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The trilobite Redlichia Cossmann, 1902 is an abundant element of the lower Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstatte on Kangaroo Island, South Australia. Well-preserved...

Studies that reveal detailed information about trilobite growth, particularly early developmental stages, are crucial for improving our understanding of the phylogenetic relationships within this iconic group of fossil arthropods. Here we document an essentially complete ontogeny of the trilobite Redlichia cf. versabunda from the Cambrian Series 2 (late Stage 4) Ramsay Limestone of Yorke Peninsula in South Australia, including some of the best-preserved protaspides (the earliest biomineralized trilobite larval stage) known for any Cambrian trilobite. These protaspid stages exhibit similar morphological characteristics to many other taxa within the Suborder Redlichiina, especially to closely related species such as Metaredlichia cylindrica from the early Cambrian period of China. Morphological patterns observed across early developmental stages of different groups within the Order Redlichiida are discussed. Although redlichiine protaspides exhibit similar overall morphologies, certain ontogenetic characters within this suborder have potential phylogenetic signal, with different superfamilies characterized by unique trait combinations in these early growth stages.

A taxonomic study of the trilobites found in the Marianian parastratotype of the Iberian Chains, north‐east Spain, results in the recognition of the new redlichiid Redlichia isuelaensis sp. nov., the ellipsocephalid Lusatiops ribotanus, and the saukiandids Onaraspis garciae sp. nov., Paulaspis tiergaensis gen. et sp. nov. and Luciaspis matiasi gen. et sp. nov. The diagnosis of the new Subfamily Onaraspininae (Saukiandidae) and its genera takes into account distinct differences in the thorax, which is subdivided into prothorax with spinose and/or macropleural tergites and opistothorax with micropleurid segments. Onaraspis geyeri sp. nov. is erected based on material previously described in Jordan, which was assigned to poorly preserved material of Myopsolenites palmeri from Israel. The temporal correlation of Marianian endemic‐dominant trilobites throughout the Variscan tectonostratigraphic units of the Iberian Peninsula is not supported by acritarchs, archaeocyaths or trilobites. Three diachronous horizons have been proposed to mark the base of the Marianian (based on the first occurrence of two trilobite genera and one archaeocyathan assemblage zone) and two diachronous horizons for the top (based on the first and last occurrence of different trilobite genera). As a result, the Cambrian Epoch‐2 Marianian Stage is ill‐defined and rendered invalid for correlation throughout the Iberian Peninsula., This paper is a contribution to project CGL2017‐87631‐P from Spanish MINECO.

Burgess Shale-type biotas have been widely reported from the Cambrian in North America, Siberia, Greenland, China, and Australia; they are crucial in reconstructing the biotic evolution and ecological interactions of early metazoans. Here, we report an atypical Burgess Shale-type fossil assemblage from the Shilongdong Formation (Cambrian Stage 4) in the Jingshan area, central Hubei Province, South China. The newly recovered fauna is preserved in a nearly two-meter-thick yellowish-green shale unit intercalated within the massive dolomite and dolomitic limestone succession of the upper Shilongdong Formation. The fossil-bearing shale unit is likely deposited in the deep subtidal zone below storm wave base with occasional influence of weak storm flows, which was likely situated in the relatively low location with the interior of the restricted carbonate platform. The presence of the trilobite Redlichia guizhouensis assigns the Jingshan fossil assemblage to the Longwangmiaoan Stage (Cambrian Series 2, Stage 4), which is of similar age to the Jianhe biota, but younger than the Guanshan, Balang, and Shipai biotas, and slightly older than the Kaili biota, South China. The Jingshan assemblage is fossiliferous, containing common shelly and some soft-bodied fossils. It comprises algae, brachiopods, arthropods, hyoliths, priapulid worms, echinoderms, possible cnidarians, molluscs, and some enigmatic organisms. The fossils retain soft parts, including brachiopods with pedicles and delicate setae, a naraoiid with the antenna preserved and digestive tracts. The diversity of the assemblage is limited compared with better-known biotas of similar age, but investigation is at a preliminary stage. It is an important geographical extension of the Burgess Shale-type biotas in China and provides more information about the Cambrian Explosion of life and biodiversity by comparing fossiliferous horizons in a chronological framework.

