Calpionella

Calpionella is an extinct genus of calpionellid, a group of single celled eukaryotes. Their fossils are found in rocks of Upper Jurassic to Lower Cretaceous age.
Etymology.
The name is derived from the Greek "κάλπις", meaning "water jug".
Biostratigraphic significance.
The first occurrence of the species "Calpionella alpina" marks the beginning of the Berriasian and thus Cretaceous.
Distribution.
Fossils of the genus have been found in: