Phytodinosauria

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Phytodinosauria
Temporal range: Late Triassic–Late Cretaceous
Holotype specimen of
Brontosaurus excelsus (YPM 1980), Peabody Museum of Natural History
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: †Phytodinosauria
Bakker, 1986
Subgroups

Phytodinosauria is a group of

polyphyletic. Modern studies either combine the Theropoda and Sauropodormorpha in the Saurischia or the Theropoda and Ornithischia in the Ornithoscelida
.

History

In 1888,

Archosauria.[2]

Robert T. Bakker
.

In 1974 however,

symplesiomorphy, which suggested the possibility that the two main saurischian groups, the Theropoda and Sauropodomorpha, are not closely related.[3][4]

Bakker and Galton had based their analysis on a study of the basal sauropodomorph

theropods. In 1986, Bakker openly proposed this in his book The Dinosaur Heresies:

Therefore all the plant-eating dinosaurs of every sort really constitute one, single, natural group branching out from one ancestor, a primitive anchisaurlike dinosaur. And a new name is required for this grand family of vegetarians. So I hereby christen them the Phytodinosauria, the "plant dinosaurs".

Both sauropodomorphs and ornithischians are characterized by their “blunt, spoon-crowned teeth suitable for cropping plants” and these would not be an instance of convergent evolution, both groups adapting to a herbivorous mode of living, but a sign they were descended from a plant-eating common ancestor. Bakker classified the Phytodinosauria as a superorder of mostly herbivorous dinosaurs within the Dinosauria.[5]

Even before 1986, authors had combined the sauropodomorphs and ornithischians. Freelance researcher

therizinosaurs — then known as "segnosaurs" — to be the "relics of the prosauropod-ornithischian transition".[6] In his 1988 book Predatory Dinosaurs of the World: A Complete Illustrated Guide he repeated his hypothesis that therizinosaurs were late-surviving basal sauropodomorphs.[7] In 1985, Michael Robert Cooper placed the sauropodomorphs and ornithischians in a cohort Ornithischiformes. This was based on two synapomorphies, regarding the shape and placement of the teeth.[8]

Bonaparte, Bakker, and Paul argued that ornithischians were descended from basal sauropodomorphs, with segnosaurs being transitional taxa as depicted in the phylogeny below.

Dinosauria

Theropoda

†Phytodinosauria

The Phytodinosauria hypothesis is not supported by current data: most phylogenies maintain a monophyletic Saurischia.[9] In such a phylogeny therizinosaurs are maniraptoran dinosaurs more closely related to birds, and any similarity between sauropodomorphs and ornithischians is due to convergence.[10] In 2017, an analysis did split the Saurischia but to the contrary proposed that it were the theropods that are more closely related to ornithischians, instead of the sauropodomorphs.[11] However, in a series of additional phylogenetic analyses that were carried out by Parry, Baron and Vinther (2017), Phytodinosauria was recovered, but only when using certain optimality criteria and once certain modifications had been made to original morphological dataset of Baron, Norman and Barrett (2017). They recovered a polytomy showing herrerasaurs, Eodromaeus, Daemonosaurus, theropods, and a clade that includes Guaibasauridae and Phytodinosauria as shown below:[12]

Dinosauromorpha

See also

References

  1. doi:10.1098/rspl.1887.0117
    .
  2. ^
    S2CID 4220935
    .
  3. ^ Charig, A. J. (1976). "Dinosaur monophyly and a new class of vertebrates: A critical review". Morphology and Biology of Reptiles. London, UK. pp. 65–104.{{cite book}}: CS1 maint: location missing publisher (link)
  4. ^ Bonaparte, J. F. (1976). "Pisanosaurus mertii Casamiquela and the origin of the Ornithischia". Journal of Paleontology. 50 (5): 808–820.
  5. ISBN 9780688042875
    .
  6. doi:10.1080/02724634.1984.10012026
    .
  7. ISBN 9780671619466
    .
  8. ^ Cooper, M. R. (1985). "A revision of the Ornithischian dinosaur Kangnasaurus coetzeei Haughton, with a classification of the Ornithischia". Annals of the South African Museum. 95 (8): 281–317.
  9. PMID 27839975
    .
  10. doi:10.1139/e93-183
    .
  11. S2CID 205254710.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  12. PMID 29134086
    .
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