Caribbean Neogene Research Articles

Drilling predation increased in response to changing environments in the Caribbean Neogene

AbstractChanges in the physical environment are major drivers of evolutionary change, either through direct effects on the distribution and abundance of species or more subtle shifts in the outcome of biological interactions. To investigate this phenomenon, we built a fossil data set of drilling gastropod predation on bivalve prey for the last 11 Myr to determine how the regional collapse in Caribbean upwelling and planktonic productivity affected predator–prey interactions. Contrary to theoretical expectations, predation increased nearly twofold after productivity declined, while the ratio of drilling predators to prey remained unchanged. This increase reflects a gradual, several-fold increase in the extent of shallow-water coral reefs and seagrass meadows in response to the drop in productivity that extended over several million years. Drilling predation is uniformly higher in biogenic habitats than in soft sediments. Thus, changes in predation intensity were driven by a shift in dominant habitats rather than a direct effect of decreased productivity. Most previous analyses of predation through time have not accounted for variations in environmental conditions, raising questions about the patterns observed. More fundamentally, however, the consequences of large-scale environmental perturbations may not be instantaneous, especially when changes in habitat and other aspects of local environmental conditions cause cascading series of effects.

Resource Partitioning and Paleoecology of Neogene Free-Living Corals as Determined from Skeletal Stable Isotope Composition

Changes in the Caribbean coral fauna associated with Plio-Pleistocene extinctions are unique in that origination preceded extinction. This pattern is particularly evident in free-living solitary and flabello-meandroid (FSFM) corals. Here we use the stable isotopes of carbon and oxygen to assess the paleoautecology of pre-turnover FSFM corals from the Cibao Basin, northern Dominican Republic. We assess photosymbiosis and resource utilization within FSFM corals and how changing Neogene paleoclimatic and paleoceanographic conditions may have contributed to originations and extinctions within this unique ecological group. Measurements of[deltha]13C and [deltha]18O were compared between two known zooxanthellate coral species, two known azooxanthellate species, and six FSFM species of the Cibao Basin. Skeletal[deltha]13C provided the best indicator of resource utilization by FSFM corals. For both modern reef corals and Mio-Pliocene reef corals from the Cibao Basin, values of [deltha]13C fall between 0%o and -2%o whereas the [deltha]13C values of azooxanthellate corals generally fall between -3%o and -9%o. Both modern and fossil FSFM corals lie intermediate to these end members. FSFM values of [deltha]13C fall between -1%o and -4%o and suggest reduced photosymbiosis in comparison to typical reef corals. Reduced photosymbiosis of FSFM corals in comparison to reef corals is also reflected in a stronger covariation between [deltha]13C and [deltha]18O. Though FSFM corals are clearly utilizing translocated carbon from associated algal symbionts, the more depleated values of [deltha]13C and covariation with [deltha]18O suggest a greater dependence on heterotrophic feeding. This ecological lifestyle likely has made FSFM corals sensitive to changes in primary productivity that characterize the Caribbean Neogene.

Changes in bivalve functional and assemblage ecology in response to environmental change in the Caribbean Neogene

We documented changes in the relative abundance of bivalve genera and functional groups in the southwest Caribbean over the past 11 Myr to determine their response to oceanographic changes associated with the closure of the Central American Seaway ca. 3.5 Ma. Quantitative bulk samples from 29 localities yielded 106,000 specimens in 145 genera. All genera were assigned to functional groups based on diet, relationship to the substrate, and mobility. Ordinations of assemblages based on quantitative data for functional groups demonstrated strong shifts in community structure, with a stark contrast between assemblages older than 5 Ma and those younger than 3.5 Ma. These changes are primarily due to an increase in the abundance of attached epifaunal bivalves (e.g.,Chama,Arcopsis, andBarbatia) and a decrease in infaunal bivalves (e.g.,VaricorbulaandCaryocorbula). Taxa associated with seagrasses, including deposit-feeding and chemosymbiotic bivalves (e.g.,Lucina), also increased in relative abundance compared to suspension feeders. The composition of bivalve assemblages is correlated with the carbonate content of sediments and the percentage of skeletal biomass that is coral. Our results strongly support the hypothesis that increases in the extent of coral reefs andThalassiacommunities were important drivers of biologic turnover in Neogene Caribbean benthic communities.

