New ornithomimosaurian (Dinosauria: Theropoda) pelvis from the Upper Cretaceous Erlian Formation of Nei Mongol, North China

Yao, Xi; Sullivan, Corwin; Tan, Qi; Xu, Xing

doi:10.1016/j.cretres.2022.105234

Cited by 5 publications

(3 citation statements)

References 55 publications

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“…However, ornithomimids are rare in the Maastrichtian faunas of western North America (DeCourten and Russell, 1985;Claessens and Loewen, 2015). In Asia, ornithomimids were common in pre-Campanian strata of Uzbekistan and China (Gilmore, 1933;Smith and Galton, 1990;Kobayashi and Lü, 2003;Sues and Averianov, 2016;Yao, Sullivan, Tan, and Xu, 2022), but are rare in the Campanian of Mongolia (Chinzorig et al, 2017). However, the greatest taxonomic diversity of ornithomimosaurs is known from the Maastrichtian Nemegt Formation of Mongolia (Osmólska and Roniewicz, 1970;Osmólska, Roniewicz, and Barsbold, 1972;Barsbold, 1988;Kobayashi and Barsbold, 2006;Bronowicz, 2011;Lee et al, 2014;Chinzorig et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

First find of an ornithomimid theropod dinosaur in the Upper Cretaceous of the Russian Far East

Averianov,

Skutschas,

Bolotsky

et al. 2023

BioComm

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A fragmentary tibia of an actively growing sub-adult individual from the Upper Cretaceous (Maastrichtian) Udurchukan Formation at Kundur, Amur oblast, Far East, Russia, is similar to the tibia of Qiupalong henanensis from the Maastrichtian of Henan Province, China, in bearing a weak posteromedial ridge at the distal end and equally projecting distal malleoli. Qiupalong had a transcontinental distribution and likely originated in North America. Similarly, lambeosaurine hadrosaurids from the Udurchukan Formation have American affinities and their ancestors may had dispersed from North America to East Asia together with a Qiupalong-like ornithomimid. Q. henanensis and Ornithomimidae indet. from Kundur are the only records of the Maastrichtian Ornithomimidae in Asia outside Gobi Desert.

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Section: Discussionmentioning

confidence: 99%

First find of an ornithomimid theropod dinosaur in the Upper Cretaceous of the Russian Far East

Averianov,

Skutschas,

Bolotsky

et al. 2023

BioComm

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“…In certain taxa of theropods, the pelvis may show partial or complete fusion in large individuals. The pubis and ilium fuse in the microraptorine Hesperonychus elizabethae (Longrich and Currie 2009), and the ilium, ischium, and pubis fuse in Coelophysoidea (Raath, Carpenter et al 1990), Abelisauridae (Iori, de Araújo-Júnior et al 2021) Rauhut 2012, Cerroni, Baiano et al 2022)and in Ornithomimidae (Osborn 1917, Xu, Kobayashi et al 2011, Macdonald and Currie 2019, Yao, Sullivan et al 2022. Fusion of the pubis and ischium occurs in a large individual of T. rex (Brochu 2003), and the pubes are completely fused in Daspletosaurus UALVP 52981.…”

Section: Histology Supports Existence Of Mature Nanotyrannusmentioning

confidence: 99%

Taxonomic status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea) — a distinct taxon of small-bodied tyrannosaur

