Unikont

The term Unikonta consists of a specific group of eukaryotes ( Eukaryota ). For all Unikonta come (or probably came originally ) unikonte cells before. Unikonte cells are cells which move by means of a single flagellum. Nowadays, certain protozoa from the group of Amoebozoa could still resemble this original look strong. A modified variant would be, for example, the human sperm.

The group of Unikonta include both the Amoebozoa. The members of this group are indeed mostly amoeba -like unbegeißelt, but also simply comprise just flagellated forms. The group of Unikonta other hand, include the thrust Geissler ( Opisthokonta ). The Opisthokonta further subdivide itself, especially in the major groups of animals ( Animalia ) and the Chitinpilze ( True fungi, Fungi ).

All other Eukaryota are no Unikonta. They should instead form the major group of Bikonta. Among other things, should belong to the Bikonta such well-known forms of life such as red algae, land plants, brown algae, diatoms and ciliates. Bikonte beings have (or had probably originally ) bikonte cells, ie cells with two flagella. This differentiates them fundamentally cytologically by the Unikonta.

Characteristics to distinguish Unikonta - Bikonta

The Unikonta settle by certain molecular biological and cell biological characteristics of all other organisms with nucleated cells. These other Eukaryota are then summarized as Bikonta and compared with the Unikonta as a sister group.

Feature fusion genes

To distinguish on the molecular level and Unikonta Bikonta, the state of five specific genes is considered. All five genes are required for the construction of nucleotides. They are therefore essential for the synthesis of DNA and RNA molecules:

Molecular biological the Unikonta can be identified with them that the three genes are fused for the enzymes carbamoyl phosphate synthase II, aspartate transcarbamylase and dihydroorotase to a gene. After the first three letters of the enzymes these triple -gene fusion CAD ​​is called. CAD is transcribed as a contiguous mRNA. Upon translation, the gene product is a coherent, trifunctional protein ( multi- enzyme protein): large macropeptide that performs the three catalytic functions carbamoylphosphate synthase II, aspartate transcarbamylase and dihydroorotase simultaneously. In this way, the first three steps of the six-step synthesis route for the preparation of uridine monophosphate be time-saving catalyzes together in the same molecule. In contrast to the Unikonta Bikonta have no CAD. The Bikonta the three genes are present individually.

The Bikonta in turn have a simple genetic fusion of the genes thymidylate synthase and dihydrofolate reductase. The gene product is a coherent, difunctional protein: a macro peptide that perform both catalytic functions of dihydrofolate reductase and thymidylate synthase at the same time. During the catalysis of thymidylate synthesis falls to dihydrofolate. The subsequent reduction of the substance to tetrahydrofolate is catalyzed time-saving in the same macro peptide. In contrast to the Bikonta this gene fusion can not be found in the Unikonta. The Unikonta the two genes are present individually.

Feature phosphofructokinase

Furthermore, the Unikonta have a particularly large form of the enzyme phosphofructokinase. The enzyme is about twice as large as the phosphofructokinase in Prokaryota in Unikonta. With the increase improved controllability is associated. Although both types of phosphofructokinase can also be activated by ADP and AMP, but unikonte phosphofructokinase can also be activated by fructose-1 ,6 -bisphosphate. In addition, the latter can be inhibited by ATP and citrate. The gene for the enzyme phosphofructokinase likely reached with the endosymbiotic the mitochondrion into the eukaryotic cell. The last common ancestor of all today occurring Unikonta the gene was duplicated so that two gene copies present. Subsequently, the two gene copies of a fused gene. The gene product of this gene thus possessed two active centers for the same catalysis. Then evolved that of the active site, which was closer to the carboxy terminus, to a new allosteric center. This new allosteric center owes the unikonte variant of phosphofructokinase their extensive adjustability. The large and extensively regulated phosphofructokinase is a common feature of all Unikonta. It is not found in Bikonta, just as the mitochondrial Vorläufergen. Presumably it was lost in the Bikonta. Variants of the enzyme phosphofructokinase, which are now found in Bikonta not resemble the unikonten shape and represent your own developments that are likely to go back to various horizontal gene transfer.

