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Zoom Dinosaurs
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By Date By Type of Dinosaur General Dino. Qns. Qns. About Other Animals Geological Era Qns.

Questions about Geological Eras
Go to a detailed geological time chart. Go to a shorter version of the geological time chart.

Q: I know that the Jurassic period was the 2nd period in the dinosaur period. Right after the Triassic and before the Cretatious. But when did it start and when did it end? Like, how many million years ago did it start and end?
from Linley A, San Antonio, Texas, USA; December 2, 1998

A: For the dates and more information about these periods, see this page.

Q: When did the Jurassic period start and how long did it last? What were some of the characteristics of the plant life at that time?
from Stephanie, San Antonio, TX, USA; December 1, 1998

A: Click here for information about the Jurassic period.

Q: What were the dominant Carnivores and Herbivores of the Cretaceous Period?
from Paul G., Arvada, Colorado, USA; November 16, 1998

A: This varied from area to area and through time. The Cretaceous period lasted about 81 million years; a lot of genera came and went during this time. For example, Suchomimus dominated at least part of Africa during the early Cretaceous. Also during this time, Giganotosaurus may have dominated South America. Later in the Cretaceous, T. rex was is western North America, etc. See the section on the Cretaceous period for more details. Q: what geological events occurred during the permian period
from Josh L., Arvada, Colorado, USA; November 16, 1998

A: The Permian Period (also known as the "Age of Reptiles") is best known for the largest mass extinction that happened at its end (about 248 million years ago).

Q: What was the land like in the late Cretaceous period?
from Ian O., Norfolk, New York, USA; November 19, 1998

A: There was no polar ice during the mild warm, subtropical Cretaceous period. The land was covered with forests surrounded by shallow seas. Seasonality was increasing. Most of the land mass was at or around sea level until the mid-Cretaceous, a time of high tectonic activity (continental plate movement) and accompanying volcanic activity . This is when many mountain ranges were formed , including California's Sierra Nevadas, the Rocky mountains in the western USA and the European Alps. The sea levels rose during the mid-Cretaceous, covering about one-third of the land area. Toward the end of the Cretaceous, there was a drop in sea level, causing land exposure on all continents, more seasonality, and greater extremes between equatorial and polar temperatures. Also, the continents were taking on their modern-day forms. For more information about the Cretaceous period, click here.

Q: What dinosaurs lived during the Permian period? What did they look like and what was their background information.
from Yoshi, Texas, Texas, USA; November 29, 1998

A: No dinosaurs lived during the Permian period. Dinosaurs evolved later, during the mid-Triassic period about 225 million years ago.

Q: In what period did Diplodocus and Spinosaurus live in?
from David H, Timaru, New Zealand, USA; October 21, 1998

A: Diplodocus lived in the late Jurassic Period, from 155-145 million years ago. Spinosaurus lived during the late Cretaceous period, about 98 to 95 million years ago.

Q: What are the periods that the Stegosaurus, Plesiosaur, Triceratops and Megalasaurus lived?
from Andrea, Troy, Michigan, USA; October 20, 1998

A: Stegosaurus lived during the late Jurassic period. Megalasaurus lived during the mid-Jurassic. Triceratops lived during the late Cretaceous period. Various Plesiosaurs lived from the early Jurassic to the end of the Cretaceous.For more exact dates, click on the name of the animal to go to an information sheet about it.

Q: what were some of the oxygen breathing animals in the early paleozoic era?
from centennial middle school, georgetown, ontario, Canada; September 24, 1998

A: Early in the Paleozoic Era was the Cambrian Period or "The Age of Trilobites," 540 to 500 million years ago. There was a huge surge in the development of life forms in which all existant phyla developed; this was called the Cambrian explosion of life. Animals in existence include trilobites, shell-fish, echinoderms, brachiopods, mollusks, etc. All animals except anaerobic bacteria breathe oxygen - they didn't use lungs at this point, but they still needed oxygen to survive. No land animals or plants had appeared yet. For more information on the Paleozoic Era, click here to see a chart of geological time.

from Lucas F., cambridge, waikato, N.Z.; June 8, 1998

A: Humans (homo sapiens) first appeared about 200,000 years ago.

