CAMBRIAN
CLOSED
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Submissions for the CAMBRIAN subphase are closed
Beginning - 30th May 2024
Deadline - 30th June 2024
Read the rules before participating in this contest.
CAMBRIAN
538.8 - 485.4 mya
The Cambrian is the first geological period of the Paleozoic Era, and therefore, also the first period of the Phanerozoic Eon. It is unique for being a very ancient period of time that happens to have a lot of data about its existing biology, so we even know more about the biology of the Cambrian than some more recent time periods. It is marked by a sharp increase in the diversity of multicellular life, which, despite having grown increasingly common in the later parts of the previous Precambrian, it is in the Cambrian that we see mineralized organisms becoming far more common than before. The Cambrian begins with the so called Cambrian Explosion, that would give rise to many of the lineages that culminate in the animal phylla known from our timeline's today.
The Cambrian period was named by Adam Sedgwick in 1835, dividing it into three groups: Lower, Middle and Upper. Around this time, the exact borders of the Cambrian weren't exactly clear, with a gap of disputed stratigraphy being debated to belong to either the Cambrian or the Silurian periods. The definitions of the Cambrian period grew clearer as a more identifiable fossil record was realized. However, stratigraphical debates would keep on going for decades, until the eventual nomination of the Ordovician period, that serves as a border between the Cambrian and the Silurian.
Currently, the Cambrian is defined based on a Global Boundary Stratotype Section and Point (GSSP), using a single formation that identifies the lower boundary of this period. A continuous sedimentary sequence in Newfoundland was settled to serve as the base of the Cambrian period, characterized by the earliest presence of the ichnospecies Treptichnus pedum, an indicator of prevailing burrowing behaviours in animals, one of the most fundamental biotic shifts between Precambrian and Cambrian ecosystems. The exact date of the lower boundary for the Cambrian period had different proposals in the past, with estimates dating back to 570 million years, at one point, being accepted. However, a ash horizon from Oman, yields an estimated date of 538.8 million years for the lower boundary, corresponding to a decline in carbon-13, correlating with similar excursions across the globe, and also to the disappearance of Ediacaran fossils, such as Namacalathus and Cloudina (though the exact date is still being debated to this day, and the lower boundary may even date back to a slightly older time). The first half of the Cambrian is divided into its two first epochs: the Terreneuvian (538.8 - 521 mya) and the unnamed Cambrian Series 2 (521 - 509 mya), the latter divided by the Cambrian Stage 3 (521-514 mya) and the Cambrian Stage 4 (514-509 mya). The third epoch of the Cambrian is named Miaolingian, lasting from 509 to 497 million years ago. The Miaolingian is divided into three stages: Wuliuan (509 - 504.5 mya), Drumian (504.5 - 500.5 mya) and Guzhangian (500.5 - 497 mya). The boundary between the Cambrian Series 2 and the Miaolingian (c. 509 mya) is characterized for a mass extinction that (presumably) killed off the olenellid and eodiscid trilobites, as well as most redlichiid trilobites. The final epoch of the Cambrian is the Furongian, dated from 497 to 485.4 million years ago.
The position and organization of the continents, during the Cambrian, is something we can infer from palaeomagnetic, palaeobiogeographic, tectonic, geological and palaeoclimatic data. Early in the Cambrian period, for example, we know that the south pole laid around what is today western South America, and by the middle of the Cambrian, the south pole would be located where what is now northwest Africa (both of these regions would be located in the giant continent of Gondwana). Smaller continents existed too, like the one that included Annamia and South China, situated off north central Gondwana. The continent of Laurentia would have recently split out of Gondwana, forming the Iapetus Ocean, separating Laurentia from both Gondwana and Baltica, and during the mid-late Cambrian, Laurentia would be mostly covered by shallow seas. The cratons that formed Gondwana itself would have formed around the Neoproterozoic or early Cambrian. The Kuunga Orogeny, situated between northern Gondwana (corresponding to modern Congo, Madagascar and India) and southern Gondwana (southern Africa and east Antarctica) was still ongoing, forming metamorphic proccesses and igneous intrusions. Subduction zones extended around much of Gondwana's margins, from northwest Africa southwards round South America, South Africa, East Antarctica, and the eastern edge of West Australia, with shorter subduction zones existing north of Arabia and India. Large continental flood basalts coming from the Kalkarindji large igneous province (situated in modern day northern Australia) were among the largest in the entire Phanerozoic eon, and might have contributed to mass extinctions occurying in the early-mid Cambrian. The smaller continent of Baltica rotated more than 60º anti-clockwise during the Cambrian, beginning to drift northwards, being separated by Gondwana due to the Ran Ocean. Baltica itself was separated in two, by a shallow sea, forming the Fennoscandia (Scandinavia) and Sarmatia (Ukraine) subcontinents. The sediments deposited in these unconformably overlay Precambrian basement rocks. Around the northeastern margin of Baltica we observe the end of the Ediacaran Timanian Orogeny, and this region sees no sediment deposition across the early-mid Cambrian, being followed by sedimentation and rifting during the late Cambrian. Another continent was Siberia, whose northern edge (corresponding to the modern southern siberian edge) was mountainous. A series of island arcs accreted in the northeastern margin of Siberia, forming what is now the Altai-Sayan terranes (correspondng to the modern day borders of Russia, Kazakhstan, China and Mongolia). Along the then western siberian margin, during the early Cambrian, rifting was followed by the development of a passive margin. Central Asia was a island archipelago, with its northern margin being characterized by thick sequences of platform carbonates and fluvial to marine sediments resting unconformably on Precambrian basement. Then there is the North China continent, located in tropical latitudes, and then the single continent of South China and Annamia.
