scholarly journals A starfish bed in the Middle Miocene Grand Bay Formation of Carriacou, The Grenadines (West Indies)

2013 ◽  
Vol 151 (3) ◽  
pp. 381-393 ◽  
Author(s):  
JOHN W. M. JAGT ◽  
BEN THUY ◽  
STEPHEN K. DONOVAN ◽  
SABINE STÖHR ◽  
ROGER W. PORTELL ◽  
...  
Keyword(s):  
Deep Sea ◽  
Fossil Record ◽  
West Indies ◽  
Middle Miocene ◽  
Entire Surface ◽  
Western Atlantic ◽  
Single Row ◽  
Active Volcanism ◽  
Grand Bay ◽  
Plate Shape

AbstractThe first starfish bed to be recognized from the Antilles is a lensoid body in the middle Miocene Grand Bay Formation of Carriacou, The Grenadines (West Indies). This unit was deposited in a turbidite basin in a region of active volcanism fed from one centre and preserves common deep-water taxa more typical of the Palaeozoic, such as crinoids and brachiopods. The starfish bed is a channel-fill deposit laid down in at least 150–200 m water depth, although the specimens may have been derived from shallower water. A goniasterid asteroid and an ophiacanthid ophiuroid have been recognized. The first articulated asteroid from the Antillean fossil record is Paragonaster(?) haldixoni sp. nov. In all skeletal features it appears close to the extant Atlantic species Paragonaster grandis H. L. Clark and P. subtilis (Perrier), but differs in having a single row of rectangular abactinal ossicles extending to the arm tip; these are longer than wide. The brittlestar, Ophiocamax ventosa sp. nov., is described on the basis of a fragmentary disc and arms from this deposit. The closest similarities are with the extant tropical western Atlantic species Ophiocamax hystrix Lyman and O. austera Verrill. However, the new species has thorns covering the entire surface of dorsal arm plates, while arm spines have a multitude of small thorns, loosely arranged in numerous rows and dorsal arm plate shape differs markedly. The occurrence of O. ventosa sp. nov. suggests that Ophiocamax has been a deep-sea taxon at least since the Miocene.

A new deep-sea species of Mitromorpha (Gastropoda: Conoidea: Conidae) off Brazil

2009 ◽  
Vol 90 (3) ◽  
pp. 599-603
Author(s):  
Silvio Felipe Barbosa Lima ◽  
José Carlos Nascimento Barros ◽  
Jonata de A. Francisco
Keyword(s):  
Deep Sea ◽  
West Indies ◽  
The Body ◽  
Western Atlantic ◽  
North East ◽  
North Eastern ◽  
Body Whorl ◽  
Species Being ◽  
A New Species ◽  
Spiral Bands

A new species of Conidae is described from Brazilian waters. Mitromorpha santosi sp. nov. from the Continental Slope off the state of Rio Grande do Norte (north-east Brazil: 04°50′60″–04°51′40″s, 35°06′01″–35°06′46″W) is compared with M. biplicata (western Atlantic), M. usta (eastern Atlantic), M. dalli (north-eastern Atlantic), M. popeae (West Indies), M. undulate (West Indies) and two unnamed Brazilian species being diagnosed as possessing strong axial ribs, second spiral cord on the body whorl more pronounced and yellowish-brown spiral bands. In addition, a lectotype for Mitromorpha undulata, is designated herein.

scholarly journals A new bathyal ophiacanthid brittle star (Ophiuroidea: Ophiacanthidae) with Caribbean affinities from the Plio-Pleistocene of the Mediterranean

Zootaxa ◽  
2020 ◽  
Vol 4820 (1) ◽  
pp. 19-30
Author(s):  
LEA D. NUMBERGER-THUY ◽  
BEN THUY
Keyword(s):  
Deep Sea ◽  
Fossil Record ◽  
Brittle Star ◽  
Morphological Comparison ◽  
Western Atlantic ◽  
Faunal Turnover ◽  
Unknown Species ◽  
Recent Species ◽  
The Mediterranean ◽  
New Discovery