Feature of α -amylase

Many procaryotic and eukaryotic life forms have genes for production of the enzyme α -amylase. α -amylases catalyze the hydrolysis of polysaccharides, amylose and amylopectin to maltotriose, maltose and glucose. It has been found that most Unikonta use the same version of the α -amylase. This variant was found for the first time in a slime mold, in the Amoebozoa genus Dictyostelium. It is therefore referred to as α -amylase from Dictyo type. Genes for α -amylases from Dictyo type found in the Unikonta groups of Amoebozoa and the Nucletmycea ( Chitinpilze and similar ). α -amylases from Dictyo type also occur in animals. Here, however, only in groups that do not belong to the two- page animals ( Bilateria ), ie at Choanoflagellata, sponges and coelenterates.

It is believed that this is a common feature of all derived Unikonta in α -amylase from Dictyo type. As an exception, the α -amylase from Dictyo type in the Amoebozoa genus Entamoeba missing. Here, the gene could have been lost in the course of their parasitic way of life. The α -amylase from Dictyo type is also missing in all two-sided animals ( Bilateria ). Instead found in them their own form of α -amylases. It is called animal -amylase, although it is exactly enough, is a bilaterian -amylase, while the remaining animals still possess α -amylases from Dictyo type ( Choanoflagellata, sponges and coelenterates ). It can be assumed that the animal - amylase of the animals with two sides of bacteria of the order Alteromonadales ( Proteobacteria ) comes and passed through a horizontal gene transfer in the last common ancestor of all extant animals with two sides.

In addition, α - amylases are found from Dictyo type outside the Unikonta. They come before in some groups of Bikonta. Thus, in the alveolaten ciliates ( ciliata ) and certain representatives of the excavata ( Jakobida and the genera Naegleria, Trimastix and Malawi Monas ). This Bikonta could have received the α -amylases from Dictyo type by horizontal gene transfer from the Unikonta.

It would currently also possible to assume that the α -amylases from Dictyo type actually are not a feature of Unikonta. But that they instead represent even a common feature of all Eukaryota, so all Unikonta and all Bikonta. The genes for these amylase - type would then, however, lost much more common among Bikonta than among Unikonta so that the α -amylases today still appear merely as a common feature of Unikonta derived from Dictyo type. Currently, the taxonomic significance of α -amylases from Dictyo type seems hardly clarified. These far more extensive sequence comparisons seem necessary, as can be done today.

Features microtubules

There are three suspects fine structural differences between the cells of the original Bikonta and the original Unikonta. All three differences are based on different sources and organization of microtubules. Microtubules are tubular structures made ​​of threads of the protein tubulin. They form the cytoskeleton together with actins and intermediate filaments. There is also the centriole and the eukaryotic flagellum microtubules.

The cell of the last common ancestor of all Unikonta probably had a fairly symmetrical, conical mikrotubuläres cytoskeleton. Quite different is said to have seen in the last common ancestor of all Bikonta the microtubular Cytoskelettanteil. He was said to be rather asymmetric, with mikotubulären strands on the cell bottom. From these two hypothetical output forms, all occurring today eukaryotic cell forms could have developed.

As a second microtubular difference between Unikonta and Bikonta different numbers are accepted by centrioles. Unikonta should have originally possessed a centriole per cell. Bikonta should have originally possessed two centrioles per cell.

The most important ( and eponymous ) microtubular difference between Unikonta and Bikonta is the flagellum. Unikonta probably originally possessed a flagellum per cell. They were UNIKONT. Bikonta probably originally possessed two flagella per cell. They were Bikont.

