Issi saaneq gen. et sp. nov.—A New Sauropodomorph Dinosaur from the Late Triassic (Norian) of Jameson Land, Central East Greenland

Abstract

The Late Triassic (Norian) outcrops of the Malmros Klint Formation, Jameson Land (Greenland) have yielded numerous specimens of non-sauropod sauropodomorphs. Relevant fossils were briefly reported in 1994 and were assigned to Plateosaurus trossingensis. However, continuous new findings of early non-sauropod sauropodomorphs around the globe facilitate comparisons and allow us to now revise this material. Here, the non-sauropod sauropodomorph Issi saaneq gen. et sp. nov. is described based on two almost complete and articulated skulls. The two skulls represent a middle-stage juvenile and a late-stage juvenile or subadult. Issi saaneq differs from all other sauropodomorphs by several unique traits: (1) a small foramen at the medial surface of the premaxilla; (2) an anteroposteriorly elongated dorsoposterior process of the squamosal; (3) a relatively high quadrate relative to rostrum height; (4) a well-developed posterodorsal process of the articular. These features cannot be explained by taphonomy, ontogeny, or intraspecific variation. Issi saaneq shows affinities to Brazilian plateosaurids and the European Plateosaurus, being recovered as the sister clade of the latter in our phylogenetic analysis. It is the northernmost record of a Late Triassic sauropodomorph, and a new dinosaur species erected for Greenland. Issi saaneq broadens our knowledge about the evolution of plateosaurid sauropodomorphs.

Diversity and taxonomy of the Late Triassic sauropodomorphs (Saurischia, Sauropodomorpha) stored in the Palaeontological Collection of Tübingen, Germany, historically referred to Plateosaurus

“…Several specimens that von Huene considered robust morphotypes have been reinterpreted as new species, i.e., Schleitheimia and Gresslyosaurus in Rauhut et al (2020), andTuebingosaurus in Regalado Fernández &Werneburg (2022), after they were compared against the new type species of Plateosaurus that was designated in 2019 (ICZN 2019). In contrast, gracile individuals referred to as Plateosaurus have been redescribed as a different type of plateosaurid, i.e., Issi (Beccari et al 2021).…”

“…Recent developments in our understanding of the Late Triassic of Europe necessitate the development of a new alpha taxonomy that delineates species in a way in which variability is consistent with the information on development, palaeoecology, and physiology derived from Taxonomy 2. In the case of Issi Beccari et al, 2021, the specimens were originally assigned to the genus Plateosaurus without erecting new species; in the case of Schleitheimia Rauhut et al, 2020, Gresslyosaurus andTuebingosaurus Regalado Fernández &Werneburg, 2022, the new species were recognized after they were compared against the new type species of Plateosaurus that was designated in 2019 (ICZN 2019). In accordance with the taxonomy of von Huene (1905,1907,1914,1915,1932), all specimens referred to as Gresslyosaurus and 'Pachysaurus' are robust animals when compared to Plateosaurus 'erlenbergiensis' (species 2 in Fig.…”

“…3) has been designated the holotype of Tuebingosaurus maierfritzorum Regalado Fernández & Werneburg, 2022, because its anatomy more closely resembles a massopodan than Plateosaurus (Regalado Fernández & Werneburg 2022). Similarly, some of the Klettgau Formation material formerly considered to be Gresslyosaurus (Galton 1986) has been reassessed as a distinctive species of robust sauropodiform sauropodomorph, named Schleitheimia schutzi Rauhut et al, 2020. In contrast, the material from Jameson Land, Greenland, more gracile and previously referred to as Plateosaurus (Clemmensen et al 2016;Marzola et al 2018), has been recognized as a new species of plateosaurid, named Issi saaneq Beccari et al, 2021.…”

A nearly complete skull of the sauropod dinosaurDiamantinasaurus matildaefrom the Upper Cretaceous Winton Formation of Australia and implications for the early evolution of titanosaurs

“…By contrast, if Yoshida et al . [178] are correct in their reinterpretation of the hyobranchial apparatus of Pinacosaurus grangeri , then the identification of these as first ceratobranchials is correct; this seems likely.taxonpublished interpreted identityreferencenon-sauropodan sauropodomorphs Buriolestes schultzei hyoidCabreira et al [179]hyoidMüller et al [180] Pantydraco caducus ?hyoidKermack [181]?Corpus hyoideum + cornuaGalton & Kermack [182] Macrocollum itaqui hyoidMüller [183] Unaysaurus tolentinoi ?hyoidMcPhee et al [184] Issi saaneq ceratobranchialBeccari et al [185] Plateosaurus spp.illustrated but not identifiedJaekel [186]cornubranchial 1Fürbringer [187]hyoidHuene [188]hyoidHuene [189]hypobranchial 1Janensch [190]first ceratobranchialGalton [191]ceratobranchialLallensack et al [192] Lufengosaurus huenei (=‘ Fulengia youngi ’)ceratobranchial 1Carroll & Galton [193]ceratobranchial 1Evans & Milner [194]…”

A new phytosaur species (Archosauriformes) from the Upper Triassic of Jameson Land, central East Greenland

“…The Fleming Fjord Group of East Greenland (Clemmensen et al, 2020) comprises a diverse faunal assemblage containing chondrichthyans and actinopterygian fishes, lungfish such as Ceratodus tenuensis (Agnolin et al, 2018), theropod and sauropodomorph dinosaurs, temnospondyls, turtles, aetosaurs, phytosaurs, and pterosaurs (Jenkins et al, 1994(Jenkins et al, , 2001Sulej et al, 2014;Clemmensen et al, 2016;Marzola et al, 2017aMarzola et al, , 2018Agnolin et al, 2018;Niedzẃiedzki and Sulej, 2020;Beccari et al, 2021;Milàn et al, 2021). Furthermore, the fauna includes both teeth and skeletal elements of early mammaliaforms (Jenkins et al, 1994;Shapiro & Jenkins, 2001;Sulej et al, 2020;Beccari et al, 2021). Tracks and trackways provide evidence for abundant small to medium-sized theropod dinosaurs, sauropods, and sauropodomorphs spanning a large range of body sizes and other archosaurs (Clemmensen et al, 2016;Sulej et al, 2014;Klein et al, 2016;Lallensack et al, 2017).…”