128


Journal of Paleontology 90(1):102–132


Table 3. Characters added to the matrix of D’Emic (2012) Character #


Character


120 121


122


middle dorsal vertebrae, centrum length (without anterior condyle, if present) to base of neural arch length ratio


last few anterior and first few middle caudal vertebrae, SPOL, shape


last few anterior and first few middle caudal vertebrae, anteroposteriorly oriented ridge and fossa (‘shoulder’) between pre– and postzygapophyses


State 0


SPOL grades smoothly toward postzygapophyses


absent


State 1 approximately 1.0 1.2–1.3


SPOL abruptly ends near the anterior margin of the postzygapophyseal facet; postzygapophyses sharply set off from neural spine


present


State 2


approximately 1.5


Figure 26. Cladistic hypothesis of relationships for Sonorasaurus thompsoni (ASDM 500) from the mid-Cretaceous Turney Ranch Formation of Arizona, USA.


dorsal vertebral centra are not much longer than the base of their respective neural arch (e.g., Shunosaurus) or they are 20%–30% longer, with the neural arch displaced somewhat anteriorly (e.g., Camarasaurus, Tehuelchesaurus, Neuquensaurus,MDD personal obsservation). In some middle dorsal vertebrae of Sonorasaurus and Giraffatitan, the neural arch occupies only about the anterior 50% of the centrum, representing a third, derived state. This multistate character was treated as unordered. The second new character describes the abrupt posterior projection of the postzygapophyses and related reduction in the spinopostzygapophyseal lamina (spol), which was regarded as an autapomorphy of Lusotitan by Mannion et al. (2013) but has a wider distribution (e.g., Sonorasaurus, Giraffatitan, Europasaurus, M.D.D. personal observation). Third, a character was added to describe the anteroposterior ridge extending between the zygapophyses in middle caudal vertebrae; this character was also regarded as an autapomorphy of Lusotitan by Mannion et al. (2013), but is present in other sauropods, for example Camarasaurus, Giraffatitan, and Sonorasaurus. Finally, an error was present in character 36 of D’Emic (2012); this character deals with the posterior centroparapophyseal lamina (pcpl), not the posterior centrodiapophyseal lamina


(pcdl) as stated. All other protocols followed those outlined in D’Emic (2012), including the content of each OTU (e.g., the expanded hypodigm of Sauroposeidon based on material referred by D’Emic and Foreman, 2012 and D’Emic, 2013). The nexus file is available as supplemental information (Supplemental Data 5). Sixty equally parsimonious trees were recovered of


treelength 214. A strict consensus of these trees is identical to that of D’Emic (2012) with the addition of Sonorasaurus and Lusotitan within the Brachiosauridae (Fig. 26). Sonorasaurus is positioned as the sister taxon of Giraffatitan, with this clade nested between Europasaurus and other brachiosaurids (Brachiosaurus altithorax, Abydosaurus, Cedarosaurus, Venenosaurus, and the newly added Lusotitan), which form a polytomy. The large amount of missing data for both Sonorasaurus and Lusotitan suggests that their lower-level (i.e., sister taxon) relationships should be treated with caution, and indeed, the decay (=Bremer) index of Brachiosauridae and included clades is only 1, in contrast to the value of 3 when Sonorasaurus and Lusotitan are not included in the analysis (see D’Emic, 2012: table 7). Clades with a decay index greater than 1 include Euhelopodidae, Tehuelchesaurus + more deeply nested


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