Endocranial reconstruction of AENM 2/121 based on a CT scan.
Kundurosaurus is known from holotype AENM 2/921, a partial, disarticulated skull, including a nearly complete braincase (AENM 2/921 1-2), two quadrates (3-4), squamosal (5), postorbital (6), frontal (7) and parietal (8) bones. The referred specimens are AENM 2/45-46, two jugals; AENM 2/83-84, 2/86, maxillae; AENM 2/57-58, nasals; AENM 2/48, postorbital; AENM 2/19, quadrate; AENM 2/121, 2/928 partial braincases; AENM 2/846, 2/902, dentaries; AENM 2/906, scapula; AENM 2/913, sternal; AENM 2/117, 2/903, 2/907-908, humeri; AENM 2/905, ulna; AENM 2/904, radius; AENM 2/922, nearly complete pelvic girdle and associated sacral elements. These were found at the same level as the holotype, but may belong to other individuals. All specimens are housed in the Amur Natural History Museum of the Institute of Geology and Nature Management, Russia.[1]
All Kundurosaurus specimens were collected in the Kundur locality. The site belongs to the Wodehouseia spinata – Aquilapollenites subtilis palynozone, dating to the Maastrichtian stage, probably the Late Maastrichtian, of the Late Cretaceousperiod, about 67-66 million years ago. The Kundur site was discovered by Vladimir A. Nagorny in 1990. He collected fossil bones in a road section along the Chita – Khabarovsk highway near the village of Kundur and sent them to Yuri L. Bolotsky. Large-scale excavations started at Kundur in 1999. Besides the abundant Olorotitan arharensis material, it has yielded many disarticulated saurolophine specimens. All these specimens were assigned to Kundurosaurus because the describers considered the recovered material to be homogeneous, and suggested that there is no reason to believe that more than one single saurolophine taxon lived in the Kundur area by latest Cretaceous period.[1]
Kundurosaurus was a medium-sized hadrosaur, measuring 7 metres (23 ft) long and weighing 2 metric tons (2.2 short tons).[3] It is a saurolophine diagnosed by four autapomorphies, unique derived traits. It has a prominent and thick ridge on the lateral side of the nasal that borders caudally the circumnasal depression and invades the caudal plate of the nasal. Its caudal buttress of the proximal head of the scapula is oriented quite laterally, parallel to the pseudoacromial process. The preacetabular process of the ilium is straight and only moderately deflected ventrally by an angle of 160°. It does not reach the level of the plane formed by the bases of the iliac and pubic peduncles. Finally, with Kundurosaurus the axis of the postacetabular process of the ilium is strongly twisted along its length, so that its lateral side progressively faces dorsolaterally.[1]
Classification
Pelvic girdle of Kundurosaurus: left pubis AENM 2/922-5L (A), left ischium AENM 2/922-3L (B) and the autapomorphic left ilium AENM 2/922-7L (C) in lateral view.
A phylogenetic analysis of saurolophines performed by Godefroit, Bolotsky & Lauters (2012) indicates that Kundurosaurus is nested within a clade including Edmontosaurini and Saurolophini, possibly as a sister-taxon of Kerberosaurus. It is based on the data matrix of Prieto-Márquez (2010), however Prieto-Márquez (2010) recovered Edmontosaurini as a sister-taxon of a monophyletic clade formed by Saurolophini and Kritosaurini while in Godefroit et al. (2012) the Edmontosaurini + Saurolophini clade is well supported and excludes Kritosaurini.[1]
The position of Kundurosaurus within Edmontosaurini collapses when fragmentary taxa are excluded from the analysis. In the full analysis, Kundurosaurus is placed as the sister-taxon of Kerberosaurus, which is known from the same region. It may therefore be postulated that K. nagornyi is a second species of the genus Kerberosaurus. This clade, however, is very weakly supported and synapomorphies uniting both taxa can only been found under optimization. Furthermore, although overlapping materials between the genera are limited to their partial skulls, according to Godefroit et al. (2012) Kundurosaurus can be differentiated from Kerberosaurus on the basis of the rostrocaudally longer and more robust dorsal maxillary process, more robust and more curved downwards nasal, much more robust and proportionally higher quadrate and the strong ridge extends obliquely along the lateral side of the exoccipital condyloid in Kundurosaurus. Additionally, the frontals of Kerberosaurus are particularly narrow and do not participate in the orbital margin, the rostral margin of the parietal is depressed around the contact area with the frontals, and Kerberosaurus has hook-like palatine process.[1]
Dentaries AENM 2/846 (A-B) and AENM 2/902 (C-D).ScapulaRight nasals
On the other hand, Xing et al. (2014) considered Kundurosaurus nagornyi to be a junior synonym of Kerberosaurus manakini on the basis of their co-occurrence within the same formation and presence of shared characters in their skeletons.[4]
The cladogram below follows Godefroit et al. (2012) analysis.[1]
^Paul, Gregory S. (2016). The Princeton Field Guide to Dinosaurs 2nd Edition. New Jersey: Princeton University Press. p. 330.
^Xing, Hai; Zhao, Xijin; Wang, Kebai; Li, Dunjing; Chen, Shuqing; Mallon, Jordan C; Zhang, Yanxia; Xu, Xing (2014). "Comparative osteology and phylogenetic relationship of Edmontosaurus and Shantungosaurus (Dinosauria: Hadrosauridae) from the Upper Cretaceous of North America and East Asia". Acta Geologica Sinica - English Edition. 88 (6): 1623–1652. Bibcode:2014AcGlS..88.1623X. doi:10.1111/1755-6724.12334.
