Cambrian Trilobites Research Articles

Sphaeroidal enrolment in middle Cambrian solenopleuropsine trilobites

Esteve, J., Zamora, S., Gozalo, R. & Linan, E. 2010: Sphaeroidal enrolment in middle Cambrian solenopleuropsine trilobites. Lethaia, 10.1111/j.1502-3931.2009.00205.x Fifty specimens belonging to species of Solenopleuropsis and Pardailhania from Spain and France demonstrate sphaeroidal enrolment in Cambrian trilobites for the first time. These solenopleuropsines show novel coaptative structures in different regions of the exoskeleton: in the cephalon there are vincular furrows and notches; in the thorax an articulating facet is developed at the pleural margins, with a ball and socket connection on the adaxial most portion, and an articulating half-ring axially; the pygidium possesses an articulating facet. The interaction of these coaptative structures resulted in a sphaeroidal enrolment that was a progressive act from the first articulation between the occipital ring and the first segment to the pygidial articulating facet. A similar type of sphaeroidal enrolment is observed in the Devonian trilobite Phacops. Both Cambrian and Devonian trilobites developed a vincular furrow in the ventral surface of the cephalon to close their bodies tightly. In both cases, this is probably a convergent adaptation to protect against predators and obrution. Indeed, the enrolled trilobites are very common in obrution deposits restricted to shallow and soft muddy substrates. □Coaptative structures, convergence, Murero Formation, Pardailhania, Solenopleuropsinae, Solenopleuropsis.

A tiny eye indicating a planktonic trilobite

Cambrian trilobites mainly lived on the sea floor, and up till now few, if any, unequivocally planktonic trilobites have been reported from earlier than the Ordovician. The late Cambrian (Furongian) to late Ordovician olenids are a distinctive group of benthic (sea-floor dwelling) or nekto-benthic trilobites. Here we show, however, that one recently described, miniaturized and very spiny olenid species, Ctenopyge ceciliae must have been planktonic ( passively drifting or feebly swimming in the upper waters of the sea). This interpretation is based not only upon body form but also on the analysis of its visual system and may be one of the earliest records of the planktonic realm being invaded by trilobites.

Geological significance of middle Cambrian trilobites from near Melba Flats, western Tasmania

In western Tasmania, near Melba Flats, a basalt within the Serpentine Hill Complex is overlain unconformably by Dundas Group sediments (Hodge Slate). About 32 m above the unconformity, a siltstone contains agnostoid and polymerid trilobites that indicate correlation with the middle Cambrian Ptychagnostus punctuosus Zone (Drumian Stage of unnamed Epoch 3 of the Cambrian). This provides an upper limit of about 505.2–504.5 Ma to the emplacement of ultramafic allochthons in western Tasmania. Other fossils present include dendroids, inarticulate brachiopods, hyolithids, helcionellids and sponges. The widespread agnostoid trilobite Ptychagnostus affinis (Brøgger 1878) and the holocephalinid trilobites Meneviella and Holocephalina are recorded for the first time in Tasmania.

Ontogeny and ventral median suture of the ptychaspidid trilobite Asioptychaspis subglobosa (Sun, 1924) from the Furongian (Upper Cambrian) Hwajeol Formation, Korea

