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

Abstract

Titanosaurs were a globally distributed clade of Cretaceous sauropods. Historically regarded as a primarily Gondwanan radiation, there is a growing number of Eurasian taxa, with several putative titanosaurs contemporaneous with, or even pre-dating, the oldest known Southern Hemisphere remains. The early Late Cretaceous Jinhua Formation, in Zhejiang Province, China, has yielded two putative titanosaurs, Jiangshanosaurus lixianensis and Dongyangosaurus sinensis . Here, we provide a detailed re-description and diagnosis of Jiangshanosaurus , as well as new anatomical information on Dongyangosaurus . Previously, a ‘derived’ titanosaurian placement for Jiangshanosaurus was primarily based on the presence of procoelous anterior caudal centra. We show that this taxon had amphicoelous anterior-middle caudal centra. Its only titanosaurian synapomorphy is that the dorsal margins of the scapula and coracoid are approximately level with one another. Dongyangosaurus can clearly be differentiated from Jiangshanosaurus , and displays features that indicate a closer relationship to the titanosaur radiation. Revised scores for both taxa are incorporated into an expanded phylogenetic data matrix, comprising 124 taxa scored for 548 characters. Under equal weights parsimony, Jiangshanosaurus is recovered as a member of the non-titanosaurian East Asian somphospondylan clade Euhelopodidae, and Dongyangosaurus lies just outside of Titanosauria. However, when extended implied weighting is applied, both taxa are placed within Titanosauria. Most other ‘middle’ Cretaceous East Asian sauropods are probably non-titanosaurian somphospondylans, but at least Xianshanosaurus appears to belong to the titanosaur radiation. Our analyses also recover the Early Cretaceous European sauropod Normanniasaurus genceyi as a ‘derived’ titanosaur, clustering with Gondwanan taxa. These results provide further support for a widespread diversification of titanosaurs by at least the Early Cretaceous.

First palaeoneurological study of a sauropod dinosaur from France and its phylogenetic significance

“…Considerable advances in our understanding of titanosaurian endocranial anatomy over the last few years have been paralleled by substantial progress in our perception of the topology of titanosaurian phylogeny (see in particular Sallam et al, 2018; Gorscak & O’Connor, 2019; Mannion et al, 2019a, 2019b), which had been particularly labile until then. As it turned out, the study of the osteology of FAM 03.064 through external observation did not provide insight regarding the phylogenetic position of the species to which it belongs within Titanosauria (Díez Díaz et al, 2012).…”

“…However, D. sinensis and B. henanensis were later recovered as non-lithostrotian titanosaurs (Mannion, Allain & Moine, 2017: fig. 39, 2019a: fig. 5, 2019b: fig.…”

Myological reconstruction of the pelvic girdle and hind limb of the giant titanosaurian sauropod dinosaur Dreadnoughtus schrani

“…Despite such apparent great diversity, titanosaur remains are frequently fragmentary (Upchurch et al, 2004), and the fragmentary fossil record of these animals has limited our understanding of their phylogenetic relationships, soft tissue anatomy, and biomechanics. Recent discoveries of more complete skeletons such as those of Dreadnoughtus and Patagotitan (Carballido et al, 2017; Lacovara et al, 2014) are slowly helping to stabilize titanosaurian phylogenetic relationships, but a consensus has yet to be reached regarding the positions of many individual taxa and the validity of multiple subclades (see variation between the topologies found by Carballido et al, 2017; Gorscak & O’Connor, 2019; Mannion et al, 2019).…”

A new giant sauropod,Australotitan cooperensisgen. et sp. nov., from the mid-Cretaceous of Australia

“…In the absence of such a resolved phylogeny, we can consider the phylogenetic position of A. cooperensis using a comparative approach, using published phylogenies and the spread of characteristics hypothesized to define particular clades. The phylogenetics of titanosaurians remains in a state of flux with multiple assessments appearing in recent years investigating the relative position of taxa in a global context, covering Late Jurassic to Late Cretaceous (Carballido et al, 2017;D'Emic, 2012;González Riga et al, 2019;Gonzàlez Riga et al, 2018;Hechenleitner et al, 2020;Mannion, Allain & Moine, 2017;Mannion et al, 2013;Mannion et al, 2019a;Mannion et al, 2019b).…”

“…The most recent phylogenetic analyses that include the Winton Formation titanosaurians (González Riga et al, 2019;Gonzàlez Riga et al, 2018;Mannion, Allain & Moine, 2017; Mannion et al, 2019a;Mannion et al, 2019b) provide context for our discussion in two important ways. Firstly, there is growing support for a nearly global distribution of most titanosaurian clades by the Early Cretaceous, and by extension, titanosaurians from Cretaceous Australia could potentially represent one or more of those clades.…”