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Paleontologists don't know for certain, but perhaps a large body size protected them from most predators, helped to regulate internal body temperature, or let them reach new sources of food (some probably browsed treetops, as giraffes do today). No modern animals except whales are even close in size to the largest dinosaurs; therefore, paleontologists think that the dinosaurs' world was much different from the world today and that climate and food supplies must have been favorable for reaching great size.
Related Content
- FAQ
- Multimedia
- Publications
Do any mass extinctions correlate with magnetic reversals?
No. There is no evidence of a correlation between mass extinctions and magnetic pole reversals. Earth’s magnetic field and its atmosphere protect us from solar radiation. It’s not clear whether a weak magnetic field during a polarity transition would allow enough solar radiation to reach the Earth's surface that it would cause extinctions. But reversals happen rather frequently--every million...
No. There is no evidence of a correlation between mass extinctions and magnetic pole reversals. Earth’s magnetic field and its atmosphere protect us from solar radiation. It’s not clear whether a weak magnetic field during a polarity transition would allow enough solar radiation to reach the Earth's surface that it would cause extinctions. But reversals happen rather frequently--every million...
Did all the dinosaurs live together, and at the same time?
Dinosaur communities were separated by both time and geography. The 'Age of Dinosaurs' (the Mesozoic Era ) included three consecutive geologic time periods (the Triassic, Jurassic, and Cretaceous Periods). Different dinosaur species lived during each of these three periods. For example, the Jurassic dinosaur Stegosaurus had already been extinct for approximately 80 million years before the...
Dinosaur communities were separated by both time and geography. The 'Age of Dinosaurs' (the Mesozoic Era ) included three consecutive geologic time periods (the Triassic, Jurassic, and Cretaceous Periods). Different dinosaur species lived during each of these three periods. For example, the Jurassic dinosaur Stegosaurus had already been extinct for approximately 80 million years before the...
Did people and dinosaurs live at the same time?
No! After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth. However, small mammals (including shrew-sized primates) were alive at the time of the dinosaurs. Some scientists who study dinosaurs (vertebrate paleontologists) now think that birds are direct descendants of one line of carnivorous dinosaurs, and some consider that they in fact represent modern...
No! After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth. However, small mammals (including shrew-sized primates) were alive at the time of the dinosaurs. Some scientists who study dinosaurs (vertebrate paleontologists) now think that birds are direct descendants of one line of carnivorous dinosaurs, and some consider that they in fact represent modern...
Were dinosaurs warm-blooded or cold-blooded?
Scientists have conflicting opinions on this subject. Some paleontologists think that all dinosaurs were 'warm-blooded' in the same sense that modern birds and mammals are: that is, they had rapid metabolic rates. Other scientists think it unlikely that any dinosaur could have had a rapid metabolic rate. Some scientists think that very big dinosaurs could have had warm bodies because of their...
Scientists have conflicting opinions on this subject. Some paleontologists think that all dinosaurs were 'warm-blooded' in the same sense that modern birds and mammals are: that is, they had rapid metabolic rates. Other scientists think it unlikely that any dinosaur could have had a rapid metabolic rate. Some scientists think that very big dinosaurs could have had warm bodies because of their...
When did dinosaurs become extinct?
Dinosaurs went extinct about 65 million years ago (at the end of the Cretaceous Period), after living on Earth for about 165 million years. If all of Earth time from the very beginning of the dinosaurs to today were compressed into 365 days (one calendar year), the dinosaurs appeared January 1 and became extinct the third week of September. (Using this same time scale, the Earth would have formed...
Dinosaurs went extinct about 65 million years ago (at the end of the Cretaceous Period), after living on Earth for about 165 million years. If all of Earth time from the very beginning of the dinosaurs to today were compressed into 365 days (one calendar year), the dinosaurs appeared January 1 and became extinct the third week of September. (Using this same time scale, the Earth would have formed...
Where did dinosaurs live?
Dinosaurs lived on all of the continents. At the beginning of the age of dinosaurs (during the Triassic Period, about 230 million years ago), the continents were arranged together as a single supercontinent called Pangea. During the 165 million years of dinosaur existence this supercontinent slowly broke apart. Its pieces then spread across the globe into a nearly modern arrangement by a process...
