Introduction to Comparative Anatomy

Morphology

the study of anatomy and its significance

Functional morphology

discipline that relates a structure to its function

Primitive Traits

Trait that develops for the first time

Derived Trait

newly evolved features that developed from primitive

Archetype

Model of Organism

Vertebrate Morphology

Explains vertebrate design by clarifying the reasons for and processes that produce the structural plan of a vertebrate animal

Ontogeny

The development of an organism.

Homology

Similarity in characteristics resulting from a shared ancestry.

Analogy

features in different organisms that have similar function (but not necessarily due to common ancestry)

Homoplasy

Features in different organisms that look alike

Symmetry

how an animal meets its surrounding environment

radial symmetry

body plan in which body parts repeat around the center of the body

bilateral symmetry

Body plan in which only a single, imaginary line can divide the body into two equal halves.

Segmentation

process that divides the body into duplicated sections; segment = metamere

Evolutionary Morphology

The function of a structure and its role in adaptation and evolution.

Function

The action or property of a part as it works in the organism

Biological role

how the part is used in the environment during the organism’s lifetime

Phylogeny

evolutionary history of a group of organisms (species)

Phylogenic tree

AKA dendrogram AKA tree of life - relationships of a group in the form of a branching tree

Character

physical feature of organism

Character State

condition or type of character

Primitive Condition

an earlier (ancestral) state of a character

Plesiomorphic traits

ancestral traits ( come from primitive condition)

Derived condition

later or descendant state after transformation

Synaphomorphic or Apomorphic trait

Trait from a Derived condition

Taxon

named group of organisms

Sister group

taxon most closely related to the group we are studying

Phylogenetic systematics (cladistics)

method for determining relationships of organisms based on evolutionary history (genealogy)

Cladogram

dendrogram (tree) depicting genealogical relationships

Grade

an expression of the degree of change or level of adaptation reached by an evolving group

Clade

lineage, which is all organisms in a lineage plus the ancestor they have in common; it is also considered a monophyletic group because it includes an ancestor and its descendants (but only its descendants)

Ingroup

assortment of species (taxa) of interest in examining

Outgroup

close relative to but not party of this assortment; used for reference to determine the character state that is derived (it could be a sister group or a less related group)

Monophyletic group

taxon that includes the common ancestor and all descendant species

Paraphyletic group

taxon that includes the ancestor and some of the descendants (part of a monophyletic group)

Polyphyletic group

taxon that is formed on the basis of nonhomologous characters (ex. from convergent evolution)

Binomial

The two-part scientific name of a species

Genus

The first part of the name

taxonomic groups from broad to narrow

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Paleozoic Era

the oldest era - immediately after Precambrian; organisms developed hard parts

Mesozoic Era

middle life (245-144 million years ago); rise of mammals and dinosaurs; the rise of birds; extinction of dinosaurs, rise of flowering plants

Cenozoic Era

era that began about 66 million years ago, known as the "Age of Mammals"

Geologic record

a standard time scale that divides Earth's history into four eons and further subdivisions