Evolution-fossils

English	Photos
fossil	the remains (or an impression) of a plant or animal that existed in a past geological age and that has been excavated from the soil
petrification	gradual change of the original substances of an organism dissolve and are replaced by minerals from the water (turned to stone)
Mold	a fossil formed when an organism buried in sediment dissolves, leaving a hollow area
cast cast	the type of fossil that forms when a mold becomes filled in with minerals that harden. the cast takes on the shape of the mold creating a replica of the organism or part.
amber	a hard yellowish to brownish translucent fossil resin
imprints	Thin object falls into sediment can leave an imprint when sediment hardens.
tar pit	large pools in Southern California that contain fossil remains of many different animals
trace fossil	a type of fossil that provides evidence of the activities of ancient organisms
evolved	to develop gradually by process of growth and change
bipedal	term used to refer to two-footed locomotion
geographic time scale	categories of time into which Earth's history is divided by geologists and paleontologists: eons, eras, periods, epochs
radiometric dating	the process of measuring the absolute age of geologic material by measuring the concentrations of radioactive isotopes and their decay products
uranium	a white, radioactive metallic chemical element that weighs more than any other element in nature.
lead	led, led
tetrapod	a vertebrate animal having four feet or legs or leglike appendages
palentologist	A scientist who studies fossils