scholarly journals New protoceratopsid specimens improve the age correlation of the Upper Cretaceous Gobi Desert strata

2020 ◽  
Vol 65 ◽  
Author(s):  
Łukasz Czepiński
Keyword(s):  
Upper Cretaceous ◽  
Gobi Desert

LITHOBIOTOPES OF THE NEMEGT GOBI BASIN

2021 ◽  
Author(s):  
Tomasz Jerzykiewicz ◽  
Philip J. Currie ◽  
Federico Fanti ◽  
Jerzy Lefeld
Keyword(s):  
Upper Cretaceous ◽  
Alluvial Plain ◽  
Gobi Desert ◽  
Large Species ◽  
Physical Processes ◽  
Desert Region ◽  
Ephemeral Channels ◽  
Temporal Succession ◽  
Asymmetric Distributions ◽  
Rich Fauna

Three distinct but overlapping dinosaur-dominated faunas characterize the Upper Cretaceous Djadokhta, Baruungoyot and Nemegt formations of the Nemegt Basin of Mongolia. Documented faunal differences cannot be explained easily by temporal succession, but can be understood in the light of physical processes controlling life, death, and burial of taxa. The stratigraphy of the Gobi Desert region records tectonically driven geometries, clearly documenting preservational processes different than those acting in most other dinosaur-dominated beds worldwide. Small, asymmetric tectonic grabens were filled with Upper Cretaceous, dinosaur bearing deposits showing asymmetric distributions of facies, here termed Lithobiotopes. The water-lain fluvial and alluvial plain facies of the Nemegt Lithobiotope supported and preserved a fauna dominated by gigantic dinosaurs, but had a preservational bias against smaller animals. The Nemegt passed laterally into interdune facies of the Baruungoyot Lithobiotope, which represented a hostile environment for large species, but preserved smaller animals. This in turn passed laterally into the aeolianite facies of the Djadokhta Lithobiotope, which is characterized by remains of small dinosaurs and a rich fauna of other animals. The Nemegt Gobi Basin can be visualized as an oasis with a central pond supplied with water from ephemeral channels and surrounded by a semi-arid alluvial plain and dune fields.

Exceptional preservation of a Late Cretaceous dinosaur nesting site from Mongolia reveals colonial nesting behavior in a non-avian theropod

Geology ◽  
2019 ◽  
Vol 47 (9) ◽  
pp. 843-847 ◽  
Author(s):  
Kohei Tanaka ◽  
Yoshitsugu Kobayashi ◽  
Darla K. Zelenitsky ◽  
François Therrien ◽  
Yuong-Nam Lee ◽  
...  
Keyword(s):  
Upper Cretaceous ◽  
Bird Species ◽  
Nesting Behavior ◽  
Gobi Desert ◽  
Exceptional Preservation ◽  
Colonial Nesting ◽  
Nesting Site ◽  
High Concentrations ◽  
Lithologic Unit ◽  
Nesting Season

Abstract Colonial nesting behavior has been inferred in a variety of non-avian dinosaurs based on high concentrations of nests preserved in an area, but sedimentologic and taphonomic evidence demonstrating the contemporaneity of the nests is often lacking. A new nesting site discovered in the Upper Cretaceous Javkhlant Formation of the eastern Gobi Desert, Mongolia, preserves at least 15 egg clutches laid by a probable non-avian theropod, and provides strong evidence for colonial nesting in a non-avian dinosaur. The occurrence of the clutches at the top of a common paleosurface, the distribution of eggshell fragments within clutches, the presence of a consistent two-layer sediment infill within eggs, and a thin marker lithologic unit blanketing all the clutches indicate the clutches were laid and hatched in a single nesting season. Despite the absence of sedimentologic evidence indicative of nest structure, statistical analyses of egg characteristics and facies association reveal the clutches were likely incubated in covered or buried nests. Based on the number of hatched clutches, the hatching success rate of the colony was high (60%), similar to that of extant crocodylian populations and bird species that attend and/or protect their nests during the incubation period, which indicates nest attendance behavior in the Javkhlant theropods. Thus, colonial nesting with parental attendance, widespread in extant birds, likely evolved initially among non-brooding, non-avian dinosaurs to increase nesting success.

