Dinosaurs

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The difference between a mold fossil and a cast fossil is that mold fossil is formed when an object is placed into soft mud and is removed by decomposition or physical sources; a cast fossil happens when a mold fossil fills up with sediment. A cast fossil is three dimensional, and a mold must be present for the cast fossil to exist.

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  • What was the largest dinosaur ever?

    Q: What was the largest dinosaur ever?

    A: Most paleontologists believe that the Argentinosaurus was the largest dinosaur to have ever lived. It may have been the largest land animal to have ever existed.
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  • What is the difference between a cast fossil and a mold fossil?

    Q: What is the difference between a cast fossil and a mold fossil?

    A: The difference between a mold fossil and a cast fossil is that mold fossil is formed when an object is placed into soft mud and is removed by decomposition or physical sources; a cast fossil happens when a mold fossil fills up with sediment. A cast fossil is three dimensional, and a mold must be present for the cast fossil to exist.
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  • What was the largest carniverous dinosaur?

    Q: What was the largest carniverous dinosaur?

    A: The largest known carnivorous dinosaur is the Spinosaurus, which is so named thanks to the gigantic spikes that run down the dinosaur's back. These spikes form a "sail" that likely evolved to ward off enemies rather than predators. The Spinosaurus was likely too large to be preyed upon by other dinosaurs.
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  • What did Tyrannosaurus rex eat?

    Q: What did Tyrannosaurus rex eat?

    A: Tyrannosaurus rex primarily ate herbivore dinosaurs, including the Edmontosaurus and the Triceratops. Studies suggest that the Tyrannosaurus rex also practiced cannibalism. Paleontologists believe that if two Tyrannosaurus rex dinosaurs fought to the death, the winner would eat the loser, based on bite marks found on Tyrannosaurus bones.
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  • What is a list of omnivorous dinosaurs?

    Q: What is a list of omnivorous dinosaurs?

    A: Omnivorous dinosaurs include Anserimimus, Deinocheirus, Gallimimus and Othnielia. Fruitadens haagarorum was a small dinosaur known to be omnivorous by the presence of both sharp teeth resembling canines and leaf-shaped teeth suitable for grinding plants. As a heterdontosaurid, it exhibited a shift in diet from its earlier herbivorous relatives.
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  • Why was the brontosaurus's name changed to the apatosaurus?

    Q: Why was the brontosaurus's name changed to the apatosaurus?

    A: The gigantic, herbivorous Brontosaurus, which features an iconically long neck and tail, may be one of history's most famous dinosaurs, but its existence as a unique species was debunked in 1903, when someone realized that the skeleton that had been labeled as a Brontosaurus was actually an Apatosaurus. In this sense, the Brontosaurus was not renamed but rather determined to have never existed as a separate species. The same man, a Yale paleontologist named Othniel Charles (O.C.) Marsh, named both the Apatosaurus and the Brontosaurus, with the Apatosaurus discovery predating the Brontosaurus naming by two years.
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  • What was the spinosaur's back fin used for?

    Q: What was the spinosaur's back fin used for?

    A: There seems to be a general lack of consensus among paleontologists as to what purpose the Spinosaurus' sail served; not only is there a lack of certainty as to why the sail existed, there also seems to be some question about whether the dinosaur actually had a sail at all. All questions about the Spinosaurus' anatomy must be answered using fossil evidence, which is limited to fossilized skeletal remains that show a crest of bones protruding upward from the dinosaur's spine. While some scientists feel that these bones provided the structure for a sail-like flap of skin, other argue that this spinal structure actually supported a large hump rather than a distinct sail.
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  • Are there animals alive today that lived beside dinosaurs?

    Q: Are there animals alive today that lived beside dinosaurs?

    A: There are some animals on earth that can be traced back to the Mesozoic Era when dinosaurs walked the earth; these animals include monotremes such as the duckbill platypus, reptiles such as the crocodilians and sea creatures such as the sea urchin. For the most part, the animals that are alive today have made evolutionary changes from the forms they had when dinosaurs were alive. For example, though the event that caused dinosaurs to die out also killed many other reptile species, several surviving reptile species have direct ancestors from that era, including the crocodilians, which are smaller than their Mesozoic ancestors.
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  • When did dinosaurs become extinct?

    Q: When did dinosaurs become extinct?

    A: Dinosaurs became extinct about 65 million years ago. This extinction event occurred between the Cretaceous and Tertiary periods and wiped out about 50 percent of all other organisms then living on the planet.
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  • What was the longest dinosaur?

    Q: What was the longest dinosaur?

    A: Though there have been a few instances of scientists purporting to have found larger specimens, the longest known dinosaur that is widely accepted by paleontologists seems to be the Diplodocus, a type of sauropod dinosaur with a long neck and long tail that is said to have measured as much as 175 feet in length. There seems to be some controversy and debate around the question of which dinosaur is truly the longest, with scientists introducing competitors such as the Seismosaurus, which was once thought to be a distinct species but was eventually found to be a very large Diplodocus specimen. The Seismosaurus' discovery was announced in 1991, but its existence as a unique species was debunked just over a decade later, a fact that was announced at an academic event in 2004.
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  • What were the smallest dinosaurs?

    Q: What were the smallest dinosaurs?