Dinosaurs lived on all of the continents. At the beginning of the age of dinosaurs (during the Triassic Period, about 230 million years ago), the continents were arranged together as a single supercontinent called Pangea. During the 165 million years of dinosaur existence this supercontinent slowly broke apart. Its pieces then spread across the globe into a nearly modern arrangement by a process...
What was Pangea?
From about 300-200 million years ago (late Paleozoic Era until the very late Triassic), the continent we now know as North America was contiguous with Africa, South America, and Europe. They all existed as a single continent called Pangea. Pangea first began to be torn apart when a three-pronged fissure grew between Africa, South America, and North America. Rifting began as magma welled up through...
From about 300-200 million years ago (late Paleozoic Era until the very late Triassic), the continent we now know as North America was contiguous with Africa, South America, and Europe. They all existed as a single continent called Pangea. Pangea first began to be torn apart when a three-pronged fissure grew between Africa, South America, and North America. Rifting began as magma welled up through...
Can USGS photos of fossils be downloaded or viewed online?
Some fossil photos can be viewed and downloaded from the USGS Photographic Library and our Multimedia Gallery . Fossil photos can also be viewed as published plates within many online USGS publications. Visit the USGS Publications Warehouse to search for publications. The best keywords for searches are author names, such as William Cobban, Norm Silberling, and Glenn Scott. The USGS fossil...
Some fossil photos can be viewed and downloaded from the USGS Photographic Library and our Multimedia Gallery . Fossil photos can also be viewed as published plates within many online USGS publications. Visit the USGS Publications Warehouse to search for publications. The best keywords for searches are author names, such as William Cobban, Norm Silberling, and Glenn Scott. The USGS fossil...
Earth History of the National Capital Region – Volcanoes, Earthquakes & Dinosaurs… Oh My!
Earth History of the National Capital Region – Volcanoes, Earthquakes & Dinosaurs… Oh My!
Earth History of the National Capital Region – Volcanoes, Earthquakes & Dinosaurs… Oh My!
Reston, Virginia, was founded 47 years ago & Europeans first settled in the National Capital region 403 years ago. This human footprint can't compare to the dynamic Earth history of this region, extending back as early as 1,180 million years ago and continuing today.
Reston, Virginia, was founded 47 years ago & Europeans first settled in the National Capital region 403 years ago. This human footprint can't compare to the dynamic Earth history of this region, extending back as early as 1,180 million years ago and continuing today.
Fossil Discovery Makes History: Studying a Prehistoric Climate and Ecosystem in Colorado
Fossil Discovery Makes History: Studying a Prehistoric Climate and Ecosystem in Colorado
Fossil Discovery Makes History: Studying a Prehistoric Climate and Ecosystem in Colorado
A trio of USGS scientists has been involved in the excavation and study of a major animal and plant fossil discovery in Snowmass Village, Colo., which provides more than 100,000 years of vegetation and climate records for the area.
A trio of USGS scientists has been involved in the excavation and study of a major animal and plant fossil discovery in Snowmass Village, Colo., which provides more than 100,000 years of vegetation and climate records for the area.
How are dinosaurs named?
Listen to hear the answer.
Trilobite Fossil
Trilobite fossil, an extinct marine invertebrate. Item originally from Alnif, Morocco.
Trilobite fossil, an extinct marine invertebrate. Item originally from Alnif, Morocco.
Trilobite Fossil (Phacops rana africana)
A fossilized Trilobite, Phacops rana africana, an extinct marine invertebrate. Item originally from Alnif, Morocco.
A fossilized Trilobite, Phacops rana africana, an extinct marine invertebrate. Item originally from Alnif, Morocco.
Fossil Fish (Jiang Hanichthys)
Fossilized Jiang Hanichthys, an extinct fish that lived from the Cretaceaous to 100 million years ago. Item originally from Hubai Province, China.
Fossilized Jiang Hanichthys, an extinct fish that lived from the Cretaceaous to 100 million years ago. Item originally from Hubai Province, China.
Fossil Fish (Jiang Hanichthys)
Fossilized Jiang Hanichthys, an extinct fish that lived fromthe Cretaceaous to 100 million years ago. Item originally from Hubai Province, China.
