module 7 Flashcards
when a plant or animal dies, what is the most likely thing that will happen to its remains?
they will decompose
which forms first: a fossil mold or a fossil cast?
a fossil mold will form first, a fossil cast will form second
describe the process of a cast forming, indicating when the mold has formed and when the cast has formed
the remains of a plant or animal are encased in sediment, and the sediment eventually hardens into rock. as the remains of the plant or animal disintegrate, a hole is left in the rock, in the shape of the original remains. that is the mold. the mold might fill up with sediment or magma later and, when the filling hardens, it forms a cast.
what is required in order for petrifaction to occur?
water that has a lot of minerals in it
why does petrifaction usually produce fossils with more information than fossil casts?
because fossil casts retain only the shape and outer details of the fossil, when a fossil is petrified, its components are replaced with minerals, this means the entire fossil is preserved, which gives us more information than just the shape and outer details of the fossil
can you learn much about the thickness of an organism from carbonized remains?
no, you cannot
what type of organism is most likely to leave carbonized remains?
plants
what is so nice about fossils?
thus, tissue and other soft parts tend to be preserved
what are the four general features of the fossil record?
fossils are usually found in sedimentary rock. since most sedimentary rock is laid down by water, it follows that most fossils were laid down by water
the vast majority of the fossil record is made up of hard shelled creatures like clams. most of the remaining fossils are either water dwelling creatures or insects. only a tiny, tiny fraction of the fossils we find are of plants, reptiles, birds, and mammals.
many of the fossils we find are of organisms that are still alive today. Many of the fossils we find are of organisms that are now extinct
the fossils found in one layer of stratified rock can be considerably different from the fossils found in another layer of stratified rock
what kinds of creatures make up the vast majority of the fossil record?
clams and other hard shelled animals
approximately how many species of plants and animals have gone extinct in the last 400 years: a hundred, a thousand, ten thousand, or a hundred thousand?
a thousand
what is a trilobite? are trilobites extinct?
a creature that lived in the water and was covered in a hard outer covering, but is now extinct.
what is a placoderm? are placoderms extinct?
a kind of fish. it was much like the fish we see today, but its head was covered hard plates rather than scales and yes they are extinct
what is the Unitarianism explanation for how most sedimentary rocks formed?
sediments are laid down slowly over millions of years
what is the catastrophist explanation for how most sedimentary rocks formed?
were formed in the worldwide flood. the depth speed and direction of the flood waters determined what type of sediments were laid down, which in turn determined the kind of rock formed.
