The largest division of the geologic time scale is the _________________ eon true era false epoch false period false Single The Mesozoic Era was the Age of Reptiles, and the current Cenozoic Era is the Age of _____ birds false mammals true ice false humans false Single The _________ was an era dominated by the dinosaurs Precambrian false Paleozoic false Mesozoic true Cenozoic false Single The boundaries between _______ seem to coincide with major changes in the life forms present on Earth. Systems false Precambrian false Epochs false Eras true Single Fossils are most common in which rock types? igneous true sedimentary false metamorphic false all rocks false Single Which of the following is used by geologists to determine the relative ages in a rock sequence? fossils true stratigraphy false cross-cutting relationships false observation false Single What is the definition of Geologic Time Scale? Fossils of widely distributed organisms that lived during only one short period. false A record of the geologic events and life forms in Earth’s history true A fossil that is a copy of an organism’s shape, formed when minerals seep into a mold false Fossils of widely distributed organisms that lived during only one short period. false Single Known as the age of the mammals Mesozoic Era false Holocene Epoch false Cenozoic Era true Cambrian false Single Which shows the correct order of Geologic Time units from longest to shortest? Eon - Period - Epoch - Era false Era - Epoch - Eon - Period false Eon - Era - Period - Epoch true Period - Eon - Epoch - Era false Single Which time period is the longest? Precambrian Time true Paleozoic Era false Mesozoic Era false  Cenozoic Era false Single