When did the cenozoic era start

The Eocene (IPA: / ˈ iː ə s iː n, ˈ iː oʊ-/ EE-ə-seen, EE-oh-) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era.

One important moment in geologic time was the transition from the Mesozoic era to the Cenozoic era about 65 million years ago. The change was spurred by the asteroid impact that eventually killed ...The Cenozoic era (66 to 0 million years) is marked by long-term aberrations in carbon cycling and large climatic shifts, some of which challenge the current understanding of carbon cycle dynamics. Here, we investigate possible mechanisms responsible for the observed long-term trends by using a novel approach that features a full-fledged ocean ... The Cenozoic period describes the beginning of the evolution of modern life on Earth. This era started around 65 million years ago after the Cretaceous period. …Others note that the rise of agriculture between 10,000 and 15,000 years ago might mark the onset of the Anthropocene; however, this start time may be problematic since it roughly coincides with the beginning of the Holocene Epoch. One of the more popular views among those who push for the formalization of the Anthropocene Epoch …Paleozoic (541-252 million years ago) means ‘ancient life.’. The oldest animals on Earth appeared just before the start of this era in the Ediacaran Period, but scientists had not yet discovered them when the geologic timescale was made. Life was primitive during the Paleozoic and included many invertebrates (animals without backbones) and ...Cenozoic era. which period did the Appalachian Mountains form? Paleozoic era Students also viewed. 05.01 Geologic Time Scale. 18 terms. David ...Cenozoic Era. Cenozoic Time Span. Date range: 66.0 million years ago–Today. Length: 66.0 million years (1.5% of geologic time) Geologic calendar: December 26 (6 PM)–December 31 (Midnight) (5 days, 6 hours) Introduction. The Cenozoic Era is the "Age of Mammals." North America’s characteristic landscapes began to develop during the Cenozoic.Hadean Eon, informal division of the Precambrian occurring between about 4.6 billion and about 4.0 billion years ago. It was the time of Earth’s initial formation—the accretion of dust and gases, collisions with larger bodies, the stabilization of its core and crust, and the rise of its atmosphere and oceans.

Oct 2, 2019 · The Phanerozoic Eon is divided into three eras—the Paleozoic, the Mesozoic, and the Cenozoic ( Figure ( below ). They span from about 540 million years ago to the present. We live now in the Cenozoic Era. Earth’s climate changed numerous times during the Phanerozoic Eon. At the end of the Precambrian, much of the planet was covered with ... The Quaternary Period is the third and last of the three periods of the Cenozoic Era. You and I are living in this period, which began only 2.58 million years ago. This is less than 0.1% of all of geologic time! A thin layer of sediments deposited during the Quaternary covers much of the Earth’s land surface.The Paleocene Epoch/Series is the first of the Cenozoic Era/Erathem. It is the first of five epochs in the Tertiary Period and the first of three in the Paleogene, which is treated either as a period in its own right or as a subdivision of the Tertiary. The Paleocene succeeds the Cretaceous Period/System and precedes the Eocene Epoch.The word cenozoic derives from the Greek words meaning “recent life.”. This reflects its position following the development of life on Earth in the Paleozoic (“ancient life”) and Mesozoic (“middle life”) eras. The Cenozoic Era is divided into three periods; from oldest to youngest, these are the Paleogene (66 million to 23 million ...Cenozoic (66 million years ago until today) means ‘recent life.’. During this era, plants and animals look most like those on Earth today. Periods of the Cenozoic Era are split into …The Neogene Period is the middle period of the three periods of the Cenozoic Era. Like the other periods of the Cenozoic, it is geologically short (less than 1% of geologic time) but well-represented at the surface. Neogene sedimentary formations are often poorly lithified, because they are young and generally have not been deeply buried.The Miocene ( / ˈmaɪ.əsiːn, - oʊ -/ MY-ə-seen, -⁠oh-) [6] [7] is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.333 million years ago (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words μείων ( meíōn, "less") and καινός ( kainós, "new") [8 ...

