The oldest titanosaurian sauropod of the Northern Hemisphere

Abstract

Volgatitan simbirskiensis, gen. et sp. nov., is described based on a series of anterior and middle caudal vertebrae from a single individual discovered in the Lower Cretaceous (upper Hauterivian, Speetoniceras versicolor ammonite Zone) marine deposits at Slantsevy Rudnik vertebrate locality near Ulyanovsk City, Russia. The new taxon is characterized by strongly procoelous anterior and middle caudal vertebrae, a long centrum of the first caudal vertebra, a strong ventral ridge in the anterior and middle caudal vertebrae, a neural arch positioned at the anterior half of the centrum, hyposphene-hypantrum articulation in the anterior caudal vertebrae, and somphospondylous bone texture. Phylogenetic analysis places the new taxon as a lithostrotian titanosaur, a basal member of the lineage leading to the Lognkosauria. This lineage previously contained only South American taxa with body mass reaching 60-70 tons. Volgatitan gen. nov. is the first European and the geologically oldest representative of this lineage. Its body mass is estimated as 17.3 tons. Discovery of Volgatitan gen. nov. suggests that the lithostrotian lineage leading to the Lognkosauria had a wider distribution in the Early Cretaceous and became extinct everywhere except South America by the end of the Early Cretaceous. Citation: Citation: Averianov, A. and Efimov, V. 2018. The oldest titanosaurian sauropod of the Northern Hemisphere. Bio. Comm. 63(3): 145-162. https://doi.

New information on the Cretaceous sauropod dinosaurs of Zhejiang Province, China: impact on Laurasian titanosauriform phylogeny and biogeography

“…Contemporaneous remains from south-central Russia were described as Tengrisaurus starkovi by Averianov & Skutschas [45], who recovered this taxon within Lithostrotia. It is not currently clear to which taxa Sibirotitan and Tengrisaurus are most closely related [43,45,110]. Stratigraphically pre-dating these occurrences, Averianov & Efimov [43] erected Volgatitan simbirskiensis from the late Hauterivian of western Russia.…”

“…It is not currently clear to which taxa Sibirotitan and Tengrisaurus are most closely related [43,45,110]. Stratigraphically pre-dating these occurrences, Averianov & Efimov [43] erected Volgatitan simbirskiensis from the late Hauterivian of western Russia. Volgatitan was placed close to the ‘base’ of the clade that includes Lognkosauria and Rinconsauria in that study, suggesting affinities with Gondwanan taxa [43].…”

“…Stratigraphically pre-dating these occurrences, Averianov & Efimov [43] erected Volgatitan simbirskiensis from the late Hauterivian of western Russia. Volgatitan was placed close to the ‘base’ of the clade that includes Lognkosauria and Rinconsauria in that study, suggesting affinities with Gondwanan taxa [43]. Although Normanniasaurus also clusters with Lognkosauria in our EWP analysis, it appears to represent a lineage that is clearly distinct from Volgatitan .…”

“…However, there is a growing fossil record of Early–middle Cretaceous occurrences of titanosaurs from Eurasia, with a number of these specimens contemporaneous with, or even pre-dating, the oldest known Gondwanan remains [39–42]. These include: (i) Volgatitan simbirskiensis from the late Hauterivian of western Russia [43]; (ii) caudal vertebrae (NHMUK R5333) from the Barremian of the UK [40,44]; (iii) Tengrisaurus starkovi from the Barremian–Aptian of south-central Russia [45]; (iv) Normanniasaurus genceyi from the Albian of France [46]; (v) a caudal vertebra from the late Aptian–early Albian of Italy [47] and (vi) postcranial remains from the Cenomanian of Spain [42]. Although all of these specimens are fragmentary and highly incomplete, some appear to belong to relatively ‘derived’ titanosaurs; for example, Normanniasaurus might be an aeolosaurine [30].…”

Postcranial osteology and phylogenetic relationships of the Early Cretaceous titanosaur Tapuiasaurus macedoi Zaher et al. 2011

“…Nonetheless, although Tapuiasaurus has been incorporated into numerous recent phylogenetic analyses (e.g. Zaher et al 2011, Carballido & Sander 2014, Gorscak et al 2014, Lacovara et al 2014, Poropat et al 2015, Bandeira et al 2016, González Riga et al 2016, Martínez et al 2016, Wilson et al 2016, Averianov & Skutschas 2017, Tykoski & Fiorillo 2017, Carballido et al 2017, Gorscak et al 2017, Averianov & Efimov 2018, González Riga et al 2018, Sallam et al 2018, its postcranial skeleton has not been previously fully described and illustrated in the literature.…”