Which is a description of the paleozoic era

Epicontinental seas versus open-ocean settings: ... A double mass extinction at the end of the Paleozoic Era. Science 266: ... Towards a Mathematical Description of Biodiversity Evolution. Challenges, Vol. 5, Issue. 2, p. 324. CrossRef; …

The changes that occured to the land and life forms at the end of the Paleozoic Era was that there was the changing of climate, animals not adapting to this change, oceans and seas closing, mountain formation, and glaciers that formed in the southern parts.Nov 29, 2019 · Geology. The geologic history of Texas is recorded in rocks found in outcrops throughout the state and in rocks penetrated by boreholes drilled primarily in the search for oil and natural gas. These rocks indicate that Texas has undergone a long and dynamic history of igneous activity, structural deformation, and sedimentary processes. The term ‘Paleozoic’ has been derived from Greek words: palaiosmeaning ‘ancient’ and zoe meaning ‘life’. This era spans around 200 million years from about 542 to 252 M.A. (million years ago), and is the largest one in terms of time-span. It’s the first era of the Phanerozoic Eon, marking the beginning of life on our planet.The Paleozoic era (from the Greek palaio, meaning "old" and zoion, "animals," meaning "ancient life") is an interval of about 291 million years defined on the geologic timescale as spanning roughly from 542 to 251 million years ago (mya), and as being the earliest of three eras of the Phanerozoic eon. The Paleozoic era is followed by the Mesozoic and Cenozoic eras.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...Permian Period, in geologic time, the last period of the Paleozoic Era, lasting from 298.9 million to 252.2 million years ago. The climate was warming throughout Permian times, and, by the end of the period, hot and dry conditions were so extensive that they caused a crisis in Permian marine and terrestrial life.During the Paleozoic Era (541 to 252 million years ago) Fish diversified and marine organisms were very abundant during the Paleozoic. Common Paleozoic fossils include trilobites and cephalopods such as squid, as well as insects and ferns. The greatest mass extinction in Earth's history ended this era. Learn more and visit parks the preserve ...The Paleozoic Periods: Cambrian Ordovician Silurian Devonian Carboniferous Permian. The Paleozoic (meaning "time of ancient life)" Era lasted from 544 to 245 ...

Paleozoic was the oldest of the three geological eras of the Phanerozoic eon. It is further divided into 6 geologic periods: Cambrian, Ordovician, Silurian, …The Paleozoic Era occurred from about 541 million years ago to about 252 million years ago. The meaning of the word Paleozoic derives from the Greek Word palaios - which means "ancient" and the Greek word zoe - which means "life.". Which is an apt name for this period in Earth history because this is when life really began to take ...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 ...The Mesozoic Era is literally the era of “middle life.”. It is also known as the age of dinosaurs. It lasted from 245 to 65 million years ago and is divided into the three periods described in Figure below. The Mesozoic began with the supercontinent Pangaea. Then, during the era, Pangaea broke up and the continents drifted apart.Late Paleozoic deglaciation is Earth's first icehouse-to-greenhouse transition with extensive vegetation, but the response of tropical climate to this transition has not yet been fully addressed.Significantly, the Early Devonian to Middle Permian interval experienced climate-associated changes in environments and biotas at a scale commensurate with impending present-day global changes and, thus, is of relevance for anticipating the consequences of present and future climate change ( Karl and Trenberth, 2003; Ceballos …

