Upper Cretaceous cyclic sequences in Germany and marl–opal-rich Tortonian-Messinian strata in the Sorbas basin related to multiple sea drawdown have been correlated with Milankovitch orbital forcing.
The base of the Tortonian stage is at the last common appearance of calcareous nannoplankton Discoaster kugleri and planktonic foram Globigerinoides subquadratus.
Astroscopus countermani is an extinct species of stargazer described from a cranium found in Tortonian deposits of the Calvert Cliffs of what is now Maryland.
The top of the Serravallian (the base of the Tortonian stage) is at the last common appearance of calcareous nannoplanktons Discoaster kugleri and planktonic foram Globigerinoides subquadratus.
†Astroscopus countermani Carnevale, Godfrey & Pietsch, 2011 Extinct species described from the Tortonian deposits of Calvert Cliffs, Maryland.