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Costa Rican sedimentary rocks deposited since the Campanian are subdivided into supergroups, groups, subgroups, and formations. The Curime, Boruca and Cerece supergroups are unconformity-bounded units. The preexisting number of formations is considerably reduced. The remaining rock units described in this paper are defined by their depositional environment, using differential sedimentologic criteria. The use of sequence stratigraphic terminology is discussed.

Resumen La caracterización sistemática del género Yaberinella se propone aquí por primera vez, tras el uso de material procedente de Costa Rica. Las medidas biométricas, incluyendo el diámetro medio del proloculus y el recuento y la longitud media (en secciones axiales) de la espira, se utilizan para ayudar a determinar la afiliación de dos especies distintas. Siendo relativamente raro en el registro geológico y aparentemente restringido a la región del Caribe - con una aparición controvertida en el oeste de Omán -, vale la pena mencionar su presencia en los depósitos del lado Pacífico de Costa Rica. Además, la presencia de Yaberinella hottingeri junto con Y. panamensis sugiere una extensión del rango de tiempo de la primera especie. Abstract The genus Yaberinella is systematically described for the first time in Costa Rica. Measurements of features such as the mean proloculus diameter and the count and mean length (in axial sections) of whorls are used to help determining affiliation of two distinct species. Being relatively rare in the geological record and apparently restricted to the Caribbean region - with a controverted apparition in western Oman -, its presence in Pacific side´s deposits of Costa Rica is worth to mention. Besides, the presence of Yaberinella hottingeri together with Y. panamensis suggests an extension of the first species time slice.

The genus Yaberinella is systematically described for the first time in Costa Rica. Measurements of features such as the mean proloculus diameter and the count and mean length (in axial sections) of whorls are used to help determining affiliation of two distinct species. Being relatively rare in the geological record and apparently restricted to the Caribbean region – with a controverted apparition in western Oman –, its presence in Pacific side´s deposits of Costa Rica is worth to mention. Besides, the presence of Yaberinella hottingeri together with Y. panamensis suggests an extension of the first species time slice. La caracterización sistemática del género Yaberinella se propone aquí por primera vez, tras el uso de material procedente de Costa Rica. Las medidas biométricas, incluyendo el diámetro medio del proloculus y el recuento y la longitud media (en secciones axiales) de la espira, se utilizan para ayudar a determinar la afiliación de dos especies distintas. Siendo relativamente raro en el registro geológico y aparentemente restringido a la región del Caribe – con una aparición controvertida en el oeste de Omán –, vale la pena mencionar su presencia en los depósitos del lado Pacífico de Costa Rica. Además, la presencia de Yaberinella hottingeri junto con Y. panamensis sugiere una extensión del rango de tiempo de la primera especie.

In diesem Artikel werden die ältesten vulkanischen Produkte des Costa-Rica-Inselbogens untersucht, die Subduktions-Prozesse am westlichen Rand der Karibischen-Platte in der Unter-Kreide belegen.