The climate of the Cambrian was very variable, with the early parts of the period being believed to be rather glacial, with somewhat icehouse conditions. While in the Cambrian Stage 3 the climate was rather cool, by the following Cambrian Stage 4, the climate was rather warm, comparable to the hothouse conditions we see in the later Cretaceous and Paleogene periods. During this stage, between 511 and 510.5 million years ago, we observe the Archaecyathid Extinction Warm Event (AEWE), a moment in time that was so hot that it lead to dramatic extinctions in the characteristic archaecyathid sponges.
While continents and climate were changing in the Cambrian, so was life, such as the flora, which was rather different from the previous Precambrian, primarily composed of marine macroalgae, such as the cyanobacterium Marpolia.
The ocean fauna, however, is the largest defining differentiator of this period, with the appearence of abundant new groups of animals, such as the trilobites which, contrary to earlier beliefs, were not exactly the most abundant animals around, with that notion being simply constructed by the fact their hard exoskeletons being easier to fossilize than more fragile exoskeletons of other panarthropods. The ecosystems of the Cambrian are a product of a profound eccological revolution, characterized by the diversification of burrowing animals, that disturbed the otherwise stable microbial mats that were so characteristic of Ediacaran communities. Rapid diversification and evolution of mineralized phylla, such as the bryozoans, also began to be observed. We also start to observe the very first animal incursions onto land, although these were just occasional terrestrial visits, with the ichnofossils Protichnites and Climactichnites (respectively representative of arthropods and slug-like organisms) being evidence of this.
main source: Wikipedia
A Earth map reconstruction, some 515 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)
NO IMAGE
Name: Anomalocaris depticus
Creator: tennis ball
Size: 22.5 centimeters long (not counting the frontal appendages)
Location: Cold areas near Gondwana
Time period: 503.2 mya
Clade: Anomalocarididae, Anomalocaris
A. depticus is a filter feeder half the size of Anomalocaris canadensis. It lives on the sea bed and feeds on plankton, but can also feed on small animals. The eyes are less developed than other anomalocaridids. The mating behaviour is quite simple, after mating the female lays 5-10 eggs and leaves them. For filter feeding it has developed small bristles on its frontal appendages.
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)
Name: Guaminchina Shale
Creator: blue093835
Time period: 502.7 - 497.9 mya
Location: Argentina
Described as similar to the Burgess Shale of Canada, with some of its fauna being composed of wiwaxiids, dinocarididans and other lobopodians. It hails from the Middle Cambrian (Miaolingian).
Name: Rhodopentodon aggregor
Size: 1 - 1.6 meters long
Clade: Lobopodia, Radiodonta, Anomalocarida, Anomalocarididae
Related to Anomalocaris. Has multiple fins.
Its one of the largest radiodonts ever to exist, about the size of a wolf.
Name: Omniacanthopoda melanoleuca
Size: 1.05 meters long
Clade: Hallucishaniids, Hallucigeniidae
One of the closest relatives of Hallucigenia. The name alludes to the fact that every specimen has different leg numbers. The holotype of the species has 12 legs but other fossils are known with more or less feet.