The Cenozoic era (66 to 0 million years) is marked by long-term aberrations in carbon cycling and large climatic shifts, some of which challenge the current understanding of carbon cycle dynamics. Here, we investigate possible mechanisms responsible for the observed long-term trends by using a novel approach that features a full-fledged ocean ... The Cenozoic Era is the age of mammals. They evolved to fill virtually all the niches vacated by dinosaurs. The ice ages of the Quaternary Period of the Cenozoic led to many extinctions. The last ice age ended 12,000 years ago. By that time, Homo sapiens had evolved.Cenozoic Era. Cenozoic Time Span. Date range: 66.0 million years ago–Today. Length: 66.0 million years (1.5% of geologic time) Geologic calendar: December 26 (6 PM)–December 31 (Midnight) (5 days, 6 hours) Introduction. The Cenozoic Era is the "Age of Mammals." North America’s characteristic landscapes began to develop during the Cenozoic.Apr 27, 2023 · The Cenozoic Era is the "Age of Mammals." North America’s characteristic landscapes began to develop during the Cenozoic. Birds and mammals rose in prominence after the extinction of giant reptiles. Common Cenozoic fossils include cat-like carnivores and early horses, as well as ice age woolly mammoths. The Pleistocene Ice Ages began about 2. ... From hominids, humans evolved in the last 4 million years of the Cenozoic era. 1. The dinosaurs went extinct. Ultimately, the start of the Cenozoic Era was the demise of dinosaurs. After a 6-mile wide asteroid hit Earth 66 million years ago, a dust cloud blocked the sun. It was the Cretaceous-Paleogene (K-Pg) extinction event that wiped out ...

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Heather Scoville Updated on March 24, 2020 Following the Precambrian Time, Paleozoic Era, and Mesozoic Era on the geologic time scale is the Cenozoic Era, which began 65 million years ago and continues to the present.Paleozoic Era, or Palaeozoic Era, Major interval of geologic time, c. 542–251 million years ago. From the Greek for “ancient life,” it is the first era of the Phanerozoic Eon and is followed by the Mesozoic Era.It is divided into six periods: (from oldest to youngest) the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. ...Part of the Cenozoic Era • Began about 1.8 million years ago • “Ice Age” • Glaciers formed and did not melt for thousands of years • Mastodons and woolly ...The Quaternary ( / kwəˈtɜːrnəri, ˈkwɒtərnɛri / kwə-TUR-nə-ree, KWOT-ər-nerr-ee) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). [4] It follows the Neogene Period and spans from 2.58 million years ago to the present. [5]

Neogene Period, the second of three divisions of the Cenozoic Era. The Neogene Period encompassesthe interval between 23 million and 2.6 million years ago and includes the Miocene(23 million to 5.3 million years …The Cenozoic Era began 65 million years ago with an asteroid impact that killed off a majority of the dinosaurs and ends at the present day. The Cenozoic is commonly divided into two traditional periods: Tertiary (65.5 million years ago to 2.6 million years ago) Quaternary (2.6 million years ago to present)The Mesozoic era lasted about 180 million years ago and marked the beginning of the break up of Pangaea. The end of the Mesozoic era was marked by another mass extinction. ... and animal species, including all dinosaurs, became extinct. Briefly explain what happened in the cenozoic era. During the Cenozoic era, the final changes occurred …Apr 27, 2023 · The initial epoch of the Paleogene Period and the Cenozoic Era is the Paleocene Epoch, which marks the first subdivision of geologic time after the extinction of the dinosaurs and the end of the Cretaceous Period. In western North America, the uplift of the Rocky Mountains, which started in the Cretaceous, continued throughout the Paleocene. The start of the Quaternary period, the last and current period of the Cenozoic, is marked by the start of our current ice age 2.58 million years ago. During this time period, ice sheets advanced and retreated, most …The word cenozoic derives from the Greek words meaning “recent life.”. This reflects its position following the development of life on Earth in the Paleozoic (“ancient life”) and Mesozoic (“middle life”) eras. The Cenozoic Era is divided into three periods; from oldest to youngest, these are the Paleogene (66 million to 23 million ... The Miocene (/ ˈ m aɪ. ə s iː n,-oʊ-/ MY-ə-seen, -⁠oh-) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words μείων (meíōn, "less") and καινός (kainós, "new") and means "less recent" because it has 18% fewer modern …Pleistocene Epoch, earlier and major of the two epochs of the Quaternary Period of Earth’s history, an epoch during which a succession of glacial and interglacial climatic cycles occurred. It ended 11,700 years ago. It was preceded by the Pliocene Epoch and followed by the Holocene Epoch.The Cenozoic era (66 to 0 million years) is marked by long-term aberrations in carbon cycling and large climatic shifts, some of which challenge the current understanding of carbon cycle dynamics. Here, we investigate possible mechanisms responsible for the observed long-term trends by using a novel approach that features a full-fledged ocean ... This is part five of a five-part series on the evolution of plants. 1: The first conquerors of land. 2: Birth of the forests. 3: The Age of Coal. 4: A tale of flowers and seeds. 5: The grassland empire. fossils evolution fossils and evolution plants cenozoic grass poaceae grassland. We live on a green planet. Today we may take them for granted ...The most recent era of the earth’s history, which began 65.5 million years ago (mya), is known as the “Cenozoic Era.”. This is that time frame in which the geological changes gave rise to ...Dec 17, 2022 · For Planet Earth, This Might Be the Start of a New Age. ... CENOZOIC ERA 66 million years ago. Dinosaurs appear. 252 million years ago. First mammals appear. 178 million years ago.

