Researchers at the University of Illinois, in the United States, have found a tiny fossilized insect 50 million years old with your genital capsule, called pytophore and with the length of a grain of rice, unusually well preserved, as published in the journal “Papers in Palaeontology”.
The scientists note that it is remarkable because the insect’s physical characteristics, from the pattern of bold bands on its legs to the internal features of its genitalia, are clearly visible and they are well preserved.
Recovered from the Green River Formation in present-day Colorado, the fossil represents a new genus and species of predatory insects known as “killer insects”.
They found him with his genital capsule, called a pytophore and the length of a grain of rice, unusually well preserved (DPA).
Discovered in 2006 by breaking a slab of rock, the fossilized insect divided almost perfectly from head to abdomen. The fracture also split the pytophore in two. Later, a fossil trader sold each half to a different collector, and the researchers located and assembled them for this study.
Being able to see an insect’s genitalia is very helpful when trying to determine the place of a fossil insect in your family tree, explains Sam Heads, a paleontologist with the Illinois Natural History Study and an expert on fossil insect genitalia.
Species are often defined by their ability to successfully mate with each other, and small differences in genitalia can lead to sexual incompatibilities that, over time, can result in the emergence of new species, Swanson notes. AND
This makes the genitalia a good place to focus for determining an insect species.
The insect’s physical features, from the bold band pattern on its legs to the internal features of its genitalia, are clearly visible and well preserved (DPA).
But such structures are often hidden in compression fossils like those of the Green River Formation. “Seeing these fine structures in the internal genitalia is a rare pleasure (Swanson acknowledges). Normally, we only get this level of detail in species that currently live“.
Structures visible within the pytophore include the basal plate, a hardened stirrup-like structure that supports the phallus, he explains. The fossil also preserved the outlines of the falothek, a pocket into which the phallus can be removed.
The finding suggests that the banded assassin bugs, a group to which the new specimen is believed to belong, are about 25 million years older than previously thought, Swanson notes.
About 7,000 species of assassin insects have been described, but only about 50 fossils of these insects (DPA) are known.
“About 7,000 species of assassin insects have been described, but only about 50 fossils of these insects (Add). This only speaks of the improbability of having a fossil, much less one of this age, that offers so much information. “
However, these are not the oldest fossil insect genitalia ever discovered. “The oldest known arthropod genitalia are of a type of insect known as a gatherer that has between 400 and 412 million years, from the Rhynie Chert of Scotland (remember Heads). And there are also numerous fossil insects in amber as old as the Cretaceous Period with preserved genitalia, but it is almost unheard of for internal male genitalia to be preserved in carbonaceous compressions like ours. “
The researchers named the new assassin bug “Aphelicophontes danjuddi.” The name comes from one of the fossil collectors, Dan Judd, who donated his half of the specimen to INHS for study.
Europa Press.
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