An early Paleozoic tectonic event, the Kurgiakh orogeny, has long been known from the western Tethyan Himalaya, and it is conspicuously recorded by an angular unconformity between Cambrian marine shelf deposits and coarse Ordovician conglomerate, as well as widespread granitic plutons. Although the lateral extent of this event is poorly known, two regions in the central and eastern Himalaya, the Kumaon of India and klippen of Bhutan, contain conglomerate units that may be correlative with this event. In the Kumaon, the Ralam Formation, which contains a basal polymictic conglomerate unit with detrital zircon grains as young as ca. 512 Ma, is overlain by sandstone containing the arthropod walking trace Diplichnites gouldi , an ichnospecies known from Ordovician and younger strata. The late early Cambrian trilobite Redlichia sp., recovered from the underlying Martoli Group, indicates that the conglomerate is post−early Cambrian and, based on stratigraphic analysis, also likely records the Kurgiakh orogeny. In central Bhutan, the lower Paleozoic succession contains conglomerate units with monomictic quartz sandstone clasts and less mature sandstone matrix. These units have also been assigned to a variety of ages, but rocks that apparently underlie these strata contain the Furongian (late Cambrian) zonal trilobite Kaolishania granulosa . Here, we show that detrital zircon ages of a conglomerate clast (no grains younger than = ca. 781 Ma) are distinctly older than those of the matrix, which contains a large peak at 490−500 Ma. Thus, these conglomerate units are also potential lateral correlatives of the Ordovician conglomerate deposits of the western Himalaya. Our paleontological and geochronologic data suggest that the Kumaon and Bhutan conglomerate units, and possible equivalents in Tibet, correlate with those of the western Himalaya. This increases their known along-strike extent by over 1000 km, bringing the total extent to ∼1200 km. Thus, the Kurgiakh orogeny spanned much of the Himalayan orogen along the northern Gondwanan margin and reflected a widespread tectonic reorganization of the peri-Gondwanan realm to Andean-type margins. Recent work indicates that it also likely extended into the Lhasa block and both the North and South China blocks. This event was associated with widespread ca. 500 Ma arc-related plutonism recorded in the Himalaya, and with abundant detrital zircon grains of that age in younger Himalaya strata. Based on current fossil data, the duration of the hiatus associated with the Cambrian-Ordovician boundary, which separates pre- and postdeformational strata, ranges from 22 to 36 m.y. Available geochronological data do not provide greater constraint. If the event was close in age to the depositional age of the Ordovician molasse, then the main phase of tectonic uplift, erosion, and deposition may have been much later than the presumed Cambrian-Ordovician boundary interval age of ca. 485 Ma.

The Indian subcontinent's biota and biostratigraphy is amongst the least well known internationally of any Cambrian succession worldwide. Recent revision of previously described type material and a substantial number of new finds reveal a typical Cambrian skeletonized fauna and an organic-walled biota, as well as various trace fossils. This biota, reviewed here synoptically, currently contains 51 non-agnostoid trilobite genera belonging to 50 species; 15 genera and species of agnostoids; one species of bradoriid arthropod; 18 brachiopod genera containing 20 species; echinoderm thecal and columnal plates; a soft-bodied eldoniid; representatives of three hyolith genera; other small shelly fossils some of which are identified to species level; acritarchs; and a variety of ichnotaxa. Regional biostratigraphic zonations for trilobites, brachiopods, small shelly fossils and organic-walled, and trace fossils are herein combined into an integrated Cambrian biostratigraphical scheme that permits correlation along and across the lithotectonic zones of the Himalayan margin and southward onto cratonic India. These consist of 13 named biostratigraphic units for trilobites, seven for brachiopods, three for small shelly and organic-walled fossils, and one for trace fossils. The basal boundary of the Cambrian (~ 541 Ma) is biostratigraphically localised in the Lesser Himalaya between Ediacaran carbonate-rich beds bearing the organic-walled tubular Shaanxilithes ningqiangensis, and dark, highly stratigraphically condensed, phosphate-rich shale bearing Fortunian (~ 535 Ma) and Cambrian Stage 2 age (~ 524 Ma) small shelly fossil assemblages. The oldest macrofossils presently known are somewhat younger, and represent early Cambrian Stage 4. The Redlichia noetlingi trilobite Zone/Botsfordia granulata brachiopod Zone (~ 512 Ma), is widely represented in siliciclastic rocks across and along the Himalaya, spanning the Tethyan, Lesser, and sub-Himalayan lithotectonic zones, and possibly also extending onto the craton. Stage 5 Cambrian fauna are the most diverse and best biostratigraphically characterised, much of which are relatively well preserved in limestone, but presently known only in the Tethyan Himalaya where species-level correlation between the Zanskar and Parahio valleys has been established. There, rates of sediment accumulation were notably high, with some 2000 m of rock when compacted deposited within approximately 13 Myr. During this interval, the ranges of some trilobite and brachiopod species (and their zones) were apparently less than one million years long. The indicus trilobite zone has recently been localized, shortly below the prachina zone. Furongian (late Cambrian, ~ 493 Ma) fossils are known only in the Bhutanese Himalaya. Except where faulted, the Cambrian succession is capped by an unconformity throughout the Himalaya. In the Salt Range and Lesser Himalaya this unconformity is sub-Permian, but in the Tethyan Himalaya it is sub-Ordovician. The regional Cambrian can now be correlated globally with reasonable precision, and all parts of the Himalayan margin south of the Yarlung-Tsangpo suture have an equatorial Gondwanan biota most similar to North China, and particularly, to South China. Links with Australia are suggested by non-cosmopolitan species but Indian biotas share less in common with Australia than with parts of China. Knowledge of the Himalayan Cambrian biota serves a critical role in constraining the Caenozoic uplift and erosional history of the orogen.

