The evolution and distribution of life in the Precambrian eon-Global perspective and the Indian record 765

The evolution and distribution of life in the Precambrian eon-Global perspective and the Indian record

M SHARMA* and Y SHUKLA Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow 226 007, India *Corresponding author (Email, [email protected])

The discovery of Precambrian in 1954 opened a new vista of investigations in the fi eld of evolution of life. Although the Precambrian encompasses 87% of the ’s history, the pace of organismal evolution was quite slow. The life forms as categorised today in the three principal domains viz. the , the Archaea and the Eucarya evolved during this period. In this paper, we review the advancements made in the Precambrian palaeontology and its contribution in understanding the evolution of life forms on earth. These studies have enriched the data base on the Precambrian life. Most of the direct evidence includes fossil prokaryotes, protists, advanced algal fossils, acritarchs, and the indirect evidence is represented by the , trace fossils and geochemical fossils signatures. The Precambrian fossils are preserved in the form of compressions, impressions, and permineralized and biomineralized remains.

[Sharma M and Shukla Y 2009 The evolution and distribution of life in the Precambrian eon-Global perspective and the Indian record; J. Biosci. 34 765–776] DOI 10.1007/s12038-009-0065-8

1. Introduction suggested that all the living forms can be grouped into three principal domains viz. the Bacteria, the Archaea, and The sudden appearance and radiation of both skeletal and the Eucarya (Woese 1987, 2002; Woese et al. 1990) /or soft-bodied in the and the lack of fossils two empires viz. the Prokaryota and the Eukaryota (Mayr in the rocks of Precambrian Eon puzzled Charles Darwin 1998). Molecular phylogenies further established that these (Darwin 1859, Origin of Species, Chapter X, John Murray, domains diverged from one another during the Archaean London, p. 447). The renowned palaeobotanist Seward, who Eon. was sceptical about discovering older ancestral life forms, In this paper, we review the extensive contributions once stated that “We can’t hope to get any evidence of and important milestones in our understanding early activities of life of this period” (Seward 1931). (Precambrian) life. Signifi cant Indian contributions to Following Darwin, for almost a century, no direct record the study of Precambrian life are also cited. The direct of life was found in strata underlying the Cambrian. In 1954, evidence of Precambrian biota includes fossil prokaryotes, a seminal paper on the 2000 million (Ma) old Gunfl int protists, advanced algal fossils, acritarchs, and the indirect reporting discovery of well-preserved microbiota evidences are represented by stromatolites, trace fossils and opened a new vista of investigations into the Precambrian geochemical fossils. These evidences show varied types of life (Tyler and Barghoorn 1954). This discovery supported preservation such as compressions, impressions, and the the view that if the sudden radiation of life in the Cambrian permineralized and biomineralized remains. was any pointer, the answer and the root of evolution must be found in the Precambrian strata. Subsequent to the 2. The Precambrian geological timescale fi rst discovery of Precambrian biota, the types of evidence have increased manyfold through out the world, albeit The two broad divisions of the Earth’s geological history gradually. Recent molecular phylogenetic studies have are the Precambrian and the ; the transition

Keywords. Archaean; evolution; palaeontology; Precambrian; http://www.ias.ac.in/jbiosci J. Biosci. 34(5), November 2009, 765–776, © IndianJ. Biosci. Academy 34(5), of November Sciences 2009 765 766 M Sharma and Y Shukla from Precambrian into the Phanerozoic is marked at 542 Australia and the Onverwacht and Fig Tree Groups of South Ma (Gradstein et al. 2004). In terms of numerical age the Africa, supposed to have deposited in tectonically separated Phanerozoic encompasses only ~13% of the entire earth’s parts of a single basin. In these successions, carbonaceous history, and comprises three eras, viz. the Palaeozoic, the occurring predominantly in volcanogenic packages , and the . The fl oral and faunal diversity have yielded enigmatic carbonaceous microstructures which we see today on the earth is the result of evolution of indeterminable affi nity and biogenicity. Some better which took place mainly during the Phanerozoic. The preserved microstructures plausibly may have biogenic oldest rock (4280 Ma) has been found in the Nuvvagittuq origin (Muir and Grant 1976; Knoll and Barghoorn 1977; Greenstone belt in northern Quebec, represented Walsh and Lowe 1985; Schopf and Packer 1987; Schopf by the rock “faux amphibolite” that formed shortly after 1993; Rasmussen 2000; McKeegan et al. 2007). Presently, the earth formation and may even be the oldest preserved eight micro-fossiliferous units from the Archaean satisfy nine crustal section on earth (O’Neil et al. 2008). The pace of varied criteria for biogenicity and criteria of provenance, evolution of life indubitably had its root in the Precambrian. age indigenousness and syngenicity and should be Such a large time period has been further divided into the considered bona fi de early Archaean microfossils (Schopf Archaean Eon (4280 to 2500 Ma) and the Proterozoic 2004). However, these early Archaean fossils at best Eon (2500 to 542 Ma). The Proterozoic is further sub- manifest only the presence of a biosphere; their taxonomic divided into the Palaeoproterozoic (2500 Ma-1600 Ma), the position or physiological adaptations can be construed in (1600 to 1000 Ma) and the many ways. (1000 to 542 Ma) (Gradestein et al. 2004). Recently a new Another evidence of early Archaean biosphere is period named ‘’ has been added in the geological represented by stratiform, domal, conical and columnar timescale (Knoll et al. 2006). It is chronostratigraphically structures – stromatolites – preserved in carbonate rocks of established. For the sake of the convenience all the relevant this age. Such structures have been reported from Onverwacht fossil records are being presented under these time divisions and Warrawoona Groups (fi gure 1a) (Lowe 1980; Walter and fi nally Indian status of palaeobiological records is et al. 1980; Byerly et al. 1986). Not all stromatolites are discussed in global perspective at the end of each section. believed to be of biogenic origin. Some forms are believed to have been supposedly formed by abiogenic processes 3. Fossils in the Precambrian (precipitation) or soft sediment deformation or tectonic processes (Buick et al. 1981). Microbial origins of stratiform 3.1 Archaean fossil record stromatolites are rather convincing and comparison of these stromatolites with modern stromatolites suggests that Early Archaean (3800–3000 Ma) rocks were mostly photoautotrophic organisms might have been involved in igneous in origin. Whatever little sedimentary rocks were their formation. But whether or not were deposited have undergone geological recycling. Subsequent actively involved in their formation remains uncertain. metamorphism of these rocks makes them virtually Advent and evolution of in the atmosphere is unsuitable for palaeontological investigations though another aspect of Precambrian palaeobiology. Towe (1990) some of these rocks do hold promise for microbial fossil suggested that the early Archaean atmosphere must have investigations. of this period were minute, contained oxygen that was suffi ciently conducive for aerobic poorly preserved, and constituted of simple morphologies respiration ~1–2% of present day levels (PAL). Occurrence that could have been produced even by non-biologic of palaeosols and detrital uraninite in alluvial deposits of processes like mineralic microstructures that make it diffi cult early Archaean also support that the oxygen levels could not to differentiate between true fossils and . have been more than this. Subsequent higher oxygen level in Hence, Early Archaean palaeontological records are atmosphere probably was the result of photosynthetic activity always viewed with scepticism (Brasier et al. 2002; Dalton of cyanobacteria. Extensive Banded Iron Formations (BIFs) 2002; Van Zuilen et al. 2002). Even those recorded from in the Archaean are presented as important evidence for the the Warrawoona Group of have been cyanobacterial oxygen production. However, the possibility challenged for their antiquity and biogenicity (Awramik et that BIFs could have also formed by photo-oxidation of al. 1983; Buick 1984; Kaźmierczak and Barbara 2002). ferrous iron dissolved in anoxic Archaean oceans can not be Known Archaean fossil forms can be grouped into isolated entirely ruled out. single cells, paired probably dividing cells, ensheathed All these evidences from the early Archaean collectively colonies of coccoidal cells, and cylindrical and cylindrical suggest that microbial life was present (Figure 1e, e’, f septate-fi laments. Evidences for Archaean biosphere have f’), fl ourishing and widespread by the close of 3500 Ma been gathered from fossils, organic matter and isotopic ago (Schopf et al. 2002). The ecosystem graduated to signatures mainly from the Warrawoona Group of Western autotrophy, most probably the photoautotrophy and oxygen

