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Correlation chart of the interval of Cambrian Stage 4 through Wuliuan Stage (Miaolingian Series). Chart compiled from numerous sources, summarized principally in Yuan and Ng. (2014), Geyer (2015), Zhao et al. (2015, 2017), Hughes (2016), Sundberg et al. (2016), Peng et al. (2017) and Esteve et al. (2017).
Source publication
The International Commission on Stratigraphy and the IUGS Executive Committee have recently ratified a Global Standard Stratotype-section and Point (GSSP) defining the conterminous base of the third series and the fifth stage of the Cambrian System. The series and the stage are respectively named the Miaolingian Series and Wuliuan Stage, after the...
Contexts in source publication
Context 1
... FAD of Oryctocephalus indicus in the stratotype Wuliu-Zengjiayan section is one of the most easily recognizable horizons in the Cambrian (see Geyer and Shergold, 2000; Fig. 2). In South China, it is used for defining the base of the regional Wulingian Series and Taijiangian Stage ( Peng and Babcock, 2001). Possible suitability of the FAD of this species for marking a global stage and series boundary has been summarized principally by Shergold and Geyer (2003), and Peng et al. (2004aPeng et al. ( , b, 2006). ...
Context 2
... FAD of Oryctocephalus indicus in the stratotype Wuliu-Zengjiayan section is one of the most easily recognizable horizons in the Cambrian (see Geyer and Shergold, 2000; Fig. 2). In South China, it is used for defining the base of the regional Wulingian Series and Taijiangian Stage ( Peng and Babcock, 2001). Possible suitability of the FAD of this species for marking a global stage and series boundary has been summarized principally by Shergold and Geyer (2003), and Peng et al. (2004aPeng et al. ( , b, 2006). ...
Citations
... However, global biostratigraphical correlations for the Cambrian System are problematic, given the endemic nature of trilobite associations and other fossils. Up to the moment, the Cambrian has been divided into four series (Babcock et al., 2005(Babcock et al., , 2011: Terreneuvian Series (Landing et al., 2007), Cambrian Series 2 (undefined), Miaolingian Series (Zhao et al., 2019) and Furongian (Peng et al., 2004). Regarding the Cambrian Series 2, some of its major constraints have been the scarcity of taxa with a wide geographical distribution and, in turn, the lack of precise stratigraphical range for those taxa (Peng et al., 2020). ...
The Cambrian Series 2 is a challenging chronostratigraphical division. In Europe, its sequences are hard to identify due to the scarcity of the fossil record. An exception is the Ossa-Morena Zone (OMZ), SW Iberia, which has attracted the interest of numerous researchers throughout the 19th and 20th centuries. Four regional stages were proposed for the Cambrian Series 2 based on trilobites and archaeocyaths: Ovetian, Marianian, Bilbilian and Leonian (lower part). Among these, the Marianian is problematic, having undergone several conceptual modifications since its original erection and being characterised by a low trilobite diversity and abundance. Its usefulness through the Iberian Peninsula is still a subject of debate since its correlation with the global scheme lacks accuracy. The main goals of this thesis are to study the trilobite assemblages in order to correlate the Marianian Stage across the OMZ and other Iberian Cambrian domains, and to evaluate its potential for international correlation and subdivision within the global context of the Cambrian Series 2.
The Cambrian outcrops studied can be divided into six tectonosedimentary units: Alter do Chão-Elvas Sector, Alconera Block, Viar-Benalija Block, Cumbres Block, Herrerías Block, and Arroyomolinos Block. The stratigraphical and palaeontological record of their Marianian sequences was reassessed and correlated. The classical fossil sites were located and sampled. New fossil sites were discovered, and new materials were collected, with a total of 1299 trilobite fossils. In addition, 585 specimens of the most relevant trilobite collections of the Marianian from the OMZ were reviewed, including those from the Museu Geológico de Lisboa (Portugal), the Senckenberg Museum of Frankfurt (Germany), the Complutense University of Madrid (Spain) and the collections of Prof. Eladio Liñán at the University of Zaragoza (Spain).
