Principle of faunal succession
The principle of faunal succession, also known as the law of faunal succession, is based on the observation that sedimentary rock strata contain fossilized flora and fauna, and that these fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances. A fossilized Neanderthal bone will never be found in the same stratum as a fossilized Megalosaurus, for example, because neanderthals and megalosauruses lived during different geological periods, separated by many millions of years. This allows for strata to be identified and dated by the fossils found within.
This principle, which received its name from the English geologist William Smith, is of great importance in determining the relative age of rocks and strata. The fossil content of rocks together with the law of superposition helps to determine the time sequence in which sedimentary rocks were laid down.
Theories of evolution explain the observed faunal and floral succession preserved in rocks, which are the facts on which the understanding of evolution is based. The occurrence of faunal succession was thoroughly documented by Smith in England during the 1st decade of the 19th century, and concurrently in France by Cuvier . Archaic biological features and organisms are succeeded in the fossil record by more modern versions. For instance, paleontologists investigating the evolution of birds predicted that feathers would 1st be seen in primitive forms on flightless predecessor organisms such as feathered dinosaurs. This is precisely what has been discovered in the fossil record: simple feathers, incapable of supporting flight, are succeeded by increasingly large and complex feathers.
| In practice, the most
those with the fastest rate of
distribution; their study is termed
rocks by using the fossils
Cenozoic strata, fossilized
often used to determine
scale, each biostratigraphic
stratum that is defined on the
fossil taxa. An outline
both foraminifera and
| useful diagnostic species are
species turnover and the widest
biostratigraphy, the science of dating
contained within them. In
tests of foraminifera are
faunal succession on a refined
unit being a geological
basis of its characteristic
microfaunal zonal scheme based on
ostracoda was compiled by M. B.
| Simply, the earlier
than more recent forms, and
similar to existing forms .
| fossil life forms are simpler
more recent forms are most
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