scholarly journals A Small-Bodied Troodontid (Dinosauria, Theropoda) from the Upper Cretaceous Wulansuhai Formation of Inner Mongolia, China

2020 ◽  
Author(s):  
Shuo Wang ◽  
Qingwei Tan ◽  
Qiyue Zhang ◽  
Josef Steigler ◽  
Huitao Zhang ◽  
...  
Keyword(s):  
Inner Mongolia ◽  
Upper Cretaceous ◽  
Phylogenetic Analyses ◽  
Cervical Vertebrae ◽  
Phylogenetic Position ◽  
Gobi Desert ◽  
Mature Individual ◽  
Caudal Vertebrae ◽  
New Finding ◽  
Neural Canal

AbstractA new small-bodied troodontid (LH PV39) recovered from the Upper Cretaceous Wulansuhai Formation, Suhongtu, Inner Mongolia, China, is described. The new specimen preserves six postaxial cervical vertebrae, five completely fused sacral and four posterior caudal vertebrae in addition to two manual unguals. The completely fused neurocentral junctions indicate that a skeletally mature individual of the same species of LH PV39 would be smaller than Philovenator and comparable in body size to a skeletal mature individual of Almas. The extremely dorsoventrally compressed sacral centra and neural canal, and the middle three sacral centra that are shorter and wider than the first and the last one distinguishing LH PV39 from other known troodontids. A series of phylogenetic analyses were conducted using modified published matrices. By coding LH PV39 in different strategies, the troodontid affinity of LH PV39 is confirmed and it was recovered as the sister taxon of either Mei and Sinovenator (LH PV39 scored as a separate OTU) or Linhevenator (incorporating LH PV39 into Philovenator) in the best resolved coelurosaurian interrelationships. The referral of LH PV39 to Philovenator does not seriously alter the phylogenetic position of Philovenator nor the interrelationships of troodontids. This new finding confirms that the small and large sized troodontids are coexisted in the Gobi Desert of the Mongolia Plateau until the end of Cretaceous.

scholarly journals A new ankylosaurid skeleton from the Upper Cretaceous Baruungoyot Formation of Mongolia: its implications for ankylosaurid postcranial evolution

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jin-Young Park ◽  
Yuong-Nam Lee ◽  
Philip J. Currie ◽  
Michael J. Ryan ◽  
Phil Bell ◽  
...  
Keyword(s):  
Upper Cretaceous ◽  
Rigid Bodies ◽  
The Other ◽  
Gobi Desert ◽  
Anatomical Features ◽  
Olecranon Process ◽  
Hind Limbs ◽  
Body Shapes ◽  
Self Defence ◽  
Upper Campanian

AbstractA new articulated postcranial specimen of an indeterminate ankylosaurid dinosaur from the Upper Cretaceous (middle-upper Campanian) Baruungoyot Formation from Hermiin Tsav, southern Gobi Desert, Mongolia includes twelve dorsal vertebrae, ribs, pectoral girdles, forelimbs, pelvic girdles, hind limbs, and free osteoderms. The new specimen shows that Asian ankylosaurids evolved rigid bodies with a decreased number of pedal phalanges. It also implies that there were at least two forms of flank armor within Ankylosauridae, one with spine-like osteoderms and the other with keeled rhomboidal osteoderms. Unique anatomical features related to digging are present in Ankylosauridae, such as dorsoventrally flattened and fusiform body shapes, extensively fused series of vertebrae, anteroposteriorly broadened dorsal ribs, a robust humerus with a well-developed deltopectoral crest, a short robust ulna with a well-developed olecranon process, a trowel-like manus, and decreased numbers of pedal phalanges. Although not fossorial, ankylosaurids were likely able to dig the substrate, taking advantage of it for self-defence and survival.

scholarly journals Specializations of the mandibular anatomy and dentition ofSegnosaurus galbinensis(Theropoda: Therizinosauria)

