Gut contents from a Cretaceous Tyrannosaurid: Implications for theropod dinosaur digestive tracts

2001 ◽  
Vol 75 (2) ◽  
pp. 401-406 ◽  
Author(s):  
David J. Varricchio
Keyword(s):  
Late Cretaceous ◽  
Digestive Enzymes ◽  
Food Source ◽  
Western Montana ◽  
Gut Contents ◽  
Theropod Dinosaur ◽  
Surface Corrosion ◽  
Limb Proportions ◽  
Partial Skeleton

A partial skeleton of Daspletosaurus sp. from the Late Cretaceous (Campanian) Two Medicine Formation of western Montana preserves the first gut contents reported for a tyrannosaurid. Associated remains found with this skeleton consist of acidetched vertebrae and a fragmentary dentary from juvenile hadrosaur dinosaurs. Hadrosaur bonebed data and comparisons of hadrosaur and tyrannosaurid limb proportions suggest that juvenile hadrosaurs represented both an abundant and accessible food source. The surface corrosion exhibited by the hadrosaur elements matches that produced by stomach acids and digestive enzymes in a wide variety of living vertebrates. Based upon these and other gut contents, and also upon tooth-marked bone studies, it appears that Daspletosaurus and most theropods ingested and digested prey in a manner similar to that of extant archosaurs (crocodilians and birds), employing a two-part stomach with an enzyme-producing proventriculus followed by a thick-walled muscular gizzard. This two-part stomach appears to be an archosaur synapomorphy.

Influence of Late Cretaceous magmatism on the Sevier orogenic wedge, western Montana

Geology ◽  
2001 ◽  
Vol 29 (8) ◽  
pp. 723 ◽  
Author(s):  
David R. Lageson ◽  
James G. Schmitt ◽  
Brian K. Horton ◽  
Thomas J. Kalakay ◽  
Bradford R. Burton
Keyword(s):  
Late Cretaceous ◽  
Western Montana ◽  
Orogenic Wedge ◽  
Cretaceous Magmatism

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.

Palaeoecology of the marine reptiles of the Redwater Shale Member of the Sundance Formation (Jurassic) of central Wyoming, USA

2013 ◽  
Vol 151 (1) ◽  
pp. 167-182 ◽  
Author(s):  
JUDY A. MASSARE ◽  
WILLIAM R. WAHL ◽  
MIKE ROSS ◽  
MELISSA V. CONNELY
Keyword(s):  
Primary Productivity ◽  
Food Source ◽  
Foreland Basin ◽  
Gut Contents ◽  
Ecological Diversity ◽  
Marine Transgression ◽  
The North ◽  
Marine Reptiles ◽  
Main Food Source ◽  
Clay Formation

AbstractThe Redwater Shale Member (Oxfordian) of the Sundance Formation was deposited in the foreland basin of the Cordillera during the last and largest marine transgression of the Jurassic in North America. One ichthyosaur (Ophthalmosaurus natans), two cryptocleidoid plesiosaurs (Tatenectes laramiensis, Pantosaurus striatus) and one pliosauromorph (Megalneusaurus rex) are known from the Redwater Shale Member. Ichthyosaurs are much more abundant than plesiosaurs, making up almost 60% of the fauna. No actinopterygian fish have been found, although four species have been identified from the lower Sundance Formation. At least one hybodont shark and one neoselachian are known from rare isolated teeth. The main food source for the marine reptiles was belemnoids, as indicated by preserved gut contents for all four species. In comparison, the better known and slightly older Peterborough Member of the Oxford Clay Formation of England, has a much higher taxonomic and ecological diversity, especially in the plesiosaurs, marine crocodiles, and fish. The lower diversity in the Redwater Shale Member probably reflects a much lower primary productivity in the Sundance Sea, as well as restricted migration from the open ocean to the north.