Babies of Omniacanthopoda melanoleuca don't have legs but eventually grow to initially have four legs.
Name: Notowiwaxia argenticus
Size: 2.1 - 3.8 meters long
Clade: Halwaxiida, Wiwaxiidae
A species of soft-bodied animal much like and one of closest relatives of Wiwaxia.
It is described as being the size of a buffalo.
Name: Eschalithozoon giganteus
Size: 2.25 - 2.5 meters
Clade: Vendobionta, Petalonamae
Lives in the ancient reefs of the Guaminchina Shale. Its the last species of petalonamid, lasting from 500.2 to 498 million years ago.
It is a filter feeder but, quite like what is sometimes declared about our timeline's leaf sheep, members of this genus are described being able to engage in photosynthesis. It is probably a monotypic genus, feeding mostly on phytoplankton, but rarely in sargassum-looking algae, making it essentially a photosynthesizing herbivore.
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)
Guaminchina Shale / Argentina (502.7 - 497.9 mya) - Described as similar to the Burgess Shale of Canada, with some of its fauna being composed of wiwaxiids, dinocarididans and other lobopodians. It hails from the Middle Cambrian (Miaolingian). (blue093835)
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: Antipharyngius primitivus
Creator: YellowPanda2001
Size: 2 centimeters long
Location: Shallow seas of Chad
Time period: 530 mya
Clade: Chordata, Asphixyiozoa
530 million years ago, in a shallow inland sea of our timeline's Chad, then part of Gondwana, strange and exotic creatures swam near the sea floor. These would be Antipharyngius primitivus. These are incredibly enigmatic primitive chordates hailing from the late Fortunian age. It has a characteristic notochord, but lacks an important anatomical trait present in most other chordates: pharyngeal slits. These pharyngeal slits, or gills, are a common trait among our timeline's modern chordates, and is also present in the unrelated hemichordates, implying these were an ancestral trait among these organisms. However, the absence of these slits in Antipharyngius provides an enigma. Were pharyngeal slits lost independently in early chordate evolution, were they separately evolved in the chordate lineage, or were they lost and regained again in later chordates? Its hard to tell. What can be told is that Antipharyngius, alongside other members of its unique gilless class, the Asphixyiozoa, represent the most basal chordates to date. Such a high diversification of chordates over the first half of the Cambrian seems to suggest that the Cambrian diversity of chordates actually evolved during the earlier Ediacaran, and eventually were perpetuated in the Cambrian period with great success.
Antipharyngius is a peculiar filter feeding organism with one bucal orifice to feed on small particles found in the sand. The activity of burrowing organisms, which were abounding, globally, during the early Cambrian, provided the ideal eccological opportunities for the proliferation of these basal chordates and this species, alongside others of the clade, could therefore flourish immensely throughout the rest of the Cambrian.
Name: Vermityrannus terus
Creator: Jurassicpasick
Size: 50 centimeters long
Location: Shallow coastlines, inland pools and freshwater courses of northern Laurentia
Time period: 520 mya
Clade: ParaHoxozoa, Planulozoa, Bilateria, Protostomia, Spiralia, Trochozoa, Nemerteamorpha, Dinovermiforma, Avermiforma
Vermityrannus terus is a species of predatory worm-like animal that belongs to the Nemerteamorpha clade, making it a distant relative of our timeline's nemertean worms (also called "ribbon worms"). It evolved in the aftermath of the extinction of the Rhodesian fauna in the Precambrian, which was a faunal assemblage of great significance, for it marked a transitional stage between the typical earlier Ediacaran fauna and the later Cambrian faunal assemblages, dominated by burrowing organisms. Nemerteamorph worms went through an initial evolutionary blast, as they occupied a variety of unique niches in the early Cambrian, though in later stages of the period, this diversity would soon be mostly replaced by newer forms of life, such as annelids and the like. Vermityrannus hails specifically from the Cambrian Stage 3, becoming one of the main predators of the shallow coastline and inland pools of the northern island continent of Laurentia, a landmass nearly the size of modern Australia, and consisting of land that corresponds to the modern north american continent. This species utilizes highly derived bristles to sense its surrounding enviroment, hunting like some of our timeline's bristle worms do such as the bobbit worm (Eunice aphroditois).
