| 1. |
- Chen, Feiyang, et al.
(författare)
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Cambrian ecological complexities: Perspectives from the earliest brachiopod – supported benthic communities in the early Cambrian Guanshan Lagerstätte
- 2022
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Ingår i: Gondwana Research. - Amsterdam : Elsevier. - 1342-937X .- 1878-0571. ; 107, s. 30-41
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Tidskriftsartikel (refereegranskat)abstract
- The Cambrian radiation is characterized by the emergence of diverse bilaterian animal phyla and theestablishment of complex marine ecosystems. The Guanshan Biota records an unusual ecological transition from trilobite- to brachiopod-dominated communities during Cambrian Stage 4. This community transition is accompanied by direct evidence of in situ biological interactions such as durophagous pre-dation and kleptoparasitism. Here we describe new material from the Guanshan biota, focusing on an association of palaeoscolecidomorphs and brachiopods with parasitic tube worms that occur on micro-bedding planes. The bedding plane assemblages are dominated by the organophosphatic brachiopod Neobolus wulongqingensis encrusted with kleptoparasitic tube-dwelling worms, along with infaunal palaeoscolecidans. Taphonomic and sedimentological evidence indicates that these specimens are com-monly preserved in life position, and thus the association between individuals represent potential biological interactions. This case study reveals that ecosystems during the early Cambrian exhibited a well-developed system of tiering and a complex trophic network, easily distinguished from the simple communities typical of precursor deposits in the Ediacaran. Brachiopods forming extremely dense concentrations on the sea floor are effectively acting as ecosystem engineers, not only to stabilize the soft-substrate seafloor, but also act as an alternative substrate for the oldest empirically demonstrated kleptoparasites.The in situ biological interactions preserved in the Guanshan Biota are critical for filling gaps in ourknowledge of ecosystem complexity in the Cambrian.
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| 2. |
- Liang, Yue, et al.
(författare)
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Brachiopods from the Latham Shale Lagerstätte (Cambrian Series 2, Stage 4) and Cadiz Formation (Miaolingian, Wuliuan), California
- 2022
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Ingår i: Journal of Paleontology. - : Cambridge University Press. - 0022-3360 .- 1937-2337. ; 96:1, s. 61-80
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Tidskriftsartikel (refereegranskat)abstract
- A moderately diverse assemblage of brachiopods from the Latham Shale Lagerstätte (Cambrian Series 2, upper Stage 4) and the upper Cadiz Formation (Miaolingian, Wuliuan), California is described in detail for the first time. The fauna includes both linguliform and rhynchonelliform brachiopods—Hadrotreta primaea (Walcott, 1902), Paterina prospectensis (Walcott, 1884), Dictyonina pannula (White, 1874), and Mickwitzia occidens Walcott, 1908; and Nisusia fulleri Mount, 1981 and Wimanella highlandensis (Walcott, 1886), respectively—together with olenellid trilobites and hyolithids. The fauna differs from other Cambrian Konservat-Lagerstätten (notably Cambrian Series 2 Chengjiang and Guanshan Lagerstätten, eastern Yunnan) in that the brachiopod shell valves in many cases are still preserved with their original mineralization. Moreover, the excellently preserved shale-hosted valves even include cases with exquisite epithelial cell molds, otherwise only seen in acid-etched material from carbonate rocks. The pitted ornamentation in D. pannula closely resembles that described from Ordovician linguliforms. The unusual preservation of N. fulleri provides important clues for ancestral composition of the brachiopod shell. The two articulated rhynchonelliform species probably represent the oldest records of this group from the west Laurentia. The fauna could also represent the earliest onset of the transition from the Cambrian Evolutionary Fauna (CEF) to the Paleozoic Evolutionary Fauna (PEF).
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| 3. |
- Liang, Yue, et al.