Fossilized Jiang Hanichthys, an extinct fish that lived fromthe Cretaceaous to 100 million years ago. Item originally from Hubai Province, China.
Dinosaur Tracks
Dinosaur tracks in the Jurassic Moenave Formation. It is a popular site for tourists to stop and meet local Navajo and Moenkopi Hopi guides who lead short tours through the tracks area.
Dinosaur tracks in the Jurassic Moenave Formation. It is a popular site for tourists to stop and meet local Navajo and Moenkopi Hopi guides who lead short tours through the tracks area.
USGS Snowmastodon Research
USGS scientists working at Ziegler Reservoir near Snowmass Village, Colorado.
USGS scientists working at Ziegler Reservoir near Snowmass Village, Colorado.
Mastodon Fossil
Denver Museum of Nature and Science personnel excavate a large mastodon tusk at the Ziegler Reservoir site.
Denver Museum of Nature and Science personnel excavate a large mastodon tusk at the Ziegler Reservoir site.
Mammoth Fossils
Excavation of the initial Columbian mammoth remains found at the Ziegler Reservoir site.
Excavation of the initial Columbian mammoth remains found at the Ziegler Reservoir site.
The geology and paleontology of Tule Springs Fossil Beds National Monument, Nevada
On December 19, 2014, Tule Springs Fossil Beds National Monument, located in the Las Vegas Valley of southern Nevada, was established by Congress as the 405th unit of the National Park Service to “conserve, protect, interpret, and enhance for the benefit of present and future generations the unique and nationally important paleontological, scientific, educational, and recreational resources and va
Authors
Kathleen B. Springer, Jeffrey S. Pigati, Eric Scott
Divisions of geologic time (Bookmark)
DescriptionThis bookmark presents information that is widely sought by educators and students. Version 3.0 of this bookmark is updated according to chapter C of U.S. Geological Survey Professional Paper 1879–1. The bookmark contains names of geologic time periods and boundary age estimates ratified by the International Commission of Stratigraphy in 2023.
Authors
Why Study Paleoclimate?
U.S. Geological Survey (USGS) researchers are at the forefront of paleoclimate research, the study of past climates. With their unique skills and perspective, only geologists have the tools necessary to delve into the distant past (long before instrumental records were collected) in order to better understand global environmental conditions that were very different from today's conditions. Paleocl
Authors
Marci Robinson, Harry Dowsett
Divisions of Geologic Time—Major Chronostratigraphic and Geochronologic Units
Effective communication in the geosciences requires consistent uses of stratigraphic nomenclature, especially divisions of geologic time. A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and calibrated in years. Over the years, the development of new dating methods and refinement of previous ones have stimulated revisions to geologic time scales. Since
Authors
Dinosaurs, facts and fiction
No abstract available.
Authors
Ronald J. Litwin, Robert E. Weems, Thomas R. Holtz
Crinoids; a computer animation and paper model
No abstract available.
Authors
Tau Rho Alpha, Dorothy L. Stout, Scott W. Starratt
Chicxulub impact event; computer animations and paper models
No abstract available.
Authors
T. R. Alpha, John P. Galloway, S. W. Starratt
Mud fossils
At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away. Careful studies by scientists showed that rocks had diverse origins. Some rock layers, containing clearly identifiable fossil remains of fish and other forms of aquatic animal and plant life, originally formed in the ocean. Other layers, consisting of sand g
Authors
Make your own paper fossils; a computer animation and paper models
No abstract available.
Authors
Tau Rho Alpha, James W. Hendley, Scott W. Starratt
The Great Ice Age
The Great Ice Age, a recent chapter in the Earth's history, was a period of recurring widespread glaciations. During the Pleistocene Epoch of the geologic time scale, which began about a million or more years ago, mountain glaciers formed on all continents, the icecaps of Antarctica and Greenland were more extensive and thicker than today, and vast glaciers, in places as much as several thousand f
Authors
Louis L. Ray
Geologic time: The age of the Earth
The Earth is very old 4 1/2 billion years or more according to recent estimates. This vast span of time, called geologic time by earth scientists and believed by some to reach back to the birth of the Solar System, is difficult if not impossible to comprehend in the familiar time units of months and years, or even centuries. How then do scientists reckon geologic time, and why do they believe the
Authors
William L. Newman
Related Content
- FAQ
Do any mass extinctions correlate with magnetic reversals?
