STYRACOSTERNA, 1986

Poole, Karen E., 2016, Phylogeny of iguanodontian dinosaurs and the evolution of quadrupedality, Palaeontologia Electronica (a 30) 25 (3), pp. 1-65 : 19

STYRACOSTERNA Sereno, 1986

Phylogenetic definition. The most inclusive clade containing Parasaurolophus walkeri Parks 1922 but not Camptosaurus dispar ( Marsh, 1879) or Uteodon aphanoecetes ( Carpenter and Wilson 2008) .

Unambiguous synapomorphies. Styracosterna is characterized by five unambiguous synapomorphies: presence of denticulation on the oral margin of the premaxilla (5.1), 18-28 maxillary tooth positions (123.2), dentary teeth with a maximum of two to four ridges extending from the base to the tip of the crown on lingual side of teeth (137.1), maxillary tooth crowns mesiodistally narrower than dentary crowns (149.1), mid to posterior dorsal vertebrae with length much shorter than height (164.1).

Topology. Styracosterna has strong support in both topologies (JV=35, BS=4, PP=0.91), but within this group, relationships are resolved poorly. The parsimony tree ( Figure 7 ) has several polytomies and the Bayesian tree ( Figure 8 ) recovers several small clades within Styracosterna, but most have low support.

Figures

FIGURE 7. Time scaled parsimony tree, showing assigned age ranges and broad-scale geographic data. Jackknife values above 20 (with 10% chance of character removal) are shown above and to the left of their respective nodes. Bremer supports above one are shown below and to the left of their respective nodes, and bolded.

FIGURE 8. Maximum Clade Credibility tree produced by Bayesian analysis. Posterior probabilities are shown to the left of their nodes. The geologic timescale is shown across the top. Tips represent the average age found for each OTU across all sampled trees.