A total of 23 trilobite species were identified in the Marianian of the OMZ, four in open nomenclature. Among these species, six have been studied in detail, which results have been published in five indexed papers: Atops calanus, Callavia choffati, Chelediscus garzoni, Pseudatops reticulatus, Serrodiscus bellimarginatus and Strenuaeva sampelayoi. For the first time in OMZ, Hebediscus is figured and Kingaspis and Pseudatops have been identified, and a new species was erected (Chelediscus garzoni). The genus ‘Sdzuyomia’ is here considered a junior synonym of Callavia; and the species ‘S. melendezi’, ‘Ellipsostrenua alanisiana’ and ‘Strenuaeva marocana’ are considered junior synonyms of S. sampelayoi. The genus Callavia is assigned to ‘Judomioidea’, whereas Chelediscus is assigned to Calodiscidae, with new diagnoses being provided for both genera. Three groups (bellimarginatus, speciosus and daedalus) were proposed to encompass the species currently included in cosmopolitan Serrodiscus, revealing different lineages and clarifying its stratigraphical and palaeogeographical distribution.
From a biostratigraphical point of view, new data improve and refine intra- and interregional correlation and new links with the Central Iberian Zone and the Iberian Chains have been found. The base of the Marianian Stage is characterised by the First Appearance Datum (FAD) of Strenuella, being the lower Marianian characterised by
Delgadella souzai, Acanthomimacca? sp. and Saukianda andalusiae. The middle Marianian is defined by the FAD of Strenuaeva sampelayoi, and characterised by Delgadella souzai, Saukianda andalusiae, Alanisia guillermoi, Perrector perrectus, Eops
eo, Gigantopygus cf. bondoni, Kingaspis cf. velata, Andalusiana cornuta, Triangulaspis fusca, Callavia choffati, Rinconia schneideri, Calodiscus ibericus, Atops calanus, Hicksia elvensis, and Termierella sevillana. The base and top of the upper Marianian are marked,respectively, by the FAD and Last Appearance Datum (LAD) of Serrodiscus bellimarginatus, being this substage characterised by Triangulaspis fusca, Hebediscus sp., Chelediscus garzoni, Protaldonaia morenica, Atops calanus, and Pseudatops reticulatus.
Globally, the new biostratigraphical data strengthen the correlation with other Cambrian Series 2 sequences worldwide. Along the western Gondwana margin, the Marianian Stage correlates with the Banian Stage from Morocco and the Charlottenhof Formation from Germany. Regarding western and eastern Avalonia, it correlates with upper Callavia and lower Strenuella sabulosa Biozones. In Baltica, it correlates, on the one hand, with upper Holmia kjerulfi and lower Ellipsostrenua spinosa Biozones in Scandinavia and, on the other hand, with the upper Holmia-Schmidtiellus and lowermost Protolenus-Issafeniella Biozones in Poland. In Siberia, it is equivalent to most of the Botoman and lowermost Toyonian Stages. In addition, new biostratigraphical links have been established with the Elliptocephala asaphoides Biozone from the Laurentian
Taconic Allochthon.
... When the remaining global stages for the Terreneuvian and Cambrian Series 2 are ratified, there is no guarantee that the definitions will be easily applicable in Australia. As an example, the base of the Miaolingian Series and conterminous Wuliuan Stage is defined (Zhao et al. 2019) by the FAD of Oryctocephalus indicus (Reed, 1910), which has not been found in Australia despite the record of numerous oryctocephalid species from the Amadeus, Arafura and Georgina basins, and the Koonenberry Belt (Shergold 1969, Laurie 2004, 2006a, 2006b, Smith et al. 2015b. As a consequence, a local stadial scheme should be based on multiple independent chronological datasets to allow successful correlation of Cambrian packages across regional and intercontinental scales. ...
