Chapter 16 Flashcards
molecular clock
each additional sequence difference is like a tick of the clock, showing the amount of time that has elapsed since the time of the two species common ancestor
invertebrate
an animal lacking a backbone
relative dating
determining the age of a fossil from its position relative to layers of rock or fossils of known age
fossil
the perserved remains or impressions of once-living organisms
vertebrate
an animal with a bony or cartilaginous backbone
vestigial structure
structure inherited from an ancestor that no longer serves a clear function in the organism that possesses it
descent with modification
Darwin’s term for evolution, combining the ideas that all living things are related and that organisms have changed over time
homology
anatomical, genetic, or developmental similiarity among organisms due to common ancestory
radiometric dating
the use of radioactive isotopes as a measure for determing the age of a rock or fossil
fossil record
an assemblage of fossils arranged in order of age
provides evidence of changes in species over time
palentologist
scientist who studies ancient life by examining the fossil record
Devonian Period
“Age of the Fishes”
400-350 mya
marked by high sea levels
by mid, appearance of first terrestrial plants and land invertebrates
transitional fossil
midpoint between organisms
mixture of “old” and “new” traits
shed light on how groups of organisms were able to move into new habitats or develop new structures
DNA homology
related organisms share DNA sequences inherited from a common ancestor
lobe-finned fish
evolved in shallow streams and have sturdy fins with several skeletal supports
Tiktaalik roseae
transitional fossil (midpoint) between fish and amphibians critical period in evolution of terrestrial tetrapod vertebrates
tetrapods
animals with 4 true limbs and a backbone
