The Geologic Time Scale Flashcards
the third and last period of the Mesozoic, spanning from 145 mya to 66 mya; first appearance of flowering plants which resulted to insects’ evolution to pollinate them; Tyrannosaurus rex rawrawrawr
the Cretaceous Period
fun fact: Cretaceous comes from the Latin word “creta” which means chalk—it’s named for the large quantities of chalk rock laid down at this time in Western Europe; it ended at the Cretaceous-Paleogene Extinction Event (K-T/K-Pg) 66 mya, the last of the five major mass extinction events, which was caused by a massive asteroid, killing 75% of the species including all non-avian dinosaurs
the third and latest period of the Cenozoic, spanning from 2.58 mya to the present; divided into two epochs; marked by the several ice ages, the development of modern ecosystems, and the evolution of modern humans
the Quarternary Period
the six internationally accepted periods of the Paleozoic Era in chronological order
the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian Periods
fun fact: North American geologists divide the Carboniferous Period, the fifth period, into two, making Paleozoic’s periods seven
the first period of the Cenozoic, spanning from 66 mya to 23 mya; divided into 3 epochs; mammals started to diversify as dinosaurs left a lot of ecological niches
the Paleogene Period
fun fact: it means “old/ancient-born”—it is the first of the two divisions of the original Tertiary Period
the first epoch of the Paleogene, spanning from 66 mya to 56 mya; beginning of modern life forms following the K-T
Boundary Extinction; age of mammals began, and grasslands spread
the Paleocene Epoch
fun fact: it comes from the Greek words “paleo,” meaning ancient, and “kainos,” meaning recent or new—it is the oldest epoch in the new period and era
the first epoch of the Neogene, spanning from 23 mya to 5.3 mya; horses, rhinoceri, and elephants flourished
the Miocene Epoch
fun fact: it means “less recent”—though this was originally chosen as its name because the epoch saw a decline in marine biodiversity, this also translates to it being the older of the two epochs of the Neogene
the three Precambrian eons in chronological order
the Hadean, Archean, and Proterozoic Eons
the second period of the Paleozoic, spanning from 485 mya to 444 mya; characterized by the invertebrate’s domination of the oceans, and the plant’s colonization of the land
the Ordovician Period
fun fact: it ended at the Ordovician-Silurian Extinction Event 444 mya, the first of the five major mass extinction events, where 86% of the species at the time died
the four major divisions of the geologic time scale
eon, era, period, epoch
the second and last epoch of the Neogene, spanning from 5.3 mya to 2.58 mya; a time of global cooling after the warmer Miocene; first appearance of hominids, the ancestors of modern humans
the Pliocene Epoch
fun fact: it means “more recent”—it’s the younger of the two epochs of the Neogene
the smallest division of the geologic time scale characterized by distinct organisms
epoch
the eon spanning from 2.5 bya to 541 mya; characterized by the appearance of the earliest forms of life; cyanobacteria existed (w/o oxygen) and oxygenated the Earth
the Proterozoic Eon
fun fact: it means “earlier life”—the Proterozoic preceded the Paleozoic, in which life started to bloom
the second of latest epoch of the Quarternary, spanning from 11.7 kya to the present; hoomans
the Holocene Epoch
fun fact: it means “entirely recent”
a division in an eon that spans time periods of tens to hundreds of millions of years
era
the periods of the Cenozoic Era in chronological order
the Paleogene, Neogene, and Quarternary Periods
fun fact: the Cenozoic originally only had two periods, Tertiary and Quarternary, until Tertiary was divided into two, the Paleogene and Neogene
the current eon, which started at the Cambrian explosion in the Paleozoic Era
the Phanerozoic Eon
fun fact: it means “visible life”—there are evidences proving that life already existed in the Precambrian, but life only truly flourished during the Phanerozoic
the fourth period of the Paleozoic, spanning from 419 mya to 359 mya; also called as the golden age of fish due to their diversification; land plants became common; vascular plants (club mosses and ferns) developed
the Devonian Period
fun fact: the Late Devonian Extinctions, which happened 375 - 359 mya and was the second of the five major mass extinction events, consisted of several waves of organismal disappearance that collectively killed ~75% of Devonian species and ultimately ended the period
the second period of the Cenozoic, spanning from 23 mya to 2.58 mya; divided into 2 epochs; mammals continued to diversify; the first humans appeared; the cooling trend that started in the late Paleogene continued, leading to the onset of ice ages
the Neogene Period
fun fact: it means “newborn”—it is the second of the two divisions of the original Tertiary Period
the age of Earth
4.6 billion years old
the three eras of the Phanerozoic in chronological order
the Paleozoic, Mesozoic, and Cenozoic Eras
the eon spanning from the formation of Earth 4.5 - 4.6 bya to 4 bya; characterized by very high temperatures
the Hadean Eon
fun fact: it was named after the Greek god of the underworld—Earth was literally hellish during this eon
one of Phanerozoic’s Eon’s eras, spanning from 252 mya to 66 mya; the age of reptiles; divided into three periods; the carbon and oxygen concentrations in the atmosphere was very high
the Mesozoic Era
fun fact: it means “middle life”—the Mesozoic is the second of the three eras of the Phanerozoic Eon, in which dinosaurs dominated the Earth
the periods of the Mesozoic Era in chronological order
the Triassic, Jurassic, and Cretaceous Periods
the third and last epoch of the Paleogene, spanning from 34 mya to 23 mya; characterized by the rise of horses, antelopes, cats, oreodonts; a sudden decrease in earth’s temperature caused a permanent ice cap to form over Antarctica
the Oligocene Epoch
fun fact: it means “little recent”—the Oligocene has a low biodiversity compared to the Eocene, caused by the global cooling
