Dataset Information

Phylogeny of basal iguanodonts (Dinosauria: Ornithischia): an update.

ABSTRACT: The precise phylogenetic relationships of many non-hadrosaurid members of Iguanodontia, i.e., basal iguanodonts, have been unclear. Therefore, to investigate the global phylogeny of basal iguanodonts a comprehensive data matrix was assembled, including nearly every valid taxon of basal iguanodont. The matrix was analyzed in the program TNT, and the maximum agreement subtree of the resulting most parsimonious trees was then calculated in PAUP. Ordering certain multistate characters and omitting taxa through safe taxonomic reduction did not markedly improve resolution. The results provide some new information on the phylogeny of basal iguanodonts, pertaining especially to obscure or recently described taxa, and support some recent taxonomic revisions, such as the splitting of traditional "Camptosaurus" and "Iguanodon". The maximum agreement subtree also shows a close relationship between the Asian Probactrosaurus gobiensis and the North American Eolambia, supporting the previous hypothesis of faunal interchange between Asia and North America in the early Late Cretaceous. Nevertheless, the phylogenetic relationships of many basal iguanodonts remain ambiguous due to the high number of taxa removed from the maximum agreement subtree and poor resolution of consensus trees.

SUBMITTER: McDonald AT

PROVIDER: S-EPMC3358318 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Phylogeny of basal iguanodonts (Dinosauria: Ornithischia): an update.

McDonald Andrew T AT

PloS one 20120522 5

The precise phylogenetic relationships of many non-hadrosaurid members of Iguanodontia, i.e., basal iguanodonts, have been unclear. Therefore, to investigate the global phylogeny of basal iguanodonts a comprehensive data matrix was assembled, including nearly every valid taxon of basal iguanodont. The matrix was analyzed in the program TNT, and the maximum agreement subtree of the resulting most parsimonious trees was then calculated in PAUP. Ordering certain multistate characters and omitting t ...[more]

PMID: 22629328

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Project description:BackgroundBrachylophosaurini is a clade of hadrosaurine dinosaurs currently known from the Campanian (Late Cretaceous) of North America. Its members include: Acristavus gagslarsoni, which lacks a nasal crest; Brachylophosaurus canadensis, which possesses a flat paddle-shaped nasal crest projecting posteriorly over the dorsal skull roof; and Maiasaura peeblesorum, which possesses a dorsally-projecting nasofrontal crest. Acristavus, from the lower Two Medicine Formation of Montana (~81-80 Ma), is hypothesized to be the ancestral member of the clade. Brachylophosaurus specimens are from the middle Oldman Formation of Alberta and equivalent beds in the Judith River Formation of Montana; the upper Oldman Formation is dated 77.8 Ma.Methodology/principal findingsA new brachylophosaurin hadrosaur, Probrachylophosaurus bergei (gen. et sp. nov.) is described and phylogenetically analyzed based on the skull and postcranium of a large individual from the Judith River Formation of northcentral Montana (79.8-79.5 Ma); the horizon is equivalent to the lower Oldman Formation of Alberta. Cranial morphology of Probrachylophosaurus, most notably the nasal crest, is intermediate between Acristavus and Brachylophosaurus. In Brachylophosaurus, the nasal crest lengthens and flattens ontogenetically, covering the supratemporal fenestrae in large adults. The smaller nasal crest of Probrachylophosaurus is strongly triangular in cross section and only minimally overhangs the supratemporal fenestrae, similar to an ontogenetically earlier stage of Brachylophosaurus. Sutural fusion and tibial osteohistology reveal that the holotype of Probrachylophosaurus was relatively more mature than a similarly large Brachylophosaurus specimen; thus, Probrachylophosaurus is not simply an immature Brachylophosaurus.Conclusions/significanceThe small triangular posteriorly oriented nasal crest of Probrachylophosaurus is proposed to represent a transitional nasal morphology between that of a non-crested ancestor such as Acristavus and the large flat posteriorly oriented nasal crest of adult Brachylophosaurus. Because Probrachylophosaurus is stratigraphically and morphologically intermediate between these taxa, Probrachylophosaurus is hypothesized to be an intermediate member of the Acristavus-Brachylophosaurus evolutionary lineage.

Dataset Information

Phylogeny of basal iguanodonts (Dinosauria: Ornithischia): an update.

Publications

Phylogeny of basal iguanodonts (Dinosauria: Ornithischia): an update.

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