No. There is no evidence of a correlation between mass extinctions and magnetic pole reversals. Earth’s magnetic field and its atmosphere protect us from solar radiation. It’s not clear whether a weak magnetic field during a polarity transition would allow enough solar radiation to reach the Earth's surface that it would cause extinctions. But reversals happen rather frequently--every million...
No. There is no evidence of a correlation between mass extinctions and magnetic pole reversals. Earth’s magnetic field and its atmosphere protect us from solar radiation. It’s not clear whether a weak magnetic field during a polarity transition would allow enough solar radiation to reach the Earth's surface that it would cause extinctions. But reversals happen rather frequently--every million...
Did all the dinosaurs live together, and at the same time?
Dinosaur communities were separated by both time and geography. The 'Age of Dinosaurs' (the Mesozoic Era ) included three consecutive geologic time periods (the Triassic, Jurassic, and Cretaceous Periods). Different dinosaur species lived during each of these three periods. For example, the Jurassic dinosaur Stegosaurus had already been extinct for approximately 80 million years before the...
Dinosaur communities were separated by both time and geography. The 'Age of Dinosaurs' (the Mesozoic Era ) included three consecutive geologic time periods (the Triassic, Jurassic, and Cretaceous Periods). Different dinosaur species lived during each of these three periods. For example, the Jurassic dinosaur Stegosaurus had already been extinct for approximately 80 million years before the...
Did people and dinosaurs live at the same time?
No! After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth. However, small mammals (including shrew-sized primates) were alive at the time of the dinosaurs. Some scientists who study dinosaurs (vertebrate paleontologists) now think that birds are direct descendants of one line of carnivorous dinosaurs, and some consider that they in fact represent modern...
No! After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth. However, small mammals (including shrew-sized primates) were alive at the time of the dinosaurs. Some scientists who study dinosaurs (vertebrate paleontologists) now think that birds are direct descendants of one line of carnivorous dinosaurs, and some consider that they in fact represent modern...
Were dinosaurs warm-blooded or cold-blooded?
Scientists have conflicting opinions on this subject. Some paleontologists think that all dinosaurs were 'warm-blooded' in the same sense that modern birds and mammals are: that is, they had rapid metabolic rates. Other scientists think it unlikely that any dinosaur could have had a rapid metabolic rate. Some scientists think that very big dinosaurs could have had warm bodies because of their...
Scientists have conflicting opinions on this subject. Some paleontologists think that all dinosaurs were 'warm-blooded' in the same sense that modern birds and mammals are: that is, they had rapid metabolic rates. Other scientists think it unlikely that any dinosaur could have had a rapid metabolic rate. Some scientists think that very big dinosaurs could have had warm bodies because of their...
When did dinosaurs become extinct?
Dinosaurs went extinct about 65 million years ago (at the end of the Cretaceous Period), after living on Earth for about 165 million years. If all of Earth time from the very beginning of the dinosaurs to today were compressed into 365 days (one calendar year), the dinosaurs appeared January 1 and became extinct the third week of September. (Using this same time scale, the Earth would have formed...
Dinosaurs went extinct about 65 million years ago (at the end of the Cretaceous Period), after living on Earth for about 165 million years. If all of Earth time from the very beginning of the dinosaurs to today were compressed into 365 days (one calendar year), the dinosaurs appeared January 1 and became extinct the third week of September. (Using this same time scale, the Earth would have formed...
Where did dinosaurs live?
Dinosaurs lived on all of the continents. At the beginning of the age of dinosaurs (during the Triassic Period, about 230 million years ago), the continents were arranged together as a single supercontinent called Pangea. During the 165 million years of dinosaur existence this supercontinent slowly broke apart. Its pieces then spread across the globe into a nearly modern arrangement by a process...
Dinosaurs lived on all of the continents. At the beginning of the age of dinosaurs (during the Triassic Period, about 230 million years ago), the continents were arranged together as a single supercontinent called Pangea. During the 165 million years of dinosaur existence this supercontinent slowly broke apart. Its pieces then spread across the globe into a nearly modern arrangement by a process...
