The Salamanca Formation is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

in the

Golfo San Jorge Basin The Golfo San Jorge Basin ( es, Cuenca del Golfo San Jorge) is a hydrocarbon-rich sedimentary basin located in eastern Patagonia, Argentina. The basin covers the entire San Jorge Gulf and an inland area west of it, having one half located in Santa ...

of central Patagonia that yields well-preserved, well-dated fossils from the early Paleocene. Studies of these fossils are providing new data on plant and animal diversity following the end-Cretaceous extinction event. CC-BY_icon

Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License The Salamanca Formation crops out in the San Jorge Basin in southern Chubut and northern Santa Cruz provinces, Argentina, overlying the Cretaceous Chubut Group and is part of the Paleocene and Eocene Río Chico Group. The formation yields abundant plant remains as well as fossils of

invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

, marine macrofaunas,

reptiles Reptiles, as most commonly defined are the animals in the Class (biology), class Reptilia ( ), a paraphyletic grouping comprising all sauropsid, sauropsids except birds. Living reptiles comprise turtles, crocodilians, Squamata, squamates (lizar ...

, and

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

. The formation consists primarily of

estuarine An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

to shallow marine deposits. Palynological analysis of the Salamanca Formation shows low floral diversity after the end-Cretaceous mass extinction, followed by a rapid recovery. 50% of all pollen types are angiosperms, whereas gymnosperms accounted for only ~13% of total richness; however, ''Classopollis''

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...

, representing the extinct conifer family

Cheirolepidiaceae Cheirolepidiaceae is an extinct family of conifers. They first appeared in the Triassic, and were widespread during most of the Mesozoic era. They are united by the possession of a distinctive pollen type assigned to the form genus '' Classopolli ...

, is the most abundant palynomorph. Wood assemblages from the Salamanca Formation. are dominated by conifers, but the presence of fossil angiosperm woods indicate that they were also part of the canopy. The co-occurrence of palms, dicot woods with indistinct growth rings, and alligatorids, indicates temperature remained above freezing year-round. The results of leaf physiognomic analyses indicate that the climate in the San Jorge Basin during the early Paleocene was warm subtropical.

Paleoflora

Paleofauna

Fish

Amphibians

Reptiles

Testudines

Crocodylomorphs

Lepidosaurs

Mammals

Monotremes

Allotheres

Meridiolestidans

Meridiungulates

Metatherians

Invertebrates

After unless otherwise noted

References

{{SALMA Geologic formations of Argentina Paleocene Series of South America Paleogene Argentina Tiupampan Fossiliferous stratigraphic units of South America Paleontology in Argentina Sandstone formations Mudstone formations Tuff formations Lacustrine deposits Geology of Chubut Province Geology of Santa Cruz Province, Argentina Golfo San Jorge Basin