The chronostratigraphical scale is a hierarchical scheme that is subdivided into increasingly smaller units, from eonothem down to the level of the substage and beyond. Boundaries of chronostratigraphic intervals typically coincide with individual bioevents. As these intervals become smaller, their geographic utility tends to shrink. Typically, where the original interval is inapplicable, the next highest interval in the scale is used for communication. Where appropriate intervals are unavailable, confusion reigns. A stadial subdivision of the Australian mid–late Cambrian (equivalent to the international Miaolingian and Furongian series) was completed in
1993 with the definition of the Furongian Iverian Stage. One stage, the Ordian, was initially suggested as the lowest stage for what is now the Miaolingian, but should be considered to belong to upper Series 2 of the Cambrian. No older Cambrian stages have been proposed in Australia. Indeed, the base of the Ordian has not been defined, due in part to the incompleteness of Series 2 successions in central and northern Australia. A longstanding impediment to the establishment of lower Cambrian stages in Australia arises from the fact that the entire Australian stadial
scheme for the Miaolingian and Furongian series was established in the cratonic basins of central-northern Australia, whereas the lower Cambrian is best developed in separate South Australian basins. With the rapid increase in knowledge of the biostratigraphic successions in the South Australian lower Cambrian (Terreneuvian and Series 2) over the last three decades, the time seems ripe for the establishment of such a stadial subdivision. This will require careful correlation between the mostly Terreneuvian and Series 2 succession in South Australia and the mostly Miaolingian–Furongian succession in central and northern Australia. Taxa that can be used for such a stadial subdivision include trilobites, organophosphatic brachiopods, archaeocyaths, small shelly fossils, molluscs and acritarchs, as each has provided the basis of zonations in the South Australian successions.
... However, the Cambrian stratigraphic and paleontological record in the hinterlands of the Qinghai-Tibetan Plateau, western Kunlun, western Thailand, western Myanmar, southwestern Iran, and central Afghanistan remains least understood and awaits corroboration with additional data (King, 1937;Ruttner et al., 1968;Karapetov et al., 1971;Thein, 1973;Shareq et al., 1977;Bunopas, 1992). Furthermore, in recent decades, there have been significant revisions to the global Cambrian chronostratigraphic scheme, e.g., 4 series and 10 stages have been adopted and the GSSPs (Global Boundary Stratotype Section and Point) of 6 stages and 3 series have been established (Peng et al., 2004;Babcock et al., 2005;Zhu et al., 2019;Zhao et al., 2019). In many earlier-investigated areas around the Qinghai-Tibetan Plateau, such as Qilian tectonic belts, Qaidam basin and Baoshan areas, although many fossil assemblages have been systematically described (Zhu, 1960a(Zhu, , 1960b(Zhu, , 1960cZhu et al., 1979;Zhou et al., 1982Zhou et al., , 1996Sun and Xiang, 1979;Luo, 1982Luo, , 1983, the exact biostratigraphic and paleogeographical significance of these fossil assemblages still needs to be recalibrated under the new global chronostratigraphic scheme. ...
The Qinghai-Tibetan Plateau and its surrounding areas have a long and complex tectonic evolutionary history. Cratons and blocks, such as northern India, Lhasa, Qiangtang, Qaidam and Central Qilian, and their in-between orogenic belts constitute the main part of the Qinghai-Tibetan Plateau. During the Cambrian Period, most of these cratons and blocks were on the northwestern periphery of Gondwana, and were associated with the surrounding blocks, e.g. Arabian, Central Iran, Af-ghanistan, Tarim, Alxa, North China, South China and Sibumasu through the Proto-Tethys Ocean. The Cambrian stratigraphic sequences on these stable blocks are composed of mixed siliciclastic and carbonate rocks deposited in the shallow-water marine environments, and contain the trilobite assemblages of shelf facies. The Cambrian stratigraphic sequences in the Qilian tectonic belts, however, are characterized by the intermediate-basic igneous rocks and silicates formed in the Proto-Tethys Ocean, and contain the trilobite assemblages of deep-water slope facies. Combining with previous data, field observations and newly discovered fossils through funding by the Second Tibetan Plateau Scientific Expedition and Research, the general characteristics of the Cambrian strata in different tectonic units of the Qinghai-Tibetan Plateau and its surrounding areas have been summarized in this paper. Furthermore, efforts have been made to subdivide and correlate the Cambrian strata across these areas by utilizing available biostratigraphic and geochronological data. As a result, a comprehensive litho-and biostratigraphy chart has been compiled. Finally, from the biogeographic perspective, this paper also provides a brief overview of the Cambrian paleogeo-graphical reconstruction of the major tectonic blocks, and discusses the problems associated with the evolution of the Proto-Tethys tectonic belt.
