Editing Neoproterozoic (section)

==Paleobiology==
{{main|Ediacaran biota}}

The idea of the Neoproterozoic Era was introduced in the 1960s. Nineteenth-century paleontologists set the start of [[metazoan|multicellular]] life at the first appearance of hard-shelled [[Arthropod | arthropods]] called [[trilobite]]s and [[Archaeocyatha|archeocyathid sponges]] at the beginning of the [[Cambrian]] Period. In the early 20th century, paleontologists started finding fossils of multicellular animals that predated the Cambrian. A complex fauna was found in South West [[Africa]] in the 1920s but was inaccurately dated. Another fauna was found in South Australia in the 1940s, but it was not thoroughly examined until the late 1950s. Other possible early animal fossils were found in Russia, England, Canada, and elsewhere (see [[Ediacaran biota]]). Some were determined to be [[pseudofossil]]s, but others were revealed to be members of rather complex biotas that remain poorly understood. At least 25 regions worldwide have yielded [[metazoan]] fossils older than the classical Precambrian–Cambrian boundary (which is currently dated at {{Ma|538.8}}).<ref>{{cite journal | first = A. H. | last = Knoll |author2=Walter, M. |author3=Narbonne, G. |author4=Christie-Blick, N. | title = The Ediacaran Period: a new addition to the geologic time scale | pages = 13–30 | journal = Lethaia | volume = 39 | issue =1| year = 2006 | url =https://academiccommons.columbia.edu/doi/10.7916/D8W38687/download | doi = 10.1080/00241160500409223| bibcode = 2006Letha..39...13K }}</ref><ref name="StratChart 2022"/>

A few of the early animals appear possibly to be ancestors of modern animals. Most fall into ambiguous groups of frond-like organisms; discoids that might be holdfasts for stalked organisms ("medusoids"); mattress-like forms; small calcareous tubes; and armored animals of unknown provenance.

These were most commonly known as [[Vendian biota]] until the formal naming of the Period, and are currently known as Ediacaran Period biota. Most were soft bodied. The relationships, if any, to modern forms are obscure. Some paleontologists relate many or most of these forms to modern animals. Others acknowledge a few possible or even likely relationships but feel that most of the Ediacaran forms are representatives of unknown animal types.

In addition to Ediacaran biota, two other types of biota were discovered in China. The [[Doushantuo Formation]] (of Ediacaran age) preserves fossils of microscopic marine organisms in great detail.<ref>{{cite journal |last1=Muscente |first1=A.D. |last2=Hawkins |first2=Andrew D. |last3=Xiao |first3=Shuhai |title=Fossil preservation through phosphatization and silicification in the Ediacaran Doushantuo Formation (South China): a comparative synthesis |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=September 2015 |volume=434 |pages=46–62 |doi=10.1016/j.palaeo.2014.10.013|bibcode=2015PPP...434...46M }}</ref>{{Contradictory inline|article=Doushantuo Formation|reason=The Doushantuo Formation is of Ediacaran age. This suggests it is part of the Ediacaran biota.|section=|date=May 2024}} The [[Huainan biota]] (of late Tonian age) consists of small worm-shaped organisms.<ref>{{cite journal |last1=Malenkov |first1=A. G. |title=13C, Ontogeny, and the Paradox of Evolution |journal=Biophysics |date=May 2018 |volume=63 |issue=3 |pages=477–484 |doi=10.1134/S0006350918030156}}</ref>

[[Molecular phylogeny]] suggests that animals may have emerged even earlier in the Neoproterozoic (early Tonian), but physical evidence for such animal life is lacking. Possible [[keratose sponge]] fossils have been reported in reefs dated to {{circa}} 890 million years before the present, but remain unconfirmed.<ref>{{cite journal |last1=Turner |first1=Elizabeth C. |title=Possible poriferan body fossils in early Neoproterozoic microbial reefs |journal=Nature |date=28 July 2021 |volume=596 |issue=7870 |pages=87–91 |doi=10.1038/s41586-021-03773-z|pmid=34321662 |pmc=8338550 |bibcode=2021Natur.596...87T |doi-access=free }}</ref>

The widespread proliferation of marine algae during the Neoproterozoic caused an increased flux of algal particulate matter to benthic environments, stimulating the evolution of microbial eukaryotic predators.<ref>{{Cite journal |last1=Mills |first1=Daniel B. |last2=Vuillemin |first2=Aurèle |last3=Muschler |first3=Katharina |last4=Coskun |first4=Ömer K. |last5=Orsi |first5=William D. |date=19 February 2025 |title=The Rise of Algae promoted eukaryote predation in the Neoproterozoic benthos |url=https://www.science.org/doi/10.1126/sciadv.adt2147 |journal=[[Science Advances]] |language=en |volume=11 |issue=8 |doi=10.1126/sciadv.adt2147 |issn=2375-2548 |pmc=11838005 |pmid=39970204 |access-date=26 February 2025}}</ref>