J. Biosci. 34(5), November 2009 The evolution and distribution of life in the Precambrian eon-Global perspective and the Indian record 767

Figure 1. (a) Archaean domal from Warrawoona Group, Australia; (b) Batiola indica – Archaean stromatolite from Chitradurga Group, Karnataka, India; (c, d) Archaean stromatolite Marikanwe region Chitradurga Group, Karnataka, India; (e, f) Primaevifi lum conicoterminatum, Apex chert 3465 Ma, Western Australia; (g, h) Phormidella sandurense; i: Phormidella tenue (scale for e, f =10 μm; for g-i = 50 μm; hammer for scale in b, d; pen for scale in c). (Figure 1 a, e, e’, f, f’, Courtesy Prof. J W Schopf.)

J. Biosci. 34(5), November 2009 768 M Sharma and Y Shukla producing cyanobacteria may have appeared. Depending on 3.2 Proterozoic fossil record the level of oxygen, the life forms could have also included aerobic prokaryotes and mitochondrion bearing eukaryotic In comparison to the Archaean, the Proterozoic rock record heterotrophs, but the presence of eukaryotic algae at this is rather better preserved and fossils are abundant and well level is uncertain. preserved. Many of these fossils are comparable with modern The late Archaean (3000–2500 Ma) fossils are forms so much so that their biogenicity and biological comparatively better preserved than those from the early affi nity can easily be established. During this period Archaean, but they are equally diffi cult to assign to any appeared and probably sexual reproduction led established taxonomic group. Also, there are not many to rapid diversifi cation. The Mesoproterozoic (1600–1000 records of late Archaean fossils. Simple trichomes are Ma) holds a promise with each new discovery helping us reported from the ~2800 Ma old Fortescue Group, Western in unravelling the un-deciphered part of the evolutionary Australia (Schopf and Walter 1983). Although these history. By the close of Proterozoic, fossils of primitive forms show morphological resemblance to oscillatorian appeared in sediments overlying the global ice cyanobacteria or sulphur-oxidizing or sulphur-reducing cover known as “snow-ball earth”. Near the Precambrian- bacteria, it is diffi cult to taxonomically assign these Cambrian boundary the biological realm developed the trichomes to any of these groups. Lanier (1986) reported mechanism of also. thin fi lamentous sheaths and tiny rods from the 2500 Ma 3.2.1 Palaeoproterozoic fossils: During the Palaeo- old Transvaal Supergroup. The former were interpreted as proterozoic large scale giant carbonate platforms were primary producers and the latter as heterotrophic bacteria. formed on the intracratonic basins. Different assemblages From the same basin, Klein et al. (1987) recorded carbonate of stromatolites developed on these platforms indicate lined fi lamentous sheaths. Microfossils are known from a variety of facies that range from supratidal to deep Campbell Group, Griqualand West sequence of the Transvaal subtidal. The Gunfl int Cherts of Ontario, Canada deposited Supergroup (Altermann and Schopf 1995). during the Palaeoproterozoic and are well known for their Stromatolites in the Archaean sequences are assemblage; their study heralded the of predominantly found in carbonate units that are associated modern Precambrian palaeobiology (Tyler and Barghoorn with volcano-clastic rocks. It appears that these possible 1954; Barghoorn and Tyler 1965). Microfossils have been biogenic structures formed during the stable periods recorded in stratiform to digitate stromatolites in chert, non- of otherwise tectonically unstable and extensive volcanic stromatolitic cherts and peloids in Gunfl int arenites. The activity in the basin. Few such structures formed in assemblage includes vertically and horizontally oriented fl uvial and lacustrine environment also (see Hofmann 2000, fi laments viz. Gunfl intia minuta that are interpreted by table 1). Lanier (1989) as photoautotrophs, possibly cyanobacteria. In the Indian Archaean successions, Maithy et al. (2000) Knoll (1996) argued that an alternative interpretation is reported spheroidal and fi lamentous microfossils from 3200 possible, including considering these fi laments as iron-loving Ma old Supergroup, Singhbhum , India. The bacteria comparable to extant Leptothrix or Sphaerotilus. other record of microfossils includes mat-building fi laments Some other forms in Gunfl int microfossils assemblage such in silicifi ed stromatolites from ~2900 Ma old Donimalai as Huroniospora, Eosphaera tyleri, Kakabekia are also Fomation, India (Naqvi et al. 1987; Venkatachala et al. 1990). diffi cult to understand and are considered as problematica. The two forms recovered from the chert, viz. Phormidella The Gunfl int microfossils are invariably very small, simple; sandurense and Phormidella tenue are considered rarely show evidence of cell division, occur in dyads and comparable to extant cyanobacterium Phormidium (fi gure quartets of coccoidal fossils. Some of these forms may 1g-i). Similar fi lamentous moulds are also recorded from be cyanobacterial (Knoll et al. 1978). Such assemblages Fortescue Group (Buick 1992). Venkatachala et al. (1986) of microfossils found in subtidal carbonate sediments of recorded rod-shaped and coccoidal bacteria from 2600 Palaeoproterozoic age from other parts of the world are Ma old Bababudan Iron Formation, India. In India, late known as ‘Gunfl int-type microfossils’. On size parameter Archaean stromatolites (fi gure 1b-d) are recorded from they appear to belong to prokaryotes. The presence of of the Dharwar Supergroup Karnataka (Srinivasan et al. cyanobacteria can not be completely ruled out in such 1989; Sharma and Shukla 2004). Their presence in various assemblages and these were in plenty but the limitation Archaean units suggests that benthic microbial life forms is that we do not get any diagnostic cyanobacterial forms. constituting the stromatolitic structures were extensively However, presence of any unequivocal eukaryotes has not present during that time. Taxonomical affi nities of most of been demonstrated but many problematica or bizarre forms these remnants are assigned on the basis of morphological of the Gunfl int assemblage can be interpreted as either way. attributes. Modern taxonomical approach cannot be applied Another coeval geologic unit of Gunfl int Formation, on these fossilized entities. the Belcher Supergroup (2100–1900 Ma) also in Canada,

