Malarguesaurus González Riga, Previtera, Pirrone, 2008
Type Species. Malarguesaurus florenciae
Saurischia > Sauropoda > Titanosauriformes > Somphospondyli
Derivation of name. In reference to the Malargüe Department (Mendoza Province,
Argentina) where the specimen was found, and saurus (Greek), lizard, reptile.
Malarguesaurus florenciae González Riga, Previtera, Pirrone, 2008
Derivation of name. In honor of Florencia Fernández Favarón, who collaborated with our field works during years, and found the first fossil remain of this species.
Horizon and locality. Portezuelo Formation, Río Neuquén Subgroup, Neuquén Group,
Upper Cretaceous, upper Turonian-lower Coniacian; Quebrada Norte quarry, Paso de las
Bardas area, Malargüe Department, Mendoza Province, Argentina.
Holotype. IANIGLA-PV 110, an incomplete skeleton integrated by proximal, middle and
distal caudal vertebrae, chevrons, dorsal ribs, appendicular bones (a fragment of humerus and an incomplete femur), and several bone fragments. The holotype of Malarguesaurus corresponds to one adult individual. All fossil remains were found disarticulated but associated in the same quarry. No duplicate bones are present.
Refereed material. Two distal caudal vertebrae and an incomplete fibula (IANIGLA-PV 111) from Cerro La Torre site, 600 m south of Quebrada Norte quarry, Paso de las Bardas area, Mendoza Province.
Diagnosis. Large titanosauriform sauropod characterized by the following association of characters: (1) proximal caudal neural spines vertically directed, with a concave caudal border and a caudodorsal corner forming a right angle; (2) procoelous-opisthoplatyan proximal and middle caudal vertebrae associated with procoelous distal caudal centra; and (3) distal caudal neural spines having a concave and depressed dorsal border. These characters are associated with the following synapomorphies: neural arches placed cranially on caudal vertebrae, relatively tall and craniocaudally short proximal caudal neural arches, prominent postzygapophyseal processes in middle caudal vertebrae, and lateral bulge on the femur below the major trochanter.
Proximal caudal vertebrae in lateral view. A, Camarasaurus lewisi (redrawn from
McIntosh et al., 1996).B, Brachiosaurus brancai (redrawn from Janensch, 1950). C,
Cedarosaurus weiskopfae (redrawn from Tidwell et al., 1999). D, Phuwiangosaurus
sirindhornae (redrawn from Martin et al., 1999). E, Malarguesaurus florenciae gen. et sp.
nov. (this paper).F, Mendozasaurus neguyelap (after from González Riga, 2003). G,
Aeolosaurus sp. (redrawn from Salgado and Coria, 1993). H, Pellegrinisaurus powelli
(redrawn from Salgado, 1996). I, Neuquensaurus australis (redrawn from Salgado et al.,
2005). Scale bar: 10 cm.
Description: Malarguesaurus florenciae gen. et sp. nov. is a new and robust somphospondylian titanosauriform (Dinosauria, Sauropoda) from the Neuquén basin, Mendoza Province, Argentina. The specimen comes from Upper Cretaceous strata assigned to the Portezuelo Formation (upper Turonian-lower Coniacian). It includes proximal, middle and distal caudal vertebrae, chevrons, dorsal ribs, and appendicular bones. Malarguesaurus is characterized by the following association of characters: (1) proximal caudal neural spines vertically directed, with a concave caudal border, and a caudodorsal corner forming a right angle; (2) procoelous-opisthoplatyan proximal and middle caudal vertebrae associated with procoelous distal caudal centra; and (3) distal caudal neural spines having a concave and depressed dorsal border. A preliminar cladistic analysis placed (Ligabuesaurus + (Malarguesaurus + Phuwiangosaurus)) as a sister taxon of Titanosauria. Unique among the titanosauriforms, Malarguesaurus has procoelous distal caudal centra associated with procoelous-opisthoplatyan proximal caudals. This discovery is a new evidence of the morphologic diversity of the South American sauropods.
Cladogram showing the phylogenetic relationships of Malarguesaurus florenciae
See more images:
González Riga, B.J., Previtera, E., Pirrone, C.A. 2008. Malarguesaurus florenciae gen. et sp. nov., a new titanosauriform (Dinosauria, Sauropoda) from the Upper Cretaceous of Mendoza, Argentina,
Cretaceous Research doi: 10.1016/j.cretres.2008.06.006
