Neoproterozoic Oxygenation Event and Ediacaran Biota

When did the Neoproterozoic oxygenation event take place

~800–540 Ma

What happens to the Neoproterozoic carbon isotope excursions

This event coincides with Snowball Earth and rise of Ediacaran biota, with multiple large δ¹³C excursions in Neoproterozoic. Shuram and Bitter Springs events stand out. Potential links to oxygenation and biological innovation. Complexity in linking carbon cycles to oxygenation

Positive excursions: enhanced organic burial

Negative excursions: ocean anoxia or methane release

What are metazones

Early representatives of modern phyla or extinct phyla in the fossil record

When is the first appearance of metazoans

~600 Ma

When did the Ediacaran Biota flourish

~635–541 Ma

What are Ediacaran Biota

First unambiguous evidence of complex multicellular organisms – worldwide distribution. They have fractal-like body plans and lack of clear internal organs or feeding structures with predominantly soft-bodies. Suggested to represent an evolutionary ‘dead end’ unrelated to modern animals

What is the fossil plan on Ediacaran Biota like

Debatable evidence of some modern phyla. Primarily sessile, no preserved hard parts (e.g. no shells). Fossils are mostly impressions on shallow depth sandstone beds and largely vanish from the fossil record by the early Cambrian

What are Vendobiota

Ediacaran organisms as a distinct kingdom of life

Why was the Vendobiota concept rejected

-Improved fossil evidence shows some Ediacaran taxa share features with early animals.

-Taphonomic studies reveal previously overlooked anatomical details.

-Phylogenetic advances link some taxa (e.g., Dickinsonia) to early metazoans.

-The term ‘Vendobiota’ is now seen as overly restrictive and inconsistent with new insights into Ediacaran diversity.