(ORDO NEWS) — Paleontologists have studied the head processes of the unusual trilobite Walliserops, which lived more than 400 million years ago.
It seems that he hardly needed this tool for survival, but could be used in fights for the right to mate with a female.
Males of many modern animal species fight each other, vying for the right to mate and leave offspring. Such behavior may have extremely ancient roots, going back almost half a billion years.
The team of Richard Fortey examined the fossils of trilobites of the genus Walliserops , extinct arthropods that were extremely common in the seas of the Paleozoic period.
The head segment of Walliserops was equipped with a fairly large outgrowth, the shape of which resembles a trident. The function of this weapon is still unclear.
There are hypotheses according to which the trident was used for burrowing into soft ground at the bottom, for hunting, either for protection from predators, or in battles between males.
Professor Forti and his colleagues found new evidence in favor of the latest version by studying an unusual Walliserops specimen stored in a museum in Houston (USA).
The uniqueness of this sample is that the “head process” of the trilobite ends not with three, but with four teeth at once. No other similar fossils have yet been found.
Scientists noticed that all four teeth are the same, they do not show noticeable damage. This suggests that such a structure was not the result of trauma, but appeared as a result of a developmental disorder.
Since the trilobite had reached adult size, the defect was not too severe and did not affect the animal’s chances of survival.
Based on this, the authors concluded that the trident was unlikely to have been necessary for defense, food production, and other tasks directly related to survival.
Therefore, its function could be to compete for a female, like the antlers of the males of modern deer.
Some of them also suffer from antler developmental disorders, which does not affect their survival, but reduces the chances of leaving offspring.
However, scientists themselves draw parallels between the tridents of Walliserops and the tools used by rhinoceros beetles ( Dynastinae ).
The shape of the horns of some of them really resembles the head processes of ancient trilobites, which may indicate a similar pattern of use.
Such beetles try to hook the opponent in order to throw and turn him over on his back.
Perhaps, fights between male trilobites also took place in a similar way. Although such a throw was unlikely to be lethal or dangerous to the opponent, it could well delay him, giving the winner enough time to mate.
If Richard Forte and his co-authors are right, then the Walliserops fossils give us the oldest known example of such fights in the process of sexual selection.
But then, as in other similar cases, these trilobites should have shown sexual dimorphism – a noticeable difference in the anatomical structure of males and females.
Most likely, the females were smaller and did not have tridents.
If this is true, then the female Walliserops must have been assigned to other groups of trilobites. Perhaps a closer examination of museum collections will reveal this, confirming the conclusions of paleontologists.
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