Stage 2

System (period)	Series	Stage (age)	Lower boundary, Ma
Ordovician	Lower	Tremadocian	485.4±1.9
Cambrian	Furongian	Stage 10	~489.5
		Jiangshanian	~494
		Paibian	~497
	Miaolingian	Guzhangian	~500.5
		Drumian	~504.5
		Wuliuan	~509
	Series 2	Stage 4	~514
		Stage 3	~521
	Terreneuvian	Stage 2	~529
		Fortunian	538.8±0.2
Ediacaran			older
Subdivisions and "golden spikes" according to IUGS as of September 2023

Stage 2 is an unnamed second and upper stage of the Terreneuvian series, corresponding to the Stage 2 age of the Terreneuvian epoch. It lasted from approximately 529 Ma to around 521 Ma (million years ago). It is preceded by the Fortunian age of the Terreneuvian and is followed by the Stage 3 age of the Series 2 epoch. GSSP and naming have not yet been chosen for this stage, but geologists around the world are working on this problem. It is the lowermost unnamed stage in International Chronostratigraphic Chart.

Definition

The GSSP of Stage 2 has not yet been accepted and there are no sections selected as candidates. The first appearance of Small Shelly Fossils of Watsonella crosbyi or Aldanella attleborensis is suggested as a marker of the lower boundary of this stage by some researchers.

Coincidences with regional stages

Some regional stages overlap partially or completely with Stage 2. From upper to lower:

Siberia:

• Tommotian
• Nemakit-Daldynian (upper part)

North America:

• Begadean (central part)

West Avalonia:

• Placentian (central part)

China:

• Meishucunian (upper part)

Life during Stage 2 age

Halkieria reconstruction

Eccentrotheca

Since neither the lower nor the upper boundaries of Stage 2 have yet been defined, there is no fauna included in the corresponding age. However, various fossils of predominantly small organisms are known from the Tommotian that completely corresponds to Stage 2 age. New phyla of animals, which appeared in the previous Fortunian age, continued to actively evolve in the seas. Some of these small animals have an unclear systematic position and, apparently, later became extinct, leaving no descendants. Aculiferan molluscs (Halkieria), brachiopods (Paterina, Micromitra), hyolithohelminths (Torellella, Hyolithellus), tommotiids (Eccentrotheca, Sunnaginia) and Coleoloides, a small shelled organism, have been found in Nova Scotia, Canada. Similar biota including mobergellids (Mobergella) and hyoliths (Hyolithes) is known from Sweden. Mafangscolex, a priapulid worm, was discovered in Yunnan, China. Trilobites, the most characteristic animals of the Paleozoic, had not yet appeared at this time.

External links

• https://paleobiodb.org/classic/displayTimescale?interval=Stage%202