The Carboniferous Period is famous for its vast swamp forests, such as the one depicted here. Such swamps produced the coal from which the term Carboniferous, or "carbon-bearing," is derived. The Carboniferous Period lasted from about 359.2 to 299 million years ago* during the late Paleozoic Era. The term "Carboniferous" comes from England, in ...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 ... Overview. Gastropods occur widely if not always abundantly in Paleozoic rocks and made their first appearance in the Lower Cambrian. Determining the relationships of Paleozoic gastropod clades to one another, as well as to extant groups, is a challenging endeavor, most especially because of their paucity of shell characters, limiting their inclusion in phylogenetic analyses.The coming together of landmasses was a protracted procedure that took place in the Neoproterozoic and Paleozoic era. There is scanty paleomagnetic data on the whole process. The fragmented remains of an older supercontinent called Rodinia amalgamated first from the current area of Madagascar, India, Antarctica, and Australia.Mesozoic Era, Second of the Earth’s three major geologic eras and the interval during which the continental landmasses as known today were separated from the supercontinents Laurasia and Gondwana by continental drift.It lasted from c. 251 to c. 65.5 million years ago and includes the Triassic, Jurassic, and Cretaceous periods. The Mesozoic saw the …The Mesozoic Era (245 to 66 million years ago) is also called the Age of Reptiles because of the extensive proliferation of land and sea reptiles. Dinosaurs were one of the dominant animal groups during the Mesozoic Era. Although Wisconsin contains only a sparse geologic record of the Mesozoic, we know from the fossil record in other areas that ...

Is limestone a rock or mineral.

The Paleozoic Era ended with the approximately 47-million-year-long Permian Period, a major juncture in Earth history when the vast Pangean supercontinent continued its assembly (Fig. 1), and the global biota faced its greatest diversity crisis, the end-Permian mass extinction, the most extensive biotic decimation of the Phanerozoic.The Paleozoic Era, which ran from 541 million to 251.9 million years ago, was a time of great change on Earth. The era began with the breakup of one supercontinent and the formation of...Cambrian is the name given to a period of time in Earth 's history (i.e., Cambrian Period), which spanned 570 – 510 million years ago. The proper name Cambrian is also given to all the rocks that formed during that time (i.e., Cambrian System). In other words, the Cambrian System is the rock record of events that occurred — and organisms ...The Paleozoic Era is divided into the Cambrian, Ordovician, Silurian, Devonian, and Carboniferous periods, each with characteristic groups of fossils. The Cambrian Period saw the explosion of new kinds of invertebrate animals in the oceans, including trilobites ( Figure 2 ), primitive kinds of shellfish, including brachiopods and molluscs, and other groups of …The Paleozoic era (from the Greek palaio, meaning "old" and zoion, "animals," meaning "ancient life") is an interval of about 291 million years defined on the geologic timescale as spanning roughly from 542 to 251 million years ago (mya), and as being the earliest of three eras of the Phanerozoic eon. The Paleozoic era is followed by the ...

The boundary between the Paleozoic and Mesozoic eras was marked by the Earth’s third and largest mass extinction episode, which occurred immediately prior to the Triassic. As a result, Early Triassic biotas were impoverished, though diversity and abundance progressively increased during Middle and Late Triassic times.The Paleozoic Era, which ran from 541 million to 251.9 million years ago, was a time of great change on Earth. The era began with the breakup of one supercontinent and the formation of another ...During the Paleozoic Era, there were multi-cellular organisms like trilobites, mollusks, jawless fish, seaweeds and finally, jawed fish, sharks, plants and early amphibians and reptiles.Online exhibits: Geologic time scale. The Cenozoic Era. The Cenozoic Era is the most recent of the three major subdivisions of animal history. The other two are the Mesozoic and Paleozoic Eras. The Cenozoic spans only about 65 million years, from the end of the Cretaceous Period and the extinction of non-avian dinosaurs to the present. The Cenozoic is sometimes called the Age of Mammals ...Series: Geologic Time—Major Divisions and NPS Fossils. The National Park System contains a magnificent record of geologic time because rocks from each period of the geologic time scale are preserved in park landscapes. The geologic time scale is divided into four large periods of time—the Cenozoic Era, Mesozoic Era, Paleozoic Era, and The ...The Paleozoic Era. 543 to 248 Million Years Ago. 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 ... With respect to the early Paleozoic, a full-plate model based on an absolute reference framework is only available for the Iapetus and Rheic ocean domains (including the landmasses of Laurentia, Baltica and northwest Gondwana) (Domeier, 2016).In a landmark contribution, Wilhem et al. (2012) presented a full-plate model of central and …Continental Masses – The Paleozoic era began around 542 million years ago with a massive explosion of life forms. It ended 291 million years later with the extinction of between 90 and 95 percent of life on the planet. Its climate was marked by massive temperature fluctuations as continental masses shifted around the Earth’s surface.Answer to Solved Question 13 (1 point) In this closeup of part. Question 17 (1 point). Dinosaurs found in sandstone exposed at Dinosaur National Monument are an example of what geologic term, that refers to a large number of individual animals found together in the same stratum, and which appear to have all died at once in a single event?The Cenozoic Era literally means the era of "modern life.". It is also called the age of mammals. Mammals took advantage of the extinction of the dinosaurs. They flourished and soon became the dominant animals on Earth. You can learn more about the evolution of mammals during the Cenozoic at the link below. The Cenozoic began 65 million ...

