PRECAMBRIAN
CLOSED
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Submissions for the PRECAMBRIAN subphase are closed
Beginning - 31st March 2024
Deadline - 30th April 2024
Read the rules before participating in this contest.
PRECAMBRIAN
4567.3 - 538.8 mya
The Precambrian (also known as Pre-Cambrian or Cryptozoic) is the earliest part of Earth's geological history, predating the Phanerozoic eon, this one being the current one we are living in.
The Precambrian covers events of great importance to our Earth's geology, such as the formation of the Earth's crust (circa 4.4 billion years ago), and subsequently the Earth's water oceans, which give this planet so much uniqueness among its peers in the Solar System.
This is also the period when life on Earth first developed, though the exact date for its origin is heavily debated. There is some evidence that life may have been already on the planet some 4.2 billion years ago. They started out as unicellular creatures, but over time and by the end of the Precambrian stage, we already see well developed macroscopic and multicellular organisms, with some of the earliest appearances of shelled creatures in the fossil record marking the starting point of the subsequent Phanerozoic Eon. Already during the late Precambrian, circumstancial evidence, be it via tracks or molecular clock dating, imply that more advanced animals that would become dominant in the Phanerozoic were already present in the Precambrian, such as trackways implying leg-like appendages have already evolved, at least, some 550 million years ago. This later evolution was triggered by the earlier formation of the first lifeform via abiogenesis, though the exact circumstances for its development is largely unknown, with the RNA world hypothesis suggesting that a primitive RNA replicating system may have been behind the evolution of DNA, which would later transcribe to some form of early lifeform.
The Precambrian also saw major changes in the Earth's atmosphere, with a transition towards an oxygen-rich atmosphere, caused by the evolution of photosynthetic autotrophs, leading to a major eccological crisis, killing off several early anaerobic organisms. In the beginnings, the oxygen would have actually interacted with elements of the Earth's crust, like iron, cancelling its influence in the atmosphere, but eventually the low supply of oxidizable surfaces lead to the accumulation of this gas in the atmosphere, leading to a crescent and unstoppable change.
The Precambrian is traditionally divided into three eons: the Hadean (4567.3 – 4031 mya), Archean (4031 - 2500 mya) and Proterozoic (2500 - 538.8 mya). The Proterozoic is further divided into three eras: the Paleoproterozoic (2500 - 1600 mya), the Mesoproterozoic (1600 - 1000 mya) and the Neoproterozoic (1000 - 538.8 mya). The Neoproteroizoic, being the youngest era, borders the Cambrian period. The Neoproterozoic is further divided into three periods: the Tonian (1000 - 720 mya), the Cryogenian (720 - 635 mya) and the Ediacaran (635 - 538.8 mya). Its believed that the Tonian period might have been the period where the first animal-like lifeforms first appeared. The Paleoproterozoic would have perhaps covered the origin of the first eukaryotic organisms. The Hadean period is mostly when main geological events surrounding the formation of Earth would have occured, including the formation of the Moon, our natural satellite. Some authorities attempt to divide the Precambrian into more "natural" eons that more reliably cover main events of planetary evolution: 1. an early period of planetary formation, culminating in the formation of the Moon; 2. the Hadean (ranging from 4.5 to 3.8 billion years ago) covering much of the heavy bombardment periods when Earth was struck by multiple celestial bodies, including a potential global cooling period; 3. the Archean, defined by some of the earliest crustal formations and ending in banded iron formations that signify an early increase in atmospheric oxygen; 4. the Transition, a period of continued iron banded formation until the first continental red beds form; 5. the Proterozoic, a period with more modern plate tectonics and culminating in the appearance of the first animals.
