Comparative Anatomy Glossary

The rapid diversification of a single ancestral lineage into many species occupying different ecological niches.

Structures in different species that serve similar functions but evolved independently, not from a common ancestor.

The reappearance of a trait from a distant ancestor that had been lost in intervening generations.

The fundamental body plan or structural organization shared by members of a major animal group.

A body arrangement in which the organism can be divided into mirror-image left and right halves.

A classification method based on shared derived characteristics to determine evolutionary relationships.

The branch of biology that studies similarities and differences in the anatomy of different species to infer evolutionary relationships.

The independent evolution of similar traits in unrelated species subjected to similar environmental pressures.

Cuvier's principle that the organs of an animal are so interconnected that one part can predict the form of the whole.

The process by which related species accumulate differences as they adapt to different environments.

The study of the relationship between anatomical structure and biological function.

Anatomical features in different species that share a common evolutionary origin regardless of current function.

Similarity in form or structure between organisms that is not due to inheritance from a common ancestor.

A flexible supportive rod present in all chordate embryos, largely replaced by the vertebral column in vertebrates.

The developmental history of an individual organism from embryo to adult.

The five-digit limb structure shared by tetrapod vertebrates, a classic example of homology.

Embryonic structures that become gills in fish and jaw, ear, and throat structures in terrestrial vertebrates.

The evolutionary history and relationships of a group of organisms, often depicted as a branching tree diagram.

A body plan in which parts are arranged symmetrically around a central axis, as in jellyfish and starfish.

The repetition of structurally similar parts within a single organism, such as vertebrae or arthropod segments.

A shared derived characteristic used in cladistics to group organisms that share a common ancestor.

Any four-limbed vertebrate, including amphibians, reptiles, birds, and mammals.

The series of articulated bones (vertebrae) forming the axial skeleton of vertebrates, enclosing the spinal cord.

Anatomical features that have lost most or all of their ancestral function through evolution.

The formal system of names used to identify and classify animal species, governed by the International Code of Zoological Nomenclature.