Editing Evolutionary taxonomy (section)

==The Tree of Life==
{{main|Tree of life (biology)}}
[[File:Spindle diagram.jpg|thumb|right|Evolution of the [[vertebrate]]s at class level, width of spindles indicating number of families. Spindle diagrams are often used in evolutionary taxonomy.]]
As more and more fossil groups were found and recognized in the late 19th and early 20th century, [[paleontology|palaeontologists]] worked to understand the history of animals through the ages by linking together known groups.<ref>{{Citation|title=The Meaning of Fossils: Episodes in the History of Palaeontology|first=M. J. S.|last=Rudwick|year=1985|publisher=[[University of Chicago Press]]|isbn=978-0-226-73103-2|page=24}}</ref> The [[Tree of life (biology)|Tree of life]] was slowly being mapped out, with fossil groups taking up their position in the tree as understanding increased.{{cn|date=June 2024}}

These groups still retained their formal Linnaean [[taxonomic rank]]s. Some of them are [[paraphyly|paraphyletic]] in that, although every organism in the group is linked to a common ancestor by an unbroken chain of intermediate ancestors within the group, some other descendants of that ancestor lie outside the group. The evolution and distribution of the various taxa through time is commonly shown as a ''spindle diagram'' (often called a ''Romerogram'' after the American palaeontologist [[Alfred Romer]]) where various spindles branch off from each other, with each spindle representing a taxon. The width of the spindles is meant to imply the abundance (often a number of families) plotted against time.<ref>{{cite web|last1=White|first1= T.  |last2=Kazlev|first2= M. A.|title=Phylogeny and Systematics : Glossary - Romerogram|url=http://palaeos.com/phylogeny/glossary.html#romerogram|website=palaeos.com|access-date=21 January 2013}}</ref>

[[Vertebrate palaeontology]] had mapped out the evolutionary sequence of vertebrates as currently understood fairly well by the closing of the 19th century, followed by a reasonable understanding of the evolutionary sequence of the [[Plant|plant kingdom]] by the early 20th century. The tying together of the various trees into a grand Tree of Life only really became possible with advancements in [[microbiology]] and [[biochemistry]] in the period between the World Wars.{{cn|date=June 2024}}