    A: The smallest known dinosaur species include the Minmi, Pakicetus, Europasaurus, Phosphatherium, Microraptor, Raptorex, Microceratops, Lariosaurus and Nemicolopterus. These are all examples of the smallest dinos in a particular group, such as the smallest Raptor (Microraptor), which weighed around 2 pounds and was small enough to eat insects, and the smallest Tyrannosaur (Raptorex), which likely topped out at about 150 pounds.
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  • How did the euoplocephalus protect itself?

    Q: How did the euoplocephalus protect itself?

    A: The Euoplocephalus was a dinosaur that had several built-in defensive weapons at its disposal, including a heavy clubbed tail, spiky bone protrusions on the head and a back made of plate armor with protruding bone spikes that helped protect the dinosaur from bites and other forms of attack. Using its tail, the Euoplocephalus could not only fend off attackers but also do serious damage to their muscles, teeth and even bones. This herbivorous quadrupedal dinosaur is often called the "tank dinosaur" thanks to its extensive body armor, including its back plates and even armored eyelids, and its sturdy, stout anatomy.
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  • Where did dinosaurs live?

    Q: Where did dinosaurs live?

    A: Scientists believe that the earth looked much different during the dinosaur's lifetime than it does today; at the advent of dinosaur life, all of the landmass on earth made up one single super continent known as Pangea. Dinosaurs likely did not live on every part of Pangea, instead concentrating in certain areas, including the land that is now known as Argentina, which is the home of the oldest known dinosaur fossil. Certain dinosaur species may have been localized to certain parts of the world, including the T.Rex, which has only been discovered in fossils found in North America.
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  • What was the lifespan of a stegosaurus?

    Q: What was the lifespan of a stegosaurus?

    A: Scientists approximate dinosaur lifespan by attempting to determine the metabolism of the animal, looking at its size and bone growth, and comparing with similar animals that are still around today. Based on these factors, a stegosaurus may have lived 75 to 100 years.
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  • How long ago did dinosaurs die out?

    Q: How long ago did dinosaurs die out?

    A: The purported mass dinosaur die off known as the K-Pg extinction event took place during the end of the Cretaceous Period (K) during the Mesozoic Era some 65 million years ago. This scientific theory is based on the study of the fossil record, which shows evidence for the existence of dinosaurs during the Mesozoic Era but not during the proceeding Cenozoic Era. There is a clear line of demarcation, an actual line found in sedimentary rock layers known as the K-Pg Boundary, with the majority of the fossilized remains found below this line belonging to the "Age of Dinosaurs" not appearing in the space above the line, which marks the beginning of the Paleogene Period (Pg), the Cenozoic Era and the "Age of Mammals."
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  • What is a baby dinosaur called?

    Q: What is a baby dinosaur called?

    A: Dinosaurs are hatched from eggs, therefore new baby dinosaurs are called hatchlings, just like their reptile cousins the turtles and crocodiles. Young dinosaurs, beyond the hatchling stage, are referred to as juveniles.
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  • How many types of dinosaurs were there?

    Q: How many types of dinosaurs were there?

    A: Dinosaur discoveries occur at a rapid pace, and it may be difficult to keep up with the exact number of dinosaurs there are at any given time, particularly because specimens used to determine this number may be incomplete or disputed; however, it can be said that there are about 800 confirmed and distinct species of dinosaur. New dinosaur discoveries are announced all the time at relatively high rates of as many as 30 per year, or about one every 10 days. Paleontologists have been known to get a bit overzealous with naming a specimen as a new and distinct species, and there have been hundreds of examples of dinosaurs that were once thought to be unique that have been proven otherwise.
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  • What are the two classes of dinosaurs?

    Q: What are the two classes of dinosaurs?

    A: Beginning in 1887, dinosaurs have been divided into two main categories: saurischian, which means "lizard hipped," and ornithischian, which means "bird hipped." This classification is based on the dinosaurs' pelvic bone structure. Though the name "bird hipped" may seem to indicate that these prehistoric animals are related to birds, that is not necessarily the case.
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  • Did deinonychus hunt in packs or alone?

    Q: Did deinonychus hunt in packs or alone?

    A: While some scientists argue that Deinonychus was a pack-hunting dinosaur, not all paleontologists agree with this assertion, though there is some isolated fossil evidence showing multiple Deinonychus specimens fossilized with a much larger prey dinosaur species. This evidence may establish that there was at least one instance of Deinonychus attacking the same prey, which was arguably too large to be taken down by a single Deinonychus, but that evidence is not sufficient for all experts in the field to agree that this dinosaur was definitely a pack hunter. There is additional evidence to support this idea, including multiple fossil sites suggesting that Deinonychus regularly fed on this larger dinosaur, the Tenontosaurus.
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  • Could a dinosaur be cloned from DNA preserved in amber?

    Q: Could a dinosaur be cloned from DNA preserved in amber?

    A: It is theoretically possible, though highly unlikely, that a dinosaur clone could be created. The idea that it's possible to clone a dinosaur using DNA preserved in amber was popularized by the movie Jurassic Park. This fictionalized version of the process made it seem like a relatively easy process, but in truth it's rather complex and improbable.
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  • Did the stegosaurus have two brains?

    Q: Did the stegosaurus have two brains?

    A: Even though there was a popular theory that Stegosaurus may have had two brains, one in its head and one toward its tail or rear end, that idea has largely been discredited in paleontology. Some paleontologists may still hold on to this theory and try to find ways that it might be true, but on the whole, this is not an accepted idea.
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