Serravallian

The Serravallian is, in the geologic timescale, an age or a stage in the middle Miocene Epoch/Series, which spans the time between 13.82 Ma and 11.63 Ma (million years ago). The Serravallian follows the Langhian and is followed by the Tortonian.^[6]

Serravallian
13.82 – 11.63 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Chronology
−24 — – −22 — – −20 — – −18 — – −16 — – −14 — – −12 — – −10 — – −8 — – −6 — – −4 — – −2 — C e n o z o i c P g N e o g e n e Q O C M i o c e n e P l i o. P C Chattian Aquitanian Burdigalian Langhian Serravallian Tortonian Messinian Zanclean Piacenzian Gelasian         ← Messinian salinity crisis[1] ← North American prairie expands[2] Subdivision of the Neogene according to the ICS, as of 2023.[3] Vertical axis scale: Millions of years ago
Formerly part of	Tertiary Period/System
Etymology
Geochronological name	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
Time span formality	Formal
Lower boundary definition	Mi3b Oxygen-isotopic event (Global cooling episode)
Lower boundary GSSP	Ras il Pellegrin section, Fomm ir-Riħ Bay, Malta 35.9139°N 14.3361°E / 35.9139; 14.3361
Lower GSSP ratified	2007[4]
Upper boundary definition	LAD of the Haptophyte Discoaster kugleri
Upper boundary GSSP	Monte dei Corvi Beach section, Ancona, Italy 43.5867°N 13.5694°E / 43.5867; 13.5694
Upper GSSP ratified	2003[5]

It overlaps with the middle of the Astaracian European Land Mammal Mega Zone, the upper Barstovian and lower Clarendonian North American Land Mammal Ages and the Laventan and lower Mayoan South American Land Mammal Ages. It is also coeval with the Sarmatian and upper Badenian Stages of the Paratethys time scale of Central and eastern Europe.

Definition

The Serravallian Stage was introduced in stratigraphy by the Italian geologist Lorenzo Pareto in 1865.^[7] It was named after the town of Serravalle Scrivia in northern Italy.

The base of the Serravallian is at the first occurrence of fossils of the nanoplankton species Sphenolithus heteromorphus and is located in the chronozone C5ABr. The official Global Boundary Stratotype Section and Point (GSSP) for the Serravallian is in the 'Ras il-Pellegrin' section, located at the 'Ras il-Pellegrin' headland in the vicinity of 'Fomm ir-Rih' Bay, SW Malta.The base of the Serravallian is represented in the field as the formation boundary between the Globigerina Limestone formation and the Blue Clay formation.^[8] The base of the Serravallian is related to the Mi3b oxygen isotope excursion marking the onset of the Middle Miocene Cooling step.

The top of the Serravallian (the base of the Tortonian Stage) is at the last common appearance of calcareous nanoplanktons Discoaster kugleri and planktonic foram Globigerinoides subquadratus. It is also associated with the short normal-polarized chronozone C5r.2n.

Paleontology

Cartilaginous fish

• Lamniformes
  • Otodontidae: †Otodus^[9]

Birds

Ancestors of the long-tailed duck have been found dating from the Serravalian of Hungary

• Anseriformes
  • Anatidae: Clangula sp.^[10]

Mammals

• Primates
  • Hominidae: †Anoiapithecus^[11]

Reptiles

• Squamata
  • Agamidae: Pogona and Diporiphora diverged from their last common ancestor during the Serravallian. ^[12]
• Crocodylomorpha
  • The last known sebecid, Barinasuchus, goes extinct about 11.8 mya. Thus ending the lineage of the notosuchians.