Identifiable remains of large deep-sea invertebrates are exceedingly rare in the fossil record. Thus, every new discovery adds to a better understanding of ancient deep-sea environments based on direct fossil evidence. Here we describe a collection of dissociated skeletal parts of ophiuroids (brittle stars) from the latest Pliocene to earliest Pleistocene of Sicily, Italy, preserved as microfossils in sediments deposited at shallow bathyal depths. The material belongs to a previously unknown species of ophiacanthid brittle star, Ophiacantha oceani sp. nov. On the basis of morphological comparison of skeletal microstructures, in particular spine articulations and vertebral articular structures of the lateral arm plates, we conclude that the new species shares closest ties with Ophiacantha stellata, a recent species living in the present-day Caribbean at bathyal depths. Since colonization of the deep Mediterranean following the Messinian crisis at the end of the Miocene was only possibly via the Gibraltar Sill, the presence of tropical western Atlantic clades in the Plio-Pleistocene of the Mediterranean suggests a major deep-sea faunal turnover yet to be explored.

Patterns of morphological diversity among and within arcid bivalve species pairs separated by the Isthmus of Panama

2001 ◽  
Vol 75 (3) ◽  
pp. 590-606 ◽  
Author(s):  
Peter B. Marko ◽  
Jeremy B. C. Jackson
Keyword(s):  
Morphological Variation ◽  
Fossil Record ◽  
Eastern Pacific ◽  
Nominal Species ◽  
Western Atlantic ◽  
Isthmus Of Panama ◽  
Species Pairs ◽  
Recent Species ◽  
Discriminant Analyses ◽  
Collection Sites

Geminate species are morphologically similar sister-species found on either side of the Isthmus of Panama. The existence of all geminates in the tropical Eastern Pacific ocean and the Caribbean Sea is most often explained by vicariance: closure of the Central American Seaway 3.1 to 3.5 Ma simultaneously isolated populations of species with amphi-American distributions. In this paper, we test the potential of morphological measurements for discriminating between Recent geminate species pairs from three genera (Arca, Arcopsis, and Barbatia) in the bivalve family Arcidae and examine the prospects for distinguishing nominal species in the fossil record. Fourteen morphological variables were used to characterize shell shape and multivariate methods were used to discriminate between five Recent species pairs. Collection sites were also used as a priori groups for discrimination to describe patterns of intraspecific morphological variation and to evaluate differences among samples from different geographic regions.On average, 84 percent of specimens within geminate pairs are classified correctly following five separate discriminant analyses with nominal species as the grouping variable. Although all but one arcid species pair are discriminated with high statistical significance, some collection sites within species are highly morphologically distinct. Overall, a large proportion of specimens from each collection locality (79 percent on average) can be classified correctly to site although no single site possessed a multivariate centroid that was significantly different from all other conspecific centroids. The distinctiveness of some collection sites, however, raises the possibility that some nominal species may harbor cryptic species, indicating the need for wider geographic surveys of both molecular and morphological variation within geminate species pairs.The eigenvalue coefficients derived from the Recent samples of one geminate pair (Arca mutabilis and A. imbricata) were used to assess the potential for identifying arcid species in the fossil record. Discriminant analyses of fossil Arca indicate that the forms that characterize Recent A. mutabilis and A. imbricata are present in the fossil record as far back as the Late Early Miocene, in the Cantaure Formation of Venezuela. Because a deep water connection between the Eastern Pacific and Western Atlantic existed until the Middle Miocene, the morphological differences associated with Recent A. mutabilis and A. imbricata likely existed well before the rising Isthmus affected ocean circulation patterns in tropical America. Therefore, despite great overall morphological similarity, these putative geminate species likely have a time of divergence that is at least four times older than final seaway closure. The geographic distribution of fossils also suggests that morphological forms associated with each Recent species had amphi-American distributions both before and after isthmus formation but are now geographically restricted to either side of the isthmus in the Recent fauna.

scholarly journals Spider crabs of the Western Atlantic with special reference to fossil and some modern Mithracidae

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1301 ◽  
Author(s):  
Adiël A. Klompmaker ◽  
Roger W. Portell ◽  
Aaron T. Klier ◽  
Vanessa Prueter ◽  
Alyssa L. Tucker
Keyword(s):  
Fossil Record ◽  
Early Pleistocene ◽  
Caribbean Region ◽  
Deep Time ◽  
Western Atlantic ◽  
Extant Species ◽  
Length Width ◽  
The Caribbean ◽  
Abundance And Diversity ◽  
First Time