J. Biosci. 34(4), October 2009 The evolution and distribution of life in the Precambrian eon-Global perspective and the Indian record 769 has yielded distinct microfossil assemblage in silicifi ed occurrences have been reported from early Mesoproterozoic tidal-fl at carbonates (Hofmann 1976). The population of successions of , Montana, Gaoyuzhuang microfossils is morphologically indistinguishable from Formation, China (see for discussion Sharma and Shukla modern entophysalid cyanobacteria found in intertidal 2009a). The eukayotic organisms evolved signifi cantly zones of Arabian Gulf, Bay in Australia and many that fi nally resulted in the explosive diversifi cation other similar habitats (Golubić and Hofmann 1976). of morphologically complex eukaryotes that sharply Eoentophysalis belcherensis is probably the oldest changed the composition of microbiotas near the end of microfossil that resembles extant cyanobacteria (fi gure 2a). Mesoproterozoic (Knoll 1992; Knoll and Sergeev 1995; In later part of the Palaeoproterozoic, large carbonaceous Sergeev et al. 1996). Cyanobacteria, that evolved earlier, discs, coiled macrofossils and some sphaeromorphic occupied almost all possible ecological niches ranging from acritarchs are reported from different parts of the world. supratidal fl ats to open shelf marine environments during Han and Runnegar (1992) reported a rich collection of fossil this era. Representative cyanobacterial population belong Grypania, coiled macroscopic compressions, in 1800 Ma to entophysalid, nostocalean and oscillatorian cyanobacteria old Negaunee Iron Formation, Michigan. They considered (Sharma 2006c). Ellipsoidal to sausage - shaped forms it as probable photosynthetic and suggested assigned to Archaeoellipsoides are found as allochthonous morphological analogy with giant unicellular organisms in some of the fan-fabrics of carbonates (Horodyski and such as the green alga Acetabularia. In the absence of Donaldson 1980). Several species of Archaeoellipsoides modern analogues and any remnant of nucleated structure, (fi gure 2h) have been recorded from the Mesoproterozoic it is diffi cult to decipher if Grypania was uninucleate, sediments of , China, India and erstwhile coenocytic or multicellular or prokaryote (Sharma and Soviet Union (Sergeev et al. 1995; Srivastava 2005; Sharma Shukla 2009a). Sphaeromorphic acritarchs have also been and Sergeev 2004; Sharma 2006b). The late Mesoproterozoic reported from erstwhile Soviet Union (Timofeev 1959). type microbiotas contain mat-forming entophysalidacean, Similar leiosphaerid acritarchs and fi lamentous and disc- oscillatoriacean and nostocalean as well as mat-dwelling and shaped compressions of millimetric diameter were reported planktic chroococcacean cyanobacteria, but the most typical from the Chuanlingguo Formation, China (Zhang Z 1986; feature of these microfossil assemblages is the presence of Hofmann and Chen 1981). Assemblages of carbonaceous a stalked cyanobacterium Polybessurus bipartitus (fi gure fi lms have been reported from 1700 Ma old Tuanshanzi 2d). The characteristic microbiota of the silicifi ed peritidal Formation, China (Yan and Liu 1997) and from > 1600 carbonates contains the well-preserved and abundant Ma old Shale Formation, India (Sharma 2006a). remnants of entophysalidacean cyanobacteria (Eoentophysalis Some of these forms are suggested to represent eukaryotes. belcherensis) as well as other chroococcacean cyanobacteria of Bengtson et al. (2007) reported megascopic discoidal benthic (Gloeodiniopsis, Eosynechococcus, Sphaerophycus) fossils similar to Ediacaran and ridge pairs as (fi gure 2g) or planktic setting (Coniunctiophycus) (fi gure Myxomitodes stirlingensis from 1800 Ma old 2f). Anabaena-like akinetes of nostocalean cyanobacteria Stirling Range Formation, southwestern Australia. These (Archaeoellipsoides spp.), short and long trichomes composed remains were presumed to be multicellular eukaryotes. In a from constricted as well as non-constricted cask-like and pill- recent study, Matz et al. (2008) demonstrated that the ridged like cells (Filiconstrictosus, Oscillatoriopsis) (fi gure 2b,c), traces could have been made by giant protist testate amoeba- empty sheaths of hormogonian cyanobacteria of LPP type Gromia. Bengtson and Rasmussen (2009) also agree with (Siphonophycus) and unbranched empty cylindrical tube-like this interpretation. Distinct eukaryotic remains have not structures consisting of elongate funnel-like segments nested been found in Palaeoproterozoic sediments, however one within another known as Circumvaginalis elongatus geochemical analysis of bitumen found in the McArthur (fi gure 2e) have been recorded (Sergeev 1993, 2006; Sergeev Group in northern Australia (1700 Ma) shows the presence et al. 1995). of steranes (Summons and Walter 1990) - a derivative of Diagnostic multicellular fi lamentous eukaryotic red alga sterols - produced chiefl y by eukaryotes (Ourisson et al. Bangiomorpha pubescens (fi gure 2i) has been reported 1987). Eukaryotic biomarker have even been from ~1200 Ma Hunting Formation, Somerset Island, recognised in the sediments of late Archaean (Brock et arctic Canada (Butterfi eld 2001). Despite dominance al. 1999) but no substantiating microfossil has been so far of cyanobacteria in the assemblages, these microbiotas reported from these sediments. differ from the Neoproterozoic inhabiting the similar 3.2.2 Mesoproterozoic fossils: During Mesoprotero- environments (Knoll and Sergeev 1995; Sergeev et al. zoic, large size acritarchs and carbonaceous macrofossils 1995; Sergeev 1997; Sharma and Sergeev 2004) and are appeared. Distinctive coiled carbonaceous remains are considered as akinetes of nostocalean cyanobacteria. known as Grypania spiralis, they fi rst appeared in late However, there are lateral variations in the Mesoproterozoic Palaeoproterozoic (Han and Runnegar 1992) and other silicifi ed microfossil assemblages related to environmental 770 M Sharma and Y Shukla

Figure 2. (a) Eoentophysalis belcherensis; (b) Filiconstrictosus magnus; (c) Oscillatoriopsis media; (d) Polybessurus bipartitus; (e) Circumvaginalis elongatus; (f) Coniunctiophycus majorinum; (g) Sphaerophycus medium; (h) Archaeoellipsoides costatus; (i) Bangiomorpha pubescence; (j) Jacutianema solubila; (k) Tappania sp.; (l) Cheilofi lum hysteriopsis; (m) Obruchevella parva; (n) Obruchevella parva (scale for c-e = 50 μm; for f-h, m, n = 10 μm) (a, b, d, e, h, m, n courtesy Dr V N Sergeev and i, j, k, l courtesy Dr N J Butterfi eld).

