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.

Bivalves

NameSpeciesMemberMaterialNotes
TellinaT. sp
cf. Cyrenacf. C. sp
cf. Astartecf. A. sp
cf. Lucinacf. L. sp
SenisS. cf. elongatus
cf. Corbula or Cymbophora sp.cf. C. sp
cf. Nuculacf. N. sp

Gastropods

NameSpeciesMemberMaterialNotes
cf. Gyrodes or Natica sp.
cf. Turritellacf. T. sp

Crustaceans

NameSpeciesMemberMaterialNotes
BythocyprisB. sp
CyprideisC. sp
cf. Balanuscf. B. sp
indetermined crabs

Vertebrates

NameSpeciesMemberMaterialNotesImage
cf. Theosodoncf. T. spdistal limb bonea litoptern
Rodentia indet.tooth
MourasuchusM. sp.skull fragments, partial vertebrae & ribs
Pleurodirashell elements
HumboldtichthysHumboldtichthys kirschbaumiincompletely preserved anterior portion of the body and posterior heada Glass Knifefish
Siluriformes indet.possibly Ariidae
Characiformes or Clupeiformesa scale