Reports: B848614-B8: Tectonic Evolution of the Caribbean Basin and Gulf of Mexico: Constraints from the Paleobiogeography of Greater Antillean Late Cretaceous Ostracodes

Terry Markham Puckett , University of North Alabama

This year, faunal descriptions of Late Cretaceous (Maastrichtian) ostracodes from Jamaica were completed and include 21 new species and 7 new genera. The description of these faunas of Jamaica is a step in understanding the relationship between biological evolution and plate tectonics in the Caribbean region during the Late Cretaceous. The new species include Cytherelloidea guineacornensis, Eocytheropteron jamaicaensis, Eocytheropteron hazeli, Belokephalocytherura mitchelli (new genus and species), Hemiparacytheridea exquisita, Loxoconcha pindarsensis, Ovocytheridea rotunda, Spinicytheridea compta (new genus and species), Amphicytherura grandicribra, A. occulta, Buntonia vulgaris, Cythereis riominhoensis, Cythereis chapeltonensis, Floricythereis exquisita (new genus and species), Leiocythereis polita (new genus and species), Phrixocythere unionensis (new genus and species), Polypinnacythere pinna (new genus and species), Pterygocythereis colini, Robustacythereis sagitta (new genus and species), R. ventrocurva, and Brachycythere jamaicaensis. Two of the new genera, Floricythereis and Polypennacythere, are considered to include previously-described species from North America. All of these new species are endemic to Jamaica.

Overall, the faunas from Jamaica and from North American are startlingly different, with abundant genera occurring in one area but not the other. For example, one of the most abundant taxa in the Maastrichtian deposits of Jamaica is Buntonia, but this genus does not occur in the Late Cretaceous deposits of North America. (Interestingly, Buntonia was also abundant in the Maastrichtian Ocozocoautla Formation of Chiapas, Mexico.) Conversely, abundant genera from North America, such as Haplocytheridea, Antibythocypris, Ascetoleberis, Fissocarinocythere and many others do not occur in the Caribbean.  In this connection, samples were collected from Late Cretaceous fossiliferous sediments in Mississippi and Alabama to compare those species with the new taxa from Jamaica. This analysis indicates that some of the new genera described on the basis of Jamaican species also have relatives in North America, in spite of the overall dissimilarity of the faunas. Previous studies of ostracodes from Chiapas, Mexico (see narrative report for 2010) also indicate faunal connection to Jamaica, although the preservation of the Mexican samples was generally poor. (This past August, I met Francisco Vega of the Universidad Nacional Autónomia de México, who is a specialist in Late Cretaceous fossils, at a locality in northern Mississippi. Although several of the places to collect Late Cretaceous fossiliferous samples in Mexico are dangerous because of the drug trafficking violence, he told me he would collect samples and send them to me, possibly in December, when he was planning to go there.) The manuscript of the descriptions is now with the Jamaican specialist, Prof. Simon Mitchell at the University of the West Indies, who is writing the section on stratigraphy. The manuscript will be submitted to the journal Micropaleontology.

Two trips were made to Cuba this past year to collect for ostracodes, one in December and the other in July. The samples collected during the December trip were poor, thus necessitating the need to return in July. Travel to Cuba and conducting fieldwork is difficult, as it takes months to get permission from the Cuban authorities to travel there and the localities that we can visit are strictly controlled; further, the details of the permission are released only immediately before the trip. Although we asked for permission to travel to and collect from the fossiliferous localities around Havana, permission was denied for both trips. We were able to travel to many other places and, fortunately, the samples collected in central Cuba contain ostracodes and planktonic foraminifera. One of my field guides, Leidy Menéndez Peñate of the Museo Nacional de Historia Natural in Havana, is a specialist in planktonic foraminifera and will be identifying the foramnifera and determining the ages of the samples. Processing the samples is time consuming, thus my student, Amy Jordan (a biology major with a minor in geology) has just completed an initial scanning of the samples to determine which ones have ostracodes and the best preservation and then we will process all of the good samples with repeated washings and ultrasonic baths to get good quality specimens for imaging. This work will take several months. Ms. Menéndez Peñate will be visiting the University of North Alabama in the spring to collect images of the planktonic foraminifera with UNA’s SEM for publication. We plan on publishing at least two papers on the research, one focusing on the ostracodes to be published in English, and the other focusing on the planktonic foraminifera to be published in Spanish.

Late Cretaceous ostracodes of Cuba have only been described only once, in 1974 (Lübimova, P. S., and Sánchez-Arango, J. R., Los Ostrácodos del Cretácico Superior y del Terciario de Cuba: Instituto Cubano del Libro, Havana, 171 p.). Many of the marine species described in that work were assigned to North American species, although those identifications are not correct. The current project will focus on correctly identifying the species and naming and describing the new species.

Progress was made on the digital version of the geologic map of Cuba. Currently, the geologic map of Cuba (1:250,000 scale) is only available as a series of ~40 printed sheets. Two students, Gabe Palmer and Evan Smith, took scanned versions of this map (raster images) and entered them into ArcMap. This was a challenge, because the maps had to be entered into a geographic coordinate system before digitizing could begin. Gabe was responsible for getting the maps into the coordinate system and Evan began digitizing the Late Cretaceous formations.  The region north of Santa Clara in central Cuba was selected for digitizing because that is where most of the fossiliferous samples were collected. With the digitized geologic map of Jamaica and of Cuba, a database will be entered for each of the samples with a list of species. This information will enable quantitative studies of the species’ distributions in the region.

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