There is little information on the humoral response of sheep experimentally infected with Echinococcus granulosus. Thus, the objective of this study was to evaluate this response and measure its evolution. Doses of 10, 100, 1000 and 10000 E. granulosus eggs were prepared and inoculated via intraruminal puncture. Blood samples were obtained before inoculation and every 48 h after inoculation, until they became seropositive. Thereafter, they were taken monthly for the first year and then every three months until 1700 days of observation had been completed. An ELISA test, with total hydatid fluid antigen, was used for immunodiagnosis. The average optical density of the 12 inoculated sheep was found to be above the mean cutoff value 10 days after inoculation, went on increasing until 180 days after inoculation and remained above the cutoff level until the end of the observation period. This confirms that the antibody response of sheep to E. granulosus infection occurs before production of hydatid fluid and that activation, mobilization and establishment of oncospheres in the tissues generates a persistent response from the host's immune system. Existe pouca informação sobre a resposta imune humoral de ovinos experimentalmente infectados por Echinococcus granulosus. O objetivo deste estudo é avaliar a resposta imune por anticorpos em ovinos infectados. Os ovinos receberam doses de 10, 100, 1.000 e 10.000 ovos de E. granulosus por via intrarruminal. Amostras de sangue foram colhidas antes e após infecção, a cada 48 horas, até a detecção de anticorpos anti-E. granulosuse após, colheram-se amostras mensal e trimestralmente, no primeiro ano até 1.700 dias de infecção. No imunodiagnóstico, utilizou-se o ensaio imunoenzimático indireto (ELISA-teste) e como antígeno total, líquido hidático. Na detecção de anticorpos anti-E. granulosus no soro das 12 ovelhas, a densidade ótica esteve acima do ponto de corte, após 10 dias de infecção, aumentando até 180 dias pós-infecção, e permanecendo acima desses dias até o final do experimento. Isso confirma que a resposta por anticorpos em ovinos infectados por E. granulosus antecede a produção de líquido hidático, e que a ativação, mobilidade e permanência das oncosferas nos tecidos possibilita a resposta imune dos hospedeiros.

The southern part of the Central American isthmus is the product of an island arc. It evolved initially as a ridge of primitive island-arc tholeiites at a collision zone between the Farallon plate and proto-Caribbean crust (Albian-Santonian). During the Campanian, a major tectonic event (most probably subduction reversal) caused décollement of different units of the former plate margin. The resulting structural high was covered by a carbonate platform. From Maastrichtian to Eocenc times continuous subduction produced a stable morphotectonic configuration (trench-slope-outer-arc-fore-arccalcalkaline-arc). Fore-arc sedimentation was controlled by volcaniclastic input and tectonic activity along the outer arc's inner margin. Eustatic control is essentially recognized through lowstand signals such as extensive turbidite sand lobes. Steady accretionary uplift of the outer arc gradually closed the bypasses between forc-arc and trench slope. Eustatic control is verified by lowstand signals (sands) on the trench slope and highstand signals on the outer arc (carbonate ramps). During the Oligocene another major tectonic event affected the entire system: accretion ceased, segments decoupled, and regional compression resulted in general uplift and erosion. From latest Oligocene to Pliocene times, three episodes of tilting created a series of fault-angle depressions. Subsidence varies enormously among these basins. but sedimentation is largely shallow marine. Facies architecture reflects complex interactions between tectonic processes, changes in volcaniclastic sediment supply, and eustasy. Subsequently. very strong explosive volcanic activity resulted in excessive sediment input that overfilled most basins. The history of the island arc shows that tectonic processes largely controlled composition, distribution and geometry of the major sedimentary units. Eustatic signals do indeed occur when they are expected, but may be considered as an overprint rather than a dominating factor.

The study presents a combined sedimentological, micropaleontological and petrological approach to the Cretaceous sedimentary basement and cover sequences of the Costa Rican arc orogen. The findings show an evolved volcanic arc with explosive calc-alkaline volcanism, which was active since at least the Albian. This intraoceanic arc was built on the western Caribbean Plate boundary where the oceanic Farallon Plate was continuously subducting. Some evidence suggests that the subduction processes in southern Central America might have already begun in the Late Jurassic., In dieser Studie werden die kretazischen Subduktionsvorgänge in Südzentralamerika anhand von sedimentologischen, mikropaläontologischen und petrologischen Untersuchungen der kretazischen Sedimentabfolgen des Basements und Auflagers erforscht. Die Ergebnisse weisen auf einen intraozeanischen Bogen am Rand der Karibischen Platte hin, der seit dem Alb aktiv war. Einige Indizien zeigen, dass die Subduktionsprozesse in Südzentralamerika bereits an der Grenze Oberjura-Kreide begonnen haben könnten.

The article resumes the sedimentary record in southern Central America from tectonic uplift of the Costa Rica - Panamá arc in the Paleocene time as a consequence of the collision between the Cuban arc and the Bahamas Bank