week 3 (ch 28 & 29)

the most ancestral branch in the tree

a node that depicts an ancestral branch dividing into three or more descendent branches

a taxon that diverged prior to the taxa that are the focus if the study; helps root the tree

any genetic morphological, physiological, or behavioral characteristic to be studied

a characteristic that existed in an ancestor

a modified form of the ancestral trait found in a descendant

way of inferring a phylogenetic tree by identifying shared derived characteristics

a trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors

— allow biologists to recognize monophyletic groups

similarity in organisms due to common ancestry

similarity in organisms due to reasons other than common ancestry

an unnatural group that does not include the most common ancestor

a group that includes an ancestral population and some of its descendants, but not all.

a common cause of homoplasy

occurs when natural selection favors similar solutions to problems

a piece of physical evidence from an organism that lived in the past

the total collection of fossils that have been found throughout the world

the different biases of fossil records

organisms that love in areas where sediments are actively being deposited– including beaches, mudflats, and swamps– are much more likely to from fossils than are organisms that live in other places

organisms with hard parts such as vibes or shells are more likely to leave fossil evidence

recent fossils are much more common than ancient fossils

organisms that there are a lot of, widespread, and/ or present on earth for long periods of time leave evidence much more often

between the formation if earth and the appearance of most animal groups

2 key things about the Precambrian