scholarly journals A 5000-YEAR FOSSIL RECORD OF LARVAL SHELL MORPHOLOGY OF SUBMARINE CAVE MICROSHELLS

Evolution ◽  
2009 ◽  
Vol 63 (1) ◽  
pp. 295-300 ◽  
Author(s):  
Takao Ubukata ◽  
Akihisa Kitamura ◽  
Mayumi Hiramoto ◽  
Tomoki Kase
Keyword(s):  
Fossil Record ◽  
Shell Morphology ◽  
Larval Shell ◽  
Submarine Cave

scholarly journals MECHANICAL FEEDBACK IN SEASHELL GROWTH AND FORM

2018 ◽  
Vol 59 (4) ◽  
pp. 581-606 ◽  
Author(s):  
A. ERLICH ◽  
R. HOWELL ◽  
A. GORIELY ◽  
R. CHIRAT ◽  
D. E. MOULTON
Keyword(s):  
Fossil Record ◽  
Shell Morphology ◽  
Shell Structures ◽  
Mechanical Interaction ◽  
Modelling Framework ◽  
Local Deposition ◽  
Rigid Shell ◽  
Huge Variety ◽  
Initial Framework ◽  
Mechanical Feedback

Mollusc seashells grow through the local deposition and calcification of material at the shell opening by a soft and thin organ called the mantle. Through this process, a huge variety of shell structures are formed. Previous models have shown that these structural patterns can largely be understood by examining the mechanical interaction between the deformable mantle and the rigid shell aperture to which it adheres. In this paper we extend this modelling framework in two distinct directions. For one, we incorporate a mechanical feedback in the growth of the mollusc. Second, we develop an initial framework to couple the two primary and orthogonal modes of pattern formation in shells, which are termed antimarginal and commarginal ornamentation. In both cases we examine the change in shell morphology that occurs due to the different mechanical influences and evaluate the hypotheses in light of the fossil record.

A primitive Halobia (Bivalvia: Halobioidea) from the Triassic of northeast British Columbia

2000 ◽  
Vol 74 (4) ◽  
pp. 599-603 ◽  
Author(s):  
Christopher A. Mcroberts
Keyword(s):  
British Columbia ◽  
New Species ◽  
Shell Morphology ◽  
Larval Shell ◽  
Developmental Strategy ◽  
Widespread Distribution ◽  
Dispersal Mechanism ◽  
Sudden Appearance ◽  
External Ornamentation

Halobia daonellaformis new species is described from the lowermost Carnian of northeast British Columbia. Halobia daonellaformis n. sp. is regarded as a primitive Halobia characterized by external ornamentation similar to Daonella lommeli, but with a poorly developed anterior auricle. Morphologic characters of H. daonellaformis n. sp. suggest that Halobia may be not a natural taxon but a polyphyletic group with one or more ancestors from Daonella and Aparimella and/or other posidoniid(s). The sudden appearance of Halobia throughout the marine Triassic suggests a rapid dispersal mechanism following a Ladinian origin. Larval shell morphology indicates a planktotrophic developmental strategy for H. daonellaformis n. sp., and by extension to other halobiids, which may explain the widespread distribution of many halobiid species.

Paleocene diversification of bucciniform gastropods on Seymour Island, Antarctica

1996 ◽  
Vol 70 (6) ◽  
pp. 923-934 ◽  
Author(s):  
Anton E. Oleinik ◽  
William J. Zinsmeister
Keyword(s):  
New Species ◽  
Mass Extinction ◽  
Fossil Record ◽  
New Genus ◽  
Shell Morphology ◽  
Geographic Isolation ◽  
Extinction Event ◽  
Early Paleocene ◽  
Mass Extinction Event ◽  
Seymour Island

Following the mass extinction event at the end of the Cretaceous, the marine molluscan faunas of the high southern latitudes underwent a marked period of diversification during the early Paleocene. The appearance of four new species belonging to the new genus Seymourosphaera, tentatively placed in the subfamily Pseudolivinae, from the lower Paleocene strata of Seymour Island, Antarctic Peninsula, clearly illustrates the post-Cretaceous extinction diversification. The abrupt radiation of the buccinids during the early Paleocene, was also apparently related to geographic isolation of Antarctica during final breakup of Gondwana. Comparative analysis of shell morphology of Seymourosphaera, new genus reveals close morphologic similarities, not only with taxa within Pseudolivinae, but also with several genera and subgenera belonging to the families Buccinidae and Nassariidae. However, incompleteness of the fossil record and a “generalized” shell morphology make difficult establishment of unequivocal phylogenetic relationships for Seymourosphaera. A taxonomic review of most closely related, and possibly ancestral genus Austrosphaera Camacho, 1949, is provided. The following new species of genus Seymourosphaera new genus are described: Seymourosphaera bulloides new species, S. subglobosa new species, S. depressa new species, and S. elevata new species.

scholarly journals A Silurian myodocope with preserved soft-parts: cautioning the interpretation of the shell-based ostracod record

2013 ◽  
Vol 280 (1752) ◽  
pp. 20122664 ◽  
Author(s):  
David J. Siveter ◽  
Derek E. G. Briggs ◽  
Derek J. Siveter ◽  
Mark D. Sutton ◽  
Sarah C. Joomun
Keyword(s):  
Fossil Record ◽  
Soft Part ◽  
Circulatory System ◽  
Shell Morphology ◽  
Fifth Limb

Ostracod crustaceans are the most abundant fossil arthropods. The Silurian Pauline avibella gen. et sp. nov., from the Herefordshire Lagerstätte, UK, is an extremely rare Palaeozoic example with soft-part preservation. Based on its soft-part morphology, especially the exceptionally preserved limbs and presence of lateral eyes, it is assigned to the myodocopid myodocopes. The ostracod is very large, with an epipod on the fifth limb pair, as well as gills implying the presence of a heart and an integrated respiratory–circulatory system as in living cylindroleberidid myodocopids. Features of its shell morphology, however, recall halocyprid myodocopes and palaeocopes, encouraging caution in classifying ostracods based on the carapace alone and querying the interpretation of their shell-based fossil record, especially for the Palaeozoic, where some 500 genera are presently assigned to the Palaeocopida.

