Keywords: fossils yellowstone national park yellowstonenationalpark trilobites USNM_61523: Dated about 500 million years old and collected from the Pilgrim Limestone in Yellowstone National Park, is type trilobite Tricrepicephalus yellowstonensis (USNM 61523). This particular species is just one of over 20,000 described trilobite specimens in the fossil record. Every year new species of trilobites are being discovered all over the world. Collecting any natural resources, including rocks and fossils, is illegal in Yellowstone. Photo by Megan Norr; March 2016; Catalog #20795d; Original # USNM_61523 USNM_61523: Dated about 500 million years old and collected from the Pilgrim Limestone in Yellowstone National Park, is type trilobite Tricrepicephalus yellowstonensis (USNM 61523). This particular species is just one of over 20,000 described trilobite specimens in the fossil record. Every year new species of trilobites are being discovered all over the world. Collecting any natural resources, including rocks and fossils, is illegal in Yellowstone. Photo by Megan Norr; March 2016; Catalog #20795d; Original # USNM_61523 |