Lourinhasaurus, WITH TITANOSAURIFORMES

Mocho, Pedro, Royo-Torres, Rafael & Ortega, Francisco, 2014, Phylogenetic reassessment of Lourinhasaurus alenquerensis, a basal Macronaria (Sauropoda) from the Upper Jurassic of Portugal, Zoological Journal of the Linnean Society 170 (4), pp. 875-916 : 906-907

RELATIONSHIP OF LOURINHASAURUS WITH TITANOSAURIFORMES

Lourinhasaurus does not present several of the synapomorphies of Titanosauriformes. The camellate tissue bone on presacral vertebrae and the pneumatized dorsal ribs present in Titanosauriformes ( Wilson & Sereno, 1998; Upchurch et al., 2004; Taylor, Wedel & Cifelli, 2011) are absent in Lourinhasaurus . On the pelvic girdle, Lourinhasaurus also lacks some features commonly shared by titanosauriforms, such as an ischium shorter than the pubis and a rounded preacetabular process with significant craniodorsal development ( Upchurch, 1998; Upchurch et al., 2004; Royo-Torres, 2009). The massive iliac blade in Lourinhasaurus also differs from the thin iliac blade present in several basal Titanosauriformes (e.g. Canudo et al., 2008; Royo-Torres, 2009; Taylor, 2009; Taylor et al., 2011).

In Lourinhasaurus , the femur can be easily distinguished from those of Titanosauriformes by the absence of a bulge in the lateral margin of the femoral proximal section ( Salgado et al., 1997). Lourinhasaurus shows a strong medial deflection of the entire femoral shaft that is considered a different condition from that of basal Titanosauriformes (medial proximal deflection and a lateral bulge, Royo-Torres et al., 2012). The 10° deflection of the femoral shaft is slightly higher than is found in Tastavinsaurus and Aragosaurus (Royo-Torres, 2009; Royo-Torres et al., 2012). This combination of a marked deflection of the entire femoral shaft without a lateral bulge is considered here as autapomorphic for Lourinhasaurus alenquerensis . The Lourinhasaurus femur also differs from femora that show only a medial proximal deflection, as occurs in other sauropods such as Apatosaurus ( Marsh, 1881) , Camarasaurus (e.g. Osborn & Mook, 1921; Ostrom & McIntosh, 1966), Haplocanthosaurus ( Hatcher, 1903), Patagosaurus ( Bonaparte, 1979) , Dicraeosaurus ( Janensch, 1961) , and Tornieria ( Remes, 2006) . Saltasaurus also bears a medial deflection of the entire shaft but with a lateral bulge ( Powell, 1992). This evidence suggests that the lateral bulge present in titanosauriforms is independent of the medial displacement of the proximal third of the femur, suggesting a more restricted use of the characters applied to this anatomical region in data matrices (e.g. Wilson, 2002; Upchurch et al., 2004; Harris, 2006; Royo-Torres, 2009; Santos, Moratalla & Royo-Torres, 2009; Carballido et al., 2011; Royo- Torres et al., 2012), following, for example, more restricted character definitions (e.g. Salgado et al., 1997).

In a recent analysis ( D’Emic, 2012), some diagnostic features of Titanosauriformes that could be observed in Lourinhasaurus were discussed. D’Emic (2012) proposed as a synapomorphy of Titanosauriformes a cranial position of the neural arch in the proximal and middle caudal vertebrae, a condition observed in the proximal caudal vertebrae of Lourinhasaurus . Despite the presence of a cranial displaced neural arch in the proximal caudal vertebrae of Lourinhasaurus , also present in the most proximal caudals of Camarasaurus (e.g. Osborn & Mook, 1921; Ostrom & McIntosh, 1966; McIntosh et al., 1996a, b) and in other sauropods (e.g. Hatcher, 1901; Casanovas et al., 2001; Ouyang & Ye, 2002; Allain & Aquesbi, 2008; Remes et al., 2009; Royo-Torres & Upchurch, 2012), this feature could be diagnostic only when is referred to the last proximal caudal vertebrae and middle ones. Therefore, it is not possible to test this condition in Lourinhasaurus . Salgado et al. (1997), Wilson (2002), and Upchurch et al. (2004) used a more restricted definition for this character, considering as synapomorphic of Titanosauriformes the cranial displacement of the neural arches in the middle caudal vertebrae.

D’Emic (2012) also refers to the presence of a ventral process in the base of the scapular blade, a feature that is also present in Lourinhasaurus , as a synapomorphy of the Titanosauriformes. The presence of this process in Mamenchisaurus youngi Pi, Ouyang & Ye, 1996 , Diplodocus longus Hatcher, 1901 , and Spinophorosaurus ( Remes et al., 2009) suggests the possibility of a convergent acquisition of this character. Following this author, the ulna also bears titanosauriform features such as a caudally unexpanded distal end and a wider and longer cranial process of the proximal surface. Lourinhasaurus shares the apomorphic conditions for these characters, suggesting a more derived position with respect to other macronarians such as Camarasaurus and Tehuelchesaurus .