It stands as the only known genus of the clade Avermiforma and one of the few genera in Dinovermiforma, a group of dedicated early predatory nemerteamorph worms. It manifests itself as a very primitive version of what today we'd call an apex predator; It hides under the sand of whatever inland pool of water or shallow coastline it stalks and strikes the prey with its peculiar mouth, composed of two lateral appendages with tooth-like structures, and drags it back into the sand. It stays all of its life underwater, as the arid shores of its environment are far too deadly to be visited by an animal of this caliber, not to mention that the land is very barren compared to today, even lacking any significant sign of terrestrial plant life.
The animal itself is only half a meter long, but that already makes it one of the largest Cambrian animals. The average individual does not live past 11 years of age. Their simple brains navigate their world only with the touch of its bristles. This nevertheless makes it the very first predator to arrive into unclaimed inland waters, one would call it the very first river monster. This may appear bizarre, as most of the documented fauna from the Cambrian is largely marine, but around this time, other fossil formations already reveal that animals were colonizing the freshwater realm quite abundantly, with many species of worms, archaeocyathan sponges and even arthropods making their way to inhabit these environments. In the absence of a sustained predatory presence, the arrival of this bizarre coastal giant predatory worm presented itself as adequate.
Name: Primischeli melongi
Creator: Yp3rit
Size: Up to 25 centimeters long
Location: Shallow coastlines of Laurentia, Siberia and northern Gondwana
Time period: 515 mya
Clade: Chordata, Olfactores, Myllokunmingiida, Myllokunmingiidae
P. melongi is a basal chordate and is part of the clade Myllokunmingiida. It has an elongated body form like that of an eel and can reach to a body length of up to 25 cm. This species can be found in coastal seas around Laurentia, Siberia and northern Gondwana. This species often gathers around river mouths, in brackish water, where they feed on plankton and small animals that suffer through osmotic shock, from the difference in salinity between fresh and sea water.
Name: Neoanomalocaris deinognathus
Creator: godzilla2356
Size: 1 foot (30.4 centimeters long)
Location: Burgess Shale and nearby areas
Time period: 499 - 485.4 mya
Clade: Anomalocarida, Anomalocarididae
Males (pictured) are of a bright reddish color, and the females are of a darker red color. This animal was successful enough to have survived up until the transition to the Ordovician period.
Name: Pseudolocusta triforcipe
Creator: TheTiger773
Size: 20 centimeters long (full body)
Location: Continental slopes of northern Gondwana
Time period: 490 mya
Clade: Arthropoda, Deuteropoda, Megacheira, Cheiromorpha, Leanchoiliida, Leanchoiliidae
Pseudolocusta triforcipe is a species of megacheiran from the Furongian epoch, related to (or possibly a descendant of) the Alalcomenaeus genus. In contrast to most fauna of that time, this species inhabited a mesopelagic zone of the oceans rathen than the epipelagic zone or the coasts. This animal feeds mostly on marine snow and small arthropods. While occasionally individuals of this species may venture towards higher marine zones, they do this only at night time due to risk of predation from larger creatures.
ECOSYSTEMS
Name: Mojiang Shale or Mojiang Formation
Creator: AlDodo
Time period: 514-513 mya
Location: Mojiang County, Pu’er Prefecture, Yunnan Province, China, Asia
Found in the Yunnan province, like the Maotianshan Shale, but in younger rocks from the Mojiang County, Pu’er Prefecture, the Mojiang Shale is a nearby formation, younger by roughly 4 million years. These two formations are connected and bear high similarities in terms of fauna and flora with it. This is to a point that it is even considered to very probably be an extension of the Maotianshan Formation in many ways, given most animals found at Mojiang are from the same lineages than the one from the former but in a more derived position.
The Mojiang Shale once sat in a shallow tropical sea and is defined to have been an even more productive and biodiverse ecossytem than its older predeccessor was in terms of faunal and floral assemblages.
The main reasons for this is hypothesized to be mainly the result of climate changes ending with a more favourable context due to the warmer temperatures that arrived at the start of the Cambrian Stage 4.
The faunal assemblage found at the Mojiang Shale is overall almost identical in term of clades shared by it and the Maotianshan Shale, with however more similarities with the Guanshan Biota of the latter, which lasted between approximatively 515 to 510 mya, than the Chenjiang Biota from 518 mya to around 515 mya.
Brachiopods are present, consisting the majority of the formation's diversity, being followed by trilobites in second place of abundance.
The chancelloriids, stem-priapulids, archaeopriapulids and hyoliths are also an important presence, while the radiodonts seem to not have particulary grown in numbers compared to the previous older formation.