What was Pangea?
From about 300-200 million years ago (late Paleozoic Era until the very late Triassic), the continent we now know as North America was contiguous with Africa, South America, and Europe. They all existed as a single continent called Pangea. Pangea first began to be torn apart when a three-pronged fissure grew between Africa, South America, and North America. Rifting began as magma welled up through...
From about 300-200 million years ago (late Paleozoic Era until the very late Triassic), the continent we now know as North America was contiguous with Africa, South America, and Europe. They all existed as a single continent called Pangea. Pangea first began to be torn apart when a three-pronged fissure grew between Africa, South America, and North America. Rifting began as magma welled up through...
Can USGS photos of fossils be downloaded or viewed online?
Some fossil photos can be viewed and downloaded from the USGS Photographic Library and our Multimedia Gallery . Fossil photos can also be viewed as published plates within many online USGS publications. Visit the USGS Publications Warehouse to search for publications. The best keywords for searches are author names, such as William Cobban, Norm Silberling, and Glenn Scott. The USGS fossil...
Some fossil photos can be viewed and downloaded from the USGS Photographic Library and our Multimedia Gallery . Fossil photos can also be viewed as published plates within many online USGS publications. Visit the USGS Publications Warehouse to search for publications. The best keywords for searches are author names, such as William Cobban, Norm Silberling, and Glenn Scott. The USGS fossil...
- Multimedia
Earth History of the National Capital Region – Volcanoes, Earthquakes & Dinosaurs… Oh My!
Earth History of the National Capital Region – Volcanoes, Earthquakes & Dinosaurs… Oh My!
Earth History of the National Capital Region – Volcanoes, Earthquakes & Dinosaurs… Oh My!
Reston, Virginia, was founded 47 years ago & Europeans first settled in the National Capital region 403 years ago. This human footprint can't compare to the dynamic Earth history of this region, extending back as early as 1,180 million years ago and continuing today.
Reston, Virginia, was founded 47 years ago & Europeans first settled in the National Capital region 403 years ago. This human footprint can't compare to the dynamic Earth history of this region, extending back as early as 1,180 million years ago and continuing today.
Fossil Discovery Makes History: Studying a Prehistoric Climate and Ecosystem in Colorado
Fossil Discovery Makes History: Studying a Prehistoric Climate and Ecosystem in Colorado
Fossil Discovery Makes History: Studying a Prehistoric Climate and Ecosystem in Colorado
A trio of USGS scientists has been involved in the excavation and study of a major animal and plant fossil discovery in Snowmass Village, Colo., which provides more than 100,000 years of vegetation and climate records for the area.
A trio of USGS scientists has been involved in the excavation and study of a major animal and plant fossil discovery in Snowmass Village, Colo., which provides more than 100,000 years of vegetation and climate records for the area.
How are dinosaurs named?
Listen to hear the answer.
Which was the smartest dinosaur?
Listen to hear the answer.
Trilobite Fossil
Trilobite fossil, an extinct marine invertebrate. Item originally from Alnif, Morocco.
Trilobite fossil, an extinct marine invertebrate. Item originally from Alnif, Morocco.
Trilobite Fossil (Phacops rana africana)
A fossilized Trilobite, Phacops rana africana, an extinct marine invertebrate. Item originally from Alnif, Morocco.
A fossilized Trilobite, Phacops rana africana, an extinct marine invertebrate. Item originally from Alnif, Morocco.
Fossil Fish (Jiang Hanichthys)
Fossilized Jiang Hanichthys, an extinct fish that lived from the Cretaceaous to 100 million years ago. Item originally from Hubai Province, China.
Fossilized Jiang Hanichthys, an extinct fish that lived from the Cretaceaous to 100 million years ago. Item originally from Hubai Province, China.
Fossil Fish (Jiang Hanichthys)
Fossilized Jiang Hanichthys, an extinct fish that lived fromthe Cretaceaous to 100 million years ago. Item originally from Hubai Province, China.
Fossilized Jiang Hanichthys, an extinct fish that lived fromthe Cretaceaous to 100 million years ago. Item originally from Hubai Province, China.
