MOLLUSK SHELL δ15N VALUES AS INDICATORS OF DENITRIFICATION AND TROPHIC POSITION IN CONTRASTING SITES ACROSS CENTRAL AMERICAN ISTHMUS

Whole body asteroid fossils are rare in the geologic record and previously unreported from the Cenozoic of Florida. However, specimens of the extant species,Heliaster microbrachiusXantus, were recently discovered in upper Pliocene deposits. This marks the first reported fossil occurrence of the monogeneric Heliasteridae, a group today confined to the eastern Pacific. This discovery provides further non-molluscan evidence of the close similarities between the Neogene marine fauna of Florida and the modern fauna of the eastern Pacific. The extinction of the heliasters in the western Atlantic is consistent with the pattern of many other marine groups in the region which suffered impoverishment following uplift of the Central American isthmus.

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Jumping a geographic barrier: diversification of the mangrove species Pelliciera rhizophorae (Tetrameristaceae) across the Central American Isthmus

Tree Genetics & Genomes ◽

10.1007/s11295-014-0822-1 ◽

2014 ◽

Vol 11 (1) ◽

Cited By ~ 4

Author(s):

María Fernanda Castillo-Cárdenas ◽

Fernando Díaz-Gonzales ◽

Ivania Cerón-Souza ◽

Oris Sanjur ◽

Nelson Toro-Perea

Keyword(s):

Central American ◽

Mangrove Species ◽

Geographic Barrier ◽

Pelliciera Rhizophorae ◽

Central American Isthmus

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Graphic correlation of deep sea and shallow marine deposits from the Central American Isthmus region: implications for Late Neogene paleoclimatology

The Paleontological Society Special Publications ◽

10.1017/s2475262200006481 ◽

1992 ◽

Vol 6 ◽

pp. 88-88

Author(s):

Harry J. Dowsett

Keyword(s):

Costa Rica ◽

High Resolution ◽

Ocean Circulation ◽

Deep Sea ◽

Sea Surface ◽

Central American ◽

Major Barrier ◽

Late Neogene ◽

The Caribbean ◽

Central American Isthmus

The stratigraphic record in Panama and Costa Rica preserves the biologic and climatic changes associated with the formation of a major barrier to marine migration and ocean circulation. Creating a high resolution temporal framework within which stratigraphic sections found on the Isthmus can be interpreted is fundamental to our understanding the history and importance of these units.The Isthmus contains rich marine macro- and microfaunas and floras on both the Pacific and Atlantic margins. Planktic foraminifers and calcareous nannofossils are common and often well preserved. Preliminary analysis of these fossils reveals a rich sedimentary record spanning the Late Miocene to Pleistocene. Multivariate statistical analyses of these assemblages provide environmental estimates. Unfortunately, traditional methods of biostratigraphy are limited in their ability to create a high resolution temporal framework for the region. For example, a majority of deposits analyzed can be placed in planktic foraminiferal zone N19 (early Pliocene). In order to answer paleobiologic and paleoclimatic questions one requires more precise correlations between sections and some indication of duration of sedimentation represented by various sections.In an attempt to overcome the shortcomings of traditional biostratigraphic methods, the Graphic Correlation method has been applied to selected sequences on the Central American Isthmus. Graphic correlation (GC) is a procedure by which two sequences can be compared and correlated using a wide variety of stratigraphic information simultaneously. A GC model of late Neogene planktic foraminifer, calcareous nannofossil, and paleomagnetic reversal events has been produced through compositing of more than 26 deep sea cores and ocean margin sequences. Following routine GC procedures the positions of all fossil first and last occurrences from a number of sections on the Caribbean and Pacific sides of the Central American Isthmus (Panama and Costa Rica) have been recorded. These sections have been correlated to the GC model and hence, to each other, providing a temporal framework for the Isthmus units.Selected sections were then correlated to other sequences such as near-by deep sea cores which have been analyzed for sea surface temperature and salinity to gain a better understanding of the overall paleoceanographic development of the region between 5 and 2 Ma. For example, correlation of units on the Caribbean side of the Isthmus with DSDP Site 502 indicates little to no change in sea surface temperatures during the entire time the Isthmus was reaching closure. Mid-to-high latitude sites exhibit amplification of warming with increasing latitude. The shoaling Isthmus, while having negligible effects on tropical marine temperatures, was responsible for increased meridional heat transport which resulted in a North Atlantic warming about 3 Ma. A general model for paleoceanographic changes during the time of closure will be discussed.