In order to address the microtubular differences in detail, the British biologist Thomas Cavalier- Smith works with very specific terms. Before this passage goes into the details, the concepts presented ( and Germanized ) should be:

• Uniciliatie ( uniciliaty ): A cell is uniciliat ( uniciliate ) when she wears a scourge.
• Biciliatie ( biciliaty ): A cell is biciliat ( biciliate ) if it bears two flagella.
• Multiciliatie ( multiciliaty ): A cell is multiciliat ( multiciliate ) when she wears many flagella.
• Unicentriolarität ( unicentriolary ): A cell is unicentriolär ( unicentriolar ) if it includes a centriole.
• Bicentriolarität ( bicentriolary ): A cell is bicentriolär ( bicentriolar ), if it contains two centrioles.
• ( Original ) Unikontie ( unikonty ): The original unikonte ( UNIKONT ) cell is both uniciliat, be and have been unicentriolär.
• ( Original ) Bikontie ( biconty ): The original bikonte ( Bikont ) cell is both biciliat, as also have been bicentriolär.
• Anterokontie ( anterokonty ): A cell is anterokont ( anterokont ) when the scourge front ( anterior) is. Anterior flagella serve as Zuggeißeln. A more widespread synonym for Anterokontie is Akrokontie.
• Opisthokontie ( opisthokonty ): A cell is opisthokont ( opisthokont ) overlying the scourge rear ( posterior). Posterior flagella serve as thrust flagella.

The last common ancestor of all living today Unikonta was probably uniciliat and unicentriolär. His cell had a scourge and a centriole. This corresponds to the original Unikontie and is found today in some Amoebozoa, for example, in the single- species Phalansterium. The genus, however, is also still anterokont. Their functioning as Zuggeißel scourge and is located at the forward end of the cell. It is believed that the Unikonta were originally anterokont.

Within the group of Amoebozoa the anterokonte scourge was partially lost. The cells were akont, that is no flagellum. The development of Akontie took place when a line of development was transferred completely to the amoeboid locomotion by means of pseudopodia. This scourge loose, amoeba -like Amoebozoa are managed under the group name Lobosa. Flagellated Amoebozoa ( Amoeboflagellaten ) can still be found within the other tart Amoebozoen group of Conosa. The Conosa include, for example Phalansterium ( uniciliat, unicentriolär ) Multicilia ( multiciliat, unicentriolär ), various Archamoebae and the slime molds ( Eumycetozoa ) whose gametes are flagellated often two-fold. The double flagellum leaves the slime molds apparently closely into the Bikonta. However, their second flagellum is seen as convergent evolution to Biciliatie the Bikonta. For the gametes of slime molds are biciliat unicentriolär (two flagella and one centriole per cell) and not biciliat bicentriolär what would be expected in real Bikontie. The genus Breviata ( Protamoebae / Breviatea ) there are also among the Amoebozoa also a shape which is uniciliat bicentriolär. The Bicentriolarität but accomplished unlike Bikonta. It is thus likely to convergent evolution parallel to the Bikonta.

