Aeronian

In the geologic timescale, the Aeronian is an age of the Llandovery Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon that began 440.5 ± 1.0 Ma and ended 438.6 ± 1.0 Ma (million years ago). The Aeronian Age succeeds the Rhuddanian Age and precedes the Telychian Age, all in the same epoch.

Aeronian

440.5 ± 1.0 – 438.6 ± 1.0 Ma

PreꞒ

↓

Chronology

−444 —

–

−442 —

–

−440 —

–

−438 —

–

−436 —

–

−434 —

–

−432 —

–

−430 —

–

−428 —

–

−426 —

–

−424 —

–

−422 —

–

−420 —

–

−418 —

Paleozoic

O

Silurian

D

←

←

←

Subdivision of the Silurian according to the ICS, as of 2023.
Vertical axis scale: Millions of years ago

Etymology

Name formality

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

FAD of the graptolite Demirastrites triangulatus

Lower boundary GSSP

Hlásná Třebaň section, Czech Republic
49°55′23″N 14°12′43″E / 49.9230°N 14.2119°E

Lower GSSP ratified

2024

Upper boundary definition

FAD of the graptolite Spirograptus guerichi

Upper boundary GSSP

El Pintado section, Seville, Spain
37°59′07″N 5°55′43″W / 37.9853°N 5.9285°W

Upper GSSP ratified

2024

During the Aeronian the Sedgwickii Event occurred in which graptolite diversity was greatly reduced. This event has been attested in locations such as today's Canada, Libya as well as in La Chilca Formation in Argentina (then part of Gondwana).

It was also from this time that the first gnathostomates appeared, represented by the genera Qianodus and Fanjingshania.

GSSP

The GSSP is located in the Trefawr Track section, 500m north of Cwm-coed-Aeron Farm, Wales, UK. The GSSP lies within the gently-dipping blocky mudstones of the Trefawr Formation, which principally yield abundant and diverse shelly faunas, but also contain enough graptolites to allow recognition of several biozones.