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1885 ◽  
Author(s):  
Lindsay E. Zanno ◽  
Khishigjav Tsogtbaatar ◽  
Tsogtbaatar Chinzorig ◽  
Terry A. Gates
Keyword(s):  
Upper Cretaceous ◽  
Feeding Strategy ◽  
Niche Partitioning ◽  
Gobi Desert ◽  
Triangular Facet ◽  
Theropod Dinosaurs ◽  
The North ◽  
Initial Description ◽  
Dental Traits ◽  
North American Taxon

Definitive therizinosaurid cranial materials are exceptionally rare, represented solely by an isolated braincase and tooth in the North American taxonNothronychus mckinleyi, the remarkably complete skull of the Asian taxonErlikosaurus andrewsi, and the lower hemimandibles ofSegnosaurus galbinensis. To date, comprehensive descriptions of the former taxa are published; however, the mandibular materials ofS. galbinensishave remained largely understudied since their initial description in 1979. Here we provide a comprehensive description of the well-preserved hemimandibles and dentition ofS. galbinensis(MPC-D 100/80), from the Upper Cretaceous Bayanshiree Formation, Gobi Desert, Mongolia. The subrectangular and ventrally displaced caudal hemimandible, extreme ventral deflection of the rostral dentary, and edentulism of the caudal dentary ofS. galbinensisare currently apomorphic among therizinosaurians. Unique, unreported dental traits including lingually folded mesial carinae, development of a denticulated triangular facet on the distal carinae near the cervix, and extracarinal accessory denticles, suggest a highly specialized feeding strategy inS. galbinensis. The presence of triple carinae on the distalmost lateral tooth crowns is also unique, although may represent an abnormality. Contrasted with the simplistic dentition of the contemporaneous therizinosauridE. andrewsi, the dentition ofS. galbinensisis indicative of niche partitioning in food acquisition, processing, or resources among known therizinosaurids inhabiting Asian ecosystems in the Late Cretaceous. Although not quantitatively correlated with diet, this suite of specializations is otherwise unique among theropod dinosaurs and supports derived inferences of facultative or obligate herbivory in therizinosaurids, ultimately adding novel information to our understanding of ecomorphology in theropods.

Systematics and taxonomic diversity of squamates from the Upper Cretaceous Djadochta Formation, Bayan Mandahu, Gobi Desert, People's Republic of China

1996 ◽  
Vol 33 (4) ◽  
pp. 578-598 ◽  
Author(s):  
Keqin Gao ◽  
Lianhai Hou
Keyword(s):  
North American ◽  
Upper Cretaceous ◽  
Low Frequency ◽  
Taxonomic Diversity ◽  
Gobi Desert ◽  
Republic Of China ◽  
Terrestrial Vertebrates ◽  
The North ◽  
Central Asian ◽  
Warm Temperate

Squamate fossils collected for the Sino-Canadian dinosaur expeditions (1986–1990) include some 70 specimens from the Upper Cretaceous (Campanian) Djadochta Formation, exposed at the vicinity of Bayan Mandahu, Inner Mongolia, China. Well-preserved skulls, jaws, postcranial skeletons, and even osteodermal armor document a fossil assemblage composed of at least 18 genera in 8 families. Besides showing considerable taxonomic diversity, several families recorded in the assemblage are of importance in understanding the geologic and biogeographic distribution of the relevant groups, and the paleoenvironment in which these lizards lived. Comparison of the Gobi lizard assemblage with North American and Central Asian assemblages is briefly discussed. Taxonomic differences in the assemblage from that of the Upper Cretaceous in the North American Western Interior reflect endemism and suggest a low frequency of interchange of small terrestrial vertebrates between the two regions during Campanian time. The taphonomic setting of the squamate fossils indicates quick burial in arid to semiarid environments in the Gobi Desert, differing importantly from the Western Interior of North America, where the accumulation of disarticulated jaw fragments reflects postmortem decomposition and fluvial transportation under subtropical to warm temperate conditions.

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