... The North China Platform began to undergo deposition roughly in the Late Cambrian Epoch II, and the Cambrian Epoch II strata overlie pre-Cambrian strata from different periods, forming a "giant unconformity" similar to the North American platform [3]. The Furongian Stage of the North China Platform includes the Changshan Formation and Fengshan Formation [4]. The Zhidongyu section is located in the area of Zhidongyu Village, west of Kongcun Town, in the southern part of Pingyin County, Jinan City. ...
... The carbonate-dominated Mujin Formation, the lowermost strata of the Bopdong Group, contains the Hwangjuella Zone in the SPB, while that in the NM contains the Damesella heptaspina Zone (Table 2; Hong and Yoon, 1987;Pak et al., 2009). Blackwelderia, the typical uppermost Miaolingian taxon (see Zhang and Jell, 1987;Peng et al., 2004;Zhou and Zhen, 2008a;Park et al., 2013;Zhao et al., 2019), occurs from the overlying Kopung Formation in the SPB, the NPB, and the NM (Kim et al., 1987;Pak et al., 2009). This indicates that the Miaolingian/Furongian boundary is present within the Kopung Formation. ...
The tectonic affinity of the Korean Peninsula in reference to the Permo-Triassic collision of the Sino-Korean Craton (SKC) and the South China Craton (SCC) has been in the center of debates over the last three decades. Since the Imjingang Belt that runs through the middle part of the Korean Peninsula is thought to represent the major tectonic boundary, most part of North Korea, including the “Pyeongnam Basin” in the southern part, has been regarded as part of the SKC. However, differences in stratigraphy and the fossil occurrence have been recognized by local geologists between the southern part of “the Pyeongnam Basin” (SPB) and the northern part of the “Pyeongnam Basin” (NPB), and which have hardly been considered for the paleogeographical affinity of the regions so far. Here we provide a comprehensive review on 1,072 fossil taxa from the Neoproterozoic to middle Paleozoic sedimentary successions of North Korea, and utilize the data for determining tectonic affinity of the regions. Especailly, Cambrian trilobite genera from the SPB and NPB have been quantitatively compared with those of North China (the SKC) and the SCC, using similarity indices, the non-metric multidimensional scaling (NMDS), and PerMANOVA test. The results have revealed that the SPB is tied to the SCC, not to North China (the SKC), whereas the NPB is closely related to North China. The SCC affinity of the SPB is corroborated by stratigraphical features, such as the presence of the Precambrian–Cambrian boundary and the middle Paleozoic strata, which are largely absent in the SKC. Our results demonstrate that the SPB region likely originated from to the SCC, and thus further suggest that the collisional boundary of supracrustal rocks between the SKC and the SCC in the Korean Peninsula corresponds to the boundary of the NPB and the SPB. Accordingly, the extent of the newly-defined Pyeongnam Basin is restricted to the traditional NPB region. The SPB region is included in the extent of the newly-proposed Hwanghae District, which is bounded to the east with the Imjingang Belt by the Ryesonggang Fault. The South China Craton-originated rocks of the Hwanghae District and the Imjingang Belt are collectively termed the South China-affinity terrane (SAT).
