Silveirinha Formation

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) ~55.8–48.6 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Sub-units	Rio Mondego Member
Underlies	Bom Sucesso Formation
Overlies	Taveiro Formation
Lithology
Primary	Sandstone, siltstone
Other	Conglomerate
Location
Coordinates	40.0°N 8.8°W
Approximate paleocoordinates	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
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

• Mondegodon eutrigonus[8]

Artiodactyls

• Diacodexis antunesi[9][10]

Carnivora

• cf. Miacis sp.[7]
• Miacidae indet.[7]

Cimolesta

• Ilerdoryctes cf. sigei[11]

"Condylartha"

• Microhyus reisi[12][13]

Ferae

• Dormaalocyon latouri[7]
• cf. Viverravus sp.[7]

Glires

• Euromys cardosoi[14]
• Corbarimys paisi[10][15][16]
• Microparamys cf. nanus[10]

Hyaenodonta

• Didelphodus sp.[7]

Insectivora

• Russellmys denisae[7][17]
• Apatemys sp.[4]
• Heterohyus sp.[4]

Perissodactyls

• Paschatherium marianae[7][18]
• Pliolophus vulpiceps[7]
• Teilhardimys reisi
• cf. Lophiaspis maurettei[11]

Taeniodonta

• Eurodon silveirinhensis[7][19]

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

• Charadriiformes
  • Recurvirostridae
    • Fluviatilavis antunesi[22][23]
• Ornithurae
  • Neornithes indet.[23]

Reptiles

Crocodiles

• Diplocynodon sp.[24]

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

• Pelobatidae indet.[25]
• Salamandridae indet.[31]

Invertebrates

Mollusks

• Bithynia soaresi[32]
• Gyraulus antunesi[33]
• Chlamys sp.[33]
• Cardiacea indet.[33]

Ostracods

• Cypris silveirinhaensis[34]
• Ilyocypris lusitanicus[34]
• ?Cyclocypris sp.[34]

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

1. Silveirinha Formation at Fossilworks.org
2. De la Peña, 1995, p.30
3. Antunes, 2003, p.20
4. Estravís, 2000, p.282
5. Rage & Augé, 2003, p.103
6. Godinot & De Lapparent, 2003, p.262
7. Estravís, 2000, p.283
8. Tabuce et al., 2011, p.146
9. Estravís & Russell, 1989
10. Badiola et al., 2009, p.248
11. Estravís, 2000, p.284
12. Tabuce et al., 2006, p.41
13. Antunes et al., 1987
14. Escarguel, 1999, p.142
15. Escarguel, 1999, p.251
16. Estravís, 1994
17. Estravís, 1990
18. Estravís & Russell, 1992b
19. Estravís & Russell, 1992a, p.195
20. Tabuce et al., 2009
21. Estravís, 1996
22. Harrison, 1983
23. Antunes, 2003, p.7
24. Antunes, 2003, p.10
25. Rage & Augé, 2003, p.105
26. Rage & Augé, 2003, p.107
27. Rage & Augé, 2003, p.108
28. Rage & Augé, 2003, p.106
29. Rage & Augé, 2003, p.109
30. Lapparent de Broin, 2003, p.118
31. Rage & Augé, 2003, p.104
32. Callapez, 2003, p.84
33. Callapez, 2003, p.85
34. Colin & Antunes, 2003, p.92

Bibliography

• Tabuce, Rodolphe; Julien Clavel, and Miguel Telles Antunes. 2011. A structural intermediate between triisodontids and mesonychians (Mammalia, Acreodi) from the earliest Eocene of Portugal. The Science of Nature 98. 145–155. Accessed 2020-09-06.
• Tabuce, R.; M. T. Antunes, and B. Sige. 2009. A new primitive bat from the earliest Eocene of Europe. Journal of Vertebrate Paleontology 29. 627–630.
• Tabuce, Rodolphe; Miguel Telles Antunes; Richard Smith, and Thierry Smith. 2006. Dental and tarsal morphology of the European Paleocene/Eocene 'condylarth' mammal Microhyus. Acta Palaeontologica Polonica 51. 37–52. Accessed 2020-09-06.
• Antunes, M. T. 2003. Lower Paleogene crocodilians from Silveirinha, Portugal. Palaeovertebrata 32. 1–26. Accessed 2020-09-06.
• 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, and Miguel Telles Autunes. 2003. Limnic ostracoda from Silveirinha, Portugal (? Late Paleocene - Lowermost Eocene). Ciências da Terra 15. 91–100.
• Rage, J. C., and M. Augé. 2003. Amphibians and squamate reptiles from the lower Eocene of Silveirinha (Portugal). Ciências da Terra 15. 103–116. Accessed 2020-09-06.
• de Lapparent de Broin, F. 2003. Neochelys sp. (Chelonii, Erymnochelyinae), from Silveirinha, early Eocene, Portugal. Ciências da Terra 15. 117–132. Accessed 2020-09-06.
• Godinot, Marc, and France de Lapparent de Broin. 2003. Arguments for a mammalian and reptilian dispersal from Asia to Europe during the Paleocene-Eocene boundary interval. Deinsea 10. 255–275. Accessed 2020-09-06. ISSN 0923-9308
• Estravís, C. 2000. Nuevos mamíferos del Eoceno Inferior de Silveirinha (Baixo Mondego, Portugal). Coloquios de Paleontología 51. 281–311. Accessed 2020-09-06.
• 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. Accessed 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. Accessed 2020-09-06. ISSN 1132-1660
• 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, Paris 318. 417–420.
• Estravís, Carmen, and Donald E. Russell. 1992a. The presence of Taeniodonta (Mammalia) in the Early Eocene of Europe. Ciências da Terra 11. 191–201. Accessed 2020-09-06.
• Estravís, Carmen, and Donald E. Russell. 1992b. Paschatherium marianae, un nouveau Condylarthra de Silveirinha, Éocène inferérieur du Portugal. Bulletin du Museum 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. 761–765.
• Estravís, C., and D. E. Russell. 1989. Decouverte d'un nouveau Diacodexis (Artiocactyla, Mammalia) dans l'Eocène inférieur de Silveirinha, Portugal. Palaeovertebrata 19. 29–44.
• Antunes, M.T.; C. Estravís, and D.E. Russell. 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.