| Yecua Formation | |
| Period: | Miocene |
| Age: | Late Langhian-Early Messinian (Colloncuran-Huayquerian) ~ |
| Prilithology: | Mudstone, Sandstone[1] |
| Otherlithology: | Gypsum |
| Region: | Chaco Basin |
| Country: | |
| Underlies: | Tariquia Formation |
| Overlies: | Petaca Formation |
| Thickness: | ~50- |
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]
| Name | Species | Member | Material | Notes |
|---|---|---|---|---|
| Tellina | T. sp | |||
| cf. Cyrena | cf. C. sp | |||
| cf. Astarte | cf. A. sp | |||
| cf. Lucina | cf. L. sp | |||
| Senis | S. cf. elongatus | |||
| cf. Corbula or Cymbophora sp. | cf. C. sp | |||
| cf. Nucula | cf. N. sp | |||
| Name | Species | Member | Material | Notes |
|---|---|---|---|---|
| cf. Gyrodes or Natica sp. | ||||
| cf. Turritella | cf. T. sp | |||
| Name | Species | Member | Material | Notes |
|---|---|---|---|---|
| Bythocypris | B. sp | |||
| Cyprideis | C. sp | |||
| cf. Balanus | cf. B. sp | |||
| indetermined crabs | ||||
| Name | Species | Member | Material | Notes | Image |
|---|---|---|---|---|---|
| cf. Theosodon | cf. T. sp | distal limb bone | a litoptern | ||
| Rodentia indet. | tooth | ||||
| Mourasuchus[3] | M. sp. | skull fragments, partial vertebrae & ribs | |||
| Pleurodira | shell elements | ||||
| Humboldtichthys[4] | Humboldtichthys kirschbaumi | incompletely preserved anterior portion of the body and posterior head | a Glass Knifefish | ||
| Siluriformes indet. | possibly Ariidae | ||||
| Characiformes or Clupeiformes | a scale | ||||