Within the Unikonta the Opisthokonta form the sister group to the Amoebozoa. The cells of the Opisthokonta no longer correspond to the original unikonten construction ( uniciliat, unicentriolär ), but represent a derived form is: flagellated cell stages are indeed uniciliat, but also bicentriolär. The second centriole can be seen as a newly developed feature of Opisthokonta. Furthermore Opisthokonta have no anterokonte Zuggeißel, but a posterior, opisthokonte thrust scourge. You should have resulted from the anterokonten scourge, perhaps as an adaptation to new food niches. Also among the Opisthokonta went the flagellum lost several times. Certain representatives of the involved Mesomycetozoa their scourge in favor of amoeboid cell lines. In the multicellular animals ( Metazoa ), only the sperm flagella but not the eggs. Particularly striking, however, is the loss of the scourge among the Chitinpilzen (Fungi ). The vast majority of today's Chitinpilze not form flagellated cell stages more, so akont. The best-known exception to this are the unicellular Flagellenpilze ( potty fungi, Chytridiomycota ). Your enthusiasts still show the original uniciliate, opisthokonte flagella. Sometimes this merge two visionaries together ( act accordingly as gametes) to form Planozygoten. These are zygotes, which for a time bear the scourges of their two gametes are flagellated therefore two-fold. From this original isogamy ( fusion of two gametes look-alike ) a certain Flagellenpilz Group continues has developed Monoblepharidales. For them, the male gametes are only uniciliat, flagellated opisthokont. You go swimming to large, immovable, akonten female gametes ( ova ). Most of the approximately 500 known Flagellenpilz species live in water, some in moist soil or as parasites to cells in higher plants. Besides them there are other small groups of fungi with flagellated cells. This includes the sister group of the Flagellenpilze that Neocallimastigomycota, as well as the Blastocladiomycota and systematically unclassifiable genre Olpidium. The Neocallimastigomycota the fanatics can uniciliat be opisthokont or multiciliat. Like the Flagellenpilzen forms the fungal genus Olpidium uniciliate, opisthokonte enthusiast who also act as gametes and generate biciliate Planozygoten. The Blastocladiomycota the uniciliaten, opisthokonten male gametes are slightly smaller than the well flagellated female gametes ( Anisogamie ). The zygote carries after the merger for a short time the two flagella of gametes ( Planozygote ). All just mentioned, flagellated fungi have in common that they occur in habitats with extensive water supply. For a flagellate locomotion water is essential. For the other fungi, the scourge stages were involved, often thought to be dry in the wake of colonization, terrestrial habitats.

Uniciliate bicentrioläre cells are the hallmark of Opisthokonta. Uniciliate Bicentriolarität is, however, known by some organisms, have been reported as phylogenomisch Bikonta. These include, for example, the Pedinellales and some Prasinophyceae. For these life forms, it is assumed that their ancestors originally real Bikont ( biciliat, bicentriolär ) were, however, the second scourge secondarily lost.

In contrast to the Unikonta the last common ancestor of all modern Bikonta to have had two flagella ( Biciliatie ) and two centrioles ( Bicentriolarität ) per cell. The Biciliatie presumably evolved in several steps. Initially, the cells moved probably with a Zuggeißel ( uniciliate Anterokontie ). The Zuggeißel was then converted to thrust Scourge ( uniciliate Opisthokontie ), perhaps as an adaptation to new food niches. Then, a second, now anterior flagellum was on the opposite side of the cell created and shortened the old posterior flagellum. This form of flagella (two flagella of different length ) is referred to as heterokont.

Parallel to the Unikonta formed within the Bikonta forms in which the flagellum was fully involved ( Akontie ). This is when most of today's seed plants of the case and was probably in the wake of increasing adaptation to terrestrial habitats: the seed plants ( Spermatophytina ) belong to the sprout plants ( Tracheophyta ), a subgroup of the Embryophyten ( Plantae, Embryophyta ), which together with certain green algae form group of Charophyta ( Archaeplastida / Chloroplastida ). The charophyte including the Chara ( Characeae ). Your sperm carry two flagella which are close together at the anterior end of the cell ( Zuggeißeln ). The flagella have the same structure and the same length, so it is no longer about the postulated original heterokonte Biciliatie the Bikonta, but a derived isokonte Biciliatie. Very similar spermatozoids are formed by the mosses. They are also found in the simplest plants sprout, the Bärlapppflanzen ( Lycopodiophytina ). In the ferns, there are then often flagellated sperm. Similar multiciliat flagellated sperm there are in the two evolutionarily ancient seed plant groups of the ginkgo plant ( Ginkgophyta ) and cycads ( Cycadophyta ). All other seed plants form no ciliated cells. This Akontie is a convergent evolution of the majority also unbegeißelten fungi.

