8 10 Module Bio Notes Essay

Submitted By mrobb
Words: 1428
Pages: 6

Evolution in fossil record, laboratory studies, natural population

-Fossils give information about the kinds of organisms that lived, what they look like, where and how they live
-Fossil lions in Europe show there was once a deeper range

-Some fossils are obvious, some less so
-Specialists learn to recognize the structures and patterns of anatomical features

-Not all organisms are equally likely to fossilize
-Remains must avoid being trampled, scavenged, or decomposed
-Being buried in dry/anoxic environments are best
-Body plan matters hard parts > soft parts
Large bones > small bones

-Forming fossil-taphonomy

Fossil formation: once remains are buried, minerals in the dirt around it will soak into bone/shell
-the rock a fossil is in must be exposed to the surface
-fossils can be destroyed by weathering, erosion or transformation of rocks in that area
-Mineralized or impression
-Relative dating: based on position, compares older v. younger, but no numeral age
-Radiometric dating: uses rate of decay of radioactive isotopes to assign numerical ages

-3 types of rocks, igneous (new rock, from lava), sedimentary (hardened layers of sediment), metamorphic (igneous or sedimentary rock that has been changed due to extreme pressure and heat)
-Fossils only form in sedimentary rocks

Relative dating: the principle of superposition
-in the sequence of sedimentary rocks, the oldest layer is at bottom newest is at top layers are strata
-the principle of faunal succession: William Smith, the same types of fossils appear in the saem order in different deposits

Radiometric dating: an isotope of an element has the same number of protons but different numbers of neutrons
-The half-life of an isotope is the time that it takes for half the original isotopes to decay (lose neutrons)
-time it takes for half of the atoms in isotope to change to the next isotope is the half-life
-Radiometric dating: different isotopes can be used to date difference materials/ages
-Potassium argon dating-used to date igneous rock
-By dating igneous rock layers above/below a sedimentary rock layer we can determine the age of fossils in sedimentary rock

How good is the fossil record?
-Some organisms fossilize easier than others
-The way fossilization happens or doesn’t means there will be gaps
-Darwin acknowledged this, but predicted scientists would eventually find the missing fossils

homologous traits: traits that were present in and inherited from a common ancestor vestigial traits: a trait that once had a function but is no longer used
Descent with modification: can see similarities in morphology, behavior, development and or DNA sequences
Post-anal tail to vertebrae

The theory of evolution—what Darwin called descent with modification—draws two main conclusions about life on Earth: that all living things are related, and that the different species we see today have emerged over time as a result of natural selection operating over millions of years.

prokaryotes appear before eukaryotes, single-cell organisms before multicellular ones, water-dwelling organisms before land-dwelling ones, fish before amphibians, reptiles before birds.

-History on earth goes back about 3.5 billion years
-photosynthetic prokaryotes:2.5
-eukaryotes: 1.5
-multicellular eukaryotes: 1.2 billion years ago

Cambrian Explosion: 540 mya first appearance of representatives of the major animal phyla
-land plants appeared around 400 mya
-Terrestiral anthropods followed-scorpions, centipedes
-First vertebraes moved onto land 380 mya

Geological time scale:
History of earth is divided into segments of time. Eras are subdivided into periods, each period is characterized by specific animals, plants, climates, positions of continents
-precambrian- single-celled organism

99% of species that have ever lived are now extinct boundaries between periods are marked by extiniction events-types of fossils in one layer disappear in the next mass extinctions- extinctions that separate the eras…