Latest Miocene-Pliocene Larger Foraminifera and depositional environments of the carbonate bank of La Désirade Island, Guadeloupe (French Antilles)

In this paper we present first results of the study of planktonic Foraminifera, large benthic Foraminifera and carbonate facies of La Désirade, aiming at a definition of the age and depositional environments of the Neogene carbonates of this island. The study of planktonic Foraminifera from the Detrital Offshore Limestones (DOL) of the Ancienne Carrière allows to constrain the biochronology of this formation to the lower Zone N19 and indicates a latest Miocene to early Pliocene (5.48–4.52 Ma) age. Large benthic Foraminifera were studied both as isolated and often naturally split specimens from the DOL, and in thin sections of limestones from the DOL and the Limestone Table (LT). The assemblages of Foraminifera include Nummulitidae, Amphisteginidae, Asterigerinidae, Peneroplidae, Soritidae, Rotalidae (Globigerinidae: Globigerinoides, Sphaeroidenellopsis, Orbulina) and incrusting Foraminifera ( Homotrema and Sporadotrema). The genera Amphistegina, Archaias and Operculina are discussed. Concerning the Nummulitidae we include both “ Paraspiroclypeus” chawneri and “ Nummulites” cojimarensis, as well as a newly described species, Operculina desiradensis new species, in the genus Operculina, because the differences between these 3 species are rather on the specific than the generic level, while their morphology, studied by SEM, is compatible with the definition of the genus Operculina (D’Orbigny emend. Hottinger) . The three species can be easily distinguished on the basis of their differences in spiral growth: while O. desiradensis has an overall logarithmic spiral growth, O. cojimarensis and especially O. chawneri show a tighter and more geometric spiral growth. O. cojimarensis and O. chawneri were originally described from Cuba in outcrops originally dated as Oligocene and later redated as early Pliocene. Therefore, O. chawneri was considered until now as restricted to the early Pliocene. However, in the absence of a detailed morphometric and biostratigraphic study of the Caribbean Neogene nummulitids, it is difficult to evaluate the biochronologic range of these species. The history of the carbonates begins with the initial tectonic uplift and erosion of the Jurassic igneous basement of La Désirade, that must have occurred at latest in late Miocene times, when sea-level oscillated around a long-term stable mean. The rhythmic deposition of the Désirade Limestone Table (LT) can be explained by synsedimentary subsidence in a context of rapidly oscillating sea-level due to precession-driven (19–21 kyr) glacio-eustatic sea-level changes during the latest Miocene-Pliocene. Except for a thin reef cap present at the eastern edge of the LT, no other in-place reefal constructions have been observed in the LT. The DOL of western Désirade are interpreted as below wave base gravity deposits that accumulated beneath a steep fore-reef slope. They document the mobilisation of carbonate material (including Larger Foraminifera) from an adjacent carbonate platform by storms and their gravitational emplacement as debris and grain flows. The provenance of both the reefal carbonate debris and the tuffaceous components redeposited in the carbonates of La Désirade must be to the west, i.e. the carbonate platforms of Marie Galante and Grande Terre.

Pacific elements in the Caribbean Neogene gastropod fauna: the source-sink model, larval development, disappearance, and faunal units

Abstract A key fact in the history of Neogene Caribbean marine molluscs is the disappearance of the “paciphile” taxa that occurred throughout Tropical America during the Miocene and the Pliocene, but subsequently suffered a range contraction, and became largely or entirely restricted to the eastern Pacific portion of their original distribution. What forces led to the disappearance of these paciphile taxa in the Atlantic portion of their original distribution is at present unclear, as there seem to be no obvious common environmental factor or ecological requirements uniting this paciphilic assemblage of taxa. It is suggested that for paciphile species the emergence of the isthmus during the Late Pliocene cut off the source populations of the planktonically-dispersing molluscs dependent on Pacific source populations. The sink populations thus became stranded on the Atlantic coast of South America and elsewhere in the Caribbean, where they became unsustainable and eventually disappeared. A reappraisal of all known paciphile species indicates an inferred planktotrophic larval development, which supports this hypothesis. Paciphiles did not disappear simultaneously, but seem to have suffered a steep decline during the Late Pliocene. A revision of all known gastropod paciphile generic, subgeneric and specific taxa allowed us to recognise three Gatunian Neogene Paciphile Molluscan Units (GNPMU). GNPMU 1 is characterized by the highest number of paciphile taxa. This unit is already in place in the Early Miocene and ends at the beginning of the Late Pliocene. GNPMU 2 is characterized by an impoverished number of paciphilic elements, devoid of the two largest paciphilic groups; the cancellarids and the muricids. This unit straddled the Pliocene-Pleistocene boundary and ends during the Early Pleistocene. GNPMU 3 is characterized by the absence of any paciphilic elements in their assemblages, and runs into Recent times. Based on these paciphile generic, subgeneric and specific taxa, for the Gatunian Province, two pulses of local disappearance from the Atlantic portion of their original distribution can be identified. The first marked by the overall decrease in Atlantic paciphile diversity and the total disappearance of all the paciphilic cancellarids and muricids, roughly corresponding with the timing given for the closure of the CAS. The second marked by the complete disappearance of all paciphiles from the Atlantic roughly coincides with the total closure of all connections between the Atlantic and Pacific.

