Sauropod resilience in the southeastern Neuquén Basin at the end-Cretaceous: new titanosaurian evidence from the Allen Formation (late Maastrichtian) of Patagonia, Argentina

However, the Maastrichtian record is still poorly represented, particularly when compared to the sauropod evidence from the Cenomanian or Santonian–Campanian time-lapses. Here, we describe new sauropod specimens from the Allen Formation of the Bajo de Santa Rosa (Patagonia, Argentina), including a single individual (MML-Pv-1031) with disarticulated but associated cranial (one tooth), axial (several dorsal ribs, one caudal vertebra and three hemal arches), and appendicular elements (two sternal plates, two metacarpals, one ischium, and two fibulae).

An additional isolated tooth (MML-Pv-1032) was also found in the same site. The strongly procoelic articulation of the caudal vertebra, the dorsoventrally low ischium, the semilunar sternal plates, and the slender, straight fibulae with a prominent lateral trochanter of MML-Pv-1031 resemble the morphological conditions of several titanosaurian taxa. Furthermore, some features of the sternal plates and fibulae of MML-Pv-1031 differ from the four titanosaurian species with overlapping elements from the Allen Formation, <i>Aeolosaurus rionegrinus</i>, <i>Bonatitan</i>, <i>Menucocelsior</i>, and <i>Rocasaurus</i>.