USNM_35227 (pictured) and USNM_35225: Multiple trilobite fragments are fossilized in the same rock, these are commonly known as hash beds. "Hash" is an indicator of a near-shore environment, where waves could h More
USNM_35225 and USNM_35227: Pictured are multiple trilobite fragments fossilized in the same rock. These are commonly known as hash beds. "Hash" is an indicator of a near-shore environment, where waves could hav More
YELL-165706 and YELL-165715 (pictured here): Many times when fossils are collected they are only casts of the specimen, such as the pictures above of a few nearly complete Ptychopariid trilobite (YELL-165706 an More
USNM_35236: Charles D. Walcott, renowned invertebrate paleontologists, identified trilobite specimen Solenopleura? weedi (USNM 35236) from the Upper Cambrian (~500 million years ago) Pilgrim limestone in northw More
YELL-92020: This head of a roughly 520 million year old Ptychopariid trilobite (YELL-92020) is one among many identified from the Pilgrim Limestone, on Mt. Holmes in Yellowstone National Park. Trilobite order P More
Trace_Fossil_1: The photo shows burrows from possibly a trilobite. This sample was collected from the Park Shale in Yellowstone National Park during a field investigation on Mount Holmes back in 2001, in which More
YELL_134174 (1) and (2): These pictures show the second molar of a brontothere that was discovered in Yellowstone National Park in the late 1990s. The tooth is the black-colored part, while the jaw bone is the More
YELL-92017 and YELL-92024 (pictured here): Both the inarticulate (YELL-92017) and articulate brachiopods (YELL-92024) existed about 520 million years ago. The inarticulate was collected from the Park Shale, whi More
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 j More
USNM_96488: The trilobite Blountia polita (USNM 96488) (pictured) was discovered in the Middle Cambrian (~520 million years ago), Pilgrim Formation of Yellowstone National Park. As trilobites continued to evolv More
YELL_92933: Due to events and processes associated with the volcanic activity now preserved as the Absoraka Supergroup, there is a great concentration of petrified forests and fossilized leaves within Yellows More
YELL-165705: A small, Agnostid trilobite (YELL-165705) head is shown here. How did these little arthropods survive 500 million years ago? From their lack of eyes and poorly suited swimming body, scientists infe More
USNM_35218 (pictured here) and YELL-92021: Hyolithes gallatinensis (USNM 35218) was collected from the Snowy Range Formation and is now reposited at the Smithsonian National Museum of Natural History. Hyolitha More
USNM_90667: During the Cambrian period and throughout the Paleozoic era, an inland sea occupied the Greater Yellowstone area, unlike its present landscape of mountains, geysers, and rivers. Fossils, like this t More
YELL_94359: Rarely found within the park are fossilized cones that were produced from trees during the Eocene Epoch. Featured above is a well-preserved fossil cone of a Pinus macrolepis, collected in the Lamar More
YELL-92021 and USNM_35218: Hyolitha YELL-92021 (pictured) was collected from the Pilgrim Limestone and is housed with the Yellowstone collection. Hyolithes gallatinensis (USNM 35218) was collected from the Sn More
YELL-92017 (pictured here) and YELL-92024: Both the inarticulate (YELL-92017) and articulate brachiopods (YELL-92024) existed about 520 million years ago. The inarticulate was collected from the Park Shale, wh More
YELL-165706 (pictured) and YELL-165715: Many times when fossils are collected they are only casts of the specimen, such as these pictures of a few nearly complete Ptychopariid trilobite (YELL-165706 and YELL-16 More
2015 Mosaics in Science Program participant working on National Fossil Day materials at the Smithsonian National Museum of Natural History, Washington DC.