Part of the Cenozoic Era • Began about 1.8 million years ago • “Ice Age” • Glaciers formed and did not melt for thousands of years • Mastodons and woolly ...

Life went through a lot of diversification and adaptation during the Mesozoic era, which began around 252 million years ago after the end of the Paleozoic era. This era ended about 66 million years ago after a mass extinction, which gave rise to the Cenozoic era. The three main periods into which the Mesozoic era are divided are the Triassic ...The start of the Paleozoic era, between roughly 542 mya and 530 mya, is a time when a large number of body plans appears for the first time in the fossil record. This Cambrian explosion , as it is called, offers a particularly stimulating challenge for all who would attempt to explain the phenomena. On the Geologic Time Scale, the Cenozoic Era covers from approximately 66 million years ago to the present. This period of time corresponds with the extinction of the dinosaurs and the rise of mammals and therefore known as the Cenozoic Era which means “new life” in Greek. This era is divided into 2 periods which include the Tertiary and ... After the Permian Extinction wiped out over 95% of ocean-dwelling species and 70% of land species, the new Mesozoic Era began about 250 million years ago. The first period of the era was called the Triassic Period. The first big change was seen in the types of plants that dominated the land. Most of the species of plants that survived the ...The Cenozoic could have been called the "Age of Flowering Plants" or the "Age of Insects" or the "Age of Teleost Fish" or the "Age of Birds" just as accurately. The Cenozoic is divided into two main sub-divisions: the Tertiary and the Quaternary. Most of the Cenozoic is the Tertiary, from 65 million years ago to 1.8 million years ago.CENOZOIC ERA 66 million years ago. Dinosaurs appear. 252 million years ago ... especially for archaeologists and anthropologists who would have to start referring to World War II artifacts as ...Overview of early developments A timeline of major milestones of the Information Age, from the first message sent by the Internet protocol suite to global Internet access Library expansion and Moore's law. Library expansion was calculated in 1945 by Fremont Rider to double in capacity every 16 years where sufficient space made available. He advocated …http://ocean.si.edu/through-time/cenozoic-era The Cenozoic Era

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Tertiary Period, former official interval of geologic time lasting from approximately 66 million to 2.6 million years ago. It is the traditional name for the first of two periods in the Cenozoic Era (66 million years ago to the present); the second is the Quaternary Period (2.6 million years ago to the present).To those scientists who do think the Anthropocene describes a new geological time period, the next question is, when did it begin, which also has been widely debated. A popular theory is that it began at the start of the Industrial Revolution of the 1800s, when human activity had a great impact on carbon and methane in Earth’s …A warm climate persisted into the Cenozoic; in fact there is evidence that the Paleocene (~50 to 60 Ma) was the warmest part of the Phanerozoic since the Cambrian (Figure 16.3). A number of tectonic events during the Cenozoic contributed to persistent and significant planetary cooling since 50 Ma.An era is the second largest geochronologic time unit and is the equivalent of a chronostratigraphic erathem. [7] [12] As of April 2022 [update] there are currently ten defined eras/erathems, [2] namely the Eoarchean , Paleoarchean , Mesoarchean , Neoarchean , Paleoproterozoic , Mesoproterozoic , Neoproterozoic , Paleozoic , Mesozoic and …The Quaternary Period (2.6 million years ago to the present) is composed of the Pleistocene and Holocene epochs. The Holocene Epoch began 11,700 years ago and continues into modern time. The vast interval of time that spans Earth’s geologic history is known as geologic time. It began roughly 4.6 billion years ago when Earth began to form as a ...Mesozoic The middle of three eras that constitute the Phanerozoic period of time. The Mesozoic (literally ‘middle life’) was preceded by the Palaeozoic Era and followed by the Cenozoic Era. It began with the Triassic approximately 245 Ma ago and ended around 65 Ma at the start of the Tertiary.This event occurred approximately 850 to 635 million years ago during the Neoproterozoic era. ... Surprisingly, the earth is currently experiencing a glacial period. This one started about 2.58 million years ago and is still going on, ... Cenozoic: 2: Karoo: 360 – 260: Carboniferous and Permian, Paleozoic: 3:The Pleistocene Epoch. This mammoth (right), found in deposits in Russia, was one of the largest land mammals of the Pleistocene, the time period that spanned from 2.6 million to 11,700 years ago.