Beverley J. Glover
- Published in print:
- 2007
- Published Online:
- January 2008
- ISBN:
- 9780198565970
- eISBN:
- 9780191714009
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198565970.003.0001
- Subject:
- Biology, Plant Sciences and Forestry
Flowers are relatively recent innovations. The first land plants arose around 470 million years ago, but fossil evidence indicates that only after another 340 million years did the angiosperms ...
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Flowers are relatively recent innovations. The first land plants arose around 470 million years ago, but fossil evidence indicates that only after another 340 million years did the angiosperms (flowering plants) appear. However, following their appearance in the fossil record of the early Cretaceous period, the angiosperms spread geographically from their point of origin in the tropics and diversified dramatically to become the ecologically dominant plant group in the great majority of terrestrial habitats. This extraordinary radiation into an enormous range of morphological diversity took a mere 40 million years. This chapter examines the origin of the flowering plants, and then looks in detail at those first flowers, considering their morphology, their development, and their diversification.Less
Flowers are relatively recent innovations. The first land plants arose around 470 million years ago, but fossil evidence indicates that only after another 340 million years did the angiosperms (flowering plants) appear. However, following their appearance in the fossil record of the early Cretaceous period, the angiosperms spread geographically from their point of origin in the tropics and diversified dramatically to become the ecologically dominant plant group in the great majority of terrestrial habitats. This extraordinary radiation into an enormous range of morphological diversity took a mere 40 million years. This chapter examines the origin of the flowering plants, and then looks in detail at those first flowers, considering their morphology, their development, and their diversification.
Richard P. Hilton
- Published in print:
- 2003
- Published Online:
- March 2012
- ISBN:
- 9780520233157
- eISBN:
- 9780520928459
- Item type:
- chapter
- Publisher:
- University of California Press
- DOI:
- 10.1525/california/9780520233157.003.0003
- Subject:
- Biology, Evolutionary Biology / Genetics
Dinosaurs were the result of the evolutionary changes that took place in reptiles during the Paleozoic Era. This chapter discusses the taxonomy and evidence of dinosaur fossils in California. ...
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Dinosaurs were the result of the evolutionary changes that took place in reptiles during the Paleozoic Era. This chapter discusses the taxonomy and evidence of dinosaur fossils in California. Dinosaurs arose from one branch of the diapsids, a group of reptiles characterized with two holes in the skull behind the eye socket. One of the most diagnostic traits separating dinosaurs not only from mammals but also from their reptilian relatives is the numerous and unique positioning of the openings and cavities found in the bones of the skull. Because all dinosaurs are diapsids, they have two pairs of main openings behind the eye. The great majority of the dinosaur fossils found in California are from the Cretaceous Period. Dinosaurs from this period have been found from southern Oregon, throughout the length of California, and into northern Baja California. Hadrosaurs were perhaps the most common dinosaur to have inhabited the Pacific coastal region of California, and indeed, more fossil hadrosaurian remains have been found in California than those of any other dinosaur.Less
Dinosaurs were the result of the evolutionary changes that took place in reptiles during the Paleozoic Era. This chapter discusses the taxonomy and evidence of dinosaur fossils in California. Dinosaurs arose from one branch of the diapsids, a group of reptiles characterized with two holes in the skull behind the eye socket. One of the most diagnostic traits separating dinosaurs not only from mammals but also from their reptilian relatives is the numerous and unique positioning of the openings and cavities found in the bones of the skull. Because all dinosaurs are diapsids, they have two pairs of main openings behind the eye. The great majority of the dinosaur fossils found in California are from the Cretaceous Period. Dinosaurs from this period have been found from southern Oregon, throughout the length of California, and into northern Baja California. Hadrosaurs were perhaps the most common dinosaur to have inhabited the Pacific coastal region of California, and indeed, more fossil hadrosaurian remains have been found in California than those of any other dinosaur.
T. R. Hitchings
- Published in print:
- 2008
- Published Online:
- March 2012
- ISBN:
- 9780520098688
- eISBN:
- 9780520943803
- Item type:
- chapter
- Publisher:
- University of California Press
- DOI:
- 10.1525/california/9780520098688.003.0007
- Subject:
- Biology, Animal Biology
This chapter examines the post-glacial population distribution of mayflies in New Zealand. It explains that the mayfly population was isolated after New Zealand was separated from Antarctica and the ...
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This chapter examines the post-glacial population distribution of mayflies in New Zealand. It explains that the mayfly population was isolated after New Zealand was separated from Antarctica and the eastern coast of Australia during the late Cretaceous period, and that the survivors evolved into the present fauna, which includes 42 species. The result of the analysis supports the view that a center of population dispersal of double gilled leptophlebiid was in northern New Zealand and that glaciations in the south resulted in a different pattern of radiation of some single-gilled species. The chapter argues that the pattern of distribution is not necessarily purely the result of biogeographical processes.Less
This chapter examines the post-glacial population distribution of mayflies in New Zealand. It explains that the mayfly population was isolated after New Zealand was separated from Antarctica and the eastern coast of Australia during the late Cretaceous period, and that the survivors evolved into the present fauna, which includes 42 species. The result of the analysis supports the view that a center of population dispersal of double gilled leptophlebiid was in northern New Zealand and that glaciations in the south resulted in a different pattern of radiation of some single-gilled species. The chapter argues that the pattern of distribution is not necessarily purely the result of biogeographical processes.
