Carbonate blocks with silicified fossils were recovered from a newly recognized cold seep deposit, the Satsop  Weatherwax site, in the basal Humptulips Formation, along the West Fork of Satsop River in Washington State, USA. The petrography and the stable carbon isotope signature of the carbonate, with values as low as -43.5‰, indicate that these carbonate blocks formed at an ancient methane seep. The fossils recovered from this block include five vesicomyid specimens, two fragments of a thyasirid, five specimens of the peltospirid Depressigyra, two specimens of the hyalogyrinid Hyalogyrina, 25 specimens of the neritimorph Thalassonerita eocenica, and three limpet specimens of two different species. Five species can be described as new: Nuculana acutilineata (Nuculanoidea), Desbruyeresia belliatus (Provannidae), Provanna fortis (Provannidae), Orbitestella dioi (Orbitestellidae), and Leptochiton terryiverseni (Polyplacophora). Other fossils recovered from this site are numerous serpulid tubes, echinoid spines, one brachiopod fragment and two neogastropods. Almost all species recovered belong to extant genera and the fauna has a modern character, but are different from species found in younger seeps in Washington State. This is the first record of an orbitestellid from an ancient cold seep deposit, the first fossil provannids from the Humptulips Formation, and the first fossil record of Desbruyeresia from North America.

Thirteen fossiliferous limestone deposits from Cenozoic strata in the Talara Basin in northern Peru are identified as ancient methane-seep deposits. Planktonic foraminifera and the existing stratigraphical framework of the Talara Basin indicate an early Oligocene, or possibly late Eocene, age of these deposits. They are found in three distinct areas - Belen, Cerro La Salina and Cerros El Pelado - and differ in their petrography, stable isotope signatures, and lipid biomarker and macrofaunal contents. At Belen, the carbon stable isotope signature of the carbonate and the abundance of n-alkanes indicates the possibility of oil seepage in addition to methane seepage; for Belen and Cerro La Salina the high abundance of the biomarker crocetane indicates a dominance of anaerobic methane-oxidizing archaea of the ANME-2 group, whereas the rather small combined crocetane/phytane peak of a Cerros El Pelado limestone agrees with mixed ANME-1/ANME-2 input. The macrofauna consists mainly of molluscs; the Cerro La Salina sites include mostly infaunal thyasirid and lucinid bivalves and only few vesicomyid bivalves; gastropods include Provanna antiqua, the limpet Pyropelta and several vetigastropods. The Belen site is dominated by the elongate vesicomyid bivalve Pleurophopsis lithophagoides. The most common bivalve at the Cerros El Pelado sites is an undetermined, possible vesicomyid, and a smooth provannid gastropod. Biogeographically the faunas are most similar to those of the northwestern United States, as indicated by two joint species; similarities on the genus level (Conchocele, Lucinoma, Pleurophopsis, Provanna, Colus) exist also with Japan and the Caribbean region.

A total of 25 species of mollusks and crustaceans are reported from Oligocene seep deposits in the Talara Basin in northern Peru. Among these, 12 are identified to the species-level, including one new genus, six new species, and three new combinations. Pseudophopsis is introduced for medium-sized, elongate-oval kalenterid bivalves with a strong hinge plate and largely reduced hinge teeth, rough surface sculpture and lacking a pallial sinus. The new species include two bivalves, three gastropods, and one decapod crustacean: the protobranch bivalve Neilo altamirano and the vesicomyid bivalve Pleurophopsis talarensis; among the gastropods, the pyropeltid Pyropelta seca, the provannid Provanna pelada, and the hokkaidoconchid Ascheria salina; the new crustacean is the callianassid Eucalliax capsulasetaea. New combinations include the bivalves Conchocele tessaria, Lucinoma zapotalensis, and Pseudophopsis peruviana. Two species are shared with late Eocene to Oligocene seep faunas in Washington state, USA: Provanna antiqua and Colus sekiuensis; the Talara Basin fauna shares only genera, but no species with Oligocene seep fauna in other regions. Further noteworthy aspects of the molluscan fauna include the remarkable diversity of four limpet species, the oldest record of the cocculinid Coccopigya, and the youngest record of the largely seep-restricted genus Ascheria. Eucalliax is recorded for the first time from a seep and from the Oligocene.