The Silveirinha Formation is an Early Eocene (Ypresian, or MP7 or Neustrian in the ELMA classification) geologic formation of the Mondego Basin in the Região Centro of central-western Portugal. The sandstones, siltstones and conglomerates were deposited in an alluvial environment.[1]
| Silveirinha Formation | |
|---|---|
| Stratigraphic range: Ypresian (MP7 or Neustrian) ~ | |
| Type | Geological formation |
| Sub-units | Rio Mondego Member |
| Underlies | Bom Sucesso Formation |
| Overlies | Taveiro Formation |
| Lithology | |
| Primary | Sandstone, siltstone |
| Other | Conglomerate |
| Location | |
| Coordinates | 40°00′N 8°48′W / 40.0°N 8.8°W |
| Approximate paleocoordinates | 35°36′N 10°00′W / 35.6°N 10.0°W |
| Region | Região Centro |
| Country |  Portugal |
| Extent | Mondego Basin |
| Type section | |
| Named for | Silveirinha clay pit |
| Named by | Autunes et al. |
| Location | Silveirinha clay pit |
| Year defined | 1981 |
| Coordinates | 40°00′29.0″N 8°49′16.7″W / 40.008056°N 8.821306°W |
| Region | Coimbra District |
  Silveirinha Formation (Portugal) | |
The formation has provided fossils of many mammals, birds, amphibians and reptiles, as well as mollusks and ostracods, and is considered one of the richest Early Eocene faunal assemblages of Europe. The taeniodont, typically known as a North American order; Eurodon silveirinhensis and the ostracod Cypris silveirinhaensis have been named after the formation.
Description
The Silveirinha Formation, named after the Silveirinha clay pit, crops out in the western part of the Mondego Basin in the Região Centro of central-western Portugal.[2] The formation comprises fossiliferous lenticular calcitic conglomerates as well as laminated and cross bedded sands and brownish-red silts.[1]
The conglomerates are interpreted as crevasse-splay deposit in a alluvial plain environment, which eventually flooded and where bogs and possibly oxbows developed, crossed by channels depending on a river system that drained higher areas more north or eastwards.[3]
Climate
The climate in the Early Eocene was substantially warmer than today.
Paleontological significance
The Silveirinha clay pit after which the formation is named was first discovered in 1977 by Rui Pena dos Reis of Coimbra University.[4] The unit is one of few earliest Eocene fossiliferous formations that provided a rich amphibian and reptile fauna.[5] Most fossils were deposited in the channels after short transportation. Vegetation should have been rich in nearby areas, supporting a rich fauna. Ostracods,gastropods, amphibians and pelomedusid chelonians indicate fresh waters, although rare bivalves show that salt or at least brackish waters were not very far away.[3]
It is hypothesized that the species D. antunesi in the genus Diacodexis was more primitive than the earliest Wasatchian D. ilicis of North America, strongly supporting a Europe to America dispersal of this genus.[6]
Fossil content
The formation has provided the following fossils:[1]
Mammals
- Primates
- Arcius zbyszewskii[7]
- Donrussellia lusitanica[7]
- Acreodi
- Artiodactyls
- Carnivora
- Cimolesta
- Ilerdoryctes cf. sigei[11]
- "Condylartha"
- Ferae
- Glires
- Hyaenodonta
- Didelphodus sp.[7]
- Insectivora
- Russellmys denisae[7][17]
- Apatemys sp.[4]
- Heterohyus sp.[4]
- Perissodactyls
- Taeniodonta
- Theriiformes
- Archaeonycteris praecursor[20]
- Leptacodon nascimentoi[7][21]
- Peratherium cf. constans[4]
- cf. Leptacodon sp.[7]
- ?Talpavus sp.[7]
- Creodonta indet.[7]
- Nyctitheriidae indet.[7]
Birds
Reptiles
- Crocodiles
- Lizards
- Geiseltaliellus sp.[25]
- cf. Melanosaurus sp.[26]
- cf. Tinosaurus sp.[25]
- Amphisbaenidae indet.[27]
- Glyptosaurinae indet.[26]
- Glyptosaurini indet.[28]
- Gekkonidae indet.[28]
- Iguanidae indet.[25]
- Melanosaurini indet.[26]
- Scincomorpha indet.[28]
- ?Anguinae indet.[26]
- ?Varanidae indet.[27]
- Snakes
- Dunnophis matronensis[29]
- Boidae indet.[27]
- Turtles
- Neochelys sp.[30]
Amphibians
Invertebrates
- Mollusks
- Ostracods
See also
- List of fossiliferous stratigraphic units in Portugal
- Nanjemoy Formation, contemporaneous fossiliferous formation of the eastern United States