Spider crabs (Majoidea) are well-known from modern oceans and are also common in the western part of the Atlantic Ocean. When spider crabs appeared in the Western Atlantic in deep time, and when they became diverse, hinges on their fossil record. By reviewing their fossil record, we show that (1) spider crabs first appeared in the Western Atlantic in the Late Cretaceous, (2) they became common since the Miocene, and (3) most species and genera are found in the Caribbean region from the Miocene onwards. Furthermore, taxonomic work on some modern and fossil Mithracidae, a family that might have originated in the Western Atlantic, was conducted. Specifically,Maguimithraxgen. nov. is erected to accommodate the extant speciesDamithrax spinosissimus, whileDamithraxcf.pleuracanthusis recognized for the first time from the fossil record (late Pliocene–early Pleistocene, Florida, USA). Furthermore, two new species are described from the lower Miocene coral-associated limestones of Jamaica (Mithrax arawakumsp. nov. andNemausa windsoraesp. nov.). Spurred by a recent revision of the subfamily, two known species from the same deposits are refigured and transferred to new genera:Mithrax donovanitoNemausa, andMithrax unguistoDamithrax. The diverse assemblage of decapods from these coral-associated limestones underlines the importance of reefs for the abundance and diversity of decapods in deep time. Finally, we quantitatively show that these crabs possess allometric growth in that length/width ratios drop as specimens grow, a factor that is not always taken into account while describing and comparing among taxa.

Exploratory deep-sea fishing in the Falkland Islands, south-western Atlantic

1996 ◽  
Vol 49 (sa) ◽  
pp. 298-310 ◽  
Author(s):  
R. A. Coggan ◽  
C. P. Nolan ◽  
M. J. A. George
Keyword(s):  
Deep Sea ◽  
Falkland Islands ◽  
Western Atlantic

Deep-Sea Faunal Zonation of Benthos along Beaufort-Bermuda Transect in the North-western Atlantic

1972 ◽  
Vol 73 ◽  
pp. 183-194 ◽  
Author(s):  
Robert Y. George ◽  
Robert J. Menzies
Keyword(s):  
Deep Sea ◽  
Abiotic Factors ◽  
Global Scale ◽  
Species Level ◽  
Red Clay ◽  
Generic Level ◽  
Western Atlantic ◽  
The North ◽  
Shelf Slope ◽  
Abyssal Zone

SynopsisIn this paper the subject of faunal zonation in the ocean floor from the intertidal, and over the continental shelf, slope and rise and to the abyssal plain is examined on the basis of faunal change at the generic and species level. The region investigated over a period of five years aboard R/V Eastward is a Beaufort-Bermuda transect, approximately 75 kilometres wide and 500 kilometres long and bounded between 32° and 36°N latitude and 64° and 79°W longitude. A new method, involving numerical indices reflecting changes in the composition of taxa, endemism and diversity between adjacent depth levels, was developed for defining faunal boundaries. Isotherms and isobaths utilised by earlier authors for characterising deep-sea boundary on a global scale do not coincide with natural faunal boundaries. This study analyses the vertical distribution of 128 species of isopod crustaceans and 28 species of large epibenthic invertebrates. The zonation patterns seem to correspond with correlations in environmental conditions such as currents, topography and sediments.We suggest four major vertical faunal provinces, characterised at the generic level, namely (1) the Intertidal Faunal Province; (2) the Shelf Faunal Province; (3) the Archibenthal Zone of Transition; and (4) the Abyssal Faunal Province and internal zones within these characterised at the species level. The main aspects of interest include the presence of a narrow ‘meso abyssal zone’ with a species maximum, the demonstration of the true transitional nature of the Archibenthal Zone in biotic and abiotic factors and the characteristic low-biomass Red Clay environment showing definite faunal isolation from the continental margin.