A new eocrinoid locality of the Balang Formation (Cambrian Series 2) near Kaili City is reported. The fauna is associated with index trilobites, such as Redlichia ( Pteroredlichia ) murakamii Resser and Endo in Kobayashi, 1935 and Arthricocephalus chauveaui Bergeron, 1899 , that are common in the Balang Biota (Cambrian Series 2) but absent in the younger Kaili Biota (Cambrian Series 3). This new locality contains a new eocrinoid fauna ( n = 22) that is different from Guizhoueocrinus yui Zhao, Parsley and Peng, 2007a in bearing a smaller theca, a shorter stalk, and a robust attachment disk; thus, a taxon Globoeocrinus zhaoyuanlongensis n. sp. is proposed.

Polymeroid trilobite fauna from two stratigraphic sections (Godbondar and Kuhbanan) of the Kuhbanan Formation in northern Kerman (central Iran) were studied and subjected to biostratigraphic analysis. Eleven genera and species are recognised from the latest Early Cambrian and Middle Cambrian Peri-Gondwanian successions of the study sections. The recognised fauna includes Afghanocare lategenatum, Blountia blountia, Iranoleesia sp., Iranoleesia pisiformis, Kermanella kuhbananensis, Kermanella lata lata, Kermanella lata minuta, Kermanella sp., Redlichia chinensis, Redlichia noetlingi and Redlichia sp. Based on trilobite distribution, three trilobite biozones were recognised in the study sections, namely Redlichia noetlingi biozone, Kermanella kuhbananensis biozone and Iranoleesia pisiformis biozone. The age of the study sections is late Early Cambrian to late Middle Cambrian based on the recognised trilobite biozones. The recognised late Early Cambrian trilobite assemblages (especially Redlichia and Kermanel...

The early Cambrian Guanshan biota of eastern Yunnan, China, contains exceptionally preserved animals and algae. Most diverse and abundant are the arthropods, of which there are at least 11 species of trilobites represented by numerous specimens. Many trilobite specimens show soft-body preservation via iron oxide pseudomorphs of pyrite replacement. Here we describe digestive structures from two species of trilobite, Palaeolenus lantenoisi and Redlichia mansuyi. Multiple specimens of both species contain the preserved remains of an expanded stomach region (a "crop") under the glabella, a structure which has not been observed in trilobites this old, despite numerous examples of trilobite gut traces from other Cambrian Lagerstatten. In addition, at least one specimen of Palaeolenus lantenoisi shows the preservation of an unusual combination of digestive structures: a crop and paired digestive glands along the alimentary tract. This combination of digestive structures has also never been observed in trilobites this old, and is rare in general, with prior evidence of it from one juvenile trilobite specimen from the late Cambrian Orsten fauna of Sweden and possibly one adult trilobite specimen from the Early Ordovician Fezouata Lagerstatte. The variation in the fidelity of preservation of digestive structures within and across different Lagerstatten may be due to variation in the type, quality, and point of digestion of food among specimens in addition to differences in mode of preservation. The presence and combination of these digestive features in the Guanshan trilobites contradicts current models of how the trilobite digestive system was structured and evolved over time. Most notably, the crop is not a derived structure as previously proposed, although it is possible that the relative size of the crop increased over the evolutionary history of the clade.