Louise H. Emmons
- Published in print:
- 2000
- Published Online:
- March 2012
- ISBN:
- 9780520222915
- eISBN:
- 9780520925045
- Item type:
- chapter
- Publisher:
- University of California Press
- DOI:
- 10.1525/california/9780520222915.003.0001
- Subject:
- Biology, Animal Biology
This introductory chapter explains the theme of this book, which is about the treeshrews of Borneo. It provides a brief overview of thought on treeshrew taxonomy and phylogeny and the search for ...
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This introductory chapter explains the theme of this book, which is about the treeshrews of Borneo. It provides a brief overview of thought on treeshrew taxonomy and phylogeny and the search for their true, but often mistaken, identity. The chapter explains that before 1900, treeshrews were generally thought to be in the order Insectivora and related to the true shrews, but by the first decade of the twentieth century comparative anatomists separated them from that order and proposed a closer relationship to other groups. It suggests that treeshrews are the most closely related living models of the very earliest primate ancestors of the late Cretaceous period, and that their lifestyles can provide a window onto our earliest antecedents, and perhaps a view of why evolution may have taken the direction it did.Less
This introductory chapter explains the theme of this book, which is about the treeshrews of Borneo. It provides a brief overview of thought on treeshrew taxonomy and phylogeny and the search for their true, but often mistaken, identity. The chapter explains that before 1900, treeshrews were generally thought to be in the order Insectivora and related to the true shrews, but by the first decade of the twentieth century comparative anatomists separated them from that order and proposed a closer relationship to other groups. It suggests that treeshrews are the most closely related living models of the very earliest primate ancestors of the late Cretaceous period, and that their lifestyles can provide a window onto our earliest antecedents, and perhaps a view of why evolution may have taken the direction it did.
Gerrit L. Verschuur
- Published in print:
- 1996
- Published Online:
- November 2020
- ISBN:
- 9780195101058
- eISBN:
- 9780197561232
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780195101058.003.0013
- Subject:
- Earth Sciences and Geography, Geophysics: Earth Sciences
Just what happened to the dinosaurs? In the mind’s eye, travel back to the Cretaceous period, 65 million years ago. First, land in a region of the world that will someday be called Oklahoma. You ...
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Just what happened to the dinosaurs? In the mind’s eye, travel back to the Cretaceous period, 65 million years ago. First, land in a region of the world that will someday be called Oklahoma. You are in the era of dinosaurs, although there are no longer as many species about, worldwide, as there were ten million or so years before. In all, 23 species roam their individual parts of the planet. It is their lack of spatial diversity that will make them vulnerable to the catastrophe that is about to befall the earth. So imagine you are there, together with triceratops, stegosaurus, velociraptors, and tyrannosaurus rex. Mostly they live off the land, and some of them live off each other. On this day none of the animals on earth can possibly have any awareness that they are about to disappear. Such a luxury will only be granted to a conscious species that has learned to explore the universe. For those who survive the initial impact explosion and its immediate consequences, the coming months will mark a terrible example of one of Cuvier’s “brief periods of terror.” In rapid succession, all life will be subject to a holocaust of staggering proportion, horrendous blast waves, searing winds, showers of molten matter from the sky, earthquakes, a terrible darkness that will cut out sunlight for a year, and freezing weather that will last a decade. The ozone layer will be destroyed, and acid rain will make life intolerable for species that survived the first few months after the impact. You are there and you have been observing an odd phenomenon in the sky. For thousands of years a great comet has loomed, repeatedly lighting up the heavens with its glorious tail and then fading away to reappear a few years later. Long ago it was seen to break into fragments, each of which was a spectacular sight in its own right. Sometimes one of those fragments seemed to loom ever so close to the earth. For thousands of years, spectacular meteor showers have been seen whenever the earth passed through the tail of one of those comets, and sometimes dust drifted down into the atmosphere and disturbed the climate.
