Genus: Sesimophis HSIOU, ALBINO, MEDEIROS, & SANTOS, 2014
Etymology: Greek, seism, "earthquake"; in allusion to the type locality Falesia do Sismito at Cajual Island, and Greek, ophis, "snake."
Species: septentrionalis HSIOU, ALBINO, MEDEIROS, & SANTOS,
Etymology: Latin, Septentrionalis, from the north, northern, refering to the type locality, which is the northermost region of Maranhao.
Holotype: CPHNA-MA VT-1221
Locality: Falesia do Sismito, 2°28'43.0"S, 44°28'10.3"W, Cajual Island, Maranhao State, Brazil.
Horizon: Alcantrar Formation, Itapecuru Group.
Age: Cenomanian Stage, Upper Gallic subepoch, Lowest Gulf Epoch, Late Early to Early Middle Cretaceous.
Material: Almost complete posterior trunk vertebra.
= cf. Seismophis septentrionalis CPHNA-MA VT-1222: Incomplete mid-trunk vertebra.