(författare)
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Shell structure, ornamentation and affinity of the problematic early Cambrian brachiopod Heliomedusa orienta
- 2020
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Ingår i: Lethaia. - : Scandinavian University Press / Universitetsforlaget AS. - 0024-1164 .- 1502-3931. ; 53:4, s. 574-587
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Tidskriftsartikel (refereegranskat)abstract
- The origin of the Brachiopoda has long been a hotly debated topic, and various models have been proposed following the latest finds of exceptionally preserved material. The lower Cambrian (Stage 3) Heliomedusa orienta from the Chengjiang Konservat‐Lagerstätte, eastern Yunnan of South China, is an important example of exceptional preservation. A wide variety of affinities have been proposed for Heliomedusa, but recently it has been suggested to reside within the mickwitziids, which may form a stem group to the Brachiopoda. Detailed studies of exceptionally preserved Heliomedusa have increased our knowledge of the soft‐part anatomy of this important early brachiopod, but unfortunately, almost nothing is known about its shell structure. Here, we describe new exceptionally preserved specimens from the Chengjiang biota to better reveal both shell structure and ornamentation. Its reticulate–pustulose ornament and tubular structure are reminiscent of traits seen in other mickwitziid brachiopods. In addition, two types of setae can be observed. Apart from the pyritized marginal mantle setae, some tubules are filled with iron oxides, potentially representing thinner and shorter penetrative setae. Both valves of H. orienta appear to have been less mineralized as compared to Mickwitzia monilifera, and the two species differ in diameter and density of tubules and pustules, and in terms of slightly less projected profile of ventral valve with lower umbo posteromedially placed. Although Heliomedusa clearly is closely related to Mickwitzia, their different preservational modes (compacted poorly mineralized/noncompacted mineralized) make detailed comparison difficult; they are provisionally kept as separate genera pending further studies of better‐preserved Chinese material.
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| 4. |
- Liu, Fan, et al.
(författare)
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Hyolithid-like hyoliths without helens from the early Cambrian of South China, and their implications for the evolution of hyoliths
- 2022
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Ingår i: BMC Ecology and Evolution. - : BioMed Central (BMC). - 2730-7182. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: A small hyolith, with a triangular operculum and a conical-pyramidal conch with a sharp apex, originally documented as Ambrolinevitus ventricosus, is revised based on new material from the Chengjiang biota. The operculum of ‘Ambrolinevitus’ ventricosus displays strong morphological similarities with the operculum of Paramicrocornus from the Shuijingtuo Formation (Cambrian Series 2), indicating that the species should be reassigned to Paramicrocornus.Results: Based on the unusual morphology of Paramicrocornus, we herein propose a new family Paramicrocornidae fam. nov. A cladistic analysis of Cambrian and Ordovician hyoliths clearly delineates hyolithids as a monophyletic group which evolved from the paraphyletic orthothecids in the early Cambrian and with Paramicrocornidae as its closest relative.Conclusions: The phylogenetic analysis, together with the distribution of hyoliths from the Cambrian to the Ordovician, reveals the presumptive evolution model of both the skeleton and soft-part anatomy of hyoliths. The Family Paramicrocornidae plays an intermediate role in hyolith evolution, representing the transitional stage in the evolution from orthothecids to hyolithids.
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| 5. |
- Liu, Fan, et al.
(författare)
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Revision of Triplicatella (Orthothecida, Hyolitha) with preserved digestive tracts from the early Cambrian Chengjiang Lagerstätte, South China
- 2021
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Ingår i: Historical Biology. - : Taylor & Francis. - 0891-2963 .- 1029-2381. ; 33:9, s. 1857-1871
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Tidskriftsartikel (refereegranskat)abstract
- The cap-shaped shells of Triplicatella are known almost exclusively from small shelly fossil assemblages with articulated specimens showing unequivocally that they represent the operculum of a hyolith. Abundant specimens of Triplicatella opimus from the fine-grained shales of the Chengjiang Lagerstätte of South China with soft-part preservation are documented herein. The soft tissues, including the feeding apparatus and complex digestive system, in T. opimus strongly suggest that Triplicatella was a deposit feeder. The digestive tract of T. opimus consists of two limbs, a spiral loop folded into a chevron-like structure and a slightly recurved to straight anal tube, which are preserved as reddish-black traces enriched in iron. The new anatomical information obtained from T. opimus in the Chengjiang Biota suggests an intermediate stage in the development of the characteristic folded gut of orthothecid hyoliths. The new anatomical information reported here shows that Triplicatella is one of the best-preserved early members of the Orthothecida and promotes our understanding of the general anatomy and evolution of the Hyolitha.
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| 6. |
- Luo, Mei, et al.