Over the course of the Precambrian, several continent arrangements can be recorded, including several supercontinents, with the earliest being Vaalbara, lasting from 3.6 to 2.8 billion years ago, with the following supercontinent, Kenorland, forming 2.7 billion years ago and splitting between 2.45 and 2.1 billion years ago into four proto-continent cratons called Laurentia, Baltica, Yilgarn and Kalahari; ultimately the supercontinent Columbia lasted from 2.1 to 1.3 billion years ago, and later the supercontinent Rodinia lasted from 1.3 to 0.6 billion years ago, splitting into eight different continents.
main source: Wikipedia
A Earth map reconstruction, some 650 mya
SUGGESTED SUBMISSIONS (not canon)
(this space will be reserved to catalogue submissions done for this contest, simply for people to get a sense of what other people are working on)
Species (singular species submissions)
Species (singular species submissions)
Name: Octopedinia pseudos
Creator: MinecraftOP67
Size: 50 cm
Location: Shallow waters of southern Pannotia
Time period: 560-527 mya
Clade: Planulozoa, Bilateria
Octopedinia pseudos is a species of bilaterian from the middle Ediacaran to the early Cambrian. These bilaterians occupied The niche of octopuses and cuttlefish are adaptable and flexible to the surrounding environment. Being able to survive the transition from the Ediacaran - the Cambrian explosion. Surviving alongside much more complex organisms, are animals that feed on algae and other invertebrates.
Name: Neodickinsonia micra
Creator: godzilla2356
Size: Smaller than Dickinsonia (less than 1.4 meters?)
Location: Lived in the same place as Dickinsonia (presumably coastal seas around Gondwana and Baltica)
Time period: 549 mya
Clade: Dipleurozoa, Dickinsoniidae
A smaller descendant of Dickinsonia. Lives a similar lifestyle to its ancestor.
Clades (multiple related species submissions; 2 - 3 species)
Clades (multiple related species submissions; 2 - 3 species)
To be added
Ecosystems (2-6 species that live in one shared real or fictional ecosystem)
Ecosystems (2-6 species that live in one shared real or fictional ecosystem)
To be added
SUGGESTED EXTINCTIONS
(clades that are suggested to go extinct in this time period)
SUGGESTED EXTINCTIONS
(clades that are suggested to go extinct in this time period)
To be added
SUGGESTED ECOSYSTEMS
(real or fictional ecosystems suggested by the community for other people to build into)
SUGGESTED ECOSYSTEMS
(real or fictional ecosystems suggested by the community for other people to build into)
To be added
CANON
CANON
OFFICIAL
(ultimate canonical compilation of submissions; official submissions, extinctions and ecosystems can only fall in this category after the deadline is over and proper judging can occur; I will have authority to canonize my own submissions before the deadline, however, and that information can be used by other people to build over the canon in anticipation)
OFFICIAL
(ultimate canonical compilation of submissions; official submissions, extinctions and ecosystems can only fall in this category after the deadline is over and proper judging can occur; I will have authority to canonize my own submissions before the deadline, however, and that information can be used by other people to build over the canon in anticipation)
SPECIES
Name: Vetusorubra rufalga
Creator: AlDodo
Size: 60-70 cm
Location: North America
Time period: 1200 mya
Clade: Archaeplastida, Rhodophyta
This species of rhodophyte is a rather basal and primtive species, probably a stem relative of the clade that includes the known Eurhodophytina and Proteorhodophytina clades (both which would split from each other shortly after this time period), and otherwise pretty typical for a member of this group known to be among the oldest and most relictual order of multicellular organisms still alive in our timeline's modern day.
It fills a niche typical of a normal alga. A primary characteristic is its pigment composition, which is composed of a single type of chlorophyll, chlorophyll a, carotenoids and characteristic pigments known as phycobiliproteins.
One of the most important traits of this creature is that it is a multicellular organism, a pretty advanced lifeform compared to most others ones it coexisted with within its habitat and era.
It lives in marine deposits of relatively shallow water that correspond to the modern north american geological sediment at the time of the Precambrian period, growing on rocks and other hard surface areas.
It is eaten by other organisms, forming already a surprising pillar to its ecosystem, and also liberating oxygen through photosynthesis.