The Paleozoic Era, meaning "ancient life" is the first of three eras that form a part of the Phanerozoic Eon, the other two periods being the Mesozoic and the Cenozoic. The Mesozoic is the age of the Dinosaurs and the Cenozoic is the era in which we now live. The Paleozoic Era spanned a longer period of time, from approximately 542 Ma to 251 Ma ...

The Cenozoic Era literally means the era of "modern life.". It is also called the age of mammals. Mammals took advantage of the extinction of the dinosaurs. They flourished and soon became the dominant animals on Earth. You can learn more about the evolution of mammals during the Cenozoic at the link below. The Cenozoic began 65 million ...The end of the Permian period (and the Paleozoic Era) was marked by the largest mass extinction event in Earth's history, a loss of an estimated 95 percent of the extant species at that time. Some of the dominant phyla in the world's oceans, such as the trilobites, disappeared completely. On land, the disappearance of some dominant species ...Media in category "Paleozoic" The following 48 files are in this category, out ... (17965274890).jpg. The Outline of History H. G. Wells Life in the Early Paleozoic, p 6.jpg. The Paleozoic era - SUMPHG.jpg. The Quarterly journal of the Geological Society of London (13860153374 ... Files are available under licenses specified on their ...Paleozoic Era: Devonian. Back. In the course of the Devonian (from 416 to 360 million years ago) the largest Palaeozoic tropical reef in Europe appeared, ...C9.P2 The Paleozoic (“old life”) Era is the first of three eras in the Phanerozoic Eon. The longest, the Paleozoic lasted from 541 million to 251.9 million years ago, a span of 289.1 million years. It is marked on the lower boundary by the appearance of complex life after the times of Snowball Earth and on the upper boundary by one of the largest mass …Mesozoic Era Scientific and public interest in the Mesozoic Era fossils preserved in the Colorado Plateau region and Glen Canyon NRA has increased due to recent scientific discoveries. The Mesozoic Era began approximately 251 million years ago (mya) at the end of the Paleozoic Era when the area that would eventually be the …The Paleozoic Era (paleo means "early life") lasted from about 540 to 250 million years ago. Much of Colorado was dominated by two very large mountain ranges spanning north to south and parallel to each other. The mountain ranges were eroding during this time span, similar to our present Rocky Mountains, so any rocks that may have been here ...The Permian period lasted from 290 to 248 million years ago and was the last period of the Paleozoic Era . The distinction between the Paleozoic and the Mesozoic is made at the end of the Permian in recognition of the largest mass extinction recorded in the history of life on Earth. It affected many groups of organisms in many different ...Oct 28, 2012 · Cambrian Case Index Geologic Time Scale. The Cambrian* Period begins the Phanerozoic Eon, the last 542 million years during which fossils with hard parts have existed. It is the first division of the Paleozoic Era (542Ma -251Ma). Marine animals with mineralized skeletons make their first appearance in the shallow seas of the Cambrian, though ...