A new faunal assemblage is reported from the Tempe Formation (Cambrian Series 2, Stage 4; Ordian) retrieved from the Hermannsburg 41 drillcore, Amadeus Basin, central Australia. Two trilobite taxa, including one new species Gunnia fava sp. nov., four brachiopod taxa, including the age-diagnostic Karathele napuru (Kruse), Kostjubella djagoran (Kruse) and Micromitra nerranubawu Kruse, together with a bradoriid, helcionellids, hyoliths, echinoderms, chancelloriids, sponges and problematic tubes are described. The fauna has close links to those of the neighbouring Daly, Georgina and Wiso basins and suggests that the Tempe Formation correlates with the Australian Ordian stage (either the Redlichia forresti or Xystridura negrina assemblage zones). The Giles Creek Dolostone in the eastern Amadeus Basin, previously regarded as coeval with the Tempe Formation, has recently been reported to be of early Templetonian age in its type section. The described taxa from the Tempe Formation confirm that these two sedimenta...

Outcropped of the Kuhbanan Formation at Dahu, near Zarand, about 63 km north of Kerman, Iran contains peri-Gondwana trilobites. In this study, 185 trilobite samples including six species and genera were identified and described from Dahu section. This trilobite’s assemblage including Redlichia noetlingi, Redlichia sp., Kermanella kuhbananensis, Kermanella lata lata, Kermanella lata minuta, Iranoleesia pisiformis, and Iranaspis sp. based on occurrence of the trilobite fauna a late Early to Middle Cambrian (Series 2–3) is suggested for this strata. These trilobite fauna help confirm conclusions from recent geological studies that place the Kerman Basin of Iran during the Cambrian.

The early Cambrian (Cambrian Series 2, Stage 4) Emu Bay Shale Lagerstatte of Kangaroo Island, South Australia is significant because it represents the best Burgess Shale type fauna in the southern hemisphere. Although the original locality near Big Gully occurs in coastal outcrops with large (up to 25 cm long) examples of the trilobite Redlichia takooensis on bedding planes, it was not discovered until 1954 by Brian Daily; this was largely due to difficulties of access. The first taxonomic paper was not produced until 1979, after which work on the Lagerstatte was intermittent, with a substantial theft of fossils from the coastal locality occurring in 1991. In 2007, excavation commenced at a new inland site. This has yielded over 50 species, including some not known from the original locality. Taxonomic papers dealing with the new locality are now being published. Refereed/Peer-reviewed

Trilobites from the Lower Cambrian succession at Angorichina in the eastern Flinders Ranges, South Australia, are described. Silicified material from the Mernmerna Formation reveals the presence of a new assemblage from the Pararaia bunyerooensis Zone, including the eponymous species, Yorkella aff. australis, Eoredlichia sp., Redlichia sp., and the new species Wutingaspis euryoptilos and Yunnanocephalus macromelos. Trilobites of the Pararaia bunyerooensis Zone show a strong affinity with those from the Yu'anshan Member of the Heilinpu Formation in Chengjiang and Jinning Counties, Yunnan Province, southwest China. The Pararaia bunyerooensis Zone is correlated with the Yunnanocephalus Assemblage subzone (upper Eoredlichia–Wutingaspis Zone) of the Chiungchussuan (=Qiongzhusian) Stage of China. Additional trilobites from Angorichina include Elicicola calva from the Wilkawillina Limestone, Estaingia occipitospina (Jell) new combination from the Oraparinna Shale, and Redlichia guizhouensis Zhou from th...

Chengjiang-type fossil brachiopods with preservation of non-mineralized tissues are reported for the first time from the Lower Cambrian Shipai Formation of the Three Gorges area, western Hubei Province, China. Recent excavation in the Wangjiaping and Aijiahe sections resulted in the new discovery of some linguloid brachiopods, showing strong similarity in preservation with those occurring in the well-known Chengjiang fauna (Yu’anshan Formation of eastern Yunnan, China). The brachiopods can be referred to Palaeobolus liantuoensis, Lingulellotreta malongensis and Eoobolus. sp. The new material of Palaeobolus exhibits a flattened impression of proximal pedicle, which also represents the first report of pedicle known from this cosmopolitan linguloid taxon. The occurrence of Lingulellotreta in the Shipai Formation (Redlichia meitanensis and Palaeolenus lantenoisi zones) represents an important geological extension of this genus to upper Tsanglangpuan Stage (Series 2, Stage 4) in the Yangtze Platform, and signifying that the FAD of Lingulellotreta in the regional Lower Cambrian of the Yangtze Platform seems not synchronous.

