Trilobites are popular enough fossils that they even have their own alliterative hashtag-day on Twitter, and that happens to be today.
This little critter was photographed at the Minnesota Science Museum. The species is known as Selenopeltis buchii (pretty sure there’s a typo in the actual label on it based on a bit of detective work). This line of trilobites is characterized by the distinct spines that protrude from the main body segments.
One of the more interesting features of paleontology is how much work there is still to be done to understand creatures like this. Paleontologists have become really good, over a period of centuries, at grouping together organisms like this based on the presence or absence of certain features, but it’s only in the last couple decades that they have focused on putting them in an evolutionary context.
Groups of trilobites would have just been put together based on presence or absence of these features, but the underlying evolution is a hugely important step. Understanding which features came first is key to unraveling the history of life and will help scientists understand what the purpose of these features actually was. They could have been defensive, they could have been for finding food, they could have been for motion or protection against currents, and they could just have helped the creatures avoid sinking in the mud.
This particular specimen probably lived around 500 million years ago, close to the boundary between the Cambrian and the Ordovician.