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History and Development of the Marine Invertebrate Faunas Separated by the Central American Isthmus

Topics in Geobiology - The Great American Biotic Interchange ◽

10.1007/978-1-4684-9181-4_13 ◽

1985 ◽

pp. 325-355 ◽

Cited By ~ 18

Author(s):

Douglas S. Jones ◽

Phyllis F. Hasson

Keyword(s):

Marine Invertebrate ◽

Central American ◽

Central American Isthmus

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Sedimentary dynamics and structural control of Neogene tropical biofacies during the formation of the Central American Isthmus

The Paleontological Society Special Publications ◽

10.1017/s2475262200006225 ◽

1992 ◽

Vol 6 ◽

pp. 62-62 ◽

Cited By ~ 1

Author(s):

Anthony Coates ◽

Jorge Obando ◽

Herman Gonzalez

Keyword(s):

Structural Control ◽

Sedimentary Basins ◽

Conclusive Evidence ◽

Central American ◽

The Pacific ◽

Pacific Side ◽

Late Neogene ◽

The Caribbean ◽

Final Closure ◽

Central American Isthmus

The central evolutionary, ecological and paleoceanographic questions of the American tropical Neogene relate to how and during what time the Central American Isthmus formed. Geographically, closure was located between the southern edge of the Chortis Block in southern Nicaragua and the Atrato Valley in Colombia. In this region we describe, on the Caribbean side, five Neogene sedimentary basins. They are the Atrato, Chucunaque, Gatun, Bocas del Toro, and Limon Basins. On the Pacific side the Neogene sediments formed as part of the Central American Trench and are well exposed in a series of uplifted blocks on the Nicoya, Osa and Burica Peninsulas. Our analysis allows 1) a construction of the sequence of contrasting sedimentary environments which characterize the different basins, giving a composite geological history of the isthmus for the Late Neogene and 2) identifies the comparable biofacies from the different basins which allow and constrain the evolutionary and ecological questions to be posed concerning the effect of the isthmus as a biogeographic barrier. Temporally, from it's partial emergence in the Middle Miocene, the isthmus shallows by the Early Pliocene (3.5–3.4 Ma) to less than 50 m (Duque-Caro, 1990) when there is a marked differentiation of shelf marine macrobenthic species between the Caribbean and the Pacific. The evidence from reliably dated, large, diverse exchanges of North and South American vertebrates on land constrains the final closure date to not later than 2.8–2.5 Ma (Marshall, 1988). Given that no conclusive evidence for final closure can come exclusively from a study of sedimentary facies, when depths of less than 50 m are involved, the present window of almost 1 Ma, during which final closure must have occurred, will only be narrowed further by the detailed study of very shallow-water fossil clades and complementary molecular data. Present studies indicate that such clades are abundantly preserved.

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Preliminary systematics and diversity patterns of cyclostome bryozoans from the Neogene of the Central American Isthmus

Journal of Paleontology ◽

10.1017/s0022336000039676 ◽

2001 ◽

Vol 75 (3) ◽

pp. 578-589 ◽

Cited By ~ 5

Author(s):

Paul D. Taylor

Keyword(s):

Central American ◽

Diversity Patterns ◽

Number Of Species ◽

Low Latitudes ◽

Preliminary Study ◽

The Caribbean ◽

Central American Isthmus

Cyclostome bryozoans are present in 83 samples collected as part of the Panama Paleontology Project (PPP) and representing sediments deposited during the Miocene-Pleistocene in several basins on the Caribbean and Pacific sides of the Central American Isthmus. Preliminary study has resulted in the identification of 23 species. Most of these are left in open nomenclature and assigned questionably to genera, pending detailed study and comparison with cyclostomes previously described from this region and elsewhere. Maximum sample diversity is 13 species and median diversity two species. An equal number of species is present in the Caribbean and Pacific basins. The cumulative collection curve for the PPP cyclostome samples shows a flattening, implying that further sampling will not increase diversity substantially. About 11 percent of calcareous species in the PPP bryozoan fauna are cyclostomes, the remainder being cheilostomes. This relatively small value is consistent with anecdotal data for Recent bryozoans which suggest a decrease in the proportion of cyclostomes within bryozoan faunas from high to low latitudes. Species with erect colonies dominate among the cyclostomes, in contrast with the PPP cheilostomes in which encrusting species greatly outnumber erect species.

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