Extinction and Appearance Practice Test

A rock column has 5 fossil layers, ordered oldest to youngest: Layer 1, Layer 2, Layer 3, Layer 4, Layer 5. Fossils found: Layer 1: trilobite, fern. Layer 2: trilobite, fern, ammonite. Layer 3: fern, ammonite. Layer 4: fern. Layer 5: fern, mammal tooth. Fossils provide evidence of extinction and appearance because they show when organisms are present in some layers but not others. Which evidence from these layers best supports that the trilobite became extinct in this area after Layer 2?

A rock column has 5 fossil layers, ordered oldest to youngest: Layer 1–Layer 5. Fossils found: Layer 1: brachiopod. Layer 2: brachiopod, sponge. Layer 3: sponge. Layer 4: sponge. Layer 5: sponge, bird bone. Fossils provide evidence of extinction and appearance because they show last occurrences and first appearances in the fossil record. A student claims: “The brachiopod is extinct in this area after Layer 2.” Which piece of evidence best supports the student’s claim while also recognizing that absence alone is not the same as extinction everywhere?