(författare)
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First Report of Small Skeletal Fossils from the Upper Guojiaba Formation (Series 2, Cambrian), Southern Shaanxi, South China
- 2023
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Ingår i: Biology. - : MDPI. - 2079-7737. ; 12:7
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Tidskriftsartikel (refereegranskat)abstract
- A small skeletal fossil assemblage is described for the first time from the bioclastic limestone interbeds of the siltstone-dominated Guojiaba Formation, southern Shaanxi, China. The carbonate-hosted fossils include brachiopods (Eohadrotreta zhujiahensis, Eohadrotreta zhenbaensis, Spinobolus sp., Kuangshanotreta malungensis, Kyrshabaktella sp., Lingulellotreta yuanshanensis, Eoobolus incipiens, and Eoobolus sp.), sphenothallids (Sphenothallus sp.), archaeocyaths (Robustocyathus sp. and Yukonocyathus sp.), bradoriids (Kunmingella douvillei), chancelloriids sclerites (Onychia sp., Allonnia sp., Diminia sp., Archiasterella pentactina, and Chancelloria cf. eros), echinoderm plates, fragments of trilobites (Eoredlichia sp.), and hyolithelminths. The discovery of archaeocyaths in the Guojiaba Formation significantly extends their stratigraphic range in South China from the early Tsanglangpuian at least to the late Chiungchussuan. Thus, the Guojiaba Formation now represents the lowest known stratigraphic horizon where archaeocyath fossils have been found in the southern Shaanxi area. The overall assemblage is most comparable, in terms of composition, to Small skeletal fossil (SSF) assemblages from the early Cambrian Chengjiang fauna recovered from the Yu’anshan Formation in eastern Yunnan Province. The existing position that the Guojiaba Formation is correlated with Stage 3 in Cambrian Series 2 is strongly upheld based on the fossil assemblage recovered in this study.Simple SummarySmall skeletal fossils are reported for the first time from the early Cambrian Guojiaba Formation, southern Shaanxi, China. All specimens were recovered from bioclastic limestone interbeds and encompass a wide variety of skeletal clades, including brachiopods, sphenothallids, archaeocyaths, bradoriids, sponge spicules, echinoderm plates, and trilobite spines. The archaeocyaths described herein are considerably older than those described from the Xiannvdong Formation, which was previously assumed to contain the lowest archaeocyath-bearing horizons in South China. The brachiopod Lingulellotreta yuanshanensis is recorded for the first time from the Fucheng area, with previous records confined mainly to the Chengjiang Fauna-bearing Yu’anshan Formation in the lower Cambrian, the eastern Yunnan Province. Micro-morphological and elemental analyses of the small skeletal fossil assemblages were carried out using SEM, BSEM, and Micro X–ray fluorescence. The skeletal fauna in the Guojiaba Formation resembles the assemblages recovered from the upper Yu’anshan Formation (Chengjiang Fauna) in eastern Yunnan Province. Based on the recovered assemblage, the biostratigraphic age of the Guojiaba Formation correlates with the Chiungchussuan Stage (Stage 3 of Cambrian Series 2).
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| 7. |
- Wang, Haizhou, 1988-
(författare)
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Origin and Lifestyles of early Brachiopods and other Lophotrochozoans : Insights from the Chengjiang and Guanshan Fossil-Lagerstätten
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the great unsolved evolutionary questions concerns the origin and phylogeny of the major animal phyla that appeared in the fossil record more than 540 million years ago, during the Cambrian explosion. Although new molecular information has been very useful, we still have little understanding about the origin of most of the phyla of bilaterians living today. The richly diverse fossil remains from this critical early Cambrian interval are particularly well exposed in China, where exceptionally-preserved fossil lophotrochozoans including brachiopods are particularly abundant. In particular the exceptionally-preserved Cambrian lophophorates from the Chengjiang and Guanshan Lagerstätten have offered new sources of critical palaeobiological data that have been shown to be important for understanding the early ecology and evolution of lophotrochozoans. This thesis comprises a detailed study of new, abundant, exceptionally-preserved material of five lophotrochozoan species from the Chengjiang and Guanshan Lagerstätten. Kuangshanotreta malungensis from Chengjiang is the earliest known example of an attached acrotretoid brachiopod representing the oldest evidence about the palaeoecology of the diverse yet, enigmatic acrotretoid linguliform stock that comprises an important component of the Cambrian evolutionary fauna. Eoglossa chengjiangensis from Chengjiang is the earliest known representative of the Glossellinae. Diandongia pista occurs abundantly both in the Chengjiang fauna and the younger Guanshan fauna, and it’s exceptionally well-preserved and strongly mineralized shells shows that it belongs within the Botsfordiidae. In contrast, the last two species from Chengjiang examined for this thesis - Yuganotheca elegans and Cotyledion tylodes belong within the stem of the Brachiopoda and the Lophotrochozoan entoprocts.