The early Cambrian Chengjiang Lagerstatte, generally regarded as late Atdabanian (Qian and Bengtson, 1989; Bengtson et al., 1990), has become celebrated for perhaps the earliest biota of soft-bodied organisms known from the fossil record and has proven to be critical to our understanding of early metazoan evolution. The Sirius Passet fauna from Peary Land, North Greenland, another important repository of soft-bodied and poorly sclerotized fossils, was also claimed as Early Cambrian (Conway Morris et al., 1987; Budd, 1995). The exact stratigraphic position of the Sirius Passet fauna (Buen Formation) is still uncertain, although the possibility of late Atdabanian age was proposed (Vidal and Peel, 1993). Recent work dates it in the “Nevadella” Biozone (Budd and Peel, 1998). It therefore appears to be simultaneous with or perhaps slightly younger than Chengjiang Lagerstatte, Eoredlichia Biozone (Zhuravlev, 1995). The Emu Bay Shale of Kangaroo Island, South Australia, has long been famous as a source of magnificent specimens of the trilobites Redlichia takooensis and Hsunaspis bilobata. It is additionally important as the only site in Australia so far to yield a Burgess-Shale-type biota (Glaessner, 1979; Nedin, 1992). The Emu Bay Shale was considered late Early Cambrian in age (Daily, 1956; Opik, 1975). But Zhang et al.(1980) reassessed its age based on data from the Chinese Early Cambrian. The occurrence of Redlichia takooensis and closely related species of Hsunaspis indicates an equivalence to the Tsanglangpuian in the Chinese sequence, and the contemporary South Australia fauna correlate with the Botomian of Siberia (Bengtson et al., 1990). Thus the Emu Bay Shale is younger than the upper Atdabanian Chengjiang Lagerstatte, Chiungchussuian.

Two species of Anomalocaris co-occur in the Emu Bay Shale (Cambrian Series 2, Stage 4) at Big Gully, Kangaroo Island. Frontal appendages of Anomalocaris briggsi Nedin, 1995, are more common than those of Anomalocaris cf. canadensis Whiteaves, 1892, at a quarry inland of the wave-cut platform site from which these species were originally described. An oral cone has the three large, node-bearing plates recently documented for Anomalocaris canadensis, confirming that Anomalocaris lacks a tetraradial 'Peytoia' oral cone and strengthening the case for the identity of the Australian specimens as Anomalocaris. Disarticulated anomalocaridid body flaps are more numerous in the Emu Bay Shale than in other localities, and they preserve anatomical details not recognized elsewhere. Transverse lines on the anterior part of the flaps, interpreted as strengthening rays or veins in previous descriptions of anomalocaridids, are associated with internal structures consisting of a series of well-bounded, striated blocks or bars. Their structure is consistent with a structural function imparting strength to the body flaps. Setal structures consisting of a series of lanceolate blades are similar to those of other anomalocaridids and are found in isolation or associated with body flaps. A single specimen also preserves putative gut diverticula. The morphology of the appendages, oral cone, gut diverticula and compound eyes of Anomalocaris, along with its large size, suggests that it was an active predator, and specimens of coprolites containing trilobite fragments and trilobites with prominent injuries have been cited as evidence of anomalocaridid predation on trilobites. Based on frontal appendage morphology, Anomalocaris briggsi is inferred to have been a predator of soft-bodied animals exclusively and only Anomalocaris cf. canadensis may have been capable of durophagous predation on trilobites, although predation (including possible cannibalism) by Redlichia could also explain the coprolites and damage to trilobite exoskeletons found in the Emu Bay Shale. © The Palaeontological Association.

The Top Springs Limestone, a carbonate unit of the northern Georgina Basin, Northern Territory, Australia, has previously yielded only the trilobite Redlichia, indicating an Ordian (early Middle Cambrian) age for at least part of the formation. New collections of trilobites. brachiopods, hyoliths. molluscs and sponges - fifteen species in all - are described here, leading to the possibility that upper parts of the formation may have been deposited during the succeeding early Templetonian stage. The fauna has a clear affinity with that in the Tindall Limestone of the Daly Basin, and to a lesser extent with the Panton Formation fauna of the Ord Basin. The new heleionellid molluscan genus Kutanjia ugalbala and new species Igorella durara are also described.