Both evolved with the Unikonta, as well as the Bikonta vielgeißelige ( multiciliate ) forms. The Unikonta for example evolved the Amoebozoa Pelomyxa and Multicilia the Multiciliatie from the original, uniciliaten state. The Bikonta evolved as the best known examples of the alveolaten ciliates ( Ciliata ) the Multiciliatie from the original, biciliaten state.

Certain difficulties made ​​the interpretation of the Multiciliatie the protista genus Stephanopogon. The genus does not belong to the Unikonta but phylogenomisch clearly one of the Bikonta ( excavata / Discoba / Percolozoa / Percolatea ). However, she is multiciliat and unicentriolär similar Pelomyxa and Multicilia ( Unikonta / Amoebozoa ). Meanwhile, it is assumed that a real Bikontie was originally present in the ancestors of Stephanopogon. However, you later lost a second centriole, so that a secondary Unicentriolarität occurred.

Feature of microtubules: Summary

• Unikonta: originally uniciliat, acrokont, unicentriolär; symmetrical, conical, mikrotubuläres cytoskeleton Amoebozoa Protamoebae Breviata: uniciliat; derived bicentriolär

• Phalansterium: uniciliat, acrokont, unicentriolär
• Multicilia: derived multiciliat, unicentriolär
• Polymyxa: derived multiciliat, unicentriolär
• Eumycetozoa: gametes often derived biciliat, unicentriolär

• Nucletmycea Fungi Chytridiomycota: uniciliat enthusiast, bicentriolär, opisthokont; Planozygoten biciliat, bicentriolär, opisthokont Monoblepharidales: male gametes uniciliat, bicentriolär, opisthokont; female gametes akont derived bicentriolär

• Mesomycetozoa: some representatives akont derived bicentriolär
• Filozoa Animalia Metazoa: male gametes uniciliat, bicentriolär, opisthokont; female gametes akont derived bicentriolär

• Bikonta: originally biciliat, bicentriolär, heterokont; asymmetric mikrotubuläres cytoskeleton with ventral microtubule strands excavata Stephanopogon: derived multiciliat derived unicentriolär - Convergence to Multicilia and Polymyxa

• Pedinellales: derived uniciliat, bicentriolär - convergence to the ciliated cells of the Opisthokonta ( Pedinellales but akrokont )
• Ciliata: derived multiciliat, bicentriolär - convergence to the enthusiasts of some Neocallimastigomycota

• Viridiplantae Chloroplastida Prasinophyceae: some representatives uniciliat derived bicentriolär - convergence to the ciliated cells of the Opisthokonta ( Prasinophyceae but akrokont )
• Charophyta Characeae: spermatozoids biciliat, bicentriolär derived isokont - convergence to the Planozygoten the Chytridiomycota, Blastocladiomycota and Olpidium ( spermatozoids of Characeae but with Zuggeißeln )
• Plants Plantae ( Embryophyta ) Moose ( Paraphylum ): spermatozoids biciliat, bicentriolär, isokont - convergence to the Planozygoten the Chytridiomycota, Blastocladiomycota and Olpidium ( spermatozoids of mosses but with Zuggeißeln )
• Tracheophyta Lycopodiophytina: spermatozoids biciliat, bicentriolär, isokont - convergence to the Planozygoten the Chytridiomycota, Blastocladiomycota and Olpidium ( spermatozoids of Lycopodiophytina but with Zuggeißeln )
• Euphyllophyta Monilophyta: spermatozoids multiciliat derived bicentriolär, isokont - convergence to the enthusiasts of some Neocallimastigomycota
• Spermatophyta Cycadophyta: spermatozoids multiciliat derived bicentriolär, isokont - convergence to the enthusiasts of some Neocallimastigomycota
• Ginkgophyta: spermatozoids multiciliat derived bicentriolär, isokont - convergence to the enthusiasts of some Neocallimastigomycota
• All other Spermatophyta: derived akont - Convergence to akonten Fungi

Phylogeny of Unikonta in the Precambrian

The last common ancestor of all Eukaryota should have had five separate genes for the enzymes Carbamoylphosphatsynthase II, dihydroorotase Aspartatcarbamoyltransferase, dihydrofolate reductase and thymidylate synthase. At a Eukaryota group, the genes for the first three enzymes fused, while the genes were isolated from the last two enzymes. This group with the triple fusion were the first Unikonta. From them came from all of today's Unikonta.