J. Biosci. 34(5), November 2009 The evolution and distribution of life in the Precambrian eon-Global perspective and the Indian record 771 distribution of microorganisms in ancient basins and in the Rohtas Formation of the Vindhyan Supergroup, India probably to palaeoenvironmental zonation. (Kumar 1995; Sharma and Shukla 2009a). Carbonaceous Presence of nucleated microorganisms, preserved mainly discs and elongated forms known as Chuaria and Tawuia are as organic-walled microfossils, in the Mesoproterozoic known from Suket Shales of the Vindhyan Supergroup (see microbial communities of middle to inner and probably of Kumar 2001). Archaeoellipsoides, Anabaena-like akinetes outer shelf settings are well known (Peat et al. 1978; Veis and of nostocalean cyanobacteria are also known from Kheinjua Vorobyeva 1992; Xiao et al. 1997; Javaux et al. 2001, 2003). Formation of the Vindhyan Supergroup (Srivastava 2005; A structurally complex microfossil Tappania plana, with Sharma 2006b). Eukaryotic remains i.e. Tappania plana are irregularly branching processes and bulbous protrusions, also recorded in the sub-surface sequence of the Ganga basin suggests the presence of cystoskelton in the microfossil, (Prasad and Asher 2001). which is a characteristic of eukaryotes. The prokaryotic 3.2.3 Neoproterozoic fossils: In comparison to cyanobacterial communities dominated extremely shallow- Palaeo-Mesoproterozoic, fossil assemblages of the water peritidal environments and have been preserved Neoproterozoic era are much better preserved, diversifi ed mainly in cherts. However, record of Mesoproterozoic and quantitatively abundant. The prokaryotes, eukaryotes, silicifi ed protista are rare and confi ned mainly to the (acritarchs, multicellular algae) proliferated further and latest Mesoproterozoic deposits (Butterfi eld 2000, 2001; distinct metazoans appeared for the fi rst time. Several Butterfi eld et al. 1990; Petrov et al. 1995; Sergeev et al. Neoproterozoic successions in different parts of the world 1997). Remains of unicellular eukaryotes preserved in chert demonstrate the diversity of biological forms present in the lenses and nodules as well as fossilised protista preserved as ecosystem of this era (Schopf 1968; Vidal 1976; Strother et compressions in shales mainly from the inner shelf facies are al. 1983; Shukla et al. 1986; Zhang 1989; German 1990; also recorded from the Mesoproterozoic. Recent discoveries Knoll et al. 1991; Zang and Walter 1992; Kumar and of numerous exceptionally well preserved silicifi ed Srivastava 1992; Kumar and Rai 1992; Tiwari and Knoll microfossil assemblages from peritidal and open marine 1994; Butterfi eld et al. 1994). environments have demonstrated taxonomic diversity The Neoproterozoic fossil assemblages can be appreciated and ecological complexity of Mesoproterozoic life. The for their complexity and unusual forms. If the Bitter Springs Mesoproterozoic silicifi ed microbiotas of peritidal settings Formation microbial assemblage (Schopf 1968) is known are, though simple in organization and chiefl y constituted for excellent preservation of cyanobacterial remains in chert of conservative cyanobacteria, yet certain degree of then the Lakhanda and Miroyedikha assemblages of Siberia biostratigraphic order can be inferred from the assemblage (German 1990) demonstrate equally well preserved delicate (Sergeev et al. 2008) for the fi rst time in Proterozoic. Beaded fossils recovered from thin layers of sapropel on mudstone. trace fossils found in the 1500 Ma old Appekunny Argillite, Lakhanda assemblage includes Eosaccharomyces ramosus, Belt Supergroup, north–western Montana (Horodyski 1982) an unusual form that consists of vesicles arranged in open, and ~1050 Ma old Manganese Subgroup of the Bangemall Group, Western Australia (Grey and Williams 1990) have web-like colonies comparable to slime moulds. Knoll (1996) been interpreted differently. Grey and Williams considered suggested that the chain like occurrence is indicative of these beaded structures as articulated seaweed comparable behavioural sophistication involving communication among to the modern brown alga Hormosira whereas Fedonkin and the cells within a colony. Large acanthomorphic acritarch Yochelson (2002) considered the beaded structures found in Trachyhystrichosphaera aimika, sphaeromorphs larger Montana as tissue-grade colonial and designated than one millimeter size and leiosphaerids showing binary as Horodyskia moniliformis. division or budding are conspicuous in Lakhanda assemblage. An assessment of the Mesoproterozoic microbial In fact, the large (100–5000 μm) complex acritarchs are assemblage brings out that during this era wide ranging characteristic of any Neoproterozoic assemblage and they planktic and benthic microbes, mainly constituted of diversifi ed during the era. The palaeobiological studies prokaryotes, were present in the ecosystem. Eukaryotes that on the Akademikerbreen Group, Svalbard (700–800 Ma) probably appeared in late Palaeoproterozoic manifested in and its correlative successions in East provide varied forms during the Mesoproterozoic. Morphological another example of rich assemblage of microfossil species diversity of unicellular and macroscopic eukaryotic fossils in cherts and shales of this group. In all, more than forty was low during the early part of the Mesoproterozoic taxa have been recorded in Lakhanda and Miroyedikha but gradually became abundant in late Mesoproterozoic. assemblages, whereas 104 species have been recorded from Grypania, beaded structures and some other macroscopic Akademikerbreen Group and its correlative successions remains probably represent extinct biological groups. in East Greenland (Knoll et al. 1991; Green et al. 1988; The Indian Mesoproterozoic successions entomb several Butterfi eld et al. 1988, 1994). Monospecifi c population of characteristic prokaryotic and eukaryotic entities. A large vaucheriacean xanthophytic algae have been recorded from population of coiled fossils, Grypania spiralis, has been found the 750 Ma old Svanbergfjellet Formation, Spitsbergen

