scholarly journals Aragonite bias exhibits systematic spatial variation in the Late Cretaceous Western Interior Seaway, North America

Paleobiology ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 571-597
Author(s):  
Christopher D. Dean ◽  
Peter A. Allison ◽  
Gary J. Hampson ◽  
Jon Hill
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Field Studies ◽  
Time Averaging ◽  
Western Interior Seaway ◽  
Molluscan Diversity ◽  
The Impact ◽  
Diversity Estimates ◽  
Preferential Dissolution ◽  
Cretaceous Western Interior Seaway

AbstractPreferential dissolution of the biogenic carbonate polymorph aragonite promotes preservational bias in shelly marine faunas. While field studies have documented the impact of preferential aragonite dissolution on fossil molluscan diversity, its impact on regional and global biodiversity metrics is debated. Epicontinental seas are especially prone to conditions that both promote and inhibit preferential dissolution, which may result in spatially extensive zones with variable preservation. Here we present a multifaceted evaluation of aragonite dissolution within the Late Cretaceous Western Interior Seaway of North America. Occurrence data of mollusks from two time intervals (Cenomanian/Turonian boundary, early Campanian) are plotted on new high-resolution paleogeographies to assess aragonite preservation within the seaway. Fossil occurrences, diversity estimates, and sampling probabilities for calcitic and aragonitic fauna were compared in zones defined by depth and distance from the seaway margins. Apparent range sizes, which could be influenced by differential preservation potential of aragonite between separate localities, were also compared. Our results are consistent with exacerbated aragonite dissolution within specific depth zones for both time slices, with aragonitic bivalves additionally showing a statistically significant decrease in range size compared with calcitic fauna within carbonate-dominated Cenomanian–Turonian strata. However, we are unable to conclusively show that aragonite dissolution impacted diversity estimates. Therefore, while aragonite dissolution is likely to have affected the preservation of fauna in specific localities, time averaging and instantaneous preservation events preserve regional biodiversity. Our results suggest that the spatial expression of taphonomic biases should be an important consideration for paleontologists working on paleobiogeographic problems.

scholarly journals Aragonite bias exhibits systematic spatial variation in the late Cretaceous Western Interior Seaway, North America.

2018 ◽  
Author(s):  
Christopher David Dean ◽  
Peter Allison ◽  
Gary J. Hampson ◽  
Jon Hill
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Field Studies ◽  
Time Averaging ◽  
Western Interior Seaway ◽  
Molluscan Diversity ◽  
The Impact ◽  
Diversity Estimates ◽  
Preferential Dissolution ◽  
Cretaceous Western Interior Seaway

Preferential dissolution of the biogenic carbonate polymorph aragonite promotes preservational bias in shelly marine faunas. Whilst field studies have documented the impact of preferential aragonite dissolution on fossil molluscan diversity, its impact on regional and global biodiversity metrics is debated. Epicontinental seas are especially prone to conditions which both promote and inhibit preferential dissolution, which may result in spatially extensive zones with variable preservation. Here we present a multi-faceted evaluation of aragonite dissolution within the late Cretaceous Western Interior Seaway of North America. Occurrence data of molluscs from two time intervals (Cenomanian-Turonian boundary, early Campanian) are plotted on new high-resolution paleogeographies to assess aragonite preservation within the seaway. Fossil occurrences, diversity estimates and sampling probabilities for calcitic and aragonitic fauna were compared in zones defined by depth and distance from the seaway margins. Apparent range sizes, which could be influenced by differential preservation potential of aragonite between separate localities, were also compared. Our results are consistent with exacerbated aragonite dissolution within specific depth zones for both time slices, with aragonitic bivalves additionally showing a statistically significant decrease in range size compared to calcitic fauna within carbonate-dominated Cenomanian-Turonian strata. However, we are unable to conclusively show that aragonite dissolution impacted diversity estimates. Therefore, whilst aragonite dissolution is likely to have affected the preservation of fauna in specific localities, time averaging and instantaneous preservation events preserve regional biodiversity. Our results suggest that the spatial expression of taphonomic biases should be an important consideration for paleontologists working on paleobiogeographic problems.

