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Western professor assists in research of trilobites

Robby Barlow

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A discovery shaping future research about the characteristics of trilobite reproduction has been made; thanks to the contributions and research from Thomas A. Hegna, Marcus J. Martin and Simon A.F. Darroch.

Hegna, an assistant professor of geology at Western Illinois University, helped on this research team to shed light on the subject of trilobite reproduction.

In upstate New York, a rare fossil of a trilobite with the ventral part of the body was found intact. The researchers were able to spot what looked like eggs in the ventral part of the body, suggesting that trilobites would brood their young before hatching.

“The discovery was made by Marcus Martin about two years ago,” Hegna said. “He is an amateur paleontologist who found the fossils in upstate New York near Watertown. Simon A.F. Darroch is a professor at Vanderbilt University and he was the one responsible for the computed tomography (CT) scanning of the fossils.”

Hegna said that the trilobite fossils the research team found had characteristics that let them know they were going to be useful towards their research.

“The fossils are ordovician in age, which means they are about 450 million years old,” Hegna said. “They were found in a black shale and the fossils themselves are replaced with pyrite. Pyrite is fool’s gold, so they are very distinctive when you see them.

“From these localities, the species triarthrus eatoni has been known for well over 100 years. What’s unique about the fossils that we found is that they have the eggs associated with the trilobite; that suggests that the trilobite may have been brooding it’s young,” Hegna said. “It’s something that other arthropods do as well, they keep the eggs with them, carry them around while the eggs finish developing before they hatch, and then go off on their own.”

Hegna then mentioned that the the way that they went about their research focused on the fact that the ventral body was intact, something that people hadn’t been able to find before.

“Also, from this locality are known examples of trilobites with preserved appendages. Trilobites are marine arthropods and they have an exoskeleton,” Hegna said. “The dorsal part of the exoskeleton is mineralized. The ventral part is soft, much more like an insect, and as a result for the first hundred years the people are finding trilobites they did not know what the ventral part was like, what their legs were like. This is one of the first places that they were able to discover legs from.”

For the research team, these findings were what made it possible for them to look into the reproductive qualities of trilobites.

“The main part of the research has been kind of justifying our initial assumptions,” Hegna said. “When we first saw the fossils, our first gut reaction was that yeah these are eggs, but what we wanted to do was be very careful before we publish that and try to rule out any other hypothesis that they could (be), and I think that we were able to effectively do that in the paper that we published.”

According to Hegna, this newfound data will help to aid in the understanding of some of the first creatures to inhabit earth.

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Western professor assists in research of trilobites