The Tsagaantsav Formation, Tsagantsab Formation or Tsagan-Tsab Formation (Russian: Tsagaantsav Svita) is an Early Cretaceous (Hauterivian to Barremian) geologic formation in Mongolia. Indeterminate sauropod and psittacosaurid remains have been recovered from the formation. Remains of the pterosaur Noripterus, which were originally given their own genus, "Phobetor" have also been recovered from the formation.
Graham et al. 2001 reported radiometric dates of 131 and 126 Ma from the formation.
Fossil content
The following fossils were reported from the fluvial to lacustrine sandstones and siltstones of the formation: Pterosaurs Dsungaripterus parvus Noripterus complicidens Dinosaurs Psittacosaurus sp. Sauropoda indet. Theropoda indet. Lizards Dorsetisauridae indet. Insects
Khutelchalcis gobiensis
Eopelecinus fragilis
E. minutus
Praeichneumon townesi
Eobraconus inopinatus
Westratia femorata
W. pachygaster
W. pentadecamera
Langtonius cynaricaudatus
Eugenodiamesa makarchenkoi
Jurochlus adustus
Ellia khara
Protanyderus mesozoicus
Metatrichopteridium cladistorum
Plectrocentropus sulis
Eoclipsis mongolica
Coptoclavisca nigricollinus
Cretorabus orientalis
Mesaclopus mongolicus
Chinocimberis dispersus
Megametrioxenoides longus
Uroperla lacerata
Trianguliperla quassa
Aphaorus curtipes
Juleyrodes ?gilli
Izinabis kerzhneri
Siberiogenites medius
Torephemera longipes
Leptoneta calyptrata
Albisca tracheata
Epeoromimus infractus
Osmylogramma martinsoni
Juraphididae indet.