Credit...Sarah Losso
The New York Times Trilobites column has a story about trilobite reproduction. Trilobites first show up in the fossil record back in the Cambrian Period, some 500 million years ago. Their closest living relative is most likely the horseshoe crab. Now, a team of paleontologists from Harvard have published a paper in the journal Geology that looks into the sex lives of trilobites. They found that they used methods similar to their modern relatives.
A recently re-examined fossil from the Burgess Shale is pulling back the shroud of mystery over the ancient arthropods’ sex lives, and revealing that some trilobites most likely sported a loving grip. In a study published Friday in Geology, paleontologists at Harvard University identified a pair of modified appendages that probably helped males of one trilobite species grasp females during copulation in a similar manner to that of modern horseshoe crabs.
The team examined several spiny Olenoides serratus trilobites collected from the Cambrian site. Most were just under four inches long. While the Burgess Shale is known for its detailed preservation of even delicate tissue, one of the Olenoides specimens the team examined at the Royal Ontario Museum in Toronto looked more like a badly broken lobster tail than an intact trilobite.
“It’s a sad looking specimen — it’s missing most of the head and half of the body,” said Sarah Losso, a Ph.D. candidate at Harvard and an author of the study.
The fragmented nature of the specimen was a lucky break because it revealed the anatomy often hidden under a trilobite’s shell. Importantly, nine of the arthropod’s rarely fossilized appendages were preserved in detail. “There are millions of broken trilobites and you don’t see limbs in many of them,” said Javier Ortega-Hernández, a co-author on the new study and Ms. Losso’s Ph.D. adviser. “Having this specimen that is broken in just the right way that you can see these limbs is a one in a million sort of situation.”