Giant-toothed white sharks and cetacean trophic interaction from the Pliocene Caribbean Paraguaná Formation

The role of the extinct giant-toothed white sharkCarcharodon megalodon (Agassiz) in the Caribbean Neogene is discussed based on new evidence of predation on cetaceans from the Lower Pliocene Paraguana Formation in Venezuela. Large sharks have occupied the highest trophic level in the marine environment. However, based on the recovery of a giant white shark tooth piercing a cetacean lumbar vertebra, the predator-prey relationship is discussed under the hypothesis of initial shark attack, subsequent floating transport of the cetacean carcass, and scavenging prior to deposition on the bottom. The scarce Caribbean fossil records of both giant-toothed sharks and cetaceans suggest that these species were transients during the Pliocene on the Venezuelan coast.

Southern Caribbean Neogene palaeobiogeography revisited. New data from the Pliocene of Cubagua, Venezuela

Based on new data from the Pliocene gastropod assemblage of Cubagua Island, Venezuela, the palaeobiogeography of the southern Caribbean is reviewed. The data obtained from the southern Caribbean assemblages demonstrate a highly endemic fauna along the northern coasts of South America, distinct from that found in the neighbouring Isthmian region to the west, which has probably been in place since at least the early Neogene. These assemblages are characterised by a relative stability at generic level, but an extremely high turnover rate at specific level. The name Colombian–Venezuelan–Trinidad Subprovince is chosen over Puntagavilanian Subprovince and chorotypes and chronotypes are selected for the Gatunian Province and the Colombian–Venezuelan–Trinidad Subprovince.

GOLIATH GROUPER (PISCES: SERRANIDAE) FROM THE UPPER MIOCENE URUMACO FORMATION, VENEZUELA

T he goliath grouper (family Serranidae, subfamily Epinephelinae) inhabits tropical and subtropical waters. The Epinephelinae serranids are comprised of about 159 species in 15 genera (Heemstra and Randall, 1993) and are represented in all oceans. According to Heemstra and Randall (1993) the goliath grouper Epinephelus itajara (Lichtenstein, 1822) occurs in the eastern Atlantic Ocean from Florida to Brazil, throughout the Gulf of Mexico and in the Caribbean Sea, in the western Atlantic Ocean from Senegal to the Congo, and in the eastern Pacific Ocean from the Gulf of California to Peru. The maximum size is about 250 cm total length and they can exceed 320 kg in weight. The grouper Epinephelus lanceolatus (Bloch, 1790) occurs throughout the Indo-Pacific region, from the Red Sea to Algoa Bay, South Africa, and eastward to the Hawaiian and Pitcairn Islands, and in the western Pacific Ocean from southern Japan to Australia in the south. The maximum size is about 231 cm total length (Schultz, 1966) and 400 kg in weight (Fourmanoir and Laboute, 1976). These two species are the largest serranids in the world. Sadovy and Eklund (1999) noted that males reach a maximum age of 26 and females 37 years in a population of E. itajara . Fossil specimens of Epinephelus Bloch, 1793 are known only from Caribbean Neogene otoliths (Nolf, 1976; Nolf and Stringer, 1992; Nolf and Aguilera, 1998; Stringer, 1998; Aguilera and Rodrigues de Aguilera, 1999, 2001) and from Atlantic Neogene skeletal remains (Purdy et al., 2001). In this paper we describe the first large and complete fossil neurocrania of Epinephelus itajara and associated bones obtained from the upper Miocene Urumaco Formation (upper member) of Venezuela. These specimens provide an example of a very long-lived tropical marine species, and the explanation for its present amphitropical American …

The ecology of extinction: molluscan feeding and faunal turnover in the Caribbean Neogene.

Molluscan faunal turnover in the Plio-Pleistocene of the tropical western Atlantic has been attributed to drops in temperature or primary productivity, but these competing hypotheses have not been assessed ecologically. To test these alternatives, we compiled data on changing molluscan life habits and trophic composition over 12 million years derived from 463 newly made collections from the southwestern Caribbean. Shelf ecosystems have altered markedly in trophic structure since the Late Pliocene. Predatory gastropods and suspension-feeding bivalves declined significantly in abundance, but not in diversity, and reef-dwellers became common. By contrast, all other ecological life habits remained remarkably stable. Food-web changes strongly support the hypothesis that declining regional nutrient supply had an increasing impact on regional macroecology, culminating in a faunal turnover.