J. Biosci. 34(5), November 2009 772 M Sharma and Y Shukla

(Butterfi eld 2004). Specimens showing linear attachment An interesting lichen-like fossil has been reported have been designated as Jacutianema solubila (fi gure 2j). from the upper , China (Yuan et Vase-shaped microfossils (VSM) are another characteristic al. 2005). These fossils suggest that fungi developed group of microfossils found in the Neoproterozoic symbiotic relationship with photoautotrophs much before the successions. VSMs have been correlated with testate evolution of vascular . The Tappania fossils (fi gure 2k) amoebae and considered to be an important evidence for occurring in the early Neoproterozoic Wynniatt Formation, hetrotrophic eukaryotes in marine realm (Porter and Knoll Canada (900-800 Ma) have been reliably considered as 2000). VSMs are recorded along with other acritarch taxa a fungi (Butterfi eld 2005a). Isolated fl anged fi lamentous in 850–800 Ma old Chuar Group (Vidal and Ford 1985). microfossil Cheilofi lum hysteriopsis (fi gure 2l) also recorded Globally the diversity of acritarch in the Neoproterozoic from the Wynniatt Formation, appears to be a large fungal reached its zenith in the sediments lying above tillites of annellophore (Butterfi eld 2005b). Tappania is also known the Varanger glaciation (610–590 Ma). An assemblage of from the Mesoproterozoic Roper Group of Australia that late Ediacaran microfossils comprising of cyanobacteria, extends the record of putative fungi to 1430 Ma. Ovoid scales, eukaryotic leiosphaerids, enigmatic microfossil Valkyria another unusual fossil, in Neoproterozoic rocks are recorded borealis and some other forms has been reported from in 700-620 Ma old diagenetic chert of the Tindir Formation, Włodawa Formation, Poland (Moczydłowska 2008). Canada (Allison and Hilgert 1986). Except for their large The assemblage provides an evidence of marine benthic size, morphologically they are similar to scales of modern and planktic microbiota that survived glaciations during chrysophytes. The affi nity of these scales are yet unresolved. Period. Large, well preserved acritarchs and Biomineralization is another landmark in the evolution of the multicellular algae have been recorded from the 580 Ma old biosphere, evidence of which is found in the Neoproterozoic silicifi ed phosphorites of the Doushantuo Formation, China sediments in the form of calcifi ed metaphytes, metazoans and (Yin 1985; Yuan and Hofmann 1998; Zhou et al. 2001; Xiao skeletal algae (Horodyski and Mankiewicz 1990; Grant et al. 2004). Helically coiled fossil Obruchevella is well known in 1991; Grotzinger et al. 2000; Hua et al. 2005). The advent of the Neoproterozoic-Cambrian Phosphorite deposits of India, animals in the Ediacaran sediments was a major event in the China and Russia (fi gure 2m, n). Comparable acritarchs have . The fossils of various groups and some been recorded in shales of 580 Ma old Pertatataka Formation, unknown groups are recorded. Australia (Zang and Walter 1992). The Pertatataka assemblage In the Indian Neoproterozoic successions various consists of 33 acritarch species including 17 species of large types of organic, metazoan and metaphytes are recorded. acanthomorphic acritarchs (>100 μm). Detailed studies on the Vendotaenia, Tyrasotaenia, Protoarenicola, Pararenicola, Ediacaran sediments of Australia have shown the presence of Sinosabellidites, helically coiled Obruchevella, Ediacaran a very rich assemblage of acritarchs (Grey 2005). Study on metazoan remains are recorded (Kumar and Rai 1992; the Murnaroo 1 drillcore in the eastern part of the Offi cer Prasad and Asher 2001; Mathur 2008, Sharma and Shukla Basin, Australia revealed the presence of 21 acritarch species 2009b). A rich assemblage of acritarchs has been recently and 14 genera (Willman et al. 2006). Twenty one acritarch recorded from the Ganga basin in India (Prasad and Asher species and 15 genera of Ediacaran acritarchs have been 2001). reported from the Giles 1 drillhole, Offi cer Basin, Australia Biomarker molecular studies in the Neoproterozoic (Willman and Moczydłowska 2008). Shales of the Kursovsky sediments indicate the presence of diverse prokaryotes Formation, Siberia have also yielded a rich assemblage and eukaryotes, including red algae, green algae, and of acritarchs (Moczydłowska et al. 1993). Studies on the heterotrophic protists and even 4-methyl steranes probably sediments of East European Platform, mainly in bore cores, derived from dinosterols (Summons et al. 1988; Summons have shown that acanthomorphic acritarchs persisted until and Walter 1990). These biomarkers closely match the other the close of the era. The wide occurrence of these acritarchs known fossil records. in Australia, Siberia, (the East European Platform), Based on these diverse microfossil remains in the India and south China suggests that acritarchs are suitable Neoproterozoic sediments, it appears that prokaryotes, very for intra-and inter-regional correlation. Assemblages in the similar to modern counterparts, and diverse eukaryotes sediments from East European Platform show additional including protists, red, green algae, fungi and some unusual presence of ribbon-like forms assigned to Vendotaenia and forms were present in the Neoproterozoic ecosystems. Tyrasotaenia (Gnilovaskaya 1988). Vendotaenia with thin Animals appeared on the scene last. wall and fi brous texture has been accepted as eukaryotic and probably algal in origin, but Vidal (1989) suggested it to be a 4. Conclusion sheath of giant bacterium; whereas Tyrasotaenia with smooth walls has also been considered eukaryotic but possibly of Studies on Precambrian life during the last fi fty fi ve animal origin (Knoll 1996). years have increased manifold and established it as a

J. Biosci. 34(5), November 2009 The evolution and distribution of life in the Precambrian eon-Global perspective and the Indian record 773 distinct multidisciplinary subject. Many new windows of Butterfi eld N J 2000 Bangiomorpha pubescens n. gen., n. sp.: investigations have enriched our understanding of the advent implications for the evolution of sex, multicellularity and the of various groups. Varied prokaryotes, eukaryotes, protista, Mesoproterozoic-Neoproterozoic radiation of eukaryotes; fungi and lichens are identifi ed and established in the 26 386–404 Precambrian successions with considerable evidence arising Butterfi eld N J 2001 Paleobiology of the late Proterozoic (ca. 1200 Ma) Hunting Formation, Somerset Island, arctic Canada; from the Indian Precambrian sedimentary successions. Precambrian Res. 111 235–256 Butterfi eld N J 2004 A vaucheriacean alga from the middle Acknowledgements Neoproterozoic of Spitsbergen: implications for the evolution of Proterozoic eukaryotes and the ; Paleobiology 30 231–252 MS thanks J W Schopf (UCLA, USA), V N Sergeev Butterfi eld N J 2005a Probable Proterozoic fungi; Paleobiology (GINRAS, Russia), and N J Butterfi eld (Cambridge, 31 165–182 UK) for providing some of the photographs used in Butterfi eld N J 2005b Reconstructing a complex early this article. Comments by reviewers S Kumar, H K Neoproterozoic eukaryote, Wynniatt Formation, arctic Canada; Maheshwari, Ashok Sahni and Sunil Bajpai are gratefully Lethaia 38 155–169 acknowledged. Sincere thanks are due to N C Mehrotra, Butterfi eld N J and Chandler F W 1992 Palaeoenvironmental Director, Birbal Sahni Institute of Palaeobotany, Lucknow distribution of Proterozoic microfossils, with an example from the for permission to publish the paper. Preparation of this Agu bay Formation, Baffi n Islands; Palaeontology 35 943–957 paper was partially supported by the grants from ILTP-DST Butterfi eld N J, Knoll A H and Swett K 1988 Exceptional (B 2.56). preservation of fossils in an upper Proterozoic shale; Nature (London) 334 424–427 Butterfi eld N J, Knoll A H and Swett K 1990 A bangiophyte red algae References from the Proterozoic of Arctic Canada; Science 250 104–107 Butterfi eld N J, Knoll A H and Swett K 1994 Paleobiology of the Neoproterozoic Svanbergfjellet Formation, Spitsbergen; Fossils Allison C W and Hilgert J W 1986 Scale microfossils from earliest Strata 34 1–84 Cambrian or latest Proterozoic Tindir Group rocks, northwest Byerly G R, Lowe D R and Walsh M M 1986 Stromatolites Canada; Precambrian Res. 43 253–294 from the 3,300-3,500-Myr Swaziland Supergroup, Barberton Altermann W and Schopf J W 1995 Microfossils from the Mountain Land, South Africa; Nature (London) 319 489–491 Campbell Group, Griqualand West sequence of Dalton R 2002 Squaring up over ancient life; Nature (London) 417 the Transvaal Supergroup, and their paleonvironmental and 782–784 evolutionary implications; Precambrian Res. 75 65–90 Darwin, C 1859 The origin of species (London: John Murray) Awramik S M, Schopf J W and Walter M R 1983 Filamentous fossil pp 447 bacteria from the of Western Australia; Precambrian Fedonkin M A and Yochelson E L 2002 Middle Proterozoic (1.5 Res. 20 357–374 Ga) Horodyskia moniliformis Yochelson and Fedonkin, the Barghoorn E S and Tyler S A 1965 Microorganisms from the Gunfl int oldest known tissue-Grade colonial eukaryote; Smithsonian chert; Science 147 563–577 Contrib. Paleobiol. 94 1–29 Bengtson S and Rasmussen B 2009 New and Ancient Trace Makers; German T N 1990 Organic world one billion years ago (Leningrad: Science 323 346–347 Nauka) pp 49 Bengtson S, Rasmussen B and Krapež B 2007 The Gnilovaskaya M B (ed.) 1988 Vendotaenids of the East-European megascopic Stirling biota; Paleobiology 33 351–381 Platform (Leningrad: Nauka) pp 143 Brasier M D, Green O R, Jephcoat A P, Kleppe A K, Van Golubić S and Hofmann H J 1976 Interpretation of microfossils Kranendonk M J, Lindsay J F, Steele A and Grassineau N V with special reference to the Precambrian; in Fossil Algae (ed.) 2002 Questioning the evidence of Earth’s oldest fossils; Nature E Flugel (Springer-Verlag, Berlin) pp 1–14 (London) 416 76–81 Gradestein F M, Ogg J G, Smith A G, Bleeker W and Lourens L Brocks J J, Logan G A, Buick, R and Summons R E 1999 Archean J 2004 A new geological Time-scale with special reference to molecular fossils and the early rise of eukaryotes; Science 285 Precambrian and ; Episodes 27 83–100 1033–1036 Grant S W F, Knoll A H and Germs G J B 1991 Probable calcifi ed Buick R 1984 Carbonaceous fi laments from North Pole, Western metaphytes in the Proterozoic , Namibia: origin, Australia: are they fossil bacteria in Archaean stromatolites?; diagenesis and implications; J. Paleontol. 65 1–18 Precambrian Res. 24 157–172 Green J W, Knoll A H and Swett K 1988 Microfossils from pisolites Buick R 1992 The antiquity of oxygenic : evidence of the Upper Proterzoic Eleonore Bay Group, central East from stromatolites in sulphate-defi cient Archaean lakes; Science Greenland; J. Paleontol. 62 835–852 255 74–77 Grey K 2005 Ediacaran of Australia; Mem. Assoc. Aust. Buick R, Dunlop J S R and Groves D I 1981 Stromatolites Palaeontol. 31 1–439 recognition in ancient rocks: an appraisal of irregularly Grey K and Williams I R 1990 Problematic bedding-plane markings laminated structures in an Early Archaean chert-barite unit from from the Middle Proterozoic Manganese Subgroup, Bangemall North Pole, Western Australia; Alcheringa 5 161–181 Basin, Western Australia; Precambrian Res. 46 307–327

