Phylum, in biology, major category, or taxon, of organisms with a common design or organization. This design is shared by all members of the phylum, even though structural details may differ greatly because of evolution.
101science.com/Taxonomy.htm 101science.com/Taxonomy.htm
A classification based strictly on the rule that all members of a group must have shared a common ancestor more recently than they have with any species outside the group is called cladistics.
users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Taxon... users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Taxonomy.html
Preview of Concepts ... is the science dealing with description, identification, nomenclature, and classification of living things. ... Dichotomous keys may be used in a variety of situations, such as for identifying rocks and minerals as well as for identifying unknown organisms to some taxonomic level (e.g., species,
www.mhhe.com/biosci/pae/zoology/cladogram/
The smallest microscopic organisms are termed protists, consequently some biologists prefer to call this kingdom the Protoctista rather than Protista. All members of this vast phylum have nucleated cells and live in aquatic habitats (freshwater and marine).
waynesword.palomar.edu/trfeb98.htm
for us it will suffice to say that it is a system for rigorously evaluating characters that results in a classification system in which all the members of a taxon share a common ancestor, and all descendants of that ancestor are included within the group.
www.marietta.edu/~biol/zoology/2morph97.html
Depending upon the arrangement, various members of a group will appear closer or farther away from each other while remaining part of the group. This polythetic approach thus demonstrates how someone can be Jewish or Christian or Buddhist and yet share little in common with others claiming that designation.
moses.creighton.edu/JRS/2002/2002-a3.html
(For example, we cannot take one species from cluster A and one from cluster B and put them together as a single genus--for this would violate the rule that all members of a higher taxon must share a common ancestor without excluding other species that are more closely related to the common ancestor.
discovermagazine.com/1992/dec/whatisaspecies165/
monophyletic meaning all members of a taxon are descended from a common ancestor ... synonym synonyms are different scientific names used for a single taxon. They might arise when someone mistakenly describes a species that has already been described, or when two described taxa are later found to be the same species.
www.reptilesdownunder.com/glossary/
Ideally, all taxa (that is, taxonomic groupings) that are defined from such phylogenies should be monophyletic. A taxon is monophyletic when all of its members are part of the same clade, and all members of that clade are members of that taxon.
www.mykoweb.com/articles/taxonomy_1.html www.mykoweb.com/articles/taxonomy_1.html
clade -- A monophyletic taxon; a group of organisms which includes the most recent common ancestor of all of its members and all of the descendants of that most recent common ancestor. From the Greek word "klados", meaning branch or twig.
www.ucmp.berkeley.edu/glossary/glossary_1.html