Examples of an undescribed species of the trilobite Redlichia from the Emu Bay Shale (Early Cambrian), Kangaroo Island, South Australia, show damage to the exoskeleton attributed to the action of predators. Injury was probably not lethal. The identity of the predators is unresolved, notwithstanding soft-part preservation within the fossil assemblage. Possible culprits include either a rare and presumably large animal such as an arthropod or conceivably cannibalism by Redlichia itself. This report provides new data on the occurrence of Cambrian predators, and casts further doubt on earlier suggestions that macrophagous predation was insignificant at this time. Aspects of trilobite predation during the Palaeozoic are reviewed, with emphasis placed on their ability to withstand substantial injuries and the possible repair mechanisms that promoted wound healing and survival.

Three forms of exuviation, involving inversion of exoskeletal elements, are described in three Australian species of the Cambrian trilobite Redlichia: R. forresti (Foord), R. idonea Whitehouse and R. micrograpta Opik. They are: inversion of the pygidium, in four specimens of R. forresti; inversion of some thoracic segments of R. idonea; and lateral inversion of a free cheek, in single specimens of R. forresti and R. micrograpta. This is the first record of thoracic segment inversion during exuviation in trilobites. Exuviae with inverted exoskeletal elements provide information on the techniques of exuviation, in particular the direction of egression of the postecdysial trilobite from the proecdysial exuvia and also in this genus, the extent of enrolment of the thorax.

The biostratigraphy of the Cambrian of Kashmir based on trilobite assemblage zones and trace fossils has been attempted. Faunal gaps occur in lower part of Lower Cambrian, upper Lower Cambrian, lower Middle Cambrian and upper part of Upper Cambrian. In the Lower Cambrian Cruziana—Rusophycus and Redlichia Zones, in the Middle Cambrian Solenopleura—Tonkinella, Tonkinella—Anomocare, Anomocare—Bailiella and Bolaspidella Zones, and in the Upper Cambrian Chuangia and Dikelocephalites Zones are recognized. The position of intrasystem boundaries is also discussed. While the various taxa have lithological preferences and are not necessarily found in a continuous sequence, an attempt has been made to interpret the ranges of different genera. The affinities of the fauna with that of other Cambrian basins of the world are discussed. It is concluded that the bulk of the fauna is of a cosmopolitan nature.

The tenth chapter is dealt with the history of research in older rocks and Cambro-Ordovician of eastern North America. In last century Pre-Cambrian stratigraphy was started in Canada, while the New York System was instituted around Albany, N. Y. and later it was correlated to the European sequence. Subsequently the Cambrian and Ordovician Systems were classified in detail. Starting with the ventral anatomy of trilobites Walcott made invaluable contributions on the Cambrian geology and palaeontology, i.e. the Olenellus fauna, unique fauna the Burgess shale and so forth. His “Cambrian Fauna of China” 1913 provided a firm basis for the Cambrian of Eastern Asia.The relation of the Cambro-Ordovician faunas of the continent to the European ones in the northern part of the Appalachian geosyncline and their distribution in the Appalachian mountains and further westerly beyond the lower Mississipy river and also in the interior lowland are briefly outlined.These systems in the Cordilleran geosyncline is described in the eleventh chapeter. Stratigraphy in the western sites is followed by notes on the Alaskan faunas in the north which were allied to the Siberian ones at the beginning, but later to the Eastern Asiatic ones also. In the south it is a remarkable fact that the Mexicoan faunas are more related to the Andean ones than those of the United States, particularly in the early Ordovician age.The Circum-Pacific Cambro-Ordovician belt is taken up in the final chapter. The history of this belt's history started in the Sinian period. In the early Cambrian age the eastern side belonged to the Olenellian province, but the other side constitued the Redlichia province. Subsequently, however, trilobites of the two sides became closer related to each other, although the early Upper Cambrian Kushan fauna was quite isolated. Trilobites were intimate between the two sides of the Northern Pacific and also on the southern Pacific side in the early Ordovician age. The aspect of the provinciality in the middle and late Ordovician ages is still obscure, sofar as trilobites are concerned.

Based on investigation of several types of Cambrian sections in eastern Yunnan, we have tentatively concluded: 1) existence of the Middle Cambrian in eastern Yunnan is definitely proved; 2) the Lower Cambrian of eastern Yunnan may be divided into four formations, of which the Mei-shu-ts'un is so named for the phosphate bearing beds; 3) judging from the lithological character we recognize that the subsiding area of eastern Yunnan is still considered in the late Early Cambrian era; 4) Paragraulos and Redlichia chinensis should not be used as zoning fossils for the Tsanglangpu and Lung-wang-miao formations, respectively; 5) the Middle Cambrian of eastern Yunnan might be correlated with the Middle Cambrian of Kueichow, because Kunming was a subsiding area in the Middle Cambrian era. – Authors.