The Silurian myodocope ostracodeEntomozoefrom the Pentland Hills, Scotland: its taxonomic, ecological and phylogenetic significance and the affinity of the bolbozoid myodocopes

1990 ◽  
Vol 81 (1) ◽  
pp. 45-67 ◽  
Author(s):  
David J. Siveter ◽  
Jean M. C. Vannier
Keyword(s):  
Fossil Record ◽  
Type Species ◽  
Soft Part ◽  
Shell Morphology ◽  
Zoological Nomenclature ◽  
Phylogenetic Significance ◽  
Taxonomic Affinity ◽  
Low Diversity ◽  
New Type ◽  
First Time

ABSTRACTThe monotypic ostracodeEntomozoe(pro Entomis) (Superorder Myodocopa) from the Silurian of Scotland, type genus of the Entomozoidae, is revised for the first time since being established in 1861. Based on the type and new collections ofEntomozoe tuberosa(Jones, 1861), the genus shows affinity to bolbozoid myodocopes rather than to forms hitherto universally considered as ‘typical’ entomozoid myodocopes. The families Entomozoidae and Bolbozoidae are considered synonymous. In the interests of stability of nomenclature, in particular to preserve the traditionally understood usage of the taxon Entomozoidae, a case must be made to the International Commission on Zoological Nomenclature to set aside any previous designations and to establish a new type-species forEntomozoe.Entomozoe, from the Llandovery Series, is the earliest known myodocope in the fossil record. It occurs as part of a low diversity, shallow water, nearshore assemblage. In contrast to other, but younger, Silurian bolbozoid myodocopes, it is probably a benthic form. The differences in the anterior shell morphology of Silurian bolbozoid taxa possibly reflect changes both in soft-part morphology and from benthic to pelagic lifestyles within the group.Both bolbozoid and ‘entomozoid’ myodocopes are assigned to the Order Myodocopida rather than to the Order Halocypridida, though the taxonomic affinity of the ‘entomozoids’ is, at best, uncertain.

SEM observations on larval shell morphology of Manila clam Ruditapes philippinarum and their utility

2012 ◽  
Vol 78 (6) ◽  
pp. 1237-1243
Author(s):  
Nariaki Inoue ◽  
Ryogen Nanbu ◽  
Natsuki Hasegawa ◽  
Junya Higano ◽  
Hisami Kuwahara ◽  
...  
Keyword(s):  
Ruditapes Philippinarum ◽  
Manila Clam ◽  
Shell Morphology ◽  
Larval Shell

The relationship of larval shell morphology to mode of development in marine prosobranch gastropods

1990 ◽  
Vol 70 (3) ◽  
pp. 611-637 ◽  
Author(s):  
Gail M. Lima ◽  
Richard A. Lutz
Keyword(s):  
Shell Morphology ◽  
Larval Shell ◽  
Crepidula Fornicata ◽  
Busycon Canaliculatum ◽  
Littorina Obtusata ◽  
Urosalpinx Cinerea ◽  
Planktotrophic Larvae ◽  
Mode Of Development ◽  
Relationship Of ◽  
The Relationship

The larval shell of molluscs contains a preserved record of the organism's growth and developmental history. Many investigators have utilized the information recorded in the larval shell morphology to infer mode of development.Marine prosobranch gastropods were collected from intertidal sites from Maine to Florida and were cultured in the laboratory. Scanning electron microscopy was used to document the relationship of larval shell morphology to development. Four species with planktotrophic larvae, Crepidula fornicata, Crepidula plana, Cerithium atratum and Ilyanassa obsoleta, and four species with non-planktotrophic development, Crepidula convexa, Littorina obtusata, Busycon canaliculatum and Urosalpinx cinerea, were successfully reared through metamorphosis.

Post-larval development of the bivalves Nucula turgida, Venus striatula, Spisula subtruncata and S. elliptica (Mollusca: Bivalvia), (with reference to the late larva)

1987 ◽  
Vol 67 (2) ◽  
pp. 441-459 ◽  
Author(s):  
C. M. Webb
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Larval Development ◽  
Shell Morphology ◽  
Larval Shell ◽  
North West ◽  
Scanning Electron ◽  
West European

Detailed studies of post-larval shell, hinge and/or internal morphogenesis, from metamorphosis to the completion of development, are available for a very small number of infaunal bivalves (for review of studies see Webb (1984). This paper continues the description, using scanning electron microscopy (SEM), of the post-larval ontogeny of some common infaunal bivalves from north-west European communities and presents the development of Nucula turgida, Venus striatula, Spisula subtruncata and S. elliptica. The association between larval shell morphology and certain features of development in some protobranch bivalves is examined.

Sign in / Sign up

Export Citation Format

Share Document