Chapter 25- Phylogenies and the History of Life

Outgroup

________ is a taxon that is not part of the taxonomic group being studied but is closely related.

Systematics

________ is the discipline of biology that characterizes and classifies the relationships among all organisms on Earth.

Paleontologists

________ are scientists who study fossils, pieces of physical evidence from an organism that lived in the past.

Synapomorphies

________ are important because they allow biologists to recognize monophyletic groups- also called clades or lineages.

Sister groups

________ are two descendants that split from the same node and therefore are each other s closest relatives.

monophyletic group

A(n) ________ is an evolutionary unit that includes an ancestral species and all of its descendants, but no others.

Paleozoic

The ________ " (ancient life) "era begins with the appearance of most major animal lineages and ends with the obliteration of almost all multicellular life- forms at the end of the Permian period.

Paleogene

The Cenozoic " (recent life) "era is divided into the ________, Neogene, and Quaternary periods.

Convergent evolution

________ is the independent evolution of similar traits in distantly related organisms due to adaptation to similar environments and lifestyles.

ancestral trait

A(n) ________ is a character that existed in an ancestor.

synapomorphy

A(n) ________ is a trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors.

Phylogeny

The branching evolutionary history of species or other groups of organisms is called a

Phylogenetic tree

\
is a simplified diagram of this history. 

Derived trait

is one that is a modified form of the ancestral trait, found in a descendant.

Tree of life

 is the most universal of all phylogenetic trees.

Fossil record

is the total collection of fossils that paleontologists and amateur collectors have found throughout the world and archived in thousands of private and public collections.