The order Asaphida has been characterized by the possession of a globular protaspis and a ventral median suture. the superfamily Dikelocephaloidea was included in the Asaphida, although there has been no reliable ontogenetic information for this superfamily, and thus whether dikelocephaloids had a protaspis of globular shape has remained unclear. the ontogenetic study of the dikelocephaloid trilobite, Asioptychaspis subglobosa, from Korea reveals that the protaspis of A. subglobosa is not of globular morphology but of general benthic adult-like morphology, heralding that the Dikelocephaloidea may not be closely related to other trilobite groups within the Order Asaphida. This protaspid morphology is clearly distinguished from the highly globular protaspis of the Remopleuridioidea, which has been considered the sister group to the Dikelocephaloidea. in addition, the ontogenetic development of the free cheeks shows that A. subglobosa possessed anteriorly yoked free cheeks during the early phase of development but formed a ventral median suture by splitting the yoked cheeks in the later phase of ontogeny. This contrasts with the previously suggested mode of ventral median suture formation of the Order Asaphida. This alternative mode of ventral median suture formation of A. subglobosa, along with non-asaphoid protaspid morphology, warrants removal of the Dikelocephaloidea from the current Order Asaphida. This study further demonstrates that the ventral median suture did not evolve only once in the evolutionary history of trilobites. With the addition of the mode here documented for Asioptychaspis, the ventral median suture is now known to have developed independently and in a different fashion at least three times in the history of Cambrian trilobites.

Integrated ichnological and sedimentological studies of the Parahio Formation (Cambrian) of the Zanskar region (Zanskar-Spiti Basin), Northwest Himalaya

Lower-Middle Cambrian (Lungwangmiaoan-Hsuchuangian stage) Parahio Formation (Kunzam La Formation) exposed at Purni Village, Niri-Tsarap Chu Valley of Zanskar region of Tethyan Himalaya has yielded a high diversity and abundant ichnofossils with myriapod trackways. It includes Cruziana isp., Phycodes palmatum, Diplocraterion isp., Diplichnites isp., Dimorphichnus isp., Tapherhelminthopsis cf. circularis, Teichichnus isp., Monomorphicnus isp., Lockeia isp., Skolithos isp., Planolites isp., Palaeophycus isp., Isopodichnus isp., and arthropod appendage marks. Integration of ichnological and sedimentological studies for measured part of the Parahio Formation (Cambrian) reveals that alternating energy conditions due to recurring storm events were superimposed on low energy fair-weather sediments. The post-depositional Arenicolites ichnofacies, preserved within the high-energy storm beds of shoreface deposits, commonly overlies the fair-weather assemblage of pre-depositional Cruziana ichnofacies of relatively more offshore deposits, which contains more diverse and varied behavioral signatures of various deposit feeders. The traces of the Cruziana ichnofacies are abruptly replaced by traces of Arenicolites ichnofacies and show reiteration throughout the measured part of the Parahio Formation. The ichnofabric indices in these deposits range from ii3–ii5. No discrete sets of tiers are observed; perhaps there were two coeval communities. Ichnologically, an idealized wave-dominated progradational cycle in the Parahio Formation is characterized, from base to top, by a Cruziana ichnofacies (lower-upper offshore to offshore transition) and storm related Arenicolites ichnofacies (shoreface). Each progradational cycle reflects a progressive increase in sand content, degree of oxygenation, hydrodynamic energy and dearth of food. These environmental factors controlled the vertical distribution of trace fossils in Parahio Formation. The occurrence of Cruziana ichnoassociation much below the Middle Cambrian trilobite horizon in the Parahio Formation restricts the age of this part of the formation to the pre-Middle Cambrian, probably series 2 of Cambrian system.

Detrital zircon geochronologic tests of the SE Siberia-SW Laurentia paleocontinental connection

Abstract. Strikingly similar Late Mesoproterozoic stratigraphic sequences and correlative U-Pb detrital-zircon ages may indicate that the Sette Daban region of southeastern Siberia and the Death Valley region of southwestern North America were formerly contiguous parts of a Grenville foreland basin. The Siberian section contains large numbers of detrital zircons that correlate with Grenville, Granite-Rhyolite, and Yavapai basement provinces of North America. The sections in both Siberia and Death Valley exhibit west-directed thrust faults that may represent remnants of a Grenville foreland thrust belt. North American detrital-zircon components do not occur in Siberian samples above a ~600 Ma breakup unconformity, suggesting that rifting and continental separation blocked transfer of clastic sediment between the cratons by 600 Ma. Faunal similarities suggest, however, that the two cratons remained within the breeding ranges of Early Cambrian trilobites and archeocyathans.

