LiveScience has a piece about the extinction of the trilobites. Trilobites existed on Earth for about 270 million years from the early Cambrian until the Permian Mass Extinction. Many organisms went extinct during that time... perhaps upward of 90% of species. But, it's still an open question that has not been completely answered. During their heyday in the Cambrian and Ordovician, their genera consisted of 10 orders. But, by the Permian, after making it through a couple mass extinctions, they had dwindled to just one family, the Proetidae. Were they out competed by other animals? Probably. But was that the whole story? Other arthropods had flourished. What was their fatal flaw?
Trilobites are weird creatures — they look like giant swimming potato bugs wearing helmets, and lived on Earth for a whopping 270 million years. These armored invertebrates, whose species once numbered in the thousands, thrived in the oceans as they scavenged and dug for food, and even managed to survive two mass extinctions.
But about 252 million years ago, trilobites disappeared from the fossil record. What finally wiped out this class of resilient bottom dwellers?
The trilobite's disappearance coincided with the end-Permian extinction (also known as the Permian-Triassic extinction), the third and the most devastating mass extinction event. Volcanic eruptions in Siberia spewed enormous amounts of lava for around 2 million years, according to Melanie Hopkins, an associate curator of paleontology at the American Museum of Natural History in New York City. These fiery eruptions sent trillions of tons of carbon dioxide into the atmosphere, triggering ocean acidification, which in turn made it very difficult for marine animals to survive, according to a 2010 paper published in the journal Proceedings of the National Academy of Sciences. Up to 95% of marine species succumbed to the end-Permian extinction, also known as the Great Dying, including the trilobites.