J. Biosci. 34(5), November 2009 774 M Sharma and Y Shukla

Grotzinger J P, Watters W A and Knoll A H 2000 Calcifi ed metazoan Kumar S 1995 Microfossils from the Mesoproterozoic Rohtas in thrombolite-stromatolite reefs of the terminal Proterozoic Formation (Vindhyan Supergroup) Katni area, central India; Nama Group, Namibia; Paleobiology 26 334–359 Precambrian Res. 72 171–184 Han T M and Runnegar B 1992 Megascopic eukaryotic algae from Kumas S 2001 Mesoproterozoic mega fossil Chuaria-Tawuia 2.1-billion--old Negaunee Iron-Formation, Michigan; Science association may represent parts of a multicellular , 257 232–235 Vindhyan Supergroup, Central India; Precambrian Res. 106 Hofmann H J 1976 Precambrian microfl ora, Belcher Island, Canada: 187–211 signifi cance and systematics; J. Paleontol. 50 1040–1073 Kumar S and Rai V 1992 Organic walled microfossil from the Hofmann H J 2000 Archean stromatolites as Microbial Archives; bedded black chert of the Krol Formation (Vendian), Solan area, in Microbial sediments (eds) R E Riding and S M Awramik Solan district, Himachal Pradesh, India; J. Geol. Soc. India 39 (Springer-Verlag) pp 315–327 229–234 Hofmann H J and Chen J 1981 Carbonaceous megafossils from Kumar S and Srivastava P 1992 Middle to Late Proterozoic the Precambrian (1800 Ma) near Jixian, northern China; Can. J. microbiota from the Deoban , Garhwal Himalaya, Earth Sci. 18 443–447 India; Precambrian Res. 56 291–318 Horodyski R J 1982 Problematic bedding plane markings from the Lanier W P 1986 Approximate growth rates of Early Proterozoic Middle Proterozoic Appekunny Argillite, belt Supergroup, north microstromatolites as deduced by biomass productivity; Palaios western Montana; J. Paleontol. 56 882–889 1 525–542 Horodyski R J and Donaldson J A 1980 Microfossils from the Lanier W P 1989 Interstitial and peloid microfossils from the 2.0 Middle Proterozoic Dismal Lakes Group, Arctic Canada; Ga Gunfl int Formation: implications for the palaeoecology of Precambrian Res. 11 125–159 the Gunfl int stromatolites; Precambrian Res. 45 291–318 Horodyski R J and Mankiewicz C 1990 Possible late Proterozoic Lowe D R 1980 Stromatolites 3,400-Myr old from the Archean of skeletal algae from the Pahrump Group, Kingston Range, Western Australia; Nature (London) 284 441–443 southeastern California Am. J. Sci. 290A 149–169 Mathur V K 2008 Ediacaran multicellular biota from Krol Group, Hua H, Chen Z, Yuan X, Zhang L and Xiao S 2005 Skeletogenesis Lesser Himalaya and its stratigraphic signifi cance – a review; and asexual reproduction in the earliest biomineralizing animal Palaeobotanist 57 53–61 Cloudina; Geology 33 277–280 Maithy P K, Kumar S and Babu R 2000 Biological remains Javaux E J, Knoll A H and Walter M R 2001 Morphology and and organosedimentary structures from Iron Ore Supergroup ecological complexity in early eukaryotic ecosystems; Nature (Archaean) Barbil area, Singhbhum, Orissa; Geol. Surv. India, (London) 412 66–69 Spl. Publ. 57 98–106 Javaux E J, Knoll A H and Walter M R 2003 Recognizing and Matz M V, Frank T M, Justin Marshall N, Widder E A and Johnsen interpreting the fossils of early eukaryotes Orig. Life Evol. Biosph. S 2008 Giant deep-sea protist produces bilaterian-like traces; 33 75–94 Curr. Biol. 18 1849–1854 Kaźmierczak Józef and Barbara Kremer 2002 Thermal alteration of Mayr E 1998 Two empires or three; Proc. Natl. Acad. Sci. USA 95 the Earth’s oldest fossils; Nature (London) 420 477–478 9720–9723 Klein C, Beukes N J and Schopf J W 1987 Filamentous McKeegan K D, Kudryavstev A and Schopf J W 2007 Raman and microfossils in the Early Proterozoic Transvaal Supergroup: ion microscopic imagery of graphitic inclusion in apatite from their morphology, signifi cance and Paleoenvironmental setting; older than 3830 Ma Akilia Supracrustal rocks, West Greenland; Precambrian Res. 36 81–94 Geology 28 707–710 Knoll A H 1992. The Early Evolution of Eukaryotes: A Geological Moczydłowska M 2008 New records of late Ediacaran microbiota Perspective; Science 256: 622–627 from Poland; Precambrian Res. 167 71–92 Knoll A H 1996 Archean and Proterozoic ; in Moczydłowska M, Vidal G and Rudavskaya V A 1993 Palynology:principles and applications vol. 1 (eds) J Jansonious Neoproterozoic (Vendian) phytoplankton from the Siberian and D C McGregor (American Association of Stratigrahic Platform, Yakutia; Paleontology 36 495–521 Palynologists Foundation) pp 51–80 Muir M J and Grant P R 1976 Micropaleontological evidence from Knoll A H and Barghoorn E S 1977 Archean microfossils showing the Onverwacht Group, South Africa; in The early history of the cell division from the Swaziland System of South Africa; Earth (ed.) B F Windley (London: Wiley) pp 595–604 Science 198 396–398 Naqvi S M, Venkatachala B S, Shukla M, Kumar B, Natarajan R Knoll A H, Barghoorn E S and Awramik S M 1978 New and Sharma M 1987 Silicifi ed cyanobacteria from the cherts of Microorganisms from the Aphebian Gunfl int Iron Formation, the Archaean Sandur Schist belt, Karnataka, India; J. Geol. Soc. Ontario; J. Paleontol. 52 976–992 India 29 535–539 Knoll A H and Sergeev V N 1995 Taphonomic and Evolutionary O’Neil J, Carlson R W, Francis D and Stevenson R K 2008 changes across the Mesoproterozoic-Neoproterozoic Transition; Neodymium-142 evidence for Mafi c Crust; Science Neues Jahrb. Geol. Pälaontol. Abh. 195 289–302 321 1828–1831 Knoll A H, Swett K and Mark J 1991 Paleobiology of a Neoprotero- Ourisson G, Rohmer M and Poralla K 1987 Prokaryotic hopanoid zoic tidal fl at/lagoonal complex: the Draken Conglomerate and other polyterpenoid sterol surrogates; Annu. Rev. Microbiol. Formation, Spitsbergen; J. Paleontol. 65 531–570 41 301–334 Knoll A H, Walter M R, Narbonne G M and Christe-Blick N 2006 Peat C R, Muir M D, Plumb K A, McKirdy D M and Norvick M S The Ediacaran Period: a new addition to the ; 1978 Proterozoic microfossils from the Roper Group, Northern Lethaia 39 13–30 Territory, Australia; J. Aust. Geol. Geophys. 3 1–17

