Upper Cretaceous (Maestrichtian) Mollusca from the Haustator bilira assemblage zone in the East Gulf Coastal Plain

1983 ◽  
Author(s):  
Norman F. Sohl ◽  
Carl F. Koch
Keyword(s):  
Coastal Plain ◽  
Upper Cretaceous ◽  
Gulf Coastal Plain ◽  
Assemblage Zone

Ostracodes and chronostratigraphic position of the Upper Cretaceous Arkadelphia Formation of Arkansas

1994 ◽  
Vol 68 (1) ◽  
pp. 111-122 ◽  
Author(s):  
Kasana Pitakpaivan ◽  
Joseph E. Hazel
Keyword(s):  
Coastal Plain ◽  
Upper Cretaceous ◽  
Gulf Coastal Plain ◽  
Number Of Species ◽  
Sublittoral Zone ◽  
Upper Maastrichtian

The ostracode assemblage of the Arkadelphia Formation, upper Maastrichtian, of southwestern Arkansas is characterized by a well-preserved, relatively diverse, and abundant fauna representing 36 podocopid species and an undetermined number of species of the platycopid genus Cytherella. Thirteen of these account for 85 percent of the fauna. The dominant forms are Cytherella spp., Brachycythere rhomboidalis (Berry, 1925), Haplocytheridea renfroensis Crane, 1965, Haplocytheridea bruceclarki (Israelsky, 1929), and Brachycythere ovata (Berry, 1925), which account for about 57 percent of the specimens found. Other species that are less common, but are characteristic of the Arkadelphia, are Antibythocypris macropora (Alexander, 1929), Ascetoleberis hazardi (Israelsky, 1929), Aversovalva fossata (Skinner, 1956), Brachycythere ledaforma (Israelsky, 1929), Curfsina communis (Israelsky, 1929), Cytheromorpha arbenzi (Skinner, 1956), Escharacytheridea micropunctata (Alexander, 1929), and Veenia arachoides (Berry, 1925). The ostracode assemblage indicates that the Arkadelphia was deposited in the inner sublittoral zone.The species Veenia parallelopora (Alexander, 1929) and Brachycythere foraminosa Alexander, 1934, are restricted to the Arkadelphia Formation and allow correlation with other Gulf Coastal Plain Upper Cretaceous units. A new ostracode interval zone, the Veenia parallelopora Zone, is proposed. This zone divides the Platycosta lixula Zone.Calcareous planktic microfossils reported from the Arkadelphia and its correlatives in the Veenia parallelopora Zone indicate that these deposits are late Maastrichtian in age, not middle Maastrichtian as some authors have thought.

TAXONOMY AND PALEOECOLOGY OF RUDIST BIVALVES FROM UPPER CRETACEOUS STRATA, GULF COASTAL PLAIN, USA

2020 ◽  
Author(s):  
Alex Zimmerman ◽  
◽  
Claudia Johnson ◽  
George E. Phillips ◽  
Dana J. Ehret
Keyword(s):  
Coastal Plain ◽  
Upper Cretaceous ◽  
Gulf Coastal Plain ◽  
Rudist Bivalves

New Ostracoda species from an Upper Cretaceous oyster reef, northern Gulf Coastal Plain, U.S.A.

1994 ◽  
Vol 68 (6) ◽  
pp. 1321-1335 ◽  
Author(s):  
T. Markham Puckett
Keyword(s):  
New Species ◽  
Late Cretaceous ◽  
Coastal Plain ◽  
Upper Cretaceous ◽  
Oyster Reef ◽  
Oyster Reefs ◽  
Total Thickness ◽  
Topographic Feature ◽  
Gulf Coastal Plain ◽  
Eutaw Formation

This paper describes new species of Ostracoda from Late Cretaceous (late Santonian) oyster reefs of the Eutaw Formation of eastern Alabama. The reefs are composed almost exclusively of Ostrea cretacea Morton, with rarer occurrences of the oysters Exogyra upatoiensis Stephenson and Lopha ucheensis (Stephenson) and the bivalve Anomia preolmstedi Stephenson. Total thickness of the reefs is about 30 m, and the reefs are a major topographic feature across most of Macon and Russell Counties, Alabama, a distance of about 60 km. The reefs are interpreted to have been backbarrier sediments deposited under brackish conditions.Eight species of ostracodes are identified, including five new species described herein. The fauna is typically well preserved, and includes males, females, and juveniles. New species include Haplocytheridea? eutawensis, Antibythocypris dimorphicus, A. nephotrema, Brachycythere asymmetrica, and Eocytheropteron mutafoveata. Also discussed and illustrated are Cytherella tuberculifera Alexander, Haplocytheridea renfroensis renfroensis Crane, and Fissocarinocythere gapensis (Alexander).

Preservational effects in paleoecological studies: Cretaceous mollusc examples

Paleobiology ◽  
1983 ◽  
Vol 9 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Carl F. Koch ◽  
Norman F. Sohl
Keyword(s):  
Coastal Plain ◽  
Time Interval ◽  
Gulf Coastal Plain ◽  
Space And Time ◽  
Assemblage Zone ◽  
Using Data ◽  
High Diversity ◽  
Species Longevity

The effect of preservational quality on paleoecologic studies is evaluated quantitatively by using data from 83 fossil collections. These collections are from a restricted Cretaceous time interval (Haustator bilira Assemblage Zone) of Maestrichtian Age and are from the Eastern Gulf Coastal Plain Province. In all, 32,335 specimens were identified, resulting in recognition of 643 different taxa. Each collection was categorized into one of six preservational types, ranging from those in which both aragonite and calcite shells are well preserved to those having only calcite shells preserved.Statistical comparisons reveal that preservation affects the faunal makeup of these collections. Specifically, collections in which both aragonite and calcite are well preserved have more taxa than collections of poorer preservational quality and contain faunal elements not found in other collections.These two effects can confound paleoecologic studies of endemism, eurytopy vs. stenotopy, species longevity and other studies of the distribution of organisms in space and time. These effects are especially significant for studies based on presence/absence data, such as published faunal lists and selectively collected samples. In such studies, collections of good preservational quality may be interpreted to represent strata of high diversity, taxa having the more durable hard parts will appear to be widespread and long ranging, and taxa that are preserved only in collections of the best preservational quality will appear stenotopic, endemic, and rare.

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