*. Pleistocene biotas were extremely close to modern ones many genera and even species of Pleistocene conifers, mosses, flowering plants, insects ...The Cenozoic Era is the age of mammals. They evolved to fill virtually all the niches vacated by dinosaurs. The ice ages of the Quaternary Period of the Cenozoic led to many extinctions. The last ice age ended 12,000 years ago. By that time, Homo sapiens had evolved. One important moment in geologic time was the transition from the Mesozoic era to the Cenozoic era about 65 million years ago. The change was spurred by the asteroid impact that eventually killed ... ….

The Palaeocene is the first epoch of the Cenozoic, which began at about 66 million year ... 4) How did the continental uplift affect glaciation?The Cenozoic Era is the present geological era on Earth. It began about 65 million years ago, about the same time an asteroid impacted the planet in what is ...Precambrian Time. Learn more about the period that occurred 4.5 billion to 542 million years ago. Precambrian time covers the vast bulk of the Earth's history, starting with the planet's creation ...Forward to Cenozoic Era Paleobiology. Mesozoic Era (245 to 65 mya) One of the most striking events in the Mesozoic Era was the rise to dominance of dinosaurs in terrestrial ecosystems. The Mesozoic lasted from 245 to 65 million years ago, and is divided into three periods. The Mesozoic, which derives its name from the Greek with a rough meaning ...Mesozoic. Mesozoic (252-66 million years ago) means 'middle life' and this is the time of the dinosaurs. This era includes the Triassic, Jurassic, and Cretaceous Periods, names that may be familiar to you. It ended with a massive meteorite impact that caused a mass extinction, wiping out the dinosaurs and up to 80% of life on Earth.Feb 7, 2020 · When did the Cenozoic era start and end? 66 million years ago – 0 million years ago Cenozoic/Occurred. What 7 periods are in the Cenozoic Era? Divisions. The Cenozoic is divided into three periods: the Paleogene, Neogene, and Quaternary; and seven epochs: the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene. After the Permian Extinction wiped out over 95% of ocean-dwelling species and 70% of land species, the new Mesozoic Era began about 250 million years ago. The first period of the era was called the Triassic Period. The first big change was seen in the types of plants that dominated the land. Most of the species of plants that survived the ...The Quaternary ( / kwəˈtɜːrnəri, ˈkwɒtərnɛri / kwə-TUR-nə-ree, KWOT-ər-nerr-ee) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). [4] It follows the Neogene Period and spans from 2.58 million years ago to the present. [5] Although life certainly started in Precambrian time, The start of the Paleozoic Era marks the point at which life developed to a variety or organisms capable of leaving fossils. Although fossilization is difficult under any circumstances, organisms with structures such as shells have a much greater chance of leaving fossilized remains than …Others note that the rise of agriculture between 10,000 and 15,000 years ago might mark the onset of the Anthropocene; however, this start time may be problematic since it roughly coincides with the beginning of the Holocene Epoch. One of the more popular views among those who push for the formalization of the Anthropocene Epoch … When did the cenozoic era start, A warm climate persisted into the Cenozoic; in fact there is evidence that the Paleocene (~50 to 60 Ma) was the warmest part of the Phanerozoic since the Cambrian (Figure 16.3). A number of tectonic events during the Cenozoic contributed to persistent and significant planetary cooling since 50 Ma., The initial epoch of the Paleogene Period and the Cenozoic Era is the Paleocene Epoch, which marks the first subdivision of geologic time after the extinction of the dinosaurs and the end of the Cretaceous Period. In