Question

in rock layers, jellyfish fossils are found lower than trilobite fossils, and trilobite fossils are found lower than ammonite fossils. what can be determined from this information?
trilobites existed before jellyfish and ammonites
jellyfish existed before trilobites and ammonites
ammonites existed before trilobites and jellyfish
jellyfish, trilobites, and ammonites lived together

Explanation:

Fossils in lower rock layers are older than those in upper layers. The problem states jellyfish fossils are lower than trilobite fossils (jellyfish older than trilobites) and trilobite fossils are lower than ammonite fossils (trilobites older than ammonites). Thus, jellyfish existed before both trilobites and ammonites.

Answer:

B. Jellyfish existed before trilobites and ammonites