Silicified Middle Cambrian trilobites from Kyrgyzstan

Abstract: A medium diversity silicified Middle Cambrian faunal assemblage occurs in an olistolith of bioclastic limestone within Silurian siliciclastic turbidites on the slopes of Arpatektyr Mountain in the eastern Alai Range, Kyrgyzstan. The fauna includes the trilobites Raragnostus cf. mirus, Altikolia kurshabica sp. nov., Corynexochina weberi, Dorypyge richthofeniformis, aff. Jincella sp., Olenoides comptus, Skreiaspis aff. spinosus and Suluktella mambetovi sp. nov. Three of these taxa (C. weberi, O. comptus and R. cf. mirus) are considered locally to be characteristic of the Pseudanomocarina Beds, although Pseudanomocarina itself is not present. Altikolia and Suluktella are endemic to early Palaeozoic terranes of Central Asia, Corynexochina also occurs in South China and Skreiaspis is known elsewhere exclusively from the Middle Cambrian of ‘West’ Gondwana. Because of preservation in full relief, the silicified trilobite fauna allows a detailed understanding of some morphological structures, related especially to trilobite enrolment, otherwise inadequately known for many Mid‐Cambrian polymerid trilobites.

Ontogeny and geographic variation of a new species of the corynexochine trilobiteZacanthopsis(Dyeran, Cambrian)

Assessment of ontogenetic and geographic variation can have substantial influence on species delimitation and thereby on perceived patterns of species-level morphological variation and diversity in space and time. Here we describe the ontogeny and intraspecific variation of the early Cambrian trilobite,Zacanthopsis palmerin. sp., based on silicified material from east-central Nevada, USA.Zacanthopsis palmeriis the oldest documented Cambrian corynexochine to shift from possessing a fused rostal-hypostomal plate to a functional hypostomal suture in mature specimens during ontogeny. Six geographically distinct samples of matureZ. palmerifrom a single silicified limestone bed traceable over tens of kilometers in east-central Nevada permit exploration of geographic variation within this species using geometric morphometric methods. No one sample encompasses all of the shape variation expressed byZ. palmeriand several geographically segregated samples show some degree of morphological separation in pairwise comparison. Nonetheless, these samples are not qualitatively or quantitatively different from one another when all samples are taken into account. The degree of variation withinZ. palmeriis similar in magnitude to the differences between other species in the genus known from much less material.

Two middle Cambrian diceratocephalid trilobites,Cyclolorenzella convexaandDiceratocephalus cornutus, from Korea: development and functional morphology

Park, T.-Y. & Choi, D.K. 2010: Two middle Cambrian diceratocephalid trilobites, Cyclolorenzella convexa and Diceratocephalus cornutus, from Korea: development and functional morphology. Lethaia, Vol. 43, pp. 73–87. Silicified sclerites of the latest middle Cambrian trilobites, Cyclolorenzella convexa and Diceratocephalus cornutus, have been recovered from the Sesong Formation, Korea. Their morphological similarity and stratigraphic occurrences suggest that D. cornutus is a descendant of C. convexa. The ontogenies of both trilobites demonstrate that a pair of long frontal horns in the cephalon of D. cornutus is an evolutionarily novel structure. It is inferred that redeployment of some pre-existing regulatory gene played a significant role in constructing the frontal horns of D. cornutus. The frontal horns may have been a defensive structure to deter predators. The facial suture of D. cornutus, which extends onto the frontal horns and splits them into the dorsal and ventral halves, was a solution to enable easier forward egression during ecdysis. □Functional morphology, Korea, Middle Cambrian, ontogeny, trilobites.