... The Cambrian strata of the NCP can be subdivided into nine third-order depositional sequences based on the cyclicity reflected by succession of sedimentary facies (e.g., Mei 2010;Catuneanu 2006) (DS 1 to DS 9 ; Fig. 2; Feng et al. 1990Feng et al. , 2004Meng et al. 1997;Mei et al. 1997;Riaz et al. 2023). Furthermore, based on depositional trends reflected by cyclic sedimentation (Helland-Hansen and Gjelberg 1994;Catuneanu 2006;Mei et al. 2005), a new scheme of lithostratigraphic division is used in this paper, which is a modification of the lithostratigraphic scheme proposed by Lu et al. (1994) and Meng et al. (1997) that was determined under a more complete chronostratigraphic division (e.g., Peng and Babcock 2008;Peng 2009;Peng et al. 2012;Peng and Zhao 2018). ...
Based on their mesostructures, carbonate microbialites are divided into four major groups: laminated stromatolite, clotted thrombolites, structureless leiolites, and dendritic dendrolite. Among the various types of microbialites, leiolites, also known as “cryptomicrobial deposits,” are uncommon in the stratigraphic records. This is exacerbated by leiolites relatively structureless and aphanitic structure, making their identification and characterization more challenging. Previous studies have revealed that leiolites have contrasting fabrics at different scale, heterogeneous microscopic fabrics and structureless mesoscopic to macroscopic fabrics. While it is widely assumed that cyanobacteria play a significant role in the formation of carbonate microbialites in marine environments, the origin and controlling mechanisms of variations in leiolites microstructures and macrostructures remain enigmatic. In the central part of the North China Platform, two excellent exposures of massive, structureless Cambrian bioherms (Furongian) dominated by leiolites were observed (Qijayu section). The Qijayu-section leiolites offer a unique opportunity to investigate the role of cyanobacterial input in governing the formation and textural heterogeneities of such microbialites. In addition, the significance of the Furongian leiolites stems from their association with a period of global development of microbial-dominated carbonate platforms. Our findings suggest that these Furongian leiolites developed during the forced-regressive systems tract. At the microscopic level, these Furongian leiolites exhibit a high degree of heterogeneity which is controlled by the presence of various types of cyanobacteria (Hedstroemia, Subtifioria, Girvanella), sponge mummy, and benthic ooids. The Hedstroemia, Subtifioria and Girvanella excreted extracellular polymeric substances that form multiple biofilms in cyanobacterial microbial mats where Furongian leiolites grew. The role of cyanobacteria in the microscale heterogeneity of Cambrian leiolites is evident, and this provides new insights into the development of microbial-dominated carbonate platforms in similar settings elsewhere. As a result, this study provides not only a reference example for global correlation but also some solid clues for further understanding the growth style of leiolites in the geologic record.
... The study area was located in Jianhe County, 240 km to the southeast of Guiyang City, and belonged to the transition slope area between the Yangtze platform and Jiangnan basin [30]. The Cambrian strata in the Jianhe area are widely distributed, including the Niutitang, Jiumengchong, Bianmachong, Balang, Tsinghsutung, Kaili, Jialao, and Loushanguan formations in ascending order [31,32]. ...
... The studied section is located in Songshan, Balang Village, Jianhe County, and is adjacent to the Wuliu-Zengjiayan section, the Global Stratotype Section of the Cambrian Miaolingian [31,32]. The Tsinghsutung Formation of the Songshan section is in conforming contact with the overlying Kaili Formation and underlying Balang Formation, and the sedimentary age is assigned to the Cambrian Epoch 2, Age 4, with a lithological composition of limestone, dolomite, and mudstone. ...
