Unveiling the Past: Latest Insights into Cretaceous OAEs and Extinct Caribbean Mammals

Hello everyone,

It's been a while since my last post, and I'm excited to share an update on my recent research and findings.

My latest work has been focused on studying the sedimentary records throughout the Cretaceous period, particularly those that show intermittent intervals of organic-rich strata due to severe oxygen depletion in the ocean, known as Oceanic Anoxic Events (OAEs). These deposits, which generated large amounts of hydrocarbons, indicate significant changes in the global carbon cycle (Weissert et al., 1979; Weissert, 1989). Although such records are well-documented in the Americas, they have not been well-characterized in the Antilles until now.

Using high-resolution chemostratigraphy, we conducted an assessment of Lower Cretaceous, organic-rich limestones from Sierra de los Órganos, Western Cuba. This succession, accumulated along the passive margin of the Maya Block due to the expansion of the Proto-Caribbean Seaway in the middle Mesozoic, became part of Cuba during the Eocene and now comprises the Guaniguanico Terrain.

The occurrence of calpionellids Tintinopsella cf. carpathica and Calpionellites cf. darderi supports the chronostratigraphic correlation up to the earliest Hauterivian (Pszczółkowski, 1999; Mutterlose et al., 2021; Giraldo-Gómez et al., 2022). Our results reveal that the widespread oxygen-deficient conditions associated with the Valanginian "Weissert" oceanic anoxic event are also recorded in the Proto-Caribbean Basin.

I presented these findings at the 14th Romanian Symposium on Paleontology in Bucharest in September 2023 and at the SEPM International Sedimentary Geosciences Congress in Flagstaff, Arizona in May 2024.

In addition to my work on OAEs, I have also been researching the extinct, shrew-like mammal Nesophontes, endemic to the Greater Antilles. The Cuban taxa within this genus have a challenging taxonomic history due to the ample size variation observed in skeletal remains. My detailed systematic revision of Cuban species through multivariate morphometric and qualitative analyses, including discrete osteological characteristics and stable isotope analysis, supports the presence of three species divided into two morphotypes. These findings were published in the Journal of South American Earth Sciences in August 2023 and are available here.

Stay tuned for more updates as we continue to explore the fascinating history of the Caribbean's paleontological and geological past.

Idealized reconstruction of Nesophontes micrus based on sketches and augmented

using AI (DALL-E) software. Image copyright of J. Orihuela.