J. Biosci. 34(5), November 2009 The evolution and distribution of life in the Precambrian eon-Global perspective and the Indian record 775

Petrov P Y, Semikhatov M A and Sergeev V N 1995 Development Vindhyan Supergroup, India; J. Palaeontol. Soc. India 51 of the Riphean and distribution of silicifi ed 27–35 microfossils: the Sukhaya Tunguska Formation, Turukhansk Sharma M 2006b Small-sized akinetes from the Mesoproterozoic Uplift, Siberia; Stratigr.Geol.Correlation 3 79–99 Salkhan Limestone, Semri Group, Bihar, India; J. Palaeontol. Porter S and Knoll A H 2000 Testate amoebae in the Neoproterozoic Soc. India 51 109–118 Era: evidence from vase-shaped microfossils in the Chuar Sharma M 2006c Palaeobiology of Mesoproterozoic Salkhan Group, Grand Canyon; Paleobiology 26 360–385 Limestone, Semri Group, Rohtas, Bihar, India: Systematics and Prasad B and Asher R 2001 Acritarch and Signifi cance; J. Earth Syst. Sci. 115 67–98 lithostratigraphic classifi cation of Proterozoic and lower Sharma M and Sergeev V N 2004 Genesis of carbonate precipitate sediments (Pre-Unconformity Sequence) of Ganga patterns and associated microfossils in Mesoproterozoic Basin, India; Palaeontogr. Indica 5 1–151 formations of India and Russia – a comparative study; Rasmussen B 2000 Filamentous microfosils in a 3,235-million Precambrian Res. 134 317–347 year-old volcanogenic massive sulphide deposite; Nature Sharma M and Shukla M 2004 A new Archaean stromatolites (London) 405 676–679 from the Chitradurga Group, Dharwar Craton, India and its Schopf J W 1968 Microfl ora of the Bitter Springs Formation, Late signifi cance; Palaeobotanist 53 5–16 Precambrian, Central Australia; J. Paleontol. 42 651–688 Sharma M and Shukla Y 2009a Taxonomy and affi nity of Early Schopf J W 1993 Microfossils of the Early Archaean Apex Mesoproterozoic megascopic helically coiled and related fossils Chert: New Evidence of the Antiquity of Life; Science 260 from the Rohtas Formation, the Vindhyan Supergroup, India; 640–646 Precambrian Res. 173 105–122 Schopf J W 2004 Earth’s earliest biosphere: Status of the hunt; in Sharma M and Shukla Y 2009b Megacopic carbonaceous The Precambrian Earth: Tempos and events (eds) P G Eriksson, compression fossils from Neoproterozoic Bhima basin, W Altermann, D R Nelson, W U Mueller and O Catuneanu Karanataka, south India; J. Geol. Soc. London (submitted) (Amsterdam: Elsevier) pp 516–539 Shukla M, Tewari V C and Yadav V K 1986 Late Precambrian Schopf J W, Kudryavtsev A B, Agresti D G, Wdowiak T J and microfossils from the Deoban Limestone Formation, Lesser Czaja A D 2002 Laser-Raman imagery of Earth’s earliest Himalaya; Palaeobotanist 35 347–356 fossils; Nature London) 416 73–76 Srinivasan R, Shukla M, Naqvi S M, Yadav V K, Venkatachala B Schopf J W and Packer B M 1987 Early Archean (3.3-billion to S, Uday Raj B and Subba Rao D V 1989 Archaean stromatolites 3.5 billion-year-old) micro-fossils from Warrawoona Group, from the Chitradurga Schist Belt, Dharwar Craton South India; Australia; Science 237 70–73 Precambrian Res. 43 239–250 Schopf J W and Walter M R 1983 Archean microfossils, new Srivastava P 2005 Vindhyan Akinetes: An indicator of evidence of ancient microbes; in Earth’s earliest biosphere: Mesoproterozoic Biosphere Evolution; Orig. Life Evol Biosph. its origin and evolution (ed) J W Schopf (Princeton: Princeton University Press) pp 214–239 35 175–185 Sergeev V N 1993 Silicifi ed Riphean microfossils of the Anabar Srivastava P and Kumar S 2003 New microfossils from the Meso- Uplift; Stratigr. Geol. Correlation 1 264–278 Neoproterozoic Deoban Limestone, Garhwal Lesser Himalaya, Sergeev V N 1997 Mesoproterozoic Microbiotas of the Northern India; Palaeobotanist 52 13–47 Hemisphere and the Meso-Neoproterozoic Transition; Proc. 30th Strother P K, Knoll A H and Barghoorn E S 1983 Micro-organisms Int. Geol Congr. 1 177–185 from the late Precambrian Narssarssuk Formation, north- Sergeev V N 2006 Precambrian microfossils in cherts: their western Greenland; Paleontology 26 1–32 paleobiology, classifi cation and biostratigraphic usefulness Summons R E, Brassell S C, Eglinton G, Evans E J, Horodyski (GEOS, Moscow, 2005) pp 280 (in Russian) R J, Robinson N and Ward D M 1988 Distinctive hydrocarbon Sergeev V N, Knoll A H and Petrov P Y 1997 Paleobiology of the bomarkers from fossiliferous sediments of the late Proterozoic Mesoproterozoic - Neoproterozoic Transition: The Sukhaya Walcott Member, Chuar Group, Grand Canyon, USA; Geochim. Tunguska Formation, Turukhansk Uplift, Siberia; Precambrian Cosmochim. Acta 52 2625–2673 Res. 85 201–239 Summons R E and Walter M R 1990 Molecular fossils and Sergeev V N, Knoll A H and Grotzinger J P 1995. Paleobiology of microfossils of prokaryotes and protists from Proterozoic the Mesoproterozoic Billyakh Group, Anabar Uplift, Northeastern sediments; Am. J. Sci. 290-A 212–244 Siberia; Paleontol. Soc. Mem. 39 37 pp Timofeev B V 1959 Ancient fl ora of the Baltic area and its Sergeev V N, Knoll A H and Zavarzin G A 1996 First three billion stratigraphic signifi cance; Tr. Vses. Neft. Nauchno-Issled. Geol. years of life: from prokaryotes to eukaryotes; Priroda 6 54–67 (in Inst. (VNIGRI) 129 1–320 Russian) Tiwari M and Knoll A H 1994 Large acanthomorphic acritarchs Sergeev V N, Sharma M and Shukla Yogmaya 2008 Mesoproterozoic from the Infrakrol Formation of the Lesser Himalaya and their silicifi ed microbiotas of Russia and India—Characteristics and stratigraphic signifi cance; J. Him. Geol. 5 193–201 Contrasts; Palaeobotanist 53 323–358 Towe K M 1990 Aerobic respiration in the Archaean?; Nature Seward A C 1931 Plant Life through the ages (Cambridge (London) 384 54–56 University Press) 601 pp Tyler S A and Barghoorn E S 1954 The occurrence of structurally Sharma M 2006a Late Palaeoproterozoic () carbonaceous preserved plants in Precambrian rocks of the Canadian ; fi lms from the Olive Shale (Koldaha Shale), Semri Group, Science 119 606–608