The genes for dihydrofolate reductase and thymidylate synthase are with the Unikonta before unfused. However, in all other Eukaryota, ie at the Bikonta, they are united in a double fusion. That is why the Unikonta should have been the first group to split from the rest of Eukaryota. This event took place deep in the Precambrian.

The oldest evidence of eukaryotic life are biomarkers ( cholestane ) from the Pilbara craton shale (Western Australia). The slate comes from the Neoarchaikum (upper Archean ) and is approximately 2.77 billion years old. On the other hand, the earliest Unikonta fossils come from a genus called Tappania and are 1.43 billion years younger. But is very likely that the first appearance of Unikonta place much earlier, although in older rocks unique fossils are missing.

In order to estimate the time of the Erstauftretens Unikonta closer, help fossils from the Bikonta group. There are some known fossils that are much older than Tappania and possibly can be regarded as Bikonta. It is now, however, also known that the Unikonta as the first of the other Eukaryota - should have separated - ie from the later Bikonta. The timing of this separation must therefore be recognized before the onset of Bikonta fossils. If a Bikonta fossil is found, it must therefore be assumed that the same Unikonta were already present. However, these early Unikonta left no fossils or at least no fossils that can be unambiguously assigned to them: perhaps located between the highly heterogeneous, early Acritarcha some Unikonta.

The oldest known fossils of the genus could be Bikonta Grypania from the Negaunee iron formation (Michigan). The formation comes from the Rhyacium ( older middle Paleoproterozoic ) and is about 2,100 million years old. In Grypania it maybe was a eukaryotic alga and thus to Bikonta (more precisely Archaeplastida ). This classification was based primarily on the size of these spiral fossils that are just about an inch long. On the other hand, it could be at Grypania as to chain-like colonies (similar to today's Anabaena ) have acted out particularly large bacteria. The largest cells of today's bacteria reach at least diameter of up to 0.75 mm ( Thiomargarita namibiensis ).

The oldest Acritarcha that can be identified as Eukaryota with some certainty come from the Chuanlinggou Formation ( northern China ). The formation comes from the Statherium (upper Paleoproterozoic ) and is about 1730 million years old. The Acritarcha question is egg-shaped microfossils.

The oldest trace fossils, probably dating back to Bikonta, are located in the Chorhat Sandstone (India). The sandstone comes from the Statherium (upper Paleoproterozoic ) and has an age of 1632 to 1628 million years ago. The trace fossils look as if worm-like creatures were crawling across the sand. More likely, however, that they were drawn from large protozoa. It was observed off the Bahamas at 750 m to 780 m water depth that the Riesenamöbe Gromia leaves similar signs on the seabed. Gromia is counted among the Bikonta (more precisely Rhizaria ). If the trace fossils of Chorhat actually should come from living things that were close to the present - Gromia Riesenamöbe, would Bikonta ( and thus something Unikonta ) was already present prior to 1.632 billion years.

The earliest fossils that go back with some certainty on Unikonta, derived from a living benthic genus named Tappania. In the fossil hyphae are seen, so it was probably at Tappania a fungus. The mycelia were both in the Wynniatt formation ( Victoria Iceland, Northwest Canada ) and in the Roper Group ( Australia) found. The findings come from the upper Calymmium (lower Mesoproterozoikum ) and are approximately 1.43 billion years old. The cell walls of a mycelium composed of chitin. Therefore, it can relatively easily fossilize. For this reason, the fungi could occur as the first Unikonta in the fossil record. The UNIKONT Tappania is around 230 million years older than the first truly indisputable identifiable Bikont called Bangiomorpha pubescens. This alga was found in the Hunting Formation ( Somerset Iceland, Canada). The formation comes from the oldest Stenium (upper Mesoproterozoikum ) and is about 1,200 million years old.