... The Tsinghsutung Formation has a thickness of about 272.2 m. It is divided into a lower portion composed of greyish-grey, mediumthick limestone, an upper part comprising a medium-thick layer, a thin layer of limestone and a thick silty muddy layer, and a top layer of grey-black dolomite ( Figure 1) [31][32][33]. Zhang et al. considered the Tsinghsutung Formation of the Songshan section in Jianhe to have been deposited in a low-energy, deep-water shelf-shelf margin environment [34]. In terms of biostratigraphy based on trilobites, the Tsinghsutung Formation in the Songshan section of Jianhe is divided into an Arthricocephalus chauveaui zone in the lower part and a Protoryctocephalus arcticus zone in the middle-to-top part. ...
Hadrotreta is a worldwide acrotretoid brachiopod reported from the Cambrian Series 2 to Miaolingian. Here, a number of well-preserved fossils of Hadrotreta, identified as Hadrotreta cf. H. timchristiorum, were found in the Protoryctocephalus arcticus Zone of the Tsinghsutung Formation of Cambrian Series 2, Stage 4 in Jianhe, Guizhou, south China. This is the first report of Hadrotreta in China, which enriches its global palaeogeographical distribution. Hadrotreta is very similar to acrotretoids such as Kostjubella, Vandalotreta, Linnarssonia, and Eohadrotreta. It differs from them with its well-developed ventral boss-like apical process, apical pits, and dorsal median sulcus. In view of the palaeogeography of Hadrotreta, this genus was mainly distributed in low-latitude regions. Hadrotreta was only found in south China and Laurentia during the Cambrian Age 4, then expanded its distribution to other regions such as Siberia, Baltica, the Kazakh Terranes, the Far East, and Gondwana Pange during the Miaolingian Epoch. Hadrotreta seems to have shifted from deeper water to shallow-water environments during the period from the Cambrian Series 2 to the Miaolingian.
... Palaeogeographically, the Cambrian Kaili Biota is located along the southeastern margin of the Yangtze Platform ( Figure 1A, 1B). It is perfectly exposed near the Balang village, Jianhe County of Guizhou, where the Kaili Formation at the Wuliu-Zengjiayan section ( Figure 1C) was recently ratified as the GSSP (Global Stratotype Section and Point) for the Cambrian Miaolingian Series and Wuliuian Stage (Zhao et al. 2019). ...
... The thickness of the formation varies between sections, 214 m in the Wuliu-Zengjiayan section and 156 m in the Miaobanpo section ( Figure 1C, 1D) where its lowermost part is cut by a small fault (Zhao et al. 2005). Lithologically, the Kaili Formation is subdivided into three parts, the lower part comprises thinly bedded limestones with shale interbeds and belongs to Cambrian Stage 4, the middle part consists of calcareous silty mudstones and shales , belonging to the early of the Cambrian Wuliuian (within the trilobite Oryctocephalus indicus zone; , Zhao et al. 2019, and the upper part consists of bedded limestone layers grading into grainy dolostones ( Figure 1C). The middle part of the Kaili Formation contains a Burgess Shale-type Lagerstätte that known as the Kaili Biota. ...
Diverse chancelloriids from two sections of the Kaili Biota (Cambrian Wuliuan Stage) in Guizhou Province, China, are systematically described. A total of 25 complete individuals were collected from calcareous silty mudstones of the Cambrian Kaili Formation and are assigned to 3 genera and 6 species, including Archiasterella anchoriformis sp. nov., Chancelloria zhaoi sp. nov., C. eros, Allonnia erjiensis, Al. phrixothrix, and Al. sp. The new species Ar. anchoriformis with sclerites characterised by a large angle between two marginal-lateral rays and an obvious apical tuft represents the first unambiguous Archiasterella scleritome in South China. The C. zhaoi is dominated by a series of bilaterally symmetrical, rosette-like sclerites that composed of five or six lateral rays and a central ray. Moreover, based on a careful survey of the spatialtemporal distribution of chancelloriids (including both scleritome and isolated sclerite fossils) in South China, two flourishing ages, though may be related to preservational bias, of this metazoan group are recognised: 1) a significant diversification in the upper Stage 2 to Stage 3 and 2) a thriving in the Wuliuan Stage.