western North America, the uplift of the Rocky Mountains, which started in the Cretaceous, continued throughout the …, The Paleozoic is bracketed by two of the most important events in the history of animal life. At its beginning, multicelled animals underwent a dramatic "explosion" in diversity, and almost all living animal phyla appeared within a few millions of years. At the other end of the Paleozoic, the largest mass extinction in history wiped out approximately 90% of all …, The Cenozoic era existed from 248-68 million years ago and the Cenozoic era began 68 million years ago. Complete step by step answer: Cenozoic era is about ..., 8.8: Cenozoic. Figure 8.8. 1: Paraceratherium, seen in this reconstruction, was a massive (15-20 ton, 15 foot tall) ancestor of rhinos. The Cenozoic, meaning "new life," is known as the age of mammals because it is in this era that mammals came to be a dominant and large life form, including human ancestors., Large limestone outcrops, like the one pictured here, are evidence of these periodic incursions of continental seas. The Paleozoic Era is bracketed by the times of global super-continents. The era opened with the breakup of the world-continent Pannotia and closed with the formation of Pangea, as the Earth's continents came together once again., label each era. Era Time Range in mybp Color Cenozoic 0 -6 6 yellow Mesozoic 66 -251 green Paleozoic 251 -542 blue Precambrian 542 -4,600 red Step 4 : Add the key events information given on the Geologic Time Scale to your time line in the correct location. You may need to write v ery small and/or, Cenozoic Era, third of the major eras of Earth's history, beginning about 66 million years ago and extending to the present. It was the interval of time during which the continents assumed their modern configuration and geographic positions and during which Earth's flora and fauna evolved toward those of the present., The Precambrian, Paleozoic, Mesozoic, and Cenozoic Eras. The Geologic Time Scale is the history of the Earth broken down into four spans of time marked by various events, such as the emergence of certain species, their evolution, and their extinction, that help distinguish one era from another. Strictly speaking, Precambrian Time is not an ..., Pre-Cambrian Animal Life. The time before the Cambrian period is known as the Ediacaran period (from about 635 million years ago to 543 million years ago), the final period of the late Proterozoic Neoproterozoic Era (Figure 1). It is believed that early animal life, termed Ediacaran biota, evolved from protists at this time., Cenozoic Era In the wake of the extinction of the dinosaurs 65 million years ago, Earth as we know it today began to take shape. Pangaea had split apart, shifting the continents into the positions ..., Life During the Paleozoic. The Paleozoic Era is literally the era of “old life.”. It lasted from 544 to 245 million years ago and is divided into six periods. Major events in each period of the Paleozoic Era are described in Figure below. The era began with a …, Late Cenozoic Ice Age. The Late Cenozoic Ice Age falls within the Cenozoic Era which started 66 million years ago. The Cenozoic Era is part of the Phanerozoic Eon which started 541 million years ago. ^ a b In standard nomenclature the Pleistocene Epoch lasts from 2.58 Ma to 11.7 ka and the Holocene epoch lasts from 11.7 ka to present., The first period of the Cenozoic Era was the Paleogene Period and it began approximately 66 million years ago and ran until about 23 million years ago. During ..., Volume 5. Scott A. Elias, in Encyclopedia of Geology (Second Edition), 2021 Paleogene Period. The earliest part of the Cenozoic was the Paleogene Period, including the Paleocene, Eocene, and Oligocene epochs, spanning the interval of 64–23 mya. The first drop in pCO 2 levels marked in proxy records was during the transition from the …, One important moment in geologic time was the transition from the Mesozoic era to the Cenozoic era about 65 million years ago. The change was spurred by the asteroid impact that eventually killed ..., Geologic Time Scale. Today, the geologic time scale is divided into major chunks of time called eons. Eons may be further divided into smaller chunks called eras, and each era is divided into periods. Figure 12.1 shows you what the geologic time scale looks like. We now live in the Phanerozoic eon, the Cenozoic era, and