Ontogeny, systematics, and evolution of the effaced Early Cambrian trilobitesPeachellaWalcott, 1910 andEopeachellanew genus (Olenelloidea)

Although used in biostratigraphy and in studies of early Cambrian trilobite evolution, the olenelloid genusPeachellahas received little research attention. The ontogenetic and evolutionary origins of its derived features—an effaced cephalon and grossly inflated genal spines—have remained mysterious. Based on examination of new and existing collections,P. iddingsiandP. brevispinaare here described in detail, including aspects of their respective ontogenies and the first description of the thorax ofP. iddingsi.A new monotypic genus,Eopeachella, is also described from recently collected material from the Delamar Member of the Pioche Formation, Nevada.Eopeachella angustispinan. gen. n. sp., is less derived and stratigraphically older than bothPeachellaspecies and bridges the morphological gap betweenPeachellaand typical olenelloids. The study reveals that cephalic effacement was progressively attained during both ontogeny and phylogeny in theEopeachella + Peachellaclade. Comparative ontogeny with other olenelloids reveals that progressive effacement was a trend superimposed upon and independent of a conserved pattern of ontogenetic shape change in the glabella and did not represent a peramorphic “extension” of glabellar ontogeny. Genal spine inflation was also achieved progressively (in a proximal-to-distal direction) through both ontogeny and phylogeny in theEopeachella + Peachellaclade. Genal spine inflation that convergently arose in later trilobite groups may have been similarly ontogenetically dynamic. Discovery ofE. angustispinaandP. brevispinain the Delamar Member raises olenelloid diversity in this member to at least 20 species; a higher diversity than in any coeval unit.

Bathynotus: A key trilobite taxon for global stratigraphic boundary correlation between Cambrian Series 2 and Cambrian Series 3

The Cambrian trilobite Bathynotus is a special morphology of Redlichiid, which is characterized by a wider thorax axis and an 11th macropleural segment bearing a long, backwardly directed spine. Additionally, its 12th and 13th pleural segments are narrow and they terminate at a fulcrum where they fuse together and to the posterior edge of the long macropleural spine. The genus is widely distributed, occurring in North America, Siberia, the Altay-Sayan fold belt of Russia, South China, the Tarim Basin of China, and Australia. It occurs primarily in deposits of the upper part of the continental slope, at the transition between stable platform settings and subsiding margins of the late Early Cambrian. Here, we recognize three species of Bathynotus from China, including B. holopygus which is widespread around the world. Although six species of Bathynotus have been reported from Siberia and the Altay-Sayan fold belt area of Russia, data presented here suggest that only three of these species are valid. Bathynotus exhibits a short geological range, with its first occurrence late in the unnamed Cambrian Series 2 and the last appearance datum of Bathynotus at the boundary of Cambrian Series 2 and Cambrian Series 3. The late appearance datum (LAD) of Bathynotus provides an important global stratigraphic marker of the boundary between Cambrian Series 2 and Cambrian Series 3.

Middle Cambrian trilobites of the suborders Agnostina and Eodiscina from the Oslo Region, Norway

Middle Cambrian trilobites of the suborders Agnostina and Eodiscina from the Oslo Region, Norway

Faunas and Cambrian volcanism on the Avalonian marginal platform, southern New Brunswick

The Cambrian inlier at Beaver Harbour, southern New Brunswick, is now confidently referred to the marginal platform of the late Proterozoic–Early Paleozoic Avalon microcontinent. The sub-trilobitic Lower Cambrian Chapel Island and Random Formations are unconformably overlain by the mafic volcanic-dominated Wade's Lane Formation (new). Late Early Cambrian trilobites and small shelly taxa in the lowest Wade's Lane demonstrate a long Random–Wade's Lane hiatus (middle Terreneuvian–early Branchian). Latest Early–middle Middle Cambrian pyroclastic volcanism produced a volcanic edifice at Beaver Harbour that is one of three known volcanic centers that extended 550 km along the northwest margin of Avalon. Middle Middle Cambrian sea-level rise, probably in theParadoxides eteminicusChron, mantled the extinct volcanics with gray-green mudstone and limestone of the Fossil Brook Member. Black, dysoxic mudstone of the upper Manuels River Formation (upper Middle Cambrian,P. davidisZone) is the youngest Cambrian unit in the Beaver Harbour inlier.Lapworthella cornu(Wiman, 1903) emend., a senior synonym of the genotypeL. nigra(Cobbold, 1921),Hyolithellus sinuosusCobbold, 1921, and probablyAcrothyra seraMatthew, 1902a, range through the ca. 8 m.y. of the trilobite-bearing upper Lower Cambrian, andH. sinuosusandA. serapersist into the middle Middle Cambrian.Lapworthella cornuandH. sinuosusreplaced the tropical taxaL. schodackensis(Lochman, 1956) andH. micansBillings, 1872, in cool-water Avalon.

