Читать книгу Hadrosaurs - David A. Eberth - Страница 41

Running the data matrix with characters unordered produced a fairly well resolved topology in the strict consensus tree. Twelve most-parsimonious trees (MPTs) were produced, each with a tree length of 262 steps (Consistency Index [CI]: 0.56, Retention Index [RI]: 0.74). The strict consensus tree based on these analyses is represented in Figure 2.24. The lack of resolution revolves around the character distributions seen in the 11 taxa that fall across the center of the cladogram. The 50% majority rule tree (Fig. 2.25, top) and Adams consensus tree (Fig. 2.25, bottom) derived from the 12 MPTs produce a measure of resolution (as expected) within this taxon plexus. A second search of the data matrix using the same protocols, but with the characters run as “ordered,” generated a well-resolved topology represented by three MPTs of 267 steps, a CI of 0.55, and a RI of 0.75. The strict consensus tree shown in Figure 2.26 is identical to the 50% majority rule tree (Fig. 2.25, top) generated from the first analysis. The strict consensus tree reveals an unresolved trichotomy between Barilium, Iguanodon, and Mantellisaurus within a clade (= Iguanodontidae) containing the additional taxa Bolong and Jinzhousaurus.

2.24. The strict consensus tree (based on 12 MPTs) generated by running the data matrix with characters unweighted and coded as unordered.