the Quarternary period., From hominids, humans evolved in the last 4 million years of the Cenozoic era. 1. The dinosaurs went extinct. Ultimately, the start of the Cenozoic Era was the demise of dinosaurs. After a 6-mile wide asteroid hit Earth 66 million years ago, a dust cloud blocked the sun. It was the Cretaceous-Paleogene (K-Pg) extinction event that wiped out ..., The start of the Paleozoic era, between roughly 542 mya and 530 mya, is a time when a large number of body plans appears for the first time in the fossil record. This Cambrian explosion , as it is called, offers a particularly stimulating challenge for all who would attempt to explain the phenomena. , As the Earth cooled, grasslands began to expand and forests shrank. Animals evolved to fit the new, open landscape and many fast-running prey and predator ..., The Cenozoic Era began about 65 million years ago and continues today. ~Pinksakuraeya. ... When did the Cenozoic era begin? Wiki User. ∙ 2015-10-11 02:43:30. Study now. See answer (1) Best Answer., The term Neogene is widely used in Europe as a geologic division, and it is increasingly employed in North America, where the Cenozoic Era has traditionally been divided into the Tertiary Period (66 million to 2.6 million years ago) and the Quaternary Period (2.6 million years ago to the present)., On the Geologic Time Scale, the Cenozoic Era covers from approximately 66 million years ago to the present. This period of time corresponds with the extinction of the dinosaurs and the rise of mammals and therefore known as the Cenozoic Era which means “new life” in Greek. This era is divided into 2 periods which include the Tertiary and ..., When Did the Cenozoic Era Start? The Cenozoic era began 65 million years ago after the mass extinction of the dinosaurs at the end of the Mesozoic era. The Cenozoic era has not yet ended, but it ..., The Cenozoic Era – mountains and mammals Geology and atmosphere. The Cenozoic Era is considered to be divided into several periods: the “Tertiary” (65-1.8 Mya), commonly broken down into the Paleogene (65-23 Mya) and; the Neogene (23-1.8 Mya); the Quaternary (from 1.8 Mya). Each period is broken down into two or three epochs., Holocene Epoch, younger of the two formally recognized epochs of the Quaternary Period, covering the most recent 11,700 years of Earth’s history. Holocene sediments cover the largest area of any epoch in the geologic record; the epoch is also coincident with the late and post-Stone Age history of human beings., The Cretaceous ( IPA: / krɪˈteɪʃəs / krih-TAY-shəs) [2] is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin ..., Cenozoic Era (65 million years ago to present) The KT Event set the stage for the Cenozoic Era Cenozoic Era that began 65 million years ago. As the dinosaurs perished at the end of the Cretaceous, the mammals took center stage. Even as mammals increased in numbers and diversity, so too did the birds, reptiles, fish, insects, trees, grasses, and ... , The word cenozoic derives from the Greek words meaning “recent life.”. This reflects its position following the development of life on Earth in the Paleozoic (“ancient life”) and Mesozoic (“middle life”) eras. The Cenozoic Era is divided into three periods; from oldest to youngest, these are the Paleogene (66 million to 23 million ..., Oct 30, 2012 · Salix sp. leaf. Liquidambar sp. seed pod. The Paleogene Period* is the first of three periods comprising the Cenozoic Era. The Cenozoic, sometimes known as the "Age of Mammals", as the Mesozoic was the "Age of Reptiles", is known by its Epochs. The Paleogene is composed of the first three of these Epochs, (Paleocene, Eocene, and Oligocene Epochs). , The 2 periods in the Cenozoic Era and the Epochs within them are described below, as shown in the "Fossils Tell a Scientific Story" exhibit in the Hall of Evolution. Click on images to enlarge. Tertiary Period (66 to 2 million years ago) …, III.D.2 Cenozoic Tectonics. By the beginning of the Cenozoic Era, about 66 m.y. ago, the continents had begun to achieve their modern shapes (Fig. 12). The Atlantic Ocean continued to widen at the expense of the Pacific, and the Indian Ocean continued to open as India drifted northward. India began to collide with mainland Asia in the Eocene., Learn what the geologic time scale is. Identify eons, eras, periods, and epochs on the time scale, and study the history and development of the...