Two middle Cambrian trilobite genera, Cyclolorenzella Kobayashi, 1960 and Jiulongshania gen. nov., from Korea and China

Cyclolorenzella is an important member of the middle Cambrian trilobite faunas in China and Korea. Morphometric analysis based on well-preserved new material assignable to Cyclolorenzella from China and Korea reveals that most of the species assigned previously to Cyclolorenzella in China are morphologically distinct from the genotype. Accordingly, the new genus Jiulongshania, with J. acalle (Walcott, 1905) as type species, is proposed to accommodate the following species: J. acalle, J. regularis (Walcott, 1906), J. rotundata (Resser & Endo in Endo & Resser, 1937), J. longispina (Wittke & Zhu in Zhu & Wittke, 1989), J. acuta (Duan in Duan et al., 2005) and J. longa sp. nov. Species tentatively transferred to Jiulongshania are J.? subcylindrica (Chu, 1959), J.? yentaiensis (Chu, 1959), J.? humilis (Zhang in Qiu et al., 1983), and J.? latisulcata (Zhang in Qiu et al., 1983). This taxonomic revision results in only two species remaining in Cyclolorenzella, the type species C. quadrata (Kobayashi, 1935) and C. convexa (Resser & Endo in Endo & Resser, 1937). Jiulongshania has a relatively long stratigraphic range from the Damesella–Yabeia Zone to the Blackwelderia Zone of China, whereas Cyclolorenzella is restricted to the stratigraphically younger Drepanura Zone in China and Korea.

Ontogeny of the Middle Cambrian Trilobite Shantungia spinifera Walcott, 1905 from North China and Its Taxonomic Significance

The cambrian trilobite Shantungia Walcott, 1905 is a monotypic genus, with S. spinifera Walcott, 1905 as the genotype and is characterized by its long frontal spine extending medially from the anterior cranidial border. The genus has hitherto been known restricted in occurrence to the traditional Drepanura Zone of North China (Walcott, 1913; Endo and Resser, 1937; Qiu et al., 1983; Zhang and Jell, 1987). As Drepanura Bergeron, 1899 is preoccupied by a collembolan insect and Neodrepanura Ozdikmen, 2006 was proposed as a replacement, this zone is referred to as the Neodrepanura Biozone herein. Recently collected trilobites from the Kushan Formation in Shandong Province of North China contain forty specimens of Shantungia spinifera , including protaspid and meraspid forms. Interestingly, the juvenile specimens of S. spinifera are morphologically closely comparable to the specimens recently assigned to Oculishumardia hunania Peng et al., 2003 from the uppermost middle Cambrian Liostracina bella Zone of South China (Peng et al., 2004). Peng et al. (2003) claimed that Oculishumardia is the oldest shumardiid and phylogenetically represents an intermediate stage between ptychoparioids and shumardiids. This note describes the ontogenetic development of Shantungia spinifera from North China and, based on this information, raises the possibility that Oculishumardia may represent meraspid stages of a damesellid trilobite and will explore its taxonomic and phylogenetic significance. All of the specimens examined in this study were collected from the Kushan Formation of the Tangwangzhai section, Shandong Province, China (Fig. 1). The Tangwangzhai section (116°51′42″E and 36°30′33″N) has served as the type section of middle Cambrian to Furongian (upper Cambrian) strata of North China and comprises the Changhia, Kushan, and Chaumitien formations in ascending order (Bureau of Geology and Mineral Resources of Shandong Province, 1996). The Kushan Formation in the section measures ca. 62 m in thickness and is generally …