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MIT geologists have now reconstructed a timeline of the Earth’s temperature during the early Paleozoic era, between 510 and 440 million years ago — a pivotal period when animals became abundant in a previously microbe-dominated world. In a study appearing today in the Proceedings of the National Academy of Sciences, the …The Paleozoic Era is the longest and oldest era within the Phanerozoic Eon. The Paleozoic definition breaks down the term into its Greek units. Paleo means "primitive" or "ancient", while zo means ...The discovery reveals oxygen changes at the seafloor across nearly 120 million years of the early Paleozoic era, a time that fostered the most rapid development and diversification of complex ...Classified under: Nouns denoting time and temporal relations. Synonyms: Paleozoic; Paleozoic era Instance hypernyms: era; geological era (a major division of geological time; an era is usually divided into two or more periods). Meronyms (parts of "Paleozoic"): Permian; Permian period (from 280 million to 230 million years ago; reptiles). Carboniferous; Carboniferous period (from 345 million to ...The Paleozoic era (from the Greek palaio, meaning "old" and zoion, "animals," meaning "ancient life") is an interval of about 291 million years defined on the geologic timescale as spanning roughly from 542 to 251 million years ago (mya), and as being the earliest of three eras of the Phanerozoic eon. The Paleozoic era is followed by the ... Descriptive research in psychology describes what happens to whom and where, as opposed to how or why it happens. Descriptive research methods are used to define the who, what, and where of human behavior and other psychological phenomena. ...Life During the Paleozoic. The Paleozoic Era is literally the era of “old life.”. It lasted from 541 to 252 million years ago and is divided into six periods (see the Figure below ). The era began with a spectacular burst of new life. This is called the Cambrian explosion. The era ended with the biggest mass extinction the world had ever seen.Life: In the Paleozoic Era, life diversified rapidly and fantastically on land and in the ocean. Life in the sea changed drastically during this time. Trilobites, mollusks, urchins, and star fish appeared at the beginning of the Paleozoic as part of the "Cambrian Explosion." Later, jawless fish evolved, then fish with jaws, and even sharks ...The meaning of PALEOZOIC is of, relating to, originating in, or being an era of geologic history that extends from the beginning of the Cambrian to the close of the Permian and is marked by the culmination of nearly all classes of invertebrates except the insects and in the later epochs by the appearance of terrestrial plants, amphibians, and reptiles; also : relating to the corresponding ... 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 spectacular burst of new life. This is called the Cambrian explosion. ….