... Nevertheless, the Cambrian rocks of the South China in the Guizhou Province have provided hundreds of nicely preserved trilobites suitable for biostratigraphy Zelditch et al. 2004;Zhao et al. 2015Zhao et al. , p. 2019. This fact has allowed the definition of two GSSP points in South China (Peng et al. 2009;Zhao et al. 2019a). Among these complete (i.e. ...
... The specimens of Protoryctocephalus arcticus from China were collected from six different horizons (q50, q51, q52, q52, q54 and q55) from the 'Tsinghsutung' Formation in Wuliu-Zengjiayan GSSP Section at Balang (Zhao et al. 2019a). This formation is mainly composed of grey to dark grey thin-bedded limestone, intercalated with grey-yellowish shale and mudstone, grey thinbedded argillaceous limestone and grey thin-to medium-bedded dolomite in the upper part. ...
... Geyer et al. (2019) in the systematic review of this taxa stated that the 'Tsinghsutung' Formation belongs to the Cambrian Series 3 (current Miaolingian), Stage 4. This is mistake, 'Tsinghsutung' Formation belongs to the Cambrian Series 2, Stage 4. The specimens of Protoryctocephalus arcticus from northern Greenland were collected in the Henson Gletscher Formation see Geyer and Peel (2011 for detailed locality information). The specimens of Protoryctocehalus balangensis used in this study were collected from lowermost part of the Kaili Formation also from the Wuliu-Zengjiayan GSSP Section at Balang (Zhao et al. 2019a). In the Balang area, the Kaili Formation is composed mainly of a calcareous mudstone. ...
Studies focused on morphological variation are key for chrono- and biostratigraphy. Morphological variability can be induced by biological and taphonomical biases. Their distinction can become a difficult task due to the lack of population control. Here, we analyse three populations belonging to the genus Protoryctocephalus, two populations from China (P. arcticus and P. balangensis) and a third population of P. arcticus from Greenland. Protoryctocephalus balangensis was collected from the lowermost part of the Kaili Formation where fossils are tectonically deformed while P. arcticus from the ‘Tsinghsutung’ and Greenland specimens are non-deformed. Geometric morphometrics analysis shows that these three populations indeed belong to the same species. However, the large allometry measured in P. balangensis compared with the ‘Tsinghsutung’ population and the Greenland population, which is represented by meraspid and early holaspid individuals, suggested that the morphological variation is taphonomically controlled and non-biological. The results suggest that Protoryctocephalus arcticus from the ‘Tsinghsutung’ Formation is suitable for international correlation, and further studies focus on different aspects such as ontogeny, segment development or fluctuating asymmetry and modularity.
... It may help us to understand both the success of oryctocephalids, the typical slope trilobite at the early-middle Cambrian transition (e.g. Sundberg and McCollum 1997;Zhao et al. 2019b), and the evolution of early deeper water trilobites. ...
... These indicate the potential of oryctocephalids for glabella specialisation and the remarkable evolutionary rate of this group. This extensive and rapid adaptive change is probably the reason why oryctocephalids were the earliest successes of slope trilobites: they have a global distribution (Sundberg and McCollum 1997) and are used as a standard for global comparison (Zhao et al. 2019b). ...
The lower Cambrian trilobite Eodontopleura Chien and Lin in Yin and Lee 1978 from South China was once thought to be an ancestor of the post-Cambrian trilobite Odontopleurida due to its unique odontopleurid-like glabella. Here, we revise this genus as an oryctocephalid based on the articulated exoskeletons found recently in the Balang Formation (Cambrian Series 2, Stage 4) of South China. Phylogenetic analysis supports that Eodontopleura represents a typical example of trilobite convergent evolution, suggesting that even the most exclusive features may have been repeated in the evolutionary history of trilobites, which additionally reminds us of the universality of convergence and its possible misleading effect on trilobite taxonomic studies. Moreover, our discovery indicates the remarkable specialisation potential of oryctocephalids, which highlights the evolution of early deep-water trilobites.