Name: Thalassocampana tetrabrachia
Creator: Captain Knorke
Size: Just over 1 millimeter in length
Location: Coastal seas of the supercontinent Pannotia between what is now South America and Africa
Time period: 585-580 mya
Clade: Animalia, Eumetazoa
Thalassocampana tetrabrachia is a eumetazoan of uncertain affinities (probably a stem-ctenophore). It is characterized as a planktonic, bell-shaped gastrea, a bit more than one millimeter in length. Its diminute size implies it feeds mostly on unicellular eukaryotes. A row of cilia surrounding the oral opening creates a water current that is used to suck the prey into the digestive cavity. No separate anus is observed. Gametes form from cells in the wall of the digestive cavity and are released through the oral opening. Its most unusual feature are strange four tentacles which are innervated by the apical organ and allow the animal to have some control of its movement. T. tetrabrachia went extinct during the Gaskiers glaciation, which was just starting by the point in time it went extinct.
Name: Succuiscolex rostratus
Creator: mrblueshark
Size: 1 millimeter long
Location: Coastal seas around Gondwana and Baltica
Time period: 564 - 550 mya
Clade: Bilateria, Xenambulacraria, Totixenacoelomorpha, Undulatia, Parvorhyncha, Parvorhynchiformes, Parvorhynchoideae
In the shallow seas of the Edicaran, strange and exotic organisms can be observed living on the large ones that feed on the vast microbial mats. These are representatives of the Parvorhynchiformes order, and they represent one of the oldest known parasites, among advanced animals. They're strange bilaterians with unclear affinities, though their relationships seem to most promptly conform with the Totixenacoelomorpha clade, a large clade that is only represented by the Xenacoloemorpha in our timeline's present. Back in the Precambrian, stem-xenacoelomorphs appear to have been more diverse in shape and form, reflecting a hidden diversity. The parvorhynchiforms appear to have been early specialists of parasitism in these early moments of Earth's evolution.
The species Succuiscolex rostratus specifically specializes in members of the Dickinsonia genus, proarticulates widespread across the coastal seas around Gondwana and Baltica.
They are oviparous. Their eggs are incredibly tiny white spheres only 0.05 millimeters in diameter. Once laid and fertilized in microbial mats on the seafloor, Dickinsonia are bound to graze and enter into contact with them; once they do, the eggs make their way to their digestive system. Despite the ingenuity of this strategy, it is without refinements, as many of the eggs actually don't endure this travel and are destroyed, however a sufficient number is sure to survive and hatch into minuscule 0.1 millimeter hatchlings in the interior of Dickinsonia.
The hatchlings spread across the internal structures of their host and attach their hard un-mineralised mouthparts to the walls to feed off the nutrients of their host.
After about 60 days, they grow up to 1 millimeter adults capable of reproduction. They make their way out of their host and into the sand where individuals will find each other via pheromones. The cycle restarts once they deposit eggs and sperm to externally fertilise them. The adults will die, shortly after mating.
This cycle of reproduction has proved relatively benefitial for these strange precambrian worms, and especially during the times of abundance in the Ediacaran. However, conditions would change before the start of the Cambrian, leading to the extinction of many characteristic Ediacaran groups, jeopardizing the survival of the parvorhynchiform group.
ECOSYSTEMS
Name: Rhodesian Biota
Creator: YellowPanda2001
Time period: 544 mya
Location: Shallow seas outside of what is today's South Africa
The Rhodesian Biota, is the name given to a peculiar shallow ocean ecosystem located off the coast of what is today South Africa. This shallow sea, merely six million years before the beginning of the Cambrian period, shows a plethora of unique living organisms that are not found in other Ediacaran sites. This unique biota is a reflection of the vast evolutionary and biological shifts that were occuring at the end of the Ediacaran, during the beginnings of the Baykonurian glaciation, which is hypothesized to have triggered the so called Cambrian explosion. In this environment, only some of the organisms represented leave much of a legacy in later time periods, showing a mosaic of lineages that would perish alongside those that would flourish later, another indicator of the volatility of these short-lived environments.