Longrich,

Saitta

2023

Preprint

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Tyrannosaurs, giant predatory dinosaurs from the end of the Cretaceous, are among the most intensively researched and best-known groups of dinosaurs. Despite this, their relationships and systematics are highly controversial, and the number of tyrannosaur species occurring in the latest Cretaceous in North America is debated. An ongoing debate concerns the status of Nanotyrannus lancensis, which has variously been interpreted as a distinct taxon of small-bodied tyrannosaur or a juvenile of the coeval Tyrannosaurus rex. Here, we review multiple lines of evidence and show that the totality of evidence strongly supports recognition of Nanotyrannus as a distinct species: 1. The high diversity of Late Cretaceous tyrannosaurs and predatory dinosaurs in general is consistent with the idea that more than one species lived in the late Maastrichtian of Western North America; 2. Nanotyrannus shows few if any diagnostic characters allowing referral specifically to Tyrannosaurus or even Tyrannosaurinae, but is differentiated from T. rex by at least 77 morphological characters, while intermediate forms, combining characteristics of Nanotyrannus and T. rex, remain unknown; 3. Histological evidence shows that individuals previously referred to Nanotyrannus lancensis show (i) skeletal fusions consistent with maturity, (ii) skull bone textures consistent with maturity, (iii) slow growth rates relative to T. rex, (iv) decelerating growth in their final years of life, and (v) growth curves predicting adult body sizes of ~1500 kg or less, implying that these animals are young adults, not juveniles of Tyrannosaurus; 4. Juveniles of other tyrannosaurids, including Gorgosaurus and Tarbosaurus, do not show the kinds of changes proposed for a Nanotyrannus-Tyrannosaurus growth series, suggesting the Nanotyrannus morphology cannot simply be explained as the result of immaturity; 5. Small T. rex exist, comparable in size to Nanotyrannus, which exhibit diagnostic features of Tyrannosaurus, and which differ from Nanotyrannus; 6. Phylogenetic analysis suggests that Nanotyrannus is not a tyrannosaurid. Taken together, the totality of the evidence rejects referral of Nanotyrannus to T. rex. Phylogenetic analysis tentatively supports placement of Nanotyrannus outside of Tyrannosauridae as a non-tyrannosaurid member of Tyrannosauroidea. Tyrannosaur diversity appears to have been higher than previously appreciated in the latest Cretaceous before the K-Pg extinction. The difficulties in recognizing species based on fossils alone mean that paleontologists may be systematically biased towards underestimating the species diversity of ancient ecosystems.

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“…In some theropods, the pelvis shows partial or complete fusion in large individuals. The pubis and ilium fuse in the microraptorine Hesperonychus elizabethae [119]; the ilium, ischium, and pubis fuse in Coelophysoidea [120], Abelisauridae [121][122][123], and Ornithomimidae [124][125][126][127]. Fusion of the pubis and ischium also occurs in a large individual of T. rex [7]; the pubes and ischia are fused in Daspletosaurus UALVP 52981.…”

Section: Skeletal Fusionmentioning

confidence: 99%

Taxonomic Status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea)—A Distinct Taxon of Small-Bodied Tyrannosaur

Longrich,

Saitta

2024

Fossil Studies

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Tyrannosaurs are among the most intensively studied and best-known dinosaurs. Despite this, their relationships and systematics are highly controversial. An ongoing debate concerns the validity of Nanotyrannus lancensis, interpreted either as a distinct genus of small-bodied tyrannosaur or a juvenile of Tyrannosaurus rex. We examine multiple lines of evidence and show that the evidence strongly supports recognition of Nanotyrannus as a distinct species for the following reasons: 1. High diversity of tyrannosaurs and predatory dinosaurs supports the idea that multiple tyrannosaurids inhabited the late Maastrichtian of Laramidia; 2. Nanotyrannus lacks characters supporting referral to Tyrannosaurus or Tyrannosaurinae but differs from T. rex in >150 morphological characters, while intermediate forms combining the features of Nanotyrannus and T. rex are unknown; 3. Histology shows specimens of Nanotyrannus showing (i) skeletal fusions, (ii) mature skull bone textures, (iii) slow growth rates relative to T. rex, (iv) decelerating growth in their final years of life, and (v) growth curves predicting adult masses of ~1500 kg or less, showing these animals are subadults and young adults, not juvenile Tyrannosaurus; 4. growth series of other tyrannosaurids, including Tarbosaurus and Gorgosaurus, do not show morphological changes proposed for a Nanotyrannus–Tyrannosaurus growth series, and deriving Tyrannosaurus from Nanotyrannus requires several changes inconsistent with known patterns of dinosaur development; 5. Juvenile T. rex exist, showing diagnostic features of Tyrannosaurus; 6. Phylogenetic analysis suggests that Nanotyrannus may lie outside Tyrannosauridae. Tyrannosaur diversity before the K-Pg extinction is higher than previously appreciated. The challenges inherent in diagnosing species based on fossils mean paleontologists may be systematically underestimating the diversity of ancient ecosystems.

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New ornithomimosaurian (Dinosauria: Theropoda) pelvis from the Upper Cretaceous Erlian Formation of Nei Mongol, North China

Cited by 5 publications

References 55 publications

First find of an ornithomimid theropod dinosaur in the Upper Cretaceous of the Russian Far East

First find of an ornithomimid theropod dinosaur in the Upper Cretaceous of the Russian Far East

Taxonomic status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea) — a distinct taxon of small-bodied tyrannosaur

Taxonomic Status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea)—A Distinct Taxon of Small-Bodied Tyrannosaur

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