Dinosaur Tracks
Dinosaur tracks in the Jurassic Moenave Formation. It is a popular site for tourists to stop and meet local Navajo and Moenkopi Hopi guides who lead short tours through the tracks area.
Dinosaur tracks in the Jurassic Moenave Formation. It is a popular site for tourists to stop and meet local Navajo and Moenkopi Hopi guides who lead short tours through the tracks area.
USGS Snowmastodon Research
USGS scientists working at Ziegler Reservoir near Snowmass Village, Colorado.
USGS scientists working at Ziegler Reservoir near Snowmass Village, Colorado.
Mastodon Fossil
Denver Museum of Nature and Science personnel excavate a large mastodon tusk at the Ziegler Reservoir site.
Denver Museum of Nature and Science personnel excavate a large mastodon tusk at the Ziegler Reservoir site.
Mammoth Fossils
Excavation of the initial Columbian mammoth remains found at the Ziegler Reservoir site.
Excavation of the initial Columbian mammoth remains found at the Ziegler Reservoir site.
- Publications
The geology and paleontology of Tule Springs Fossil Beds National Monument, Nevada
On December 19, 2014, Tule Springs Fossil Beds National Monument, located in the Las Vegas Valley of southern Nevada, was established by Congress as the 405th unit of the National Park Service to “conserve, protect, interpret, and enhance for the benefit of present and future generations the unique and nationally important paleontological, scientific, educational, and recreational resources and va
Authors
Kathleen B. Springer, Jeffrey S. Pigati, Eric Scott
Divisions of geologic time (Bookmark)
DescriptionThis bookmark presents information that is widely sought by educators and students. Version 3.0 of this bookmark is updated according to chapter C of U.S. Geological Survey Professional Paper 1879–1. The bookmark contains names of geologic time periods and boundary age estimates ratified by the International Commission of Stratigraphy in 2023.
Authors
Why Study Paleoclimate?
U.S. Geological Survey (USGS) researchers are at the forefront of paleoclimate research, the study of past climates. With their unique skills and perspective, only geologists have the tools necessary to delve into the distant past (long before instrumental records were collected) in order to better understand global environmental conditions that were very different from today's conditions. Paleocl
Authors
Marci Robinson, Harry Dowsett
Divisions of Geologic Time—Major Chronostratigraphic and Geochronologic Units
Effective communication in the geosciences requires consistent uses of stratigraphic nomenclature, especially divisions of geologic time. A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and calibrated in years. Over the years, the development of new dating methods and refinement of previous ones have stimulated revisions to geologic time scales. Since
Authors
Dinosaurs, facts and fiction
No abstract available.
Authors
Ronald J. Litwin, Robert E. Weems, Thomas R. Holtz
Crinoids; a computer animation and paper model
No abstract available.
Authors
Tau Rho Alpha, Dorothy L. Stout, Scott W. Starratt
Chicxulub impact event; computer animations and paper models
No abstract available.
Authors
T. R. Alpha, John P. Galloway, S. W. Starratt
Mud fossils
At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away. Careful studies by scientists showed that rocks had diverse origins. Some rock layers, containing clearly identifiable fossil remains of fish and other forms of aquatic animal and plant life, originally formed in the ocean. Other layers, consisting of sand g
Authors
Make your own paper fossils; a computer animation and paper models
No abstract available.
Authors
Tau Rho Alpha, James W. Hendley, Scott W. Starratt
The Great Ice Age
The Great Ice Age, a recent chapter in the Earth's history, was a period of recurring widespread glaciations. During the Pleistocene Epoch of the geologic time scale, which began about a million or more years ago, mountain glaciers formed on all continents, the icecaps of Antarctica and Greenland were more extensive and thicker than today, and vast glaciers, in places as much as several thousand f
Authors
Louis L. Ray
Geologic time: The age of the Earth
The Earth is very old 4 1/2 billion years or more according to recent estimates. This vast span of time, called geologic time by earth scientists and believed by some to reach back to the birth of the Solar System, is difficult if not impossible to comprehend in the familiar time units of months and years, or even centuries. How then do scientists reckon geologic time, and why do they believe the
Authors
William L. Newman