Durophagous predation on scaphitid ammonoids in the Late Cretaceous Western Interior Seaway of North America

Lethaia ◽  
2015 ◽  
Vol 49 (1) ◽  
pp. 28-42 ◽  
Author(s):  
Yusuke Takeda ◽  
Kazushige Tanabe ◽  
Takenori Sasaki ◽  
Neil H. Landman
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Western Interior Seaway ◽  
Cretaceous Western Interior Seaway

scholarly journals Endemicity analysis of global Cretaceous dinosaurian faunas

1992 ◽  
Vol 6 ◽  
pp. 132-132
Author(s):  
Thomas R. Holtz
Keyword(s):  
North America ◽  
South America ◽  
Late Cretaceous ◽  
Late Jurassic ◽  
Continental Drift ◽  
Gobi Desert ◽  
Western Interior Seaway ◽  
Faunal Assemblages ◽  
Terrestrial Vertebrate ◽  
Herbivore Communities

It has often been assumed that the intensively studied dinosaur faunal assemblages of western North America and the Gobi Desert of Mongolia and China represent “typical” Late Cretaceous terrestrial vertebrate communities. This assumption has led to a paleoecological scenario in which a global ecological shift occurs from the dominance of high-browsing saurischian (i.e., sauropod) to low-browsing ornithischian (i.e., iguanodontian, marginocephalian, ankylosaurian) herbivore communities. Furthermore, the assumption that the Asiamerican dinosaur faunas are communities “typical” of the Late Cretaceous has forced the conclusion that the sauropod-dominated Argentine population must have been an isolated relict ecosystem of primitive taxa (i.e., titanosaurid sauropods, abelisaurid ceratosaurs). Recent discoveries and reinterpretations of other Late Cretaceous assemblages, however, seriously challenge these assumptions.Paleogeography and paleobiogeography have demonstrated that terrestrial landmasses became progressively fractionated from the Late Jurassic (Kimmeridgian-Tithonian) to the Late Cretaceous (Campanian), owing to continental drift and the development of large epicontinental seas (the Western Interior Seaway, the Turgai Sea, etc.). The Maastrichtian regressions resulted in the reestablishment of land connection between long isolated regions (for example, western and eastern North America). These geographic changes are reflected in changes in the dinosaurian faunas. These assemblages were rather cosmopolitan in the Late Jurassic (Morrison, Tendaguru, and Upper Shaximiao Formations) but became more provincialized throughout the Cretaceous.Cluster analysis of presence/absence data for the theropod, sauropod, and ornithischian clades indicates that previous assumptions for Late Cretaceous dinosaurian paleoecology are largely in error. These analyses instead suggest that sauropod lineages remained a major faunal component in both Laurasia (Europe, Asia) and Gondwana (South America, Africa, India, and Australia). Only the pre-Maastrichtian Senonian deposits of North America were lacking sauropodomorphs. Furthermore, the abelisaurid/titanosaurid fauna of Argentina is, in fact, probably more typical of Late Cretaceous dinosaurian communities. Rather, it is the coelurosaurian/ornithischian communities of Asiamerica (and particularly North America) that are composed primarily of dinosaurs of small geographic distribution. Thus, the Judithian, Edmontonian, and Lancian faunas, rather than being typical of the Late Cretaceous, most likely represent an isolated island-continent terrestrial vertebrate population, perhaps analogous to the extremely isolated vertebrate communities of Tertiary South America. Furthermore, the shift from high-browsing to low-browsing herbivore “dynasties” more likely represents a local event in Senonian North America and does not represent a global paleoecological transformation of Late Cretaceous dinosaur community structure.

Remains of Clidastes Cope, 1868, an unexpected mosasaur in the upper Campanian of NW Germany

2005 ◽  
Vol 84 (3) ◽  
pp. 213-220 ◽  
Author(s):  
M.W. Caldwell ◽  
C.G. Diedrich
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Vertebral Column ◽  
Gulf Coast ◽  
Anterior Part ◽  
Western Interior Seaway ◽  
Southern Sweden ◽  
Nw Germany ◽  
The Village ◽  
Upper Campanian

AbstractThe mosasaurine Clidastes sp. is recognised from cranial and post-cranial remains collected at four localities in NW Germany. Cranial material was found in pelagic turbiditic marls which crop out near the village of Beckum, while post-cranial skeletal elements were collected from sandy limestones exposed near the villages of Schöppingen, Coesfeld and Billerbeck. In stratigraphic order, the units producing these specimens of Clidastes are the Coesfeld, Baumberge and Beckum formations of late Campanian (Late Cretaceous) age. The cranial material comprises the anterior part of a skull and a single isolated tooth, while post-cranial bones comprise a few isolated vertebrae and a partial skeleton including forelimb bones and an articulated vertebral column. Clidastes is known to date from the western North Sea Basin (England), southern Sweden, as well as from North America (Western Interior Seaway and Gulf Coast).

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