50 Million-Year-Old Assassin Bug Fossil Has Oddly Preserved Genitalia

A fossil of a 4mm Cretaceous assassin bugWhen it comes to fossils dating back to many million years ago, each and every one matters, as it helps scientists understand how species we formed and later evolved. That’s why when a 50 million-year-old assassin bug fossil was uncovered in Green River Formation (present-day Colorado) with unusually well-preserved genitalia, archeologists had to investigate.

The Assassin Bug Fossil Is One of Its Kind

The fossilized assassin bug found in Colorado is the only one of its genus to have fully preserved physical characteristics. From the internal features of its genital capsule (known as a pygophore) to the bold banding pattern on its leg, this predatory insect was a remarkable discovery for scientists.

The newly discovered assassin bug species with its intact genitalia, the Aphelicophontes danjuddiNot Exactly a New Find

Although archeologists were able to study the fossil just recently, it was first discovered in 2006 while breaking open a slab of rock. When that happened, the fossil split in two, from head to abdomen, fracturing the pygophore in two perfect halves. The two halves were then sold by a fossil dealer to two separate collectors. It took a while for researchers to track them down and reunite the amber halves for the study.

The Significance of the Study

Although it may be difficult for an outsider to understand the importance of looking at ancient bug’s genitalia, it’s actually an important part of learning about species development. Paleontologist Sam Heads who led the research said that studying the pygophore of an insect helps scientists determine its place in the family tree. That is crucial in tracking differences in genitalia because sexual incompatibilities often result in the rise of new species. The compression fossil of the assassin bug is a rare find as it had retained the basal plate and the contours of the phallotheca.

The main lesson from this study so far has been that the new insect specimen is actually 25 million years older than insects of this group were previously thought to be. That’s a major find from such a small fossil. Who knows what else Heads and his team are yet to uncover from it?