Lampropeltastes, a new name for the genus Lampropeltis Öpik, 1967 (Trilobita: Plethopeltidae) preoccupied by Lampropeltis Cope, 1860 (Serpentes: Colubridae)

An australian paleontologist would not be expected to be familiar with the genera of recent snakes in the Western Hemisphere. Thus, when A. A. Öpik erected the genus Lampropeltis to receive certain Middle Cambrian trilobites from the Mindyallan of Queensland (Öpik 1967, p. 182), he was appropriately unaware that the name had already been coined for a genus of smooth-scaled colubrids, the kingsnakes (Cope, 1860; Blanchard, 1921).

Middle cambrian trilobites and biostratigraphy of the daegi formation (Taebaek Group) in the Seokgaejae section, Taebaeksan Basin, Korea

The Daegi Formation in the Taebaeksan Basin of Korea is composed of shallow marine carbonate facies and has been known to yield relatively diverse invertebrate fossils of middle Cambrian age. This paper describes seventeen trilobite species belonging to fifteen genera from the Daegi Formation exposed in the Seokgaejae section, located at southeastern corner of the Taebaeksan Basin. They comprise two agnostoid species(Ammagnostus laiwuensis andAmmagnostus sp.) and fifteen polymerid taxa (Dorypyge richthofeni, Amphoton deois, Blackwelderia sp.,Teinistion? sp.,Palaeadotes? sp.,Anomocarella temenus, ptychopariid gen. and sp. indeterminate.,Changqingia deprati, Crepicephalina damia, Cyclolorenzella rotundata, Cyclolorenzella sp.,Proasaphiscus sp.,Manchuriella macar, Ignotogregatus manholi, and Metanomocarella tumida). The stratigraphic distribution of these trilobites provides a basis for establishment of new trilobite zones within the formation: Le., theCrepicephalina, Amphoton, andCyclolorenzella zones in ascending order. TheCrepicephalina Zone is dominated byCrepicephalina damia, Manchuriella macar, Ignotogregatus sp. cf.I. manholi, andAmmagnostus laiwuensis. TheAmphoton Zone is recognized by the restricted occurrence ofAmphoton deois and dominance ofDorypyge richthofeni. TheCyclolorenzella Zone is characterized by the occurrence ofCyclolorenzella rotundata and some damesellid trilobites. These three biozones belong to middle to upper middle Cambrian in age and are closely correlated with theCrepicephalina, Amphoton, andDamesella-Yabeia zones of North China, respectively.

Trilobites of thePseudokoldinioidiaFauna (Uppermost Cambrian) from the Taebaek Group, Taebaeksan Basin, Korea

ThePseudokoldinioidiaFauna is a newly documented uppermost Cambrian trilobite assemblage from the Dongjeom Formation of the Taebaek Group, Taebaeksan Basin, Korea. It is characterized by low species diversity comprising six trilobite taxa:Micragnostus chiushuensis, Koldinioidia typicalis, leiostegiid genus and species indeterminate,Pseudokoldinioidia perpetis, Onychopyge borealis, and pilekiid genus and species indeterminate. Of these, special attention has been paid toPseudokoldinioidia perpetis, which was originally assigned toMissisquoia, an index fossil for the uppermost Cambrian in Laurentia.Pseudokoldinioidiais restricted to eastern Asia, whereasMissisquoiais confined to Laurentia. The appearance of thePseudokoldinioidiaFauna is interpreted as contemporaneous with the base of the‘Missisquoia’ perpetisZone of North China, which in turn is correlated with the base of theMissisquoia typicalisSubzone of Laurentia. The associatedKoldinioidiaandOnychopygemake it possible to compare thePseudokoldinioidiaFauna of Korea and North China with the latest Cambrian trilobite assemblages of South China, Australia, South America, and Mexico, and also suggests an interesting biogeographic connection among these areas in the latest Cambrian.

