Diversity and distribution of molluscan fauna of Asthamudi estuary, Kerala, India

2021 ◽  
Author(s):  
Raveendhiran Ravinesh ◽  
Appukuttannair Biju Kumar ◽  
Vidhyadharan Lailasy Anjana
Keyword(s):  
Molluscan Fauna

Functional significance of preserved color patterns of mollusks from the Gosport Sand (Eocene) of Alabama

1988 ◽  
Vol 62 (01) ◽  
pp. 83-87 ◽  
Author(s):  
Patricia H. Kelley ◽  
Charles T. Swann
Keyword(s):  
Functional Morphology ◽  
Functional Significance ◽  
Intraspecific Variability ◽  
Color Pattern ◽  
Color Patterns ◽  
Historical Factors ◽  
Life Mode ◽  
Molluscan Fauna ◽  
Excellent Preservation ◽  
Architectural Constraints

The excellent preservation of the molluscan fauna from the Gosport Sand (Eocene) at Little Stave Creek, Alabama, has made it possible to describe the preserved color patterns of 15 species. In this study the functional significance of these color patterns is tested in the context of the current adaptationist controversy. The pigment of the color pattern is thought to be a result of metabolic waste disposal. Therefore, the presence of the pigment is functional, although the patterns formed by the pigment may or may not have been adaptive. In this investigation the criteria proposed by Seilacher (1972) for testing the functionality of color patterns were applied to the Gosport fauna and the results compared with life mode as interpreted from knowledge of extant relatives and functional morphology. Using Seilacher's criteria of little ontogenetic and intraspecific variability, the color patterns appear to have been functional. However, the functional morphology studies indicate an infaunal life mode which would preclude functional color patterns. Particular color patterns are instead interpreted to be the result of historical factors, such as multiple adaptive peaks or random fixation of alleles, or of architectural constraints including possibly pleiotropy or allometry. The low variability of color patterns, which was noted within species and genera, suggests that color patterns may also serve a useful taxonomic purpose.

II.—The Petrology of the Suffolx Box-stones (Crag)

1915 ◽  
Vol 2 (6) ◽  
pp. 250-259 ◽  
Author(s):  
P. G. H. Boswell
Keyword(s):  
New Species ◽  
Recent Work ◽  
Early Pliocene ◽  
Stone Material ◽  
Molluscan Fauna ◽  
Recent Account

Although much has been written upon the palæontology of the Suffolk box-stones, no description appears hitherto to have been published of the petrology of these boulders. This is the more curious on account of the light it might throw upon the disputed question of their source, no similar sandstone having yet been recognized with certainty in situ. The most recent account of the molluscan fauna is by my friend Mr. Alfred Bell. In a preliminary paper he has given a list of sixty-three species (excluding cetacean bones, teeth, crustaceans, etc.), about twelve new species and varieties being described. Mr. Bell has now kindly let me see in advance the MS. of a revised list of Mollusca (seventy-six species), much new box-stone material having been obtained in the last few years. As a result of recent work, he considers the affinities of the fauna to be rather with the Rupelian (Continental Oligocene) than with the Bolderian or Diestian, as he formerly thought. Mr. Clement Reid, in The Pliocene Deposits of Britain (Mem. Geol. Survey, 1890), considered the box-stones to be of about the same age as the Diestian Beds, but Mr. F. W. Harmer has, in later publications, been inclined to consider them to be rather older and of very early Pliocene age.

The Cyrenaican Prehistory Project 2012: the sixth season of excavations in the Haua Fteah cave

2013 ◽  
Vol 44 ◽  
pp. 113-125 ◽  
Author(s):  
Ryan Rabett ◽  
Lucy Farr ◽  
Evan Hill ◽  
Chris Hunt ◽  
Ross Lane ◽  
...  
Keyword(s):  
Seismic Event ◽  
Middle Stone Age ◽  
Arid Environments ◽  
Stone Age ◽  
Late Stone Age ◽  
Climatic Regime ◽  
Molluscan Fauna ◽  
Trench Area ◽  
Mis 5 ◽  
Deep Sounding

AbstractThe paper reports on the sixth season of fieldwork of the Cyrenaican Prehistory Project (CPP) undertaken in September 2012. As in the spring 2012 season, work focussed on the Haua Fteah cave and on studies of materials excavated in previous seasons, with no fieldwork undertaken elsewhere in the Gebel Akhdar. An important discovery, in a sounding excavated below the base of McBurney's 1955 Deep Sounding (Trench S), is of a rockfall or roof collapse conceivably dating to the cold climatic regime of Marine Isotope Stage (MIS) 6 (globally dated to c. 190–130 ka) but more likely the result of a seismic event within MIS 5 (globally dated to c. 130–80 ka). The sediments and associated molluscan fauna in Trench S and in Trench D, a trench being cut down the side of the Deep Sounding, indicate that this part of the cave was at least seasonally waterlogged during the accumulation, probably during MIS 5, of the ~6.5 m of sediment cut through by the Deep Sounding. Evidence for human frequentation of the cave in this period is more or less visible depending on how close the trench area was to standing water as it fluctuated through time. Trench M, the trench being cut down the side of McBurney's Middle Trench, has now reached the depth of the latest Middle Stone Age or Middle Palaeolithic (Levalloiso-Mousterian) industries. The preliminary indications from its excavation are that the transition from the Levalloiso-Mousterian to the blade-based Upper Palaeolithic or Late Stone Age Dabban industry was complex and perhaps protracted, at a time when the climate was oscillating between warm-stage stable environmental conditions and colder and more arid environments. The estimated age of the sediments, c. 50–40 ka, places these oscillations within the earlier part of MIS 3 (globally dated to 60–24 ka), when global climates experienced rapid fluctuations as part of an overall trend to increasing aridity and cold.

