Gigantosaurus robustus, Fraas, 1908

Mannion, Philip D., Upchurch, Paul, Schwarz, Daniela & Wings, Oliver, 2019, Taxonomic affinities of the putative titanosaurs from the Late Jurassic Tendaguru Formation of Tanzania: phylogenetic and biogeographic implications for eusauropod dinosaur evolution, Zoological Journal of the Linnean Society 185, pp. 784-909 : 788

Gigantosaurus robustus : Janensch, 1922

Barosaurus robustus : Haughton, 1928

Tornieria robusta : Janensch, 1961

Holotype: SMNS 12144 – associated right hindlimb comprising the distal end of the femur, tibia, fibula, astragalus and complete pes.

Topotypes: left pubis [MB.R.2090.2 (B8)], right ischium [MB.R.2090.4 (B13)] and distal half of left tibia [MB.R.2090.1 (B6)] from the same locality as the holotype ( Janensch, 1914b; Bonaparte et al., 2000; Mannion et al., 2013). A second, slightly larger, right ischium [MB.R.2090.3 (B11)], indicates the presence of a second individual.

Type locality and horizon: Quarry B, approximately 900 m southeast of Tendaguru Hill, Lindi District, southeastern Tanzania ( Fig. 1); Upper Dinosaur Member (Upper Saurian Bed), Tendaguru Formation; Tithonian, Late Jurassic ( Fraas, 1908; Janensch, 1914b, 1925b, 1929a; Wild, 1991; Bonaparte et al., 2000; Aberhan et al., 2002; Remes, 2006; Bussert et al., 2009).

Referred material: All of the forelimb and hindlimb material from Quarry P (MB.R.2095 2245 and 2707), at Nterego, approximately 1.2 km northeast of Tendaguru Hill, Lindi District, southeastern Tanzania ( Fig. 1); Upper Dinosaur Member (Upper Saurian Bed), Tendaguru Formation; Tithonian, Late Jurassic ( Janensch, 1922, 1929a, 1961; Heinrich, 1999b; Bonaparte et al., 2000; Aberhan et al., 2002; Bussert et al., 2009). Note that a number of these elements are now lost (see below).

Revised diagnosis: Janenschia can be diagnosed by two autapomorphies (marked with an asterisk), as well as one local autapomorphy: (1) tibia with prominent tubercle (‘tuberculum fibularis’) on the posterior surface of the distal half of the cnemial crest; (2) extremely prominently developed projection posteromedial to the ascending process of the astragalus*; and (3) high metatarsal I to V length ratio (1.34)*.

Additional comments: A sacrum and ilium were also apparently discovered at the type locality ( Janensch, 1929a), but were either subsequently destroyed or were never collected. However, it is not entirely clear whether the missing sacrum and ilium are those discussed and photographed in Fraas (1908: pp. 126–128), or newly discovered elements. If the former is correct, as suggested in Janensch (1961: p. 201), then these elements did not come from the same locality as the holotype and the topotypic materials ( Fraas, 1908), and cannot be confidently attributed to Janenschia . Regardless, no anatomical information can be gleaned from these elements and thus we do not discuss them further. Bonaparte et al. (2000) noted that Janensch’s field catalogue also mentioned a partial forefoot from the type locality, but there is no further information on this material and it was presumably either destroyed or never collected. An alternative possibility is that this is MB.R.2093, a near complete, articulated right manus that was referred to Janenschia ( Janensch, 1922) . However, Janensch (1922, 1961) stated that this was collected from near to the Janenschia type locality, rather than from the type locality itself. Furthermore, the surrounding area also yielded the type skeleton of Tornieria , and so we cannot be certain that MB.R.2093 belongs to Janenschia . As such, we exclude MB.R.2093 from Janenschia and describe it separately (see below). Other previously referred remains also cannot unequivocally be assigned to Janenschia and are treated separately too.

DESCRIPTION AND COMPARISONS OF THE HOLOTYPE MATERIAL OF JANENSCHIA ROBUSTA