Primitive chordates (such as early fish) and eocrinoid echinoderms are higher in abundance at this site.
Name: Nektonicaris mojiangensis
Size: 80 centimeters long (average)
Clade: Arthropoda, Dinocaridida, Radiodonta, Anomalocarida, Anomalocarididae
Nektonicaris ("nektonic shrimp") is a common predator in the formation. It is a younger relative of Lenisicaris, which inhabited the older Maotianshan Shale, and it may perhaps be a descendant of it. This radiodont is the only anomalocaridid found in this ecosystem.
It is an opportunistic and generalist hunter going after any potential animal able to be consumed by it.
Name: Arthropodocetus filtrus
Size: 45 centimeters long (average)
Clade: Arthropoda, Dinocaridida, Radiodonta, Anomalocarida, Hurdiidae
Arthropodocetus ("arthropod-whale") is another common radiodont found within the formation. It is a member of the hurdiids, this animal being among the oddest, compared to its closer relatives present in the formation.
This slow moving species has a very enlarged head sclerite, fitting in a niche of what will one day be taken by baleen whales, way before these came to be a thing.
It uses its frontal appendages holding numerous, fin and small hooked spikes to capture plankton, such as zooplankton and other microscopic organisms that drift passively by the water current, leading them into its mouth.
It has no predators as an adult.
Name: Alloisoxys mojiangensis
Size: 10 centimeters long (average)
Clade: Arthropoda, Deuteropoda, Isoxyida, Isoxyidae
Alloisoxys ("other equal surfaces") is a basal deuteropod arthropod with a bivalved carapace, and a genus which is a close relative of the abundant genus Isoxys.
It is a generalist active swimming predator, using its frontal appendages to capture soft-bodied prey, with the frontalmost pairs of biramous limbs aiding in food processing and moving through swimming with rhythmic movements of the legs.
Name: Cerritulovermis immobilis
Size: 5.5 - 6 centimeters long (average)
Clade: Bilateria, Centroneuralia, Protostomia, Ecdysozoa, Cryptovermes, Lobopodia, Hallucishaniids, Hallucigeniidae
Cerritulovermis ("weird worm") is a long tubular animal with up to ten pairs of slender legs, with the first 3 leg pairs being slender and clawless while the 7 pairs each ending in 2 claws. It has a pair of rows of sclerites (spines) present above the 3rd to the 9th pairs of legs of an otherwise rather simple animal.
An inhabitant of the sea floor, not much is known about its ecology and lifestyle, other than its spines being very likely used to defend itself against potential predators.
Name: Loricaspicus armatus
Size: 7 centimeters long (average)
Clade: Lophotrochozoa, Halwaxiida, Wiwaxiidae
Loricaspicus ("cuirass with spikes") is a inhabitant of the sea floor. It is a soft-bodied short and round slug-like animal covered in many rows of carbonaceous scales and spines.
It is a bilaterally symmetrical critter, with its body being elliptical, with no distinct head or tail, and from the front or rear its almost rectangular in shape.
It is detritivorous and eats anything that presents itself as small particules of food or, otherwise, as tiny animals or plants present on the bottom of the sea.
Name: Cataphractopisces aenigmus
Size: 10.5 centimeters long (average)
Clade: Deuterostomia, Vetulicolia, Vetulicolida, Vetulicolata, Didazoonidae
Cataphractopisces ("armored-fish") is a vetulicolidan vetulicolian member of the tadpole-like family Didazoonidae.
It is a swimming animal that spends all of its time living in water, actively swimming and propelling itself at a normal pace permanently through the water column.
Despite its name, Cataphractopisces wasn’t a fish at all. It was named as such only due to its similar visual appearance.
EXTINCTIONS
Petalonamae (†498 mya): - Petalonamids go extinct 498 million years ago, with the extinction of the last species, that lived in our timeline's Argentina. (blue093835)
Maikhanellidae (†489.5 mya): a family of limpet-like "monoplacophoran" members of the mollusk lineage was present around the regions of Baltica and Siberia during the early Cambrian. However, they found declines during the early-mid Cambrian extinctions. Although no fossils of maikhanellids persisted beyond the early Cambrian, relictual survivors existed around Baltica up until the end of the Jiangshanian, roughly 489.5 million years ago, after narrowly surviving the Jiangshanian extinction that concluded less than two million years prior. (YellowPanda2001)
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