Coenobichnus currani (new ichnogenus and ichnospecies): Fossil trackway of a land hermit crab, early Holocene, San Salvador, Bahamas

2003 ◽  
Vol 77 (3) ◽  
pp. 576-582 ◽  
Author(s):  
Sally E. Walker ◽  
Steven M. Holland ◽  
Lisa Gardiner
Keyword(s):  
Hermit Crab ◽  
Fossil Record ◽  
Trace Fossil ◽  
Early Holocene ◽  
Hermit Crabs ◽  
Coastal Environments ◽  
Atlantic Region ◽  
Western Atlantic ◽  
San Salvador ◽  
Left And Right

Land hermit crabs (Coenobitidae) are widespread and abundant in Recent tropical and subtropical coastal environments, yet little is known about their fossil record. A walking trace, attributed to a land hermit crab, is described herein as Coenobichnus currani (new ichnogenus and ichnospecies). This trace fossil occurs in an early Holocene eolianite deposit on the island of San Salvador, Bahamas. The fossil trackway retains the distinctive right and left asymmetry and interior drag trace that are diagnostic of modern land hermit crab walking traces. The overall size, dimensions and shape of the fossil trackway are similar to those produced by the modem land hermit crab, Coenobita clypeatus, which occurs in the tropical western Atlantic region. The trackway was compared to other arthropod traces, but it was found to be distinct among the arthropod traces described from dune or other environments. The new ichnogenus Coenobichnus is proposed to accommodate the asymmetry of the trackway demarcated by left and right tracks. The new ichnospecies Coenobichnus currani is proposed to accommodate the form of the proposed Coenobichnus that has a shell drag trace.

Environmental versus genetic causes of morphologic variability in bryozoan colonies from the deep sea

Paleobiology ◽  
1976 ◽  
Vol 2 (2) ◽  
pp. 156-165 ◽  
Author(s):  
Thomas J. M. Schopf
Keyword(s):  
Shallow Water ◽  
Deep Sea ◽  
Fossil Record ◽  
Water Regime ◽  
Level Population ◽  
Total Variance ◽  
Genetic Causes ◽  
Single Genotype ◽  
Shallow Water Species ◽  
Water Species

Bryozoans are colonial animals and this permits the partitioning of their morphologic variability into components of within colony (i.e. within a single genotype) and between colony (i.e. between genotype) variance. These data have been obtained for four species of the endemic deep-sea genus Euginoma for a series of characters. In 8 comparisons, one component of the total variance dominated at the 5% level. Population (between colony) variance contributed significantly to the total variance in 63% of the comparisons (5 of 8); individual (within colony) variance contributed significantly to the total variance in 37% of the comparisons (3 of 8).Compared to shallow water species, the surprising feature of the deep-sea data is that the between colony component of variance is as high as it is. Possibly in the more stable, deep-sea environment, the genotypic contribution to the variance of each individual colony is expressed to a greater degree than in the more variable, shallow water regime. If so, then analyses of variability in colonial animals may be an independent means of ascertaining stability gradients in the fossil record.

Taxonomic review of two fossil crocodylians from the Cenozoic of South America and its implications for the crocodylian fauna of the continent

Zootaxa ◽  
2019 ◽  
Vol 4656 (3) ◽  
pp. 475-486
Author(s):  
GIOVANNE M. CIDADE ◽  
DANIEL FORTIER ◽  
ASCANIO DANIEL RINCÓN ◽  
ANNIE SCHMALTZ HSIOU
Keyword(s):  
South America ◽  
Fossil Record ◽  
Middle Miocene ◽  
Taxonomic Status ◽  
Junior Synonym ◽  
Diverse Group ◽  
Taxonomic Review ◽  
Nomen Dubium ◽  
Extant Species ◽  
The World

The crocodylomorph fauna of the Cenozoic of South America is one of the richest and most diverse in the world. The most diverse group within that fauna is Alligatoroidea, with nearly all of its species belonging to the Caimaninae clade. Many of the fossil alligatoroid species from the Cenozoic of South America were proposed based on very incomplete remains, and as a result their validity requires revision. Two such species are Balanerodus logimus Langston, 1965, from the middle Miocene of Colombia and Peru, and Caiman venezuelensis Fortier & Rincón, 2012, from the Pliocene-Pleistocene of Venezuela. This study has performed a thorough review of the taxonomic status of these two alligatoroid species, concluding that B. logimus is a nomen dubium and that Ca. venezuelensis is a junior synonym of the extant species Ca. crocodilus. This review offers a significantly more accurate scenario for alligatoroid diversity in the Cenozoic of South America in different epochs such as the Miocene and Pleistocene. Additionally, the record of Ca. crocodilus from the Pleistocene of Venezuela is the first fossil record that can be assigned to this species. 

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