In 1870, while searching for fossils in Russia, Herkimer County, Charles Doolittle Walcott found more than 300 trilobite fossils, which he later sold to the Museum of Comparative Zoology, at Harvard University. Two decades later, William Valiant discovered the Beecher's Trilobite Bed, a sedimentary deposit of fossils, in Oneida County, in 1892. Soon after that, Charles Emerson Beecher started to excavate the place, finding many trilobite fossils, most of them of the species Triarthrus eatoni.
Canadian paleontologists discovered the world's largest entire trilobite fossil, in northern Manitoba, in 1998. While most trilobite fossils are 1 to 4 inches in length, the Manitoba's giant fossil was more than 27 inches long, and dated 445 million years. The fossil is now part of the paleontological collection of the Manitoba Museum, in Winnipeg.
Geology professor Mark McMenamin discovered trilobite fossils of the genus Paradoxides, in South Carolina, in 2002. He found many similarities between eastern Massachusetts and South Carolina fossils. This supports a continental drift rebound theory, the Wilson cycle theory, which says that ocean basins passed through several stages during the Earth's evolution, beginning with an initial opening, going through a widening stage and finally closing.
Artur Sa, researcher at the University of Tras-os-Montes and Alto Douro in northern Portugal, discovered giant trilobite fossils measuring 19.7 and 27.6 inches in length in 2008. They also found fossilized trilobite tails, which belonged to 35.4-inch-long animals. The discovered fossils were the species Ogyginus forteyi and Hungioides bohemicus, and lived 465 million years ago. Artur Sa also found evidence that trilobites were social animals, due to the cluster formation trilobites fossils commonly appear.