Q: What animals lived during the Permian Period- where can I find pictures of these animals ?
from Meghan B., Hatboro, PA, USA; June 5, 1998

A: The Permian period (280 to 248 million years ago) is also called "the age of amphibians" since they were the dominant form of life then. Amphibians included Diplocaulus (a primitive, scaly animal with a boomerang-like head and a long body), Eryops (a 5-foot-long crocodilie-like animal), and Seymouria (a 2-feet-long amphibian that resembles a reptile). Reptiles, like dimetrodon , Eunotosaurus (a 6-inch turtle-like plated animal), and Scutosaurus (an 8-feet-long large-skulled animal with bumps on its head) were also abundant. Common animals living in the seas were brachiopods (clam-like invertebrates), ammonoids (marine predators similar to the nautilus), gastropods (mollusks related to the modern-day snail ), crinoids (echinoderms with five-sided symmetry, like the modern-day sea urchin), bony fishes , sharks , and fusulinid foraminifera (large protozoans with spindle-shaped shells). Corals and trilobites were waning.

from Adam L., Bronx, NY, USA; May 24, 1998

A: The oldest dinosaur yet found is the Eoraptor, which lived in the late Triassic period, roughly 228 million years ago. Very few dinosaurs had evolved yet during this period. For information on Eoraptor, click here.

The first life forms on earth were single-celled organisms, blue-green algae, that evolved during the Archeozoic Eon 3.9 to 2.5 billion years ago.

The first dinosaurs to be found (Megalosaurus,Iguanodon, and Hylaeosaurus) were found in England in the early 1800's.

The land on earth solidified during the Hadean Eon, 4.6 to 3.9 billion years ago. For more information on the geological eras on earth, click here.

More dinosaurs have been found in western North America than anywhere else. Montana seems to have more discoveries than other places within this area. This is partly because of the large amount of exposed Mesozoic sedimentary rock there and the ease of accessibility to these rocks.

Q: what did the cretaceous period look like? aka vegetation,life,terrain.
from Josh B., Calgary, Alberta, Canada; May 14, 1998

A: The Cretaceous period, 146-65 million years ago, was a time of great geological changes. There was a lot of volcanic activity, continental drift that changed the face of the Earth (the breakup of the supercontinent Pangaea), climate changes, and finally, a catastrophic asteroid hit at the end of the period. During the Cretaceous, flowering plants appeared as did placental mammals. Vegetation included ferns, gingkos, magnolias, cycads, palms, conifers, etc. For more information on the Cretaceous period, click here.

Q: How long was each dinosaur period?
from Heather B., West Seneca, NY, USA; May 13, 1998

A: The dinosaurs lived during the Mesozoic Era which lasted from 248 to 65 million years ago. The Mesozoic is divided into 3 periods: the Triassic period (248-208 million yeas ago), the Jurassic period (207-146 million yeas ago), and the Cretaceous period (146-65 million yeas ago).

For more information on the Mezozoic Era and its subdivisions, click here. For more information on geologic time, click here.

Q: What Was The Weather Like When The dinosaurs existed?
from St Joseph's High, Albion Park, N.S.W., Australia; May 11, 1998

A: The dinosaurs lived during the Mesozoic Era, 248 to 65 million years ago, a time when the Earth's climate and geography were very different than they are now. For most of the Mesozoic, the Earth's continents were jammed together into the supercontinent Pangaea. The climate was mostly warmer than it is now, with some periods being much warmer, with very little seasonality (that is, very little difference between winter and summer extremes), little or no polar ice, and higher sea levels. See the chart below for a little more detail. For even more details, click on Mesozoic in the margin to your left and see the sections on the periods of the Mesozoic, the Triassic, the Jurassic, and the Cretaceous.

The Age of Reptiles
The Mesozoic Era
248 - 65 million years ago
Triassic Period
248 - 208 million years ago
Jurassic Period
208-146 million years ago
Cretaceous Period
146-65 million years ago
Continental Drift
One supercontinent, Pangaea. In mid-Jurassic, Pangaea began to break apart, into Laurasia and Gondwana. Continental drift continued at a fast pace, with accompanying volcanic activity. The continents almost had their modern-day look.
Hot and dry, with strong seasonality. Hot and dry, with strong seasonality at first, changing to warm and moist with no polar ice and vast flooded areas. Temperatures were warm, seasonality was low, and global sea levels were high (no polar ice!) at the beginning of the Cretaceous. Later, sea levels dropped, seasonality increased, and there were greater extremes in temperature between the poles and the equator.
Plants and Animals
Small, fast dinosaurs appeared for the first time. The first tiny nocturnal mammals developed. Ichthyosaurs (marine reptiles) swam in the seas. Ferns , cycads , and early gymnosperms (conifers) abound. More dinosaurs, including gigantic ones, roamed the earth, and pterosaurs flew. Archaeopteryx, the first primitive dinosaur-like bird developed. Dinosaurs flourished, flowering plants (angiosperms) appeared, displacing conifers and others. A major extinction occurred at the end of the Mesozoic, 65 million years ago.