The second group of Unikonta are the Amoebozoa. The previously oldest fossils Amoebozoa are so-called vase -shaped microfossils (VSM ). These microfossils are very reminiscent Thecamoeben. VSM were salvaged from the Grand Canyon and come with an age between 736-748 million years ago from the Cryogenium (middle Neoproterozoic ).

The third important group of Unikonta are the animals. The oldest evidence for the presence of Animalia consists of the steroid 24 - Isopropylcholestan. This biomarker is currently produced by a group of sponges ( Demospongiae ). The steroid was discovered in southern Oman in sediments from the Cryogenium (middle Neoproterozoic ) originate and are at least 635 million years old.

After a very extensive, current phylogenomischen study, the Animalia (animals) share in Choanoflagellata and Metazoa. The Metazoa share in Porifera (sponges ) and Placozoa Eumetazoa. The Eumetazoa divided into Coelenterata ( Cnidaria Ctenophora and ) and bilateral ( Protostomia and deuterostomes ).

Because the biomarkers of Demospongiae ( Porifera ) come, the animal Unikonta had at that time must have been split at least twice. Once in Choanoflagellata and Metazoa and the latter then again in Porifera and Placozoa Eumetazoa.

Some microfossils from the Doushantuo phosphorites of Formation ( Southwest China ) have long been regarded as the next most recent evidence of animal life. The formation dates from the mid- Ediacaran (upper Neoproterozoic ) and is around the 590 million years old. The microfossils were interpreted as eggs and early embryonic stages of different animals. However, there are strong arguments for seeing in them rather the remnants of large sulfur bacteria. In the Doushantuo phosphorites of the formation, however, there are still other fossils whose interpretation is uncontroversial. These are fossils formerly Porifera ( Demospongiae accurate ) and soft-tissue fossils formerly Coelenterata ( Cnidaria accurate / Anthozoa / Hexacorallia / tabulata ). Under the current Fund location could be said that of all living tissue animals today the recent Anthozoa should resemble the first Eumetaza most likely.

The first fossil evidence for Bilateria are a bit younger, come from the upper Ediacaran and are 542-560 million years old. These fossils seem all flattened worm-like, and are only a few centimeters long. Among the most prominent representatives include Spriggina (possibly Protostomia ) Kimberella (possibly Protostomia ) Ernettia (possibly Deuterostomia ) and a still unnamed fossil from the Flinders Ranges (South Australia ), which is very reminiscent of Chordata and exhibited in the South Australian Museum in Adelaide.

Summary of the phylogeny of Unikonta in the Precambrian

• Neoarchaikum: biomarkers cholestane - evidence of first Eukaryota.
• Lower to middle Paleoproterozoic: Eukaryota split into Unikonta and Bikonta.
• Upper Paleoproterozoic: Unikonta split in Amoebozoa and Opisthokonta. Opisthokonta split on further, thereby arise primarily Animalia and Fungi.
• Lower Mesoproterozoikum: Tappania
• Upper Mesoproterozoikum to lower Neoproterozoic: Animalia split into Choanoflagellata and Metazoa.
• Older middle Neoproterozoic: VSM. Metazoa split in Porifera and Placozoa Eumetazoa.
• Younger mid- Neoproterozoic: biomarker 24 - Isopropylcholestan - evidence of Demospongiae ( Porifera ). Placozoa Eumetazoa split into Placozoa and Eumetazoa. The first Eumetazoa could have resembled today's Anthozoa.
• Middle Upper Neoproterozoic: soft-tissue fossils of Demospongiae and tabulata.
• Younger upper Neoproterozoic: First Bilateria, possibly already separated into the groups Protostomia and deuterostomes.