Name: Garlandius lichenomimus
Size: Up to 5 centimeters wide
Clade: Pseudofungi, Falaciomycetes
Growing like a strange marine lichen in the sediment, is the species Garlandius lichenomimus. It may appear like a fungi, but it is actually an algae. Part of the Pseudofungi group (which still exists in our timeline's today), it is a peculiar algae that has converged with fungi in a certain manner, and its believed that it did so through an ancient horizontal gene transfer, where fungi genes were incorporated into the genome of their ancestors. This allows this species and its relatives to grow long hyphae and feed through osmotrophy, quite like a fungus. This species is exceptionally large for a pseudofungus, and it is unrelated to forms that exist in our timeline's today, granting its attribution to its own distinct class, Falaciomycetes, characterized for their frequent macroscopic size.
Name: Palaeolingua cagei
Size: Up to 10 centimeters long
Clade: ParaHoxozoa, Planulozoa
A tongue-like worm travels through the sediment. Resembling a slug, it is Palaeolingua cagei. It resembles heavily the infamous proarticulates of earlier moments of the Ediacaran, with their flattened and annelated texture. However, it turns out that is just a resemblance. These worms are part of a conservative lineage of stem-bilaterians, but nevertheless closer to true bilaterians than the proarticulates. They seem to have split off from crown bilaterians shortly after these have split off from proarticulates. This living tongue feeds on organic detritus it may find in the rich sediment of these subtropics.
Name: Cuniculovermes filamentosus
Size: 1 centimeter long
Clade: ParaHoxozoa, Planulozoa
Another enigmatic, but rather stranger, organism of the Rhodesian Biota is Cuniculovermes filamentosus. This tiny slug-like organism is actually just outside of the crown Bilateria clade, but nevertheless rather close to the crown group. It has a deuterostome condition, where the anus forms before the mouth in embryonic development. This suggests that deuterostomy is ancestral to the bilaterians as a whole. Its most striking features are its short body covered in hair-like filaments, as well as very long fleshy protuberances coming out of its "head", that resemble the ears of a bunny.
Name: Eoholothura rhodesiensis
Size: 15 centimeters long
Clade: Cambroernida, Ramopoda
A peculiar worm found in the sediments of the Rhodesian environment is Eoholothura rhodesiensis. It is very reminiscent of the holothuroids, or sea cucumbers, but these haven't evolved yet by the Precambrian. Instead, this is a stem representative of the Ambulacraria clade (which contains our timeline's echinoderms and hemichordates). It is a bilaterian animal, and consistently, has bilaterian symmetry. It also resembles a penis worm (Priapulida), and could have occupied similar niches to them, before their eventual diversification. It is part of a unique but numerically reduced subphyllum, the Ramopoda, which may be included in the wider Cambrian phyllum, known as Cambroernida. It has a characteristic retractable ramified protuberance, that may be homologous to the ramified tentacles of the later Cambrian cambroernids.
Name: Rhodesius undulatus
Size: 2 centimeters long
Clade: Xenambulacraria, Totixenacoelomorpha, Undulatia
Open water swimmers only start to be formally recorded by the Cambrian period, however, free swimming animals would already have been evolving in the Precambrian. Rhodesius undulatus is a representative of this hidden diversity. Resembling a minute transparent blue eel, it is a peculiar bilateral worm that appears to be related to our timeline's xenacoelomorphs. This free swimming species resembles fairly a primitive chordate, and likewise, it even has a central cord running across its midline, which is unusual, considering its modern relatives don't have that. Chordates would eventually evolve some millions of years later and perfect this bodyplan even more profoundly.
EXTINCTIONS
- Trilobozoa (†542 mya): the so called three-lobed animals, rather successful during the Ediacaran, become extinct, 542 million years ago, in the aftermath of the Baykonurian glaciation, which was accompanied by massive biotic shifts, leading these peculiar organisms to go extinct due to competition or predation by novel groups of animals. (YellowPanda2001)
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