Q: When were the first plants seen on earth, and what climate changes occured?
from C2, Indianapolis, IN, USA; April 29, 1998

A: The first primitive land plants (like mosses) appeared during the Ordovician Period (505-438 million years ago). The first vascular plants (plants with water-conducting tissue) appeared during the Silurian period (438-408 million years ago). For more details on the evolutionary timeline, click on "Geologic Time Chart" in the margin to your left.

Q: What specific plants were living during the Late Jurassic Period and Early Cretaceous Period?
from Juliet, Beaumont, Texas, USA; April 29, 1998

A: Common plants during the Jurassic and Cretaceous periods were ferns , cycads , conifers, and horsetails (Equisetophyta). Flowering plants (anthophyta) evolved during the beginning of the Cretaceous period, and diversified tremendously in the mid-Cretaceous. Early flowering plants from the Cretaceous included the magnolia, the water lily, and glumiflorae (sedges, grasses, etc.).

Q: How did the scientists know time lines?
from Eric, Meridian, ID, USA; April 29, 1998

A: The divisions in Geologic time are based on major geological and biological events that produce changes in rock formations. For example, the beginning and end of the Mesozoic Era are bracketed by mass extinctions that were caused by huge geologic and climactic changes. Determining the dates of these pivotal events is done using radioisotope dating.

from JESSICA AND KELLIE, Port Charlotte, FL, USA; April 15, 1998

A: Geologists (notably the German geologist and meteorologist Alfred Wegener) first proposed the theory of continental drift in 1912, which states that parts of the Earth's crust slowly drift atop a liquid core. Then geologists pieced together pieces of matching coastline (for example, the west coast of Africa and east coast of South America fit together beautifully, and the layers of rock within these matching bits of coastline also matched). Wegener then hypothesized that there was an original, gigantic supercontinent 200 million years ago, which he named Pangaea, meaning "All-earth." In addition, the fossil record supports and gives credence to the theories of continental drift and plate tectonics.

Q: Were there any mice during the Jurassic period?
from Wanda A., Philadelphia, PA, USA; April 15, 1998

A: No, modern-day mice hadn't evolved yet, but there were other primitive mammals during the Jurassic period. Some primitive mammals from the Jurassic included Megazostrodon, a 4-inch-long, mouse-like mammal that ate insects, Morganucodon, another mouse-like creature, and Triconodon, a house-cat-sized meat-eater. Mammals first appeared during the Triassic period, just before the Jurassic period.

Q: what era is the "Age of Reptiles?" How long did most dinosaurs live?
from Jenn, Port Charlotte, FL, USA; April 15, 1998

A: The Mesozoic Era is called "the Age of Reptiles" because of the dominance and diversity of reptiles then. For more information on the mesozoic, click on "Mesozoic" in the margin to your left. No one knows how long individual dinosaurs lived. Some paleontologists have guessed that some of the huge sauropods (like Apatosaurus) may have lived to be over 100 years old.

Q: do you have any information on the Archaeopteryx?
from Edward M., Mokena, IL, USA; April 14, 1998

A: The Archaeopteryx is the oldest known fossil bird, and dates from the late Jurassic period (about 150 million years ago). It is now extinct. Although it had feathers and could fly, it had similarities to dinosaurs, including its teeth, skull, and certain bone structures. For more information, click on "Dinosaurs and Birds" in the main section - "All About Dinosaurs."

Q: What is the total length of time in Precambrian, Paleozoic, Mesozic, Cenozoic ?
from ???, Port Charlotte, FL, USA; April 2, 1998

A: The answer to these questions is contained in the short version of the geological time chart.

Note that the Precambrian ( meaning "before the Cambrian period") is simply all the time on Earth before the Cambrain period. The Precambrian started when the Earth formed, about 3.9 billion years ago, and ended 540 million years ago. Scientists no longer use the term Precambrian very much because its too vague. That time period is now broken into three Eons:

Q: What era means "ancient life ?" When did flowering plants appear ? When did the first plants appear ? What is the shortest and current era ? When Pangaea begins to break apart ? Sorry there are so many questions please answer as many as you can.
from Shawna R., Port Charlotte, FL, USA; April 1, 1998

A: The Archeozoic Eon ( also known as the Archean Eon) means "ancient life." Flowering plants appeared during the early Cretaceous period (late in the Mesozoic Era). The first plants appeared on land during the Ordovician period. The current era is the Cenozoic Era (the current epoch is the Holocene). Pangaea started to separate in the mid Jurassic period. For a geologic time chart with all this information and more, click here or on "Geologic Time Chart" in the margin to your left.