Strength in numbers: High phenotypic variance in early Cambrian trilobites and its evolutionary implications

Analysis of the degree of intraspecific morphological polymorphism during the evolutionary history of trilobites using an informatic approach(1) provides striking evidence of a long-suspected but previously unsubstantiated pattern: degrees of polymorphism are markedly higher in phylogenetically basal, stratigraphically early species. This unequivocal pattern prompts further exploration of the relationship between microevolutionary variance and macroevolutionary history. It demonstrates that the 'traditional' fossil record of skeletonized organisms can provide unique insight into questions of major evolutionary interest.

A review of the Late Cambrian (Furongian) palaeogeography in the western Mediterranean region, NW Gondwana

The Cambrian–Ordovician transition of the western Mediterranean region (NW Gondwana) is characterized by the record of major erosive unconformities with gaps that range from a chronostratigraphic stage to a series. The hiatii are diachronous and involved progressively younger strata along the Gondwanan margin, from SW (Morocco) to NE (Montagne Noire). They can be related to development of a multi-stage rifting (further North), currently connected to the opening of the Rheic Ocean, and concomitant erosion on southern rift shoulders. The platforms of this margin of Gondwana occupied temperate-water, mid latitudes and were dominated by siliciclastic sedimentation, while carbonate factories were only episodically active in the Montagne-Noire platform. The Upper Cambrian is devoid of significant gaps in the southern Montagne Noire and the Iberian Chains. There, the sedimentation took place in a transgressive-dominated depositional system, with common offshore deposits and clayey substrates, and was bracketed by two major regressive trends. The Late Cambrian is also associated with the record of volcanic activity ( e.g., in the Cantabrian and Ossa-Morena zones, and the northern Montagne Noire), and widespread development of a tectonic instability that led to the episodic establishment of palaeotopographies and record of slope-related facies associations. Several immigration events are recognized throughout the latest Middle Cambrian, Late Cambrian and Tremadocian. The trilobites show a stepwise replacement of Acado-Baltic-type families ( e.g., the conocoryphid–paradoxidid–solenopleurid assemblage) characterized by: (i) a late Languedocian (latest Middle Cambrian) co-occurrence of Middle Cambrian trilobite families with the first anomocarid, dorypygid and proasaphiscid invaders; (ii) a Late Cambrian immigration replacing previous faunas, composed of trilobites (aphelaspidids, catillicephalids, ceratopygids, damesellids, eulomids, idahoiids, linchakephalids, lisariids, onchonotinids, and pagodiids), linguliformean brachiopods (acrotretids, obolids, scaphelasmatids, siphonotretids, and zhanatellids), echinoderms (mitrates, glyptocystitid cystoids, and stromatocystoids), and conodonts belonging to the lower Peltura Zone; and (iii) the subsequent input of new trilobites (asaphids, calymenids, catillicephalids, nileids and remopleurids), which marks the base of the Proteuloma geinitzi Zone, associated with pelmatozoan holdfasts ( Oryctoconus), and a distinct input of late Tremadocian conodonts ( Paltodus deltifer Zone). The biogeographic distribution of latest Middle and Late Cambrian trilobites supports brachiopod data indicating strong affinities between the western Mediterranean region, East Gondwana (North China/Korea, South China, Australia, and Antarctica) and Kazakhstania during the late Languedocian, which became significantly stronger during the Late Cambrian. This major shift may suggest modification in oceanic circulation patterns throughout Gondwana across the Middle–Late Cambrian transition.