The San Sebastián Formation is a geologic formation in Puerto Rico. It preserves fossils dating back to the Oligocene period.
It was primarily deposited as limestone in a marine environment, but some localities with a significant amount of terrestrial fauna appear to have been deposited in a deltaic environment. It contains some of the earliest fossils of terrestrial Caribbean vertebrates, including chinchilloid rodents and Eleutherodactylus frogs. In addition, taxa that are no longer known from the Caribbean, such as gavialid crocodilians and geomyoid rodents, have also been recovered from the formation.
Vertebrate paleofauna Based on the Paleobiology Database:
Cartilaginous fish GenusSpeciesLocationNotesImagesGinglymostomatidae indet.A nurse shark of uncertain affinities.
Amphibians GenusSpeciesMaterialNotesImagesEleutherodactylusE. sp.Distal humerusA coquí frog.
Reptiles GenusSpeciesMaterialNotesImagesAktiogavialisA. puertoricensisIncomplete braincase, cranial elementsA gavialid crocodilian. Type locality of genus and species.Pelomedusidae indet.A pelomedusid side-necked turtle.
Mammals GenusSpeciesMaterialNotesImagesBorikenomysB. praecursorTeethA chinchilloid rodent. Type locality of genus and species.CaribeomysC. merzeraudiTeethA geomyoid rodent. Type locality of genus and species, first evidence of geomyoids from the Caribbean.CaribosirenC. turneriA dugongid sirenian.PriscosirenP. atlanticaA dugongid sirenian.
See also
List of fossiliferous stratigraphic units in Puerto Rico
References
External links