Q: what era is known as the"Age of Reptiles"?
from ?; March 31, 1998

A: The Mesozoic Era.

from ???; March 31, 1998

A: During the Devonian period (410 to 360 Million Years Ago), both primitive tetrapods (vertebrates which included lungfish and amphibians) and arthropods (which included wingless insects and early arachnids) went on land for the first time. For an extensive geologic time chart, click here.

Q: In what Era did Pangaea begin to break apart?
from K.C., Port Charlotte, Florida, USA; March 31, 1998

A: The supercontinent Pangaea began to break up in the middle of the Mesozoic Era (during the Jurassic period). In the Middle Jurassic, the supercontinent Pangaea started to drift apart. A north-south rift formed, and by the late Jurassic, the separation of the continents of Laurasia and Gondwana was almost complete. For more information on the Mesozoic Era, click here or on "Mesozoic" in the margin to the left.

Q: When did humans first appear
from ?; March 26, 1998

A: The first humans (homo sapiens) evolved about 200,000 year ago, during the Pleistocene Epoch. For more information on the Earth's geologic timeline, click here.

Q: how many million years did the Precambrian Period last?
from Lucy, ?; March 25, 1998

A: The Precambrian (before the Cambrian period) started when the Earth formed, about 3.9 billion years ago, and ended 540 million years ago. Scientists no longer use the term Precambrian very much because its too vague. That time period is now broken into three Eons: For more information on the Earth's geologic history, click here.

Q: Did mammals live during the dino's period?
from Jaimi C., Vassalboro, Maine, USA; March 19, 1998

A: Yes, mammals and dinosaurs both evolved during the Triassic period. Some scientists think that competition from mammals may have contributed to the extinction of the dinosaurs.

Q: I need help on finding out what the last 3 eras were, when they occurred, what era we live in, what continents fossils have been found in, what type of dinosaurs did early humans hunt for food, what type of dinos had fur, were dinos reptiles or mammals, what the definition of reptiles is, what the definition of mammals is, what ways dinos attracted mates, what does the name t-rex mean. Can you help me?
from Jackie der ..., Anchorage, AK, USA; March 17, 1998

A: To see a chart of the Earth's geologic eras, click on "Geologic Time Chart" in the margin to your left. Fossils have been found on every continent on Earth. Humans and dinosaurs did not live at the same time; people evolved millions of years after the dinosaurs went extinct. For definitions of reptiles, mammals, etc., click on the Dino/Paleo Dictionary to your left. Click here for information on T. Rex.

Q: who first proposed the theory of continental drift?
from ???; March 16, 1998

A: In 1912, the German geologist and meteorologist Alfred Wegener first proposed the theory of continental drift, which states that parts of the Earth's crust slowly drift atop a liquid core. For more information, click here.

Q: Where have fossils of T-rex being found in North America?
from Zachary, Aurora, Colorado, USA; March 2, 1998

Q:During what period of geologic time did Tyrannosaurus exist?
from Oluwashina T., Denver, CO, USA; March 2, 1998

Q:During what period of geologic time did the T-rex exist?
from Shina, Denver, CO, USA; Feb. 27, 1998

A: Tyrannosaurus rex lived during the late Cretaceous period, about 85 to 65 million years ago. Fossils have been found in the western USA (in Montana, Texas, Utah, and Wyoming), Canada (Alberta and Saskatchewan), and Asia (Mongolia).

Click here for an information sheet on T. rex.

Q: Please, send me all the facts about Gigantosaurus. Nikola
from Nikola K., Belgrade, Serbia, Yugoslavia; March 2, 1998

Q: What time period was the Giganotosaurus from?
from Colleen, Pennsville, NJ, USA; Feb. 28, 1998

GiganotosaurusA: Giganotosaurus lived during the mid-Cretaceous period, about 100 million years ago. For more information on Giganotosaurus, click here. Q:What does preCambrian mean?
from Tyler; November 20, 1997

A: The Precambrian Period was the earliest time period in the geologic history of the Earth, ending about 540 million years ago. It was the time in which the Earth's crust formed and the first life forms appeared in the seas. The Precambrian period usually refers to the time before the Cambrian Period, in which an explosion of life forms evolved. The Precambrian is divided into the Proterozoic Eon (2.5 billion years ago to 540 million years ago) in which multicellular life arose, the Archeozoic Eon (3.9 - 2.5 billion years ago) in which early life forms evolved, and the Hadean Eon (4.6-3.9 billion years ago) in which the Earth solidified.

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