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Fossils
This category is for questions about the bones, fragments, imprints, and other remainders from a different time. The questions and answer you will find here are history set in stone -- our past, immortalized in solid rock. You will also be able to find questions pertaining to the locations of these fossils, how you might identify them, and how they were formed.
3,454 Questions
How do paleontologists know how old fossils are?
The dating of fossils was originally done by their placement in a geologic column of rock strata. Because of the Law of Superposition, the deeper the stratum, the older it is (in an undisturbed body of rock or sediment). Fossils which were evident in a particular stratum, but missing from other strata were noted as "index" fossils. The presence of these fossils indicated the age of the stratum relative to other layers. The layers of stratum were placed in a geologic column, subdivided, and assigned names based on the presence of different types of fossil organisms.This is the basis of "relative dating" of rock layers and fossils, a dating technique that was in effect until the advent of radiometric techniques in the twentieth century.
How does a fossil come out of the ground?
Typically, fossils appear on the ground due to the erosion of the rock or material that once encased them. The minerals that replaced the fossils might be more resistant to erosion than the surrounding rock, allowing them to remain after the encasement material has disappeared.
Two conditions necessary for fossils to form?
well in your body there are made up of fossils as fossils are formed in hot places and your body is very warm
Fossils found, such as Wolly Mammoths,differ in many ways. Wolly mammoths are the ancestors to the elephants we have living today. The difference? Wolly mammoths are much longer and differ in size. For example, if you had a mammoth and an elephant stand on their hind legs, the mammoth would be taller.
Why is uranium 238 dating better than carbon 14 dating?
Uranium-238 dating is better than carbon-14 dating for dating older geological samples because its half-life is much longer (4.5 billion years compared to 5,730 years for carbon-14). This makes it ideal for dating rocks that are billions of years old, whereas carbon-14 dating is best suited for more recent materials up to about 50,000 years old.
What two methods are used to determine the age of a rock?
The two methods are relative dating and radioactive dating for fossils. I think it's the same for rocks.
Why are there so few frog fossils?
The reason frog fossils are hard to come by is because of the softness of their bones.
When the earth, soil and rocks move underground, their bones are easily destroyed. Which means fossils cannot form as easily.
But saying that, one of the most famous fossils ever recovered is one of a frog, as you can see its facial features, which is rare for a fossil in general, let alone a frog fossil. More about that on the national Geographic website (click here).
hi
A fossil is evidence of a once living animal. A fossil is created when an animal dies in a mud or other soft dirt or sediment. Over time, the animal will decompose and leave the bones. Over time, these bones will get covered by dirt, rocks water, etc. After a couple thousand years the bones will get compressed into sediment, waiting to be discovered. Something similar to a fossil is and imprint. This is where an impression of a plant or animal is pushed into a soft sediment and hardens.
Where are the oldest layers of rock in a rock formation?
older fossils are usually further in the earth because the creature died before the others so the go down further and the ones that dies more recently are closer because they died more recently so haven't had the time to move further before they where found
What is the difference between a living fossil and a lazarus taxon?
A lazarus taxon is an animal that was thought to be extinct at one point, but for a few months, years, or even centuries, the animal is found again.
One example is the Coelocanth. It was thought to become extinct millions of years ago, but one specimen in Asia (I think) was found in the 30s. It was later found in Madagascar. It is endangered. They reach up from 60 centimeters to 1 meter. They mainly eat fish, squid, octopuses and even small sharks. They are preyed on by seals, sea lions, large sharks and orcas.
Another one is the peccary. Believe it or not, this is a lazarus taxon, it was thought to be extinct in the pleistocene, but it was found again in the recent times. They are about one meter. They mainly eat vegetation, but they also eat rodents, lizards, snakes and even small birds. They are eaten by jaguars, bush dogs, coyotes and anacondas. The collared one is least concern, but the chaocoan one is endangered.
The Takhae. The takhae is a small bird from New Zealand. It was actually thought to be extinct quite recently, at the same time as the moa, at about 1500. But, it was found again in the 40s. They eat vegetation. But also eat insects and worms. They have no natural predator, but they are eaten by introduced species like stoats.
What are three geological forces that would destroy fossils?
A fossil could be destroyed by heat due to melting, pressure from colliding bodies of rock, or from weathering at the surface.
How could a geologist use acid to get a pyrite fossil out of limestone?
Hydrochloric acid is used by geologists in the field to test if a rock contains carbonate minerals and to further distinguish between calcium and magnesium carbonate rocks. When acid is poured onto a non carbonate rock sample there will usually be no reaction. However calcium carbonate (limestone) will react by fizzing vigorously and magnesium carbonate (dolomite) will also react or fizz, but much more slowly.
