Genus: Stenopterygius JAEKEL, 1904
Etymology: Greek, stenos, “narrow”, Greek, pterygion, “fin” + us: Narrow fin.
= Chacaicosaurus FERNANDEZ, 1994
Etymology: Chacaico refers to the area where the holotype was found, and saurus in Greek denotes lizard: Chacaico lizard.

Species: uniter HUENE, 1931
Etymology:

Referred material:

= Stenopterygius uniter WIMAN, 1921 (partim)

Locality: Baden-Wurttemberg State, Germany.

Horizon:

Biostratigraphy:

Age: Toarcian Stage, Upper Lias Epoch, Late Early Jurassic.

Material:

WIMAN, 1921/PARDO-PEREZ, KEAR, GOMEZ, MORONI & MAXWELL, 2018

PMU 24320: Skull and skeleton.

Note: Traumatic ingury to the mandible and presacral ribs (3 healed ribs), ankylosis vertebrae 34, 35, calluses on the right side midsection of ribs 29-34, and co-ossification of dorsal neural spines 34-45.