- Wasatch Formation, contemporaneous fossiliferous formation of the western United States
- Itaboraí Formation, contemporaneous fossiliferous formation of eastern Brazil
References
Bibliography
- Tabuce, Rodolphe; Clavel, Julien; Antunes, Miguel Telles (2011), "A structural intermediate between triisodontids and mesonychians (Mammalia, Acreodi) from the earliest Eocene of Portugal", The Science of Nature, 98 (2): 145–155, Bibcode:2011NW.....98..145T, doi:10.1007/s00114-010-0747-y, PMID 21181109, retrieved 2020-09-06
- Tabuce, R.; Antunes, M. T.; Sige, B. (2009), "A new primitive bat from the earliest Eocene of Europe", Journal of Vertebrate Paleontology, 29 (2): 627–630, Bibcode:2009JVPal..29..627T, doi:10.1671/039.029.0204
- Tabuce, Rodolphe; Antunes, Miguel Telles; Smith, Richard; Smith, Thierry (2006), "Dental and tarsal morphology of the European Paleocene/Eocene 'condylarth' mammal Microhyus", Acta Palaeontologica Polonica, 51: 37–52, retrieved 2020-09-06
- Antunes, M. T (2003), "Lower Paleogene crocodilians from Silveirinha, Portugal", Palaeovertebrata, 32: 1–26, S2CID 132993434
- Callapez, Pedro (2003), "Upper Paleocene-Early Eocene mollusks of Silveirinha (Figueira da Foz, West Central Portugal)", Ciências da Terra, 15: 83–90
- Colin, Jean-Paul; Autunes, Miguel Telles (2003), "Limnic ostracoda from Silveirinha, Portugal (? Late Paleocene - Lowermost Eocene)", Ciências da Terra, 15: 91–100
- Rage, J. C.; Augé, M. (2003), "Amphibians and squamate reptiles from the lower Eocene of Silveirinha (Portugal)", Ciências da Terra, 15: 103–116, retrieved 2020-09-06
- de Lapparent de Broin, F (2003), "Neochelys sp. (Chelonii, Erymnochelyinae), from Silveirinha, early Eocene, Portugal", Ciências da Terra, 15: 117–132, retrieved 2020-09-06
- Godinot, Marc; de Lapparent de Broin, France (2003), "Arguments for a mammalian and reptilian dispersal from Asia to Europe during the Paleocene-Eocene boundary interval", Deinsea, 10: 255–275, ISSN 0923-9308, retrieved 2020-09-06
- Estravís, C (2000), "Nuevos mamíferos del Eoceno Inferior de Silveirinha (Baixo Mondego, Portugal)", Coloquios de Paleontología, 51: 281–311, S2CID 161766178
- Escarguel, Gilles (1999), "Les rongeurs de l'Eocène inférieur et moyen d'Europe occidentale - Systématique, phylogénie, bio-chronologie et paléobiogéographie des niveaux-repères MP7 a MP14", Palaeovertebrata, 28: 89–351, retrieved 2020-09-06
- Estravís, C (1996), "Leptacodon nascimentoi n. sp., un nouveau Nyctitheriidae (Mammalia, Lipotyphla) de l'Eocène inférieur de Silveirinha (Baixo Mondego, Portugal)", Palaeovertebrata, 25: 279–286
- De la Peña Zarzuelo, Antonio (1995), "Los Peces terciarios de las cuencas continentales ibéricas: Marco histórico y registro fosil conocido - Tertiary fishes from the Iberia continental basins: History and fossil record", Coloquios de Paleontología, 47: 25–46, ISSN 1132-1660, retrieved 2020-09-06
- Estravís, C (1994), "Microparamys paisi, un nouvel Ischyromyidae (Rodentia) de l'Éocène inférieur de Silveirinha (Baixo Mondego, Portugal)", Comptes Rendus de l'Académie des Sciences de Paris, 318: 417–420
- Estravís, Carmen; Russell, Donald E. (1992a), "The presence of Taeniodonta (Mammalia) in the Early Eocene of Europe", Ciências da Terra, 11: 191–201, S2CID 59471522
- Estravís, Carmen; Russell, Donald E. (1992b), "Paschatherium marianae, un nouveau Condylarthra de Silveirinha, Éocène inferérieur du Portugal", Bulletin du Muséum National d'Histoire Naturelle, Section C, 14: 185–203
- Estravís, C (1990), "Russellmys denisae, un nouvel Apatémyidé (Mammalia) de Silveirinha, eocène inférieur du Portugal", Geobios, 23 (6): 761–765, Bibcode:1990Geobi..23..761E, doi:10.1016/S0016-6995(06)80342-6
- Estravís, C.; Russell, D. E. (1989), "Decouverte d'un nouveau Diacodexis (Artiocactyla, Mammalia) dans l'Eocène inférieur de Silveirinha, Portugal", Palaeovertebrata, 19: 29–44
- Antunes, M.T.; Estravís, C.; Russell, D.E. (1987), "A new condylarth (Mammalia) from the Early Eocene of Silveirinha, Portugal", Münchner Geowissenschaftliche Abhandlungen A, 10: 219–224
- Harrison, C. J. O (1983), "A new wader, Recurvirostridae (Charadriiformes), from the Early Eocene of Portugal", Ciencias da Terra, 7: 9–16