Yecua Formation
Stratigraphic range: Late Langhian-Early Messinian
(Colloncuran-Huayquerian)
~14–7 Ma
UnderliesTariquia Formation
OverliesPetaca Formation
Thickness~50–300 m (160–980 ft)
Lithology
PrimaryMudstone, Sandstone[1]
OtherGypsum
Location
RegionChaco Basin
Country Bolivia

The Yecua Formation is a geological Formation in what is now Bolivia. Studies suggest that the Yecua Formation preserves a coastal setting with humid to semiarid floodplains, shorelines and tidal as well as shallow marine environments including marshes, streams, lakes and brackish bodies of water. There may have been a connection to the Amazon Basin or the Paranaense Sea.[2]

Bivalves

Name Species Member Material Notes
Tellina[1] T. sp
cf. Cyrena[1] cf. C. sp
cf. Astarte[1] cf. A. sp
cf. Lucina[1] cf. L. sp
Senis[1] S. cf. elongatus
cf. Corbula or Cymbophora sp.[1] cf. C. sp
cf. Nucula[1] cf. N. sp

Gastropods

Name Species Member Material Notes
cf. Gyrodes or Natica sp.[1]
cf. Turritella[1] cf. T. sp

Crustaceans

Name Species Member Material Notes
Bythocypris[1] B. sp
Cyprideis[1] C. sp
cf. Balanus[1] cf. B. sp
indetermined crabs [1]

Vertebrates

Name Species Member Material Notes Image
cf. Theosodon[1] cf. T. sp distal limb bone a litoptern
Rodentia indet.[1] tooth
Mourasuchus[3] M. sp. skull fragments, partial vertebrae & ribs
Pleurodira[3] shell elements
Humboldtichthys[4] Humboldtichthys kirschbaumi incompletely preserved anterior portion of the body and posterior head a Glass Knifefish
Siluriformes indet.[1] possibly Ariidae
Characiformes or Clupeiformes[1] a scale

References

  1. ^ a b c d e f g h i j k l m n o p q r Marshall, L.G.; Sempere, T.; Gayet, M. (1993). "The Petaca (Late Oligocene - Middle Miocene) and Yecua (Late Miocene) Formations of the Subandean-Chaco Basin, Bolivia, and their Tectonic Significance". Travaux et Documents des Laboratoires de Géologie de Lyon. 125: 291–301.
  2. ^ Hulka, C.; Gräfe, K.U.; Sames, B.; Uba, C.E.; Heubeck, C. (2006). "Depositional setting of the Middle to Late Miocene Yecua Formation of the Chaco Foreland Basin, southern Bolivia". Journal of South American Earth Sciences. 21 (1–2): 135–150. doi:10.1016/j.jsames.2005.08.003.
  3. ^ a b Tineo, D.E.; Bona, P.; Pérez, L.M.; Vergani, G.D.; González, G.; Poiré, D.G.; Gasparini, Z.; Legarreta, P. (2015). "Palaeoenvironmental implications of the giant crocodylian Mourasuchus (Alligatoridae, Caimaninae) in the Yecua Formation (late Miocene) of Bolivia". Alcheringa. 39 (2): 1–12. doi:10.1080/03115518.2015.967162. hdl:11336/33274. S2CID 129930697.
  4. ^ Albert, J.S.; Fink, W.L. (2010). "Phylogenetic relationships of fossil neotropical electric fishes (Osteichthyes: Gymnotiformes) from the upper Miocene of Bolivia". Journal of Vertebrate Paleontology. 27 (1): 17–25. doi:10.1671/0272-4634(2007)27[17:PROFNE]2.0.CO;2. S2CID 35007130.
Categories