Science & Technology

Unusually Well-Preserved Genitalia on 50 Million-Year-Old Fossil Assassin Bug

Recovered from the Inexperienced River Formation in present-day Colorado, this fossil represents a brand new genus and species of predatory bugs referred to as murderer bugs. Researchers named the specimen Aphelicophontes danjuddi. A small beetle was additionally fossilized with the specimen. Credit score: Picture courtesy Palaeontological Affiliation

The fossilized insect is tiny and its genital capsule, known as a pygophore, is roughly the size of a grain of rice. It’s exceptional, scientists say, as a result of the bug’s bodily traits — from the daring banding sample on its legs to the interior options of its genitalia — are clearly seen and well-preserved. Recovered from the Inexperienced River Formation in present-day Colorado, the fossil represents a brand new genus and species of predatory bugs referred to as murderer bugs.

The discover is reported within the journal Papers in Palaeontology.

Illinois Pure Historical past Survey paleontologist Sam Heads co-led the research of a very well-preserved 50 million-year-old fossil insect. Credit score: Photograph by L. Brian Stauffer

Found in 2006 by breaking open a slab of rock, the fossilized bug cut up virtually completely from head to stomach. The fracture additionally cracked the pygophore in two. A fossil vendor later bought every half to a distinct collector, and the researchers tracked them down and reunited them for this research.

With the ability to see a bug’s genitalia may be very useful when making an attempt to find out a fossil insect’s place in its household tree, mentioned Sam Heads, a paleontologist on the Illinois Pure Historical past Survey and self-described fossil insect-genitalia skilled who led the analysis with Daniel Swanson, a graduate scholar in entomology on the College of Illinois Urbana-Champaign.

Species are sometimes outlined by their potential to efficiently mate with each other, and small variations in genitalia can result in sexual incompatibilities that, over time, could end result within the rise of recent species, Swanson mentioned. This makes the genitalia a very good place to focus to find out an insect species.

However such buildings are sometimes obscured in compression fossils like these from the Inexperienced River Formation.

“To see these high quality buildings within the inside genitalia is a uncommon deal with,” Swanson mentioned. “Usually, we solely get this stage of element in species which might be dwelling right now.”

The buildings seen throughout the pygophore embrace the basal plate, a hardened, stirrup-shaped construction that helps the phallus, he mentioned. The fossil additionally preserved the contours of the phallotheca, a pouch into which the phallus may be withdrawn.

U. of I. entomology graduate scholar Daniel Swanson co-led the analysis on an historic murderer bug fossil. Credit score: Photograph by L. Brian Stauffer

The discover means that the banded murderer bugs, a gaggle to which the brand new specimen is believed to belong, are about 25 million years older than beforehand thought, Swanson mentioned.

“There are about 7,000 species of murderer bug described, however solely about 50 fossils of those bugs are recognized,” he mentioned. “This simply speaks to the improbability of even having a fossil, not to mention one among this age, that gives this a lot info.”

This isn’t the oldest fossil bug genitalia ever found, nevertheless.

“The oldest recognized arthropod genitalia are from a sort of bug referred to as a harvestman that’s 400-412 million years previous, from the Rhynie Chert of Scotland,” Heads mentioned. “And there are additionally quite a few fossil bugs in amber as previous because the Cretaceous Interval with genitalia preserved.

“Nevertheless, it’s virtually extraordinary for inside male genitalia to be preserved in carbonaceous compressions like ours,” he mentioned.

The researchers named the brand new murderer bug Aphelicophontes danjuddi. The species title comes from one of many fossil collectors, Dan Judd, who donated his half of the specimen to the INHS for research.

Reference: “A brand new remarkably preserved fossil murderer bug (Insecta, Heteroptera, Reduviidae) from the Eocene Inexperienced River Formation of Colorado” by Daniel R. Swanson, Sam W. Heads, Steven J. Taylor and Yinan Wang, 19 January 2021, Papers in Paleontology.
DOI: 10.1002/spp2.1349

The INHS is a division of the Prairie Analysis Institute on the U. of I.

The Nationwide Science Basis supported this work.

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