If the geologist suspects the sample in question is marble he will attempt to crush or powder part of the specimen using his geological hammer. When the acid is poured onto powdered marble, this will also react by fizzing.
Some other sedimentary rocks, for example sandstones, may have mineral cements that are carbonates. As such acid can also be used as an aid in the identification of the cementing material.
The "fizzing" is caused by the reaction of the acid with the carbonate rocks to produce carbon dioxide gas. The reaction takes the following form:
HCl(aq) + CaCO3(s) = CaCl2(aq) + CO2(g) + H2O(l)
Where:
HCl = hydrochloric acid
CaCO3 = calcium carbonate
CaCl2 = calcium chloride
CO2 = carbon dioxide
H2O = water
If the sample still does not react with acid in any way after following the above steps, the geologist will most likely conclude that the sample is not a carbonate of any form. However they may also take the sample back to the laboratory for further study.
Please see the related links.
Which New York State fossil is found in rock's of the same period of geologic history as meekpceras?
The Sea Scorpion (Eurypterus remipes).
What is the difference between radiometric dating and relative dating?
Short Answer:
Radiometric dating is one type of method used in absolute dating. Both relative dating and absolute dating are procedures used to give temporal characteristics to a sequence of events. Both are attempting to get information on the history of events.
The primary difference in relative dating and absolute dating is that absolute dating assigns an actual time or age to an event or object. Relative dating simply says one is older than the other but no age is specified.
Tools in the category of radiometric dating are based on the known rates of radioactive decay of isotopes and this allow some samples to be assigned a certain age to within some accuracy. Radiometric techniques are one method of absolute dating and, for example, counting tree rings is another form of absolute dating.
Any technique that assigns a certain age or date is a form of absolute dating.
Relative dating is any scientific process of evaluation used to determine the relative order of past events, but does not determine the absolute age of an object.
Long Answer:
Sciences such as geology, Paleontology and archeology are very interested in identifying the age of objects found and these scientists sometimes use either relative dating or absolute dating to characterize the age of the objects they study.
Before radiometric dating it was difficult to determine the actual age of an object. Radiometric dating, based on known rates of decay of radioactive isotopes in objects, allows a specific age of an object to be determined to some degree of accuracy.
Relative dating is a scientific process of evaluation used to determine the relative order of past events, but does not determine the absolute age of an object. The circumstances of the object may allow one to say that one object is older than another without being able to assign a particular age to the objects.
For example:
If an archaeologist is studying past civilizations, the archaeologist may be able to say that in a particular location the ruins of once civilization were found to have been build on another and so the layers unearthed in an excavation convey the sequence of historical occupations without revealing the actual dates. If the archaeologist finds a sample suitable for carbon dating, then an absolute date may be assigned to an object.
Similarly for paleontologists who find layers of fossils. By deducing which fossils are formed in the sequence of time, the periods when the particular fossilized entities existed can be arranged in order without the actual dates of when the fossils were laid down. Radioactive isotopes can also be used by a paleontologists to assign an age to a fossil in some cases and that is an example of absolute dating with radiometric methods.
For geologists, it is similar. Looking at how rock formations are structured, a geologist may be able to say which rock was developed in which layer in a particular order but not be able to determine that actual geologic age of the layers. Geologists deal with the oldest of samples and radiometric dating with uranium is one of the few methods of geological absolute dating.
Radiometric dating determines how old something is using radioactive isotopes. It is the most accurate way of dating.
Relative dating is used to determine the age of a fossil by looking at its position in layers of sedimentary rocks.
fossil fuels r like decayed plants and animals (so FOSSILS) from 100 million years ago. they get turned into coal and oil and then drilled out.
Is a human fossil older than a dinosaur fossil?
No. The last dinosaurs died out 64 million years ago. In fact, there were at least 3 major extinction periods in which nearly all the species of that time were wiped out. The dinosaurs of the Jurassic and Cretacious periods were quite different, but new species began to appear millions of years after each extinction event. On the other hand, the very earliest hominids lived around 7 million years ago, and modern humans (Homo sapiens) did not appear until around 200,000 years ago. So, scientists have never found dinosaur and human fossils together in the same geological layer.
Supposed human and dinosaur footprints can be seen together in solidified volcanic ash at Glen Rose in Texas. They involve some indistinct markings of uncertain origin, and a smaller number of doctored and carved specimens. They are not human footprints.
