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.

Pictures and people. Seals, figurines and Peloponnesian imagery

2010 ◽  
Vol 3 ◽  
pp. 185-218 ◽  
Author(s):  
Erika Weiberg
Keyword(s):  
Bronze Age ◽  
Early Bronze Age ◽  
North East ◽  
The North ◽  
Initial Description ◽  
Seal Impressions ◽  
Point Of Departure ◽  
Coastal Settlement

The point of departure for this paper is the publication of two Early Helladic sealing fragments from the coastal settlement of Asine on the north-east Peloponnese in Greece. After an initial description and discussion they are set in the context of sealing custom established on the Greek mainland around 2500 BCE. In the first part of the paper focus is on the apparent qualitative differences between the available seals and the contemporary seal impressions, as well as between different sealing assemblages on northeastern Peloponnese. This geographical emphasis is carried into the second part of the paper which is a review and contextualisation of the representational art of the Aegean Early Bronze Age in general, and northeastern Peloponnese in particular. Seal motifs and figurines are the main media for Early Helladic representational art preserved until today, yet in many ways very dissimilar. These opposites are explored in order to begin to build a better understanding of Peloponnesian representational art, the choices of motifs, and their roles in the lives of the Early Helladic people.

scholarly journals Feeding strategy of mackerel in the Norwegian Sea relative to currents, temperature, and prey

2015 ◽  
Vol 73 (4) ◽  
pp. 1127-1137 ◽  
Author(s):  
Leif Nøttestad ◽  
Justine Diaz ◽  
Hector Penã ◽  
Henrik Søiland ◽  
Geir Huse ◽  
...  
Keyword(s):  
Swimming Speed ◽  
Swimming Performance ◽  
Feeding Strategy ◽  
Near Field ◽  
Norwegian Sea ◽  
Swimming Direction ◽  
Atlantic Mackerel ◽  
The North ◽  
Foraging Rate ◽  
Feeding Resources

Abstract High abundance of Northeast Atlantic mackerel (Scomber scombrus L.), combined with limited food resources, may now force mackerel to enter new and productive regions in the northern Norwegian Sea. However, it is not known how mackerel exploit the spatially varying feeding resources, and their vertical distribution and swimming behaviour are also largely unknown. During an ecosystem survey in the Norwegian Sea during the summer feeding season, swimming direction, and speed of mackerel schools were recorded with high-frequency omnidirectional sonar in four different regions relative to currents, ambient temperature, and zooplankton. A total of 251 schools were tracked, and fish and zooplankton were sampled with pelagic trawl and WP-2 plankton net. Except for the southwest region, swimming direction of the tracked schools coincided with the prevailing northerly Atlantic current direction in the Norwegian Sea. Swimming with the current saves energy, and the current also provides a directional cue towards the most productive areas in the northern Norwegian Sea. Average mean swimming speed in all regions combined was ∼3.8 body lengths s−1. However, fish did not swim in a straight course, but often changed direction, suggesting active feeding in the near field. Fish were largest and swimming speed lowest in the northwest region which had the highest plankton concentrations and lowest temperature. Mackerel swam close to the surface at a depth of 8–39 m, with all schools staying above the thermocline in waters of at least 6°C. In surface waters, mackerel encounter improved foraging rate and swimming performance. Going with the flow until temperature is too low, based on an expectation of increasing foraging rate towards the north while utilizing available prey under way, could be a simple and robust feeding strategy for mackerel in the Norwegian Sea.

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.

Parataxonomic classification of ornithoid eggshell fragments from the Oldman Formation (Judith River Group; Upper Cretaceous), southern Alberta

1996 ◽  
Vol 33 (12) ◽  
pp. 1655-1667 ◽  
Author(s):  
Darla K. Zelenitsky ◽  
L. V. Hills ◽  
Philip J. Currie
Keyword(s):  
Late Cretaceous ◽  
Shell Thickness ◽  
Upper Cretaceous ◽  
Theropod Dinosaur ◽  
Surface Sculpture ◽  
External Zone ◽  
Theropod Dinosaurs ◽  
Southern Alberta ◽  
The Family

Examination of a large number of eggshell fragments collected from the Oldman Formation of southern Alberta reveals a greater ootaxonomic diversity than is known from complete eggs or clutches. Three new oogenera and oospecies of the ornithoid-ratite morphotype and one of the ornithoid-prismatic morphotype are established, based on the eggshell fragments. Porituberoolithus warnerensis oogen. et oosp. nov. and Continuoolithus canadensis oogen. et oosp. nov. have a microstructure similar to that of elongatoolithid eggs of theropod dinosaurs. Tristraguloolithus cracioides oogen. et oosp. nov. and Dispersituberoolithus exilis oogen. et oosp. nov. possess an external zone and thus have a microstructure like modern avian eggshell. Tristraguloolithus has a shell thickness, microstructure, and surface sculpture similar to those of recent bird eggshell of the family Cracidae (order Galliformes). Dispersituberoolithus exhibits the primitive or normal eggshell condition of some recent neognathous avian taxa. The ootaxa described indicate a diversity of both avian and theropod dinosaur egg layers within Devil's Coulee and Knight's Ranch, southern Alberta, during the Late Cretaceous.

BIOLOGICAL DISTANCE PATTERNS AMONG THE NORTHERN MOCHE LORDS: DENTAL PHENOTYPES AND POLITICAL ORGANIZATION IN ANCIENT PERU

2018 ◽  
Vol 29 (4) ◽  
pp. 696-717 ◽  
Author(s):  
Haagen D. Klaus ◽  
Walter Alva ◽  
Steve Bourget ◽  
Luis Chero
Keyword(s):  
Hierarchical Cluster ◽  
Political Organization ◽  
North Coast ◽  
Biological Distance ◽  
R Matrix ◽  
One Dimensional ◽  
The North ◽  
Limited Gene Flow ◽  
Dental Traits ◽  
North Coast Of Peru

Between AD 100 and 800, the Moche culture emerged on the north coast of Peru. Diverse debates surround the nature of Moche territorial and political centralization, sociopolitical identities, and the internal social diversity of Moche society. Here we address some of these issues in a biodistance study based on phenotypic variation of inherited dental traits within and between 36 individuals in the royal tombs of Sipán (Lambayeque valley), Úcupe (Zaña valley), and Dos Cabezas (Jequetepeque valley). Metric and nonmetric dental trait data were analyzed using hierarchical cluster and R-matrix analyses. The results independently indicate that the highest-level Sipán and Dos Cabezas lords likely represented different endogamous kin groups, while limited gene flow occurred between groups of Moche lower nobility between the Lambayeque and Jequetepeque regions. Although biology and material cultural link the Lord of Úcupe to Dos Cabezas, many objects in his tomb demonstrate his participation the world of the Sipán elites. These Moche lords were, on some levels, bioculturally interconnected. Nonetheless, the data broadly lend support to a “many Moches” model of sociopolitical structure, further casting doubt on earlier one-dimensional visions of a centralized hegemonic Moche polity.

Sign in / Sign up

Export Citation Format

Share Document