User:Nwbeeson/sandbox/Cladeograms

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Snake Evolution[edit]

A family level phylogenetic overview of modern snakes.
Note: the tree only indicates relationships, not evolutionary branching times. This is not a difinitive tree. It is the best that could be done as of 2024. See original paper for a discussion of difficulties.[1]
   

Phylogeny[edit]

The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy being developed by the Angiosperm Phylogeny Group (APG). Published in 2009, it was superseded in 2016 by a further revision, the APG IV system.[2][3][4]

This APG III tree was based on a phylogenetic tree for the angiosperms which included all of the 59 orders and 4 of the unplaced families. The systematic positions of the other 6 unplaced families was so uncertain that they could not be placed in any of the polytomies in the tree. They are shown in the classification table entitled "Detailed version" above, 4 in Euasterids I and 2 in Taxa of uncertain position.

Angiospern Phylogenic Tree[edit]

The phylogenetic tree shown below was published with the APG III system,[2] but without some of the labels that are added here.

Proterosauria Tree[edit]

Archosaur Phylogeny[edit]

In 1988, paleontologists Michael Benton and J.M. Clark produced a new tree in a phylogenetic study of basal archosaurs. As in Gauthier's tree, Benton and Clark's revealed a basal split within Archosauria. They referred to the two groups as Crocodylotarsi and Ornithosuchia. Crocodylotarsi was defined as an apomorphy-based taxon based on the presence of a "crocodile-normal" ankle joint (considered to be the defining apomorphy of the clade). Gauthier's Pseudosuchia, by contrast, was a stem-based taxon. Unlike Gauthier's tree, Benton and Clark's places Euparkeria outside Ornithosuchia and outside the crown group Archosauria altogether.[5]

The clades Crurotarsi and Ornithodira were first used together in 1990 by paleontologist Paul Sereno and A.B. Arcucci in their phylogenetic study of archosaurs. They were the first to erect the clade Crurotarsi, while Ornithodira was named by Gauthier in 1986. Crurotarsi and Ornithodira replaced Pseudosuchia and Ornithosuchia, respectively, as the monophyly of both of these clades were questioned.[6][7] Sereno and Arcucci incorporated archosaur features other than ankle types in their analyses, which resulted in a different tree than previous analyses. Below is a cladogram based on Sereno (1991), which is similar to the one produced by Sereno and Arcucci:[6]

Ornithodira and Crurotarsi are both node-based clades, meaning that they are defined to include the last common ancestor of two or more taxa and all of its descendants. Ornithodira includes the last common ancestor of pterosaurs and dinosaurs (which include birds), while Crurotarsi includes the last common ancestor of living crocodilians and three groups of Triassic archosaurs: ornithosuchids, aetosaurs, and phytosaurs. These clades are not equivalent to "bird-line" and "crocodile-line" archosaurs, which would be branch-based clades defined as all taxa more closely related to one living group (either birds or crocodiles) than the another.

Benton proposed the name Avemetatarsalia in 1999 to include all bird-line archosaurs (under his definition, all archosaurs more closely related to dinosaurs than to crocodilians). His analysis of the small Triassic archosaur Scleromochlus placed it within bird-line archosaurs but outside Ornithodira, meaning that Ornithodira was no longer equivalent to bird-line archosaurs. Below is a cladogram modified from Benton (2004) showing this phylogeny:[8]

In Sterling Nesbitt's 2011 monograph on early archosaurs, a phylogenetic analysis found strong support for phytosaurs falling outside Archosauria. Many subsequent studies supported this phylogeny. Because Crurotarsi is defined by the inclusion of phytosaurs, the placement of phytosaurs outside Archosauria means that Crurotarsi must include all of Archosauria. Nesbitt reinstated Pseudosuchia as a clade name for crocodile-line archosaurs, using it as a stem-based taxon. Below is a cladogram modified from Nesbitt (2011):[9]

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  1. ^ Title, Pascal O.; Singhal, Sonal; Grundler, Michael C.; Costa, Gabriel C.; Pyron, R. Alexander; Colston, Timothy J.; Grundler, Maggie R.; Prates, Ivan; Stepanova, Natasha; Jones, Marc E. H.; Cavalcanti, Lucas B. Q.; Colli, Guarino R.; Di-Poï, Nicolas; Donnellan, Stephen C.; Moritz, Craig; Mesquita, Daniel O.; Pianka, Eric R.; Smith, Stephen A.; Vitt, Laurie J.; Rabosky, Daniel L. (23 February 2024). "The macroevolutionary singularity of snakes". Science. 383 (6685): 918–923. doi:10.1126/science.adh2449. Retrieved 22 March 2024.
  2. ^ a b Angiosperm Phylogeny Group (2009), "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III", Botanical Journal of the Linnean Society, 161 (2): 105–121, doi:10.1111/j.1095-8339.2009.00996.x, retrieved 2010-12-10
  3. ^ As easy as APG III - Scientists revise the system of classifying flowering plants, The Linnean Society of London, 2009-10-08, retrieved 2009-10-29
  4. ^ APG III tidies up plant family tree, Horticulture Week, 2009-10-08, retrieved 2009-10-29
  5. ^ Benton, M. J.; Clark, J. M. (1985). "Archosaur phylogeny and the relationships of the Crocodylia". In Benton, M.J. (ed.). The Phylogeny and Classification of the Tetrapods. Vol. 1. Oxford: Clarendon Press. pp. 295–338. ISBN 0-19-857712-5.
  6. ^ a b Cite error: The named reference SPC91 was invoked but never defined (see the help page).
  7. ^ Sereno, P. C.; Arcucci, A. B. (1990). "The monophyly of crurotarsal archosaurs and the origin of bird and crocodile ankle joints". Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 180: 21–52.
  8. ^ Cite error: The named reference BMJ04 was invoked but never defined (see the help page).
  9. ^ Nesbitt, S.J. (2011). "The early evolution of archosaurs: relationships and the origin of major clades" (PDF). Bulletin of the American Museum of Natural History. 352: 1–292. doi:10.1206/352.1.