The Great Dying. At the end of the Permian Period, which also is the end of the Paleozoic Era about 252 million years ago, approximately 95% of the species known from fossils went extinct. This is the same time, with very little uncertainty, as the greatest volcanic outpouring on Earth in the last 500 million years. The rise in CO 2 from the ...Part I: Palaeozoic Era. The Palaozoic and Precambrian Era represent the oldest geological layers in Germany. They are referred to as bedrock or basement.The Permian mass extinction marked the shift from the Paleozoic era to the Mesozoic era. During the extinction event, about 96% of all marine species and up to 70% of terrestrial vertebrates were wiped out. In addition, the largest number of insects became extinct in this period. It is believed that the extinction event occurred over 15 years ...Paleozoic Era, also spelled Palaeozoic, major interval of geologic time that began 538.8 million years ago with the Cambrian explosion, an extraordinary diversification of marine animals, and ended about 252 million years ago with the end-Permian extinction, the greatest extinction event in … See morePaleozoic global median values of trench migration trend from higher speeds (~2.5 cm/yr) in the late Devonian to rates closer to 0 cm/yr at the end of the Permian (~250 Ma), and during the ...earliest part of the Paleozoic era, when a huge diversity of animal species evolved. phyla. the second largest taxonomic category in the animal kingdom. Burgess Shale. A mid-Cambrian rock unit in the western canadian rocky Mountains that contains an abundance of fossils. punctuated equilibrium.Paleozoic Era: Devonian. Back. In the course of the Devonian (from 416 to 360 million years ago) the largest Palaeozoic tropical reef in Europe appeared, ...1) If North America (Laurentia) was covered by shallow epicontinental seas during the Paleozoic Era, predict where was the continent was most likely to be on the globe. 2) Predict what will happen to the diversity of shallow water marine invertebrates in Paleozoic epicontinental seas if there is a regression, which severely decreases the area ... Which is a description of the paleozoic era, 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 even smaller parts known as Epochs, so you will see even more signposts in this Era. Cenozoic signposts are colored yellow. , Descriptive research in psychology describes what happens to whom and where, as opposed to how or why it happens. Descriptive research methods are used to define the who, what, and where of human behavior and other psychological phenomena. ..., Geologic time period 543-490 million years ago. The Cambrian is the first period of the Paleozoic era, during which all animals and plants lived in the Earth's oceans. Many organisms that we recognize as members of modern animal groups (including the arthropods, sponges, chordates, and molluscs) made their first unmistakable appearance …, 1) A common squirrel. For many years scientists believed that almost all animal lineages burst into being during the Cambrian era (just after the end of the Precambrian super eon). However, there have been many recent findings of animal-like fossils and "trace fossils" from the late Precambrian. Which of the following best describes why it took ..., The boundary between the Paleozoic and Mesozoic eras was marked by the Earth’s third and largest mass extinction episode, which occurred immediately prior to the Triassic. As a result, Early Triassic biotas were impoverished, though diversity and abundance progressively increased during Middle and Late Triassic times., Study with Quizlet and memorize flashcards containing terms like During which of the following do you live? a. The Cenozoic Era b. The Phanerozoic Eon c. The Holocene Epoch d. all of the above, There were so many animals without backbones in the Early Paleozoic that it is often called _____. a. the boneless period b. the vertebrate era c. the age of the …, Paleozoic Era. The Paleozoic Era began and ended with two extraordinary events. The Cambrian explosion, a rapid and wide diversification of multicellular life-forms, opened the era 541 million years ago. The Permian extinction, the largest mass extinction in Earth’s history, brought the Paleozoic to a close about 252 million years ago., Geologists have determined that the Earth has existed for roughly 4.5 billion years from using radioisotope dating on its oldest rocks. This time has been split into different sections that occupy different periods of time, with older periods such as those in the Precambrian occurring for hundreds of millions of years, while younger periods ..., A number of lines of seed-bearing gymnospermous plants are discernible among fossil plants of the late Paleozoic Era (541 to 251.9 million years ago) and early to middle Mesozoic Era (251.9 to 66 million years ago). Among them a rather loose assemblage of forms, referred to as seed ferns or as pteridosperms, is well represented., In addition to their morphological similarity, molecular analyses have revealed similar sequence homologies in their DNA. Figure 27.4.1 27.4. 