A new bird from the Upper Cretaceous Two Medicine Formation of Montana

2002 ◽  
Vol 39 (1) ◽  
pp. 19-26 ◽  
Author(s):  
David J Varricchio
Keyword(s):  
Late Cretaceous ◽  
Upper Cretaceous ◽  
New Genus ◽  
Articular Surface ◽  
Type Specimen ◽  
Depositional Environments ◽  
Western Montana ◽  
New Genus And Species ◽  
Basal Position

A partial humerus, ulna, and radius compose the type specimen of a new bird, Piksi barbarulna, new genus and species, from the Late Cretaceous (Campanian) Two Medicine Formation of western Montana. This ornithothoracine taxon differs from all other birds in having an enlarged dorsal epicondyle and a reduced ventral condyle on the humerus with corresponding modifications on the articular surface of the ulna. Among modern birds, Piksi is most similar to galliforms, but the paucity of unambiguous characters and its unusual morphology defy placement within any extant "order" and strongly questions any neornithine affinities. Instead, Piksi appears to have a fairly basal position within Ornithothoraces. Several morphologic features of Piksi occur in phylogenetically diverse but morphologically similar birds, such as galliforms, tinamous, and some columbiforms. The new bird comes from an inland, relatively dry paleo-environment. Atypical for a Cretaceous avian record dominated by waterfowl, Piksi appears to represents a heavy-bodied ground bird. Searching of inland depositional environments may yield new and ecologically distinct avian varieties.

7. Measuring the Rate of Mercury Loss in Amphipod Gut and Tissues after Exposure to Contaminated Sediments

2017 ◽  
Author(s):  
Jonathan Martin
Keyword(s):  
Food Webs ◽  
Yellow Perch ◽  
Food Source ◽  
Perca Flavescens ◽  
Artificial Substrates ◽  
Gut Contents ◽  
Before And After ◽  
Aquatic Food ◽  
Health Canada ◽  
St Lawrence River

Mercury (Hg) contamination of the St. Lawrence River along the Cornwall waterfront is the result of over a century of industrial inputs. Yellow perch (Perca flavescens) are contaminated above the consumption guidelines deemed safe by Health Canada in one of three contaminated depositional zones. Amphipods are crustaceans that play an important role in aquatic food webs, and a recent study of the diet of yellow perch showed that amphipods were the primary food source of yellow perch in these zones and that amphipods showed similar patterns of Hg contamination. However, not all Hg taken up by amphipods is bioavailable. That is, not all Hg is incorporated into the tissues and available for uptake by yellow perch. To determine if Hg analyses of amphipods are biased by Hg present in their gut contents, the rate of Hg loss was measured from the gut and tissues. Amphipods were collected in the field using artificial substrates. A sample was frozen immediately upon retrieval, and the remaining amphipods were kept in a sieve in a basin of filtered river water. Amphipods were then sampled over 16 days to compare Hg concentrations in gut contents and tissues before and after they were removed from the Hg source in the field. The data were used to estimate the portion of Hg bioavailable to yellow perch. This enables us to more accurately estimate the extent of Hg contamination that is moving through the Cornwall food web, leading to elevated concentrations in top trophic fish species.

A new abelisauroid theropod from northwestern Patagonia

2006 ◽  
Vol 43 (9) ◽  
pp. 1283-1289 ◽  
Author(s):  
Rodolfo A Coria ◽  
Philip J Currie ◽  
Ariana Paulina Carabajal
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
First Record ◽  
South American ◽  
Middle Section ◽  
Theropod Dinosaur ◽  
Channel Deposits

The Argentinean record of abelisauroid theropods begins in the Early Cretaceous (Ligabueino) and spans most of the Late Cretaceous, from Cenomanian (Ilokelesia, Xenotarsosaurus, and Ekrixinatosaurus) to Campanian–Maastrichtian (Abelisaurus, Carnotaurus, Aucasaurus, and Noasaurus). A fragmentary specimen of a theropod dinosaur was collected in 2000 from the middle section of the Lisandro Formation (Turonian?) at Cerro Bayo Mesa, Neuquén Province, Argentina. The fossil-bearing level, which is part of the Lisandro Formation that also yielded the remains of the basal ornithopod Anabisetia saldiviai, corresponds to a reddish, massive mudstone linked with fluvial channel deposits. The theropod identified as MCF-PVPH-237 is an abelisauroid theropod that increases our knowledge about the evolution of South American Abelisauroidea and is the first record of this clade from the Lisandro Formation.

New theropod dinosaur from the late Cretaceous of Brazil improves abelisaurid diversity

2021 ◽  
pp. 103551
Author(s):  
Fabiano Vidoi Iori ◽  
Hermínio Ismael de Araújo-Júnior ◽  
Sandra A. Simionato Tavares ◽  
Thiago da Silva Marinho ◽  
Agustín G. Martinelli
Keyword(s):  
Late Cretaceous ◽  
Theropod Dinosaur
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