other injuries remained on its body.
It was these findings that attracted the attention of Russell Bicknell, a paleontologist at the University of New England (Australia). He studied two trilobite species from Emu Bay: Redlichia takooensis and Redlichia rex.
The specific epithet “rex” (“king”) is assigned to the second trilobite due to its impressive appearance and size. R. rex was one of the largest trilobites of its time, reaching over 25 centimeters in length.
In total, Dr. Bicknell examined 38 specimens belonging to two species of Redlichia sp . Some of them he collected himself, others he borrowed from museum collections.
The scientist paid special attention to the injuries that the animals received during their lifetime – with their help, he tried to understand who the attacker of the ancient trilobites was.
It turned out that among the trilobites with healed wounds (that is, those that lived after the attack), large specimens predominate.
Sometimes not just large, but superior in size to their offenders. At the same time, there were no small wounded trilobites, for which the scientists found one unflattering explanation.
It was fully confirmed after paleontologists drew attention to the fossilized feces of the same animals – the so-called coprolites.
Emu Bay trilobite coprolites were found to be large, at least 10 percent of their body size. But the most important discovery was their contents – fragments of exoskeletons of the same Redlichia species , including the “king trilobite”.
“Anything smaller than them, they ate and turned into these charming coprolites,” says Dr. Bicknell. “Everything bigger than them remained bitten, but still could escape.”
In addition, it turned out that trilobites preferred to attack each other from behind – in the front of their body, injuries are half as common.
The scientist suggests that the aggressor in this case was again R. rex . This whole story inspires Dr. Bicknell to compare the object of his research with a “horse crab on steroids” and to suggest that during his lifetime, the “king of trilobites” crawled along the bottom of the Cambrian seas, attacked small victims and at the same time did not disdain his own young.
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