1: (a) Earth’s history is divided into eons, eras, and periods. Note that the Ediacaran period starts in the Proterozoic eon and ends in the Cambrian period of the Phanerozoic eon., 5.0 (6 reviews) The Hadean Eon. Choose one: A. is a span of time during which the Earth's surface was entirely molten. B. is a span of time that equates to the late heavy bombardment. C. is the span of time between the formation of the Earth and the age of the oldest known rocks. D. is the span of time before the formation of the Earth., The Silurian ( / sɪˈljʊəriːən, saɪ -/ sih-LURE-ee-ən, sy-) [8] [9] [10] is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago ( Mya ), to the beginning of the Devonian Period, 419.2 Mya. [11] The Silurian is the shortest period of the Paleozoic Era. , The Devonian, part of the Paleozoic era, is otherwise known as the Age of Fishes, as it spawned a remarkable variety of fish. The most formidable of them were the armored placoderms, a group that ... , The Paleozoic might seem like an alien world with its strange marine organisms, but it serves as an important warning. Rapid climate changes played a role in both of these Paleozoic mass extinctions, as well as others I've yet to discuss. ... This era certainly gives us an important warning for the consequences of rapid climate change. From ..., Paleozoic was the oldest of the three geological eras of the Phanerozoic eon. It is further divided into 6 geologic periods: Cambrian, Ordovician, Silurian, …, Jun 20, 2013 · The Paleozoic Era, which ran from 541 million to 251.9 million years ago, was a time of great change on Earth. The era began with the breakup of one supercontinent and the formation of... , The Paleozoic (IPA: /ˌpæli.əˈzoʊ.ɪk,-i.oʊ-, ˌpeɪ-/ PAL-ee-ə-ZOH-ik, -⁠ee-oh-, PAY-; or Palaeozoic) Era is the first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of the Mesozoic Era. [2] , Three "Granite Gorges" expose crystalline rocks formed during the early-to-middle Proterozoic Era (late Precambrian). Originally deposited as sediments and lava flows, these rocks were intensely metamorphosed about 1,750 million years ago. ... Rock layers formed during the Paleozoic Era are the most conspicuous in the Grand Canyon's walls ..., Lycaenops. Nobu Tamura. Therapsids, also known as mammal-like reptiles, evolved during the middle Permian period and went on to live alongside the earliest dinosaurs. On the following slides, you'll find pictures and detailed profiles of over three dozen therapsid reptiles, ranging from Anteosaurus to Ulemosaurus. 02., By expanding your business market on eBay, you can target consumers who use the site to purchase products online. When you create an eBay listing, you can include up to 12 pictures for free. However, you may want to insert pictures directly..., Mar 2, 2014 · The dates given are recent radiometric dates and vary slightly from those used in other sources. This second period of the Paleozoic era created abundant fossils and in some regions, major petroleum and gas reservoirs. The boundary chosen for the beginning both of the Ordovician Period and the Tremadocian stage is highly useful. , definitively. Long before birds evolved, tetrapods began laying eggs on land for the first time during this period, allowing them to break away from an amphibious lifestyle. Trilobites were fading..., Silurian Period, Interval of geologic time, 443.4–419.2 million years ago, the third period of the Paleozoic Era. The Silurian follows the Ordovician Period and precedes the Devonian. It marks the first appearance of land plants and jawed fishes., Dec 11, 2015 · The event closed the Paleozoic Era and inevitably opened the door to a new burst of life in the Mesozoic. Summary The Cambrian explosion was the sudden appearance of great diversity of animals, plants, and fungi clearly related to modern species, due to lower O 2 , global warming, plate tectonics, and a critical mass of biotic change. , The name Paleozoic was first used by Adam Sedgwick (1785-1873) in 1838 to describe the Cambrian and Ordovician periods. It was redefined by John Phillips (1800–1874) in 1840 to in cover the Cambrian to Permian periods. It is derived from the Greek palaiós (παλαιός, "old") and zōḗ (ζωή, "life") meaning "ancient life"., life-forms that first appeared in the Cenozoic Era include? humans. development of ozone in the stratosphere and oxygen in atmosphere first made possible development of ? complex organisms. today, many scientist think that? birds evolved from dinosaurs, dinosaurs evolved from reptiles., The Permian period lasted from 299 to 251 million years ago* and was the last period of the Paleozoic Era. The distinction between the Paleozoic and the Mesozoic is made at the end of the Permian in recognition of the largest mass extinction recorded in the history of life on Earth. It affected many groups of organisms in many different ..., Paleozoic Mesozoic Cenozoic. The Paleozoic does not include the. Ordovician Jurassic Mississippian Permian. The _____ was an era dominated by the dinosaurs. Precambrian Paleozoic Mesozoic Cenozoic. The boundaries between _____ seem to coincide with major changes in the life forms present on Earth. Precambrian systems eras epochs, Eras of the Phanerozoic The Phanerozoic is divided into three eras : the Paleozoic , Mesozoic and Cenozoic , which are further subdivided into 12 periods . The Paleozoic features the evolution of the three most prominent animal phyla, arthropods , molluscs and vertebrates , the latter of which includes fish , amphibians and the fully terrestrial …, Paleozoic global median values of trench migration trend from higher speeds (~2.5 cm/yr) in the late Devonian to rates closer to 0 cm/yr at the end of the Permian (~250 Ma), and during the ..., Aug 10, 2012 · The Ordovician* lasted about 45 million years and saw the transition from very primitive to relatively modern life-forms in the seas. The “Ordovician radiation” which followed the late Cambrian extinctions, lead to a tripling of marine diversity, the greatest increase in the history of life, and giving the highest levels of diversity seen during the Paleozoic Era. , Section 3: The Paleozoic Era. • First four-legged animals developed began. The Paleozoic Era lasted from about 540 million years ago to about 248 million years ago. During this time period of about 292 million years, shallow seas came inland several times. Sharks and other fish, along with many other kinds of animals, lived in the water., Bryozoans (Ordovician to today with no peak period) are animals that live in a colony and excrete a skeleton to support themselves. Sometimes the skeleton is made of minerals, and sometimes it is made of chitin. Bryozoans are primarily marine, but are sometimes found in tidal or delta environments. Each animal in the colony is called a zooid.