The anatomy, phylogenetic relationships, and stratigraphic position of the Tithonian-Berriasian Spanish sauropod dinosaurAragosaurus ischiaticus

Abstract

The first dinosaur to be named from Spain, the sauropod Aragosaurus ischiaticus Sanz, Buscalioni, Casanovas and Santafé 1987, is known from associated postcranial remains of one individual from the Las Zabacheras site in Galve, Teruel Province, Spain. Results of recent fieldwork confirm that the Las Zabacheras site represents a deltaic sediment complex in the Villar del Arzobispo Formation with a Tithonian–Berriasian (latest Jurassic–earliest Cretaceous) age. Description of the anatomy of Aragosaurus (including several previously undescribed elements) enables a re‐evaluation of this taxon's relationships. Aragosaurus ischiaticus has six autapomorphies in the axial and appendicular skeleton, including the presence of epipophysis‐like protuberances on middle caudal postzygapophyses. Phylogenetic analyses, using three independent data sets, support the view that Aragosaurus is a basal macronarian sauropod, lying outside of Titanosauriformes. Aragosaurus possesses derived states that are shared with basal Titanosauriformes, indicating that some characters previously considered to represent titanosauriform synapomorphies have a slightly wider distribution. A tooth, previously described as Aragosaurus, cannot be referred to this taxon as it was recovered from a different locality, and there are no overlapping elements with the holotype; it is here regarded as representing an indeterminate titanosauriform. These results, combined with new data on the stratigraphic age of Aragosaurus, demonstrate that basal macronarian sauropods were present in Europe at the end of the Late Jurassic, alongside more derived titanosauriforms. Aragosaurus is one of four genera of sauropod recovered from the Villar del Arzobispo Formation in Spain, making the latter an important contributor to our understanding of Late Jurassic sauropod diversity alongside the well‐known contemporaneous faunas of the African Tendaguru Formation and the North American Morrison Formation. © 2014 The Linnean Society of London

The earliest known titanosauriform sauropod dinosaur and the evolution of Brachiosauridae

“…However, this position differs from other sauropod analyses in which Europasaurus has been recovered as a non-titanosauriform macronarian (Sander et al, 2006; Ksepka & Norell, 2010; Carballido et al, 2011a; Carballido et al, 2011b; Carballido et al, 2015; Carballido & Sander, 2014; Royo-Torres et al, 2014). …”

Turiasauria-like teeth from the Upper Jurassic of the Lusitanian Basin, Portugal

“…At the moment, Turiasaurus and Zby are the only turiasaurs with cranial and postcranial materials. In the light of some recent phylogenetic approaches (Royo-Torres et al 2006, 2012Royo-Torres, Upchurch, et al 2014;RoyoTorres, Cobos, et al 2014;Royo-Torres and Upchurch 2012;Mocho, RoyoTorres, Malafaia, et al 2014), the non-neosauropod eusauropods have spoon-shaped teeth. If Turiasaurus, Losillasaurus, Galveosaurus and Zby correspond to a monophyletic clade, their heart-shaped teeth could be considered as a synapomorphy of Turiasauria (the condition is unknown in Galveosaurus and Losillasaurus).…”

Articulated bone sets of manus and pedes of Camarasaurus (Sauropoda, Dinosauria)

“…The metacarpals referred to the probable non-titanosauriform macronarian Janenschia robusta are much more robust compared to Camarasaurus elements (Janensch, 1922). Aragosaurus metacarpals appear to be the most similar to Camarasaurus within Sauropoda, but only a mc I and a partial mc II are known from this taxon (Royo-Torres et al, 2014). The metacarpal II of Aragosaurus has a similar robustness as the corresponding element in Camarasaurus, and is also marked by a distinct distal concavity on its posterior side, which leads into the intercondylar groove (Royo-Torres et al, 2014).…”

“…Within Macronaria, the strongly developed distal condyles of Camarasaurus metacarpals differ from titanosauriform elements with their flat distal ends (Wilson and Sereno, 1998). Turiasaurian metacarpals have subtrapezoid rather than subtriangular proximal articular surfaces (e.g., Zby atlanticus ML 368; Mateus et al, 2014), and mc II with flat distal articular surfaces (Royo-Torres et al, 2014). The metacarpals referred to the probable non-titanosauriform macronarian Janenschia robusta are much more robust compared to Camarasaurus elements (Janensch, 1922).…”

“…The metacarpal II of Aragosaurus has a similar robustness as the corresponding element in Camarasaurus, and is also marked by a distinct distal concavity on its posterior side, which leads into the intercondylar groove (Royo-Torres et al, 2014). However, mc I of Aragosaurus has a more D-shaped proximal articular surface, compared to Camarasaurus (Royo-Torres et al, 2014), and mc II of Aragosaurus bears a distinct tubercle on the distomedial ridge on the posterior surface, just proximal to the rugose articular facet (Royo-Torres et al, 2014, figure 12), which is absent in Camarasaurus. The length ratio between the metacarpals of a single manus is highly variable among genera (Poropat et al, 2015a), but also among different Camarasaurus specimens (Table 3).…”