The first Tertiary (Paleocene) marine mollusks from the Eureka Sound Group, Ellesmere Island, Canada

1991 ◽  
Vol 65 (2) ◽  
pp. 242-248 ◽  
Author(s):  
Louie Marincovich ◽  
William J. Zinsmeister
Keyword(s):  
Atlantic Ocean ◽  
South Dakota ◽  
Arctic Ocean ◽  
Canadian Arctic ◽  
Ellesmere Island ◽  
Marine Mollusks ◽  
Molluscan Fauna ◽  
Northern Atlantic ◽  
Northern Alaska ◽  
Northern Atlantic Ocean

The gastropod Drepanochilus pervetus (Stanton) and the bivalve Cytrodaria rutupiensis (Morris) occur in the Mount Moore Formation at Strathcona Fiord, west-central Ellesmere Island, northern Canada. They are the first marine mollusks identified from the Eureka Sound Group of the Canadian arctic islands. These mollusks correlate with Paleocene faunas of the Cannonball Formation of North Dakota and South Dakota, the Prince Creek Formation of northern Alaska, the Barentsburg Formation of Svalbard, and the Thanet and Oldhaven Formations of southeastern England. These occurrences imply that the earliest Tertiary Arctic Ocean molluscan fauna was compositionally distinct from coeval faunas of the northern Atlantic Ocean.

scholarly journals Common environmental descriptors of two benthic amphi-atlantic mollusc assemblages

2006 ◽  
Vol 54 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Ricardo S. Absalão ◽  
J. Moreira ◽  
Jesus S. Troncoso
Keyword(s):  
Rio De Janeiro ◽  
Environmental Data ◽  
Multiple Discriminant Analysis ◽  
Medium Sand ◽  
Sediment Grain Size ◽  
Environmental Space ◽  
Macro Scale ◽  
Molluscan Fauna ◽  
Mollusc Assemblages ◽  
Sandy Sediments

Two benthic mollusc assemblages of the continental shelf on both sides of the Atlantic Ocean, a tropical one in Rio de Janeiro, Brazil, and another, temperate, in Galicia, Spain were investigated, with a view to finding common environmental descriptors which would explain, on a macro-scale, why these assemblages are there. Both of the assemblages concerned show approximately the same species richness, about 150 taxa each. The molluscan fauna of both regions live on sandy sediments. The Galician assemblages are at about 2-12 m depth, while those in Rio de Janeiro are at about 10-40 m depth. Malacological assemblages were defined through Cluster Analysis and Multiple Discriminant Analysis of the environmental data showed that each assemblage has its own environmental space. These assemblages have no species in common, but show the same phenological characters associated with each sedimentological facies. The same set of environmental variables (median sediment grain size, skewness, kurtosis, sorting, fine and medium sand fractions and depth) were selected as controlling these assemblages, suggesting that they play their role as general environmental descriptors.

Molluscan biostratigraphy of the lower River Bend Formation at the Martin Marietta Quarry, New Bern, North Carolina

1991 ◽  
Vol 65 (1) ◽  
pp. 80-118 ◽  
Author(s):  
Thomas J. Rossbach ◽  
Joseph G. Carter
Keyword(s):  
North Carolina ◽  
Coastal Plain ◽  
Warm Water ◽  
Gulf Coastal Plain ◽  
Generic Level ◽  
Evolutionary Transitions ◽  
Molluscan Fauna ◽  
Molluscan Diversity ◽  
Molluscan Species ◽  
River Bend

The lower River Bend Formation at the Martin Marietta New Bern quarry in Craven County, North Carolina, contains a diverse and abundant moldic molluscan fauna. This fauna, reconstructed by latex casts, suggests a Vicksburgian or a post-Vicksburgian, pre-Chickasawhayan age for the New Bern exposure. Forty-one molluscan species and subspecies are presently identified from the lower River Bend Formation, 11 of which are new: Turritella caelatura alani, Turritella neusensis, Galeodaria britti, Phalium newbernensis, Cymatium planinodum, Oocorys vadosus, Ecphora wheeleri, Lyria concinna, Scaphella saintjeani, Turricula (Orthosurcula) aequa, and Lucina (Stewartia) micraulax. This fauna is virtually identical at the generic level and similar at the species level to the Vicksburgian faunas of the Gulf Coastal Plain. About 37 percent of the New Bern species also occur in the Vicksburgian of Mississippi, although many of these species reach considerably larger sizes at New Bern. Apparent evolutionary transitions between previously known Vicksburgian and Chickasawhayan mollusks suggest a time of deposition intermediate between these two Oligocene stages.Moderately high molluscan diversity, the abundance of characteristically warm-water genera, and associated carbonate-rich sediments suggest that the lower River Bend Formation represents a subtropical, open-marine, predominantly carbonate environment immediately seaward of a nearshore lagoonal or barrier island complex.The lower River Bend Formation at New Bern differs faunally, climatically, and sedimentologically from the upper River Bend Formation in quarry exposures near Belgrade, North Carolina. The upper River Bend Formation contains a lower diversity molluscan fauna with marked dominance diversity and few warm-water taxa. It represents a slightly cooler nearshore, open-marine environment in a transitional siliciclastic-carbonate sedimentary regime. The considerable taxonomic and sedimentologic differences between the lower and upper parts of the River Bend Formation corroborate microfossil evidence suggesting that they represent temporally distinct depositional cycles.

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