Less
Just what happened to the dinosaurs? In the mind’s eye, travel back to the Cretaceous period, 65 million years ago. First, land in a region of the world that will someday be called Oklahoma. You are in the era of dinosaurs, although there are no longer as many species about, worldwide, as there were ten million or so years before. In all, 23 species roam their individual parts of the planet. It is their lack of spatial diversity that will make them vulnerable to the catastrophe that is about to befall the earth. So imagine you are there, together with triceratops, stegosaurus, velociraptors, and tyrannosaurus rex. Mostly they live off the land, and some of them live off each other. On this day none of the animals on earth can possibly have any awareness that they are about to disappear. Such a luxury will only be granted to a conscious species that has learned to explore the universe. For those who survive the initial impact explosion and its immediate consequences, the coming months will mark a terrible example of one of Cuvier’s “brief periods of terror.” In rapid succession, all life will be subject to a holocaust of staggering proportion, horrendous blast waves, searing winds, showers of molten matter from the sky, earthquakes, a terrible darkness that will cut out sunlight for a year, and freezing weather that will last a decade. The ozone layer will be destroyed, and acid rain will make life intolerable for species that survived the first few months after the impact. You are there and you have been observing an odd phenomenon in the sky. For thousands of years a great comet has loomed, repeatedly lighting up the heavens with its glorious tail and then fading away to reappear a few years later. Long ago it was seen to break into fragments, each of which was a spectacular sight in its own right. Sometimes one of those fragments seemed to loom ever so close to the earth. For thousands of years, spectacular meteor showers have been seen whenever the earth passed through the tail of one of those comets, and sometimes dust drifted down into the atmosphere and disturbed the climate.
Jonathon Keats
- Published in print:
- 2010
- Published Online:
- November 2020
- ISBN:
- 9780195398540
- eISBN:
- 9780197562826
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780195398540.003.0008
- Subject:
- Computer Science, Programming Languages
In geological time, the human life span is almost immeasurably brief. The seventeenth-century archbishop James Ussher famously calculated from biblical events that Earth was formed in 4004 BCE; ...
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In geological time, the human life span is almost immeasurably brief. The seventeenth-century archbishop James Ussher famously calculated from biblical events that Earth was formed in 4004 BCE; scientists now estimate that the planet is 4.6 billion years old, and that the six millennia since the apocryphal Creation have probably contributed less than 10 millimeters of sediment to the geological record. Geological eras are unfathomable by ordinarily temporal measurements, such as the daily spin of the planet or its annual orbit, leading some scientists to adopt the galactic year—the 250 million terrestrial years it takes our solar system to rotate around the center of the galaxy—as a standard time unit. On that scale, Homo sapiens has been around for less than a week. Yet as the technology to study the planet has improved, so too has the technology to alter it. Earth increasingly disproportionately bears our imprint, as if geological time were being accelerated to the beat of our biological clock, with the consequence that the planet seems increasingly mortal, its legacy and ours entangled. In geological terms we are in the Holocene epoch—a designation formulated from Greek roots meaning “wholly recent,” officially adopted at the 1885 International Geological Congress—and have been in the Holocene for the past ten thousand years. The question, given all that we’ve done to the planet, is whether the label remains valid, or whether we’ve now buried the stratum of our Neolithic ancestors beneath our own rubbish. The atmospheric chemist Paul Crutzen was the first to effectively challenge the conventional geological thinking. In a 2003 interview with New Scientist he recollected the circumstances: “This happened at a meeting three years ago. Someone said something about the Holocene, the geological era covering the period since the end of the last ice age. I suddenly thought this was wrong. In the past 200 years, humans have become a major geological force on the planet. So I said, no, we are not in the Holocene any more: we are in the Anthropocene. I just made up the word on the spur of the moment.Less
In geological time, the human life span is almost immeasurably brief. The seventeenth-century archbishop James Ussher famously calculated from biblical events that Earth was formed in 4004 BCE; scientists now estimate that the planet is 4.6 billion years old, and that the six millennia since the apocryphal Creation have probably contributed less than 10 millimeters of sediment to the geological record. Geological eras are unfathomable by ordinarily temporal measurements, such as the daily spin of the planet or its annual orbit, leading some scientists to adopt the galactic year—the 250 million terrestrial years it takes our solar system to rotate around the center of the galaxy—as a standard time unit. On that scale, Homo sapiens has been around for less than a week. Yet as the technology to study the planet has improved, so too has the technology to alter it. Earth increasingly disproportionately bears our imprint, as if geological time were being accelerated to the beat of our biological clock, with the consequence that the planet seems increasingly mortal, its legacy and ours entangled. In geological terms we are in the Holocene epoch—a designation formulated from Greek roots meaning “wholly recent,” officially adopted at the 1885 International Geological Congress—and have been in the Holocene for the past ten thousand years. The question, given all that we’ve done to the planet, is whether the label remains valid, or whether we’ve now buried the stratum of our Neolithic ancestors beneath our own rubbish. The atmospheric chemist Paul Crutzen was the first to effectively challenge the conventional geological thinking. In a 2003 interview with New Scientist he recollected the circumstances: “This happened at a meeting three years ago. Someone said something about the Holocene, the geological era covering the period since the end of the last ice age. I suddenly thought this was wrong. In the past 200 years, humans have become a major geological force on the planet. So I said, no, we are not in the Holocene any more: we are in the Anthropocene. I just made up the word on the spur of the moment.