J. Biosci. 34(5), November 2009 776 M Sharma and Y Shukla

Van Zuilen M A, Lepland A and Arrhenius G 2002 Reassessing Woese C R 2002 On the evolution of cells; Proc. Natl. Acad. Sci. the evidence for the earliest traces of life; Nature (London) 418 USA 99 8742–8747 627–630 Woese C R, Kandler O and Wheels M L 1990 Towards a natural Venkatachala B S, Sharma M, Srinivasan R, Shukla M and system of organisms:proposal for the domains Archaea, Bacteria Naqvi S M 1986 Bacteria from the Archaean banded iron and Eucarya; Proc. Natl. Acad. Sci. USA 87 4576–4579 Formation of Kudremukh region, Dharwar Craton, South India; Xiao S 2004 New multicellular algal fossils and acritarchs in Palaeobotanist 35 200–203 Doushantuo chert nodules (Neoproterozoic; Yangtze Gorges, Venkatachala B S, Shukla M, Sharma M, Naqvi S M, Srinivasan R south China; J. Paleontol. 78 393–401 and Udairaj B 1990 Archaean microbiota from the Donimalai Xiao S, Knoll A H, Kaufman A J, Zhang Y and Yin L 1997 Formation, Dharwar Supergroup, India; Precambrian Res. 47 Neoproterozoic fossils in Mesoproterozoic rocks? Chemo- 27–34 stratigraphic resolution of a biostratigraphic conundrum from Veis A F and Vorobyeva N G 1992 Riphean and Vendian the North China Platform; Precambrian Res. 84 197–220 microfossils of the Anabar Massif; Izvest. Akad. Nauk Ser. Geol. Yan Yu-Zhong and Liu Zhi-li 1997 Tuanshanzian macroscopic 5 36–54 algae of 1700 Ma B. P. from Tuanshanzi Formation in Jixian, Vidal G 1976 Late Precambrian microfossils from the Visingso China; Acta Micropalaeontol. Sin. 12 107–126 beds in southern Sweden; Fossils Strata 9 1–57 Yin Leiming 1985 Microfossils of the Doushantuo Formation in Vidal G 1989 Are Late Proterozoic carbonaceous megafossils the Yangtze Gorge District, western Hebei, China; Palaeontol. metaphytic algae or bacteria?; Lethaia 22 375–379 Cathayana 2 229–249 Vidal G and Ford T D 1985 Microbiotas from the late Proterozoic Yuan Xunlai and Hofmann H J 1998 New microfossils from the Chuar Group (northern Arizona) and Uinta Mountain Group Neoproterozoic (Sinian) Doushantuo Formation, Wen’an, (Utah) and their chronostratigraphic implications; Precambrian Guizhou Province, southern China; Alcheringa 22 189–222 Res. 28 349–389 Yuan Xunlai, Xiao S and Taylor T N 2005 Lichen-like symbiosis 600 Walsh M M and Lowe D R 1985 Filamentous microfossils from the million years ago; Science 308 1017–1020 3500-Myr-old Onverwacht Group, Barberton Mountain Land, Zang Wenlong and Walter M R 1992 Late Proterzoic and South Africa; Precambrian Res. 54 271–293 Early Cambrian microfossils and bostratigraphy, northern Walter M R, Buick R and Dunlop J S R 1980 Stromatolites 3,400- Anhui and Jiangsu, central-eastern China; Precambrian Res. 57 3,500 Myr old from the North Pole area, Western Australia; 243–323 Nature (London) 284 443–445 Zhang Z 1986 Clastic facies microfossils from the Chuanlinggou Willman S and Moczydłowska M 2008 Ediacaran acritarch biota Formation (1800 Ma) near Jixian, North China; J. from the Giles 1 drillhole, Offi cer Basin, Australia, and its Micropaleontol. 5 9–16 potential for biostratigrahic correlation; Precambrian Res. 162 Zhang Z 1989 Multicellular thallophytes with differentiated 498–530 tissue from Late Proterozoic phosphate rocks of South China; Willman S, Moczydłowska M and Grey K 2006 Neoproterozoic Precambrian Res. 28 1–18 (Ediacaran) diversifi cation of acritarchs- anew record from the Zhou C, Brasier M D and Xue Y 2001 Three-dimensional Murnaroo 1 drillcore, eastern Offi cer Basin, Australia; Rev. phosphatic preservation of giant acritarchs from the terminal Palaeobot. Palynol. 139 17–39 Proterozoic Doushantuo Formation in Guizhou and Hubei Woese C R 1987 Bacterial evolution; Microbiol. Rev. 51 221–271 province, South China; Palaeontology 44 1157–1178

ePublication: 2 November 2009

J. Biosci. 34(5), November 2009