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| 8. |
- Zhang, Zhifei, et al.
(författare)
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A sclerite-bearing stem group entoproct from the early Cambrian and its implications
- 2013
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Ingår i: Scientific Reports. - London : Nature Publishing Group. - 2045-2322. ; 3, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- The Lophotrochozoa includes disparate tentacle-bearing sessile protostome animals, which apparently appeared in the Cambrian explosion, but lack an uncontested fossil record. Here we describe abundant well preserved material of Cotyledion tylodes Luo et Hu, 1999, from the Cambrian (Series 2) Chengjiang deposits, reinterpreted here as a stem-group entoproct. The entoproct affinity is supported by the sessile body plan and interior soft anatomy. The body consists of an upper calyx and a lower elongate stalk with a distal holdfast. The soft anatomy includes a U-shaped gut with a mouth and aboral anus ringed by retractable marginal tentacles. Cotyledion differs from extant entoprocts in being larger, and having the calyx and the stalk covered by numerous loosely-spaced external sclerites. The description of entoprocts from the Chengjiang biota traces the ancestry of yet another lophotrochozoan phylum back to the Cambrian radiation, and has important implications for the earliest evolution of lophotrochozoans.
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| 9. |
- Zhang, Zhifei, et al.
(författare)
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An early Cambrian agglutinated tubular lophophorate with brachiopod characters
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 4:4682, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- The morphological disparity of lophotrochozoan phyla makes it difficult to predict the morphology of the last common ancestor. Only fossils of stem groups can help discover the morphological transitions that occurred along the roots of these phyla. Here, we describe a tubular fossil Yuganotheca elegans gen. et sp. nov. from the Cambrian (Stage 3) Chengjiang Lagersta¨tte (Yunnan, China) that exhibits an unusual combination of phoronid, brachiopod and tommotiid (Cambrian problematica) characters, notably a pair of agglutinated valves, enclosing a horseshoe-shaped lophophore, supported by a lower bipartite tubular attachment structure with a long pedicle with coelomic space. The terminal bulb of the pedicle provided anchorage in soft sediment. The discovery has important implications for the early evolution of lophotrochozoans, suggesting rooting of brachiopods into the sessile lophotrochozoans and the origination of their bivalved bauplan preceding the biomineralization of shell valves in crown brachiopods.
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| 10. |
- Zhang, Zhifei, et al.
(författare)
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Reconstruction of the first consumer-driven marine ecosystem on Earth, perspectives from early Cambrian small skeletal fossils from China
- 2023
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Ingår i: Estonian journal of earth sciences. - : Estonian Academy Publishers. - 1736-4728 .- 1736-7557. ; 72:1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Biological activity was the major triggering factor driving Earth's organic and inorganic cycles across the biosphere, lithosphere, and atmosphere. A key question in the evolution of Earth's ecosystem is when and how different animals emerged and flourished and how their appearance impacted the hydrosphere-atmosphere-lithosphere cycles. The Cambrian Explosion of meta -zoans in the Ediacaran-Cambrian boundary interval resulted in sudden appearance of most of the readily fossilizable modern animal groups as macro-consumers in the Earth's oceans. This explosive radiation event led for the first time to the emergence and diversification of animals on Earth, to the establishment of complex trophic webs with animals as consumers, and marks the onset of the Phanerozoic oceanic ecosystem. Our presentation aims to discuss the at least half-billion-year-old world of tubular and conical shelled organisms (sponges, conulariids, chancelloriids, hyoliths, mollusks, tommotiids, and other lophotrochozoans) that are unseen in the present-day oceans but were recovered by us from the siliciclastic and carbonate rocks in and outside of China. Additionally, to study the body fossils of exceptionally preserved biotas (Konversat-Lagerstätten) across China, efforts are underway to understand how the early animals, notably early bilaterians, created the over 500-million-year-old oceanic ecosystems without the influence of land plants, which appeared later.
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