An exceptional coastal upwelling fish assemblage in the Caribbean Neogene

We report the discovery of an extremely rich, previously undescribed Caribbean late Miocene to early Pliocene ichthyofauna represented by one hundred forty species of elasmobranchs and teleosteans from the Cubagua Formation, northeastern Venezuela. The fauna exhibits significant ecological differences compared with common neritic Caribbean Neogene assemblages. The bathymetric distributions of taxa, based on living counterparts, ranges from 0 to 100 m depth. The exceptional co-occurrence of deep water (epipelagic, mesopelagic and benthopelagic), and shallow water (neritic) taxa is best interpreted as the consequence of ocean upwelling in the proximity to the deep-water Cariaco Trench. Patterns of predator and prey are established and corroborate upwelling. Special remarks are made regarding previously unknown late Miocene to early Pliocene Caribbean ichthyofaunas, the absence or rarity of reported fossil taxa in the Recent Caribbean fauna, and a paleo- upwelling indicator (Lampadena jacksoninew species).

AN EXCEPTIONAL COASTAL UPWELLING FISH ASSEMBLAGE IN THE CARIBBEAN NEOGENE*

Abstract We report the discovery of an extremely rich, previously undescribed Caribbean late Miocene to early Pliocene ichthyofauna represented by one hundred forty species of elasmobranchs and teleosteans from the Cubagua Formation, northeastern Venezuela. The fauna exhibits significant ecological differences compared with common neritic Caribbean Neogene assemblages. The bathymetric distributions of taxa, based on living counterparts, ranges from 0 to 100 m depth. The exceptional co-occurrence of deep water (epipelagic, mesopelagic and benthopelagic), and shallow water (neritic) taxa is best interpreted as the consequence of ocean upwelling in the proximity to the deep-water Cariaco Trench. Patterns of predator and prey are established and corroborate upwelling. Special remarks are made regarding previously unknown late Miocene to early Pliocene Caribbean ichthyofaunas, the absence or rarity of reported fossil taxa in the Recent Caribbean fauna, and a paleo- upwelling indicator (Lampadena jacksoni new s...

Speciation and diversity of Caribbean Neogene to Holocene cheilostome bryozoans

Caribbean cheilostomes are a highly diverse component of the tropical American marine benthos with an excellent fossil record. Many workers have tended to lump taxa into morphologically variable, geographically widespread species originating in the Miocene, but recent morphometric and genetic analyses have revealed large suites of cryptic species, barely distinguishable morphologically, within several important genera. Most species in such suites have narrow geographic and stratigraphic ranges. In Stylopoma, for example, canonical discriminant and cluster analyses based on skeletal morphology yielded 19 late Neogene to Holocene species, most of which had been previously classified as S. spongites. Seven species were available for genetic analysis, of which six have been confirmed to differ by protein electrophoresis, either by fixed allele differences or significant genetic distances in sympatry. A combination of cladistic and stratophenetic analysis suggests that the most widely distributed and long-lasting species, which originated early in the Miocene, was ancestor to most or all of the other tropical American Stylopoma species. Despite extensive sampling, five species are narrowly distributed, with all known fossil and viving specimens separated by less than 1000 km, and all but three of the 18 descendant species have been restricted throughout their history to relatively limited parts of the tropical western Atlantic. These patterns are consistent with allopatric speciation of peripheral isolates, only a few of which have achieved wide distributions. Cladogenesis was highly episodic, reaching a peak in Late Miocene time, well before final closure of the Panamanian portal, but after formation of the sill that disrupted oceanic circulation patterns throughout the region.

Phylogeny reconstruction in the neogene bryozoan metrarabdotos: A paleontologic evaluation of methodology

An adequate stratigraphic record can not only aid in both cladistic and stratophenetic reconstruction of phytogenies, but can also serve in estimating the temporal consistency of the resulting phylogenetic trees. For hypothetical data sets, cladistically constructed trees can be as consistent with the temporal distribution of sampled populations or species as those constructed stratophenetically. Empirical testing in taxonomic groups with sufficiently dense fossil records is needed to show whether, and under what conditions, this potential can be realized. A stratophenetic tree and cladistic trees based on several approaches to character weighting were constructed for Caribbean Neogene species of the bryozoan Metrarabdotos with multiple‐character data from closely spaced sequential populations. The modular morphology and highly punctuated evolutionary pattern of these species blur the distinction between continuous and discrete characters, so that all available characters are potentially of equal signific...