KMS Nanjing Institute of Geology and Palaeonotology,CAS
Maotianshan-Shale nemathelminths - Morphology, biology, and the phylogeny of Nemathelminthes | |
Maas, Andreas; Huang, Diying (黄迪颖)![]() ![]() | |
2007-10-08 | |
发表期刊 | PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
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ISSN | 0031-0182 |
卷号 | 254期号:1-2页码:288-306 |
摘要 | We investigated individual-rich nemathelminth species from the Lower Cambrian Maotianshan-Shale (Chengjiang) biota comprising Chengjiang, Haikou and Shankou faunas near Kunming, southern China, with regard to morphology, life habits and their possible role in the early marine shallow-water ecosystems. Their body shapes can be grouped into four sets: long, worm-shaped forms, sac-like forms and tubiform forms with a conically tapering, stiff trunk, and forms with a body consisting of a grape-shaped anterior part and a similarly shaped trunk with cuticular plates along the long axis of the body. This latter shape matches the loricate trunk of extant larval priapulids and larval and adult loriciferans, both members of the scalidophoran Nemathelminthes. All Cambrian taxa share several features with the Scalidophora, comprising Loricifera, Priapulida and Kinorhyncha, such as the pharynx lined with internally curved spines and the frontal body region, introvert, which is similarly armed with hook-like spines. Living scalidophorans use their introvert for locomotion and the pharynx to swallow prey, which is assumed to be the case for the fossil forms too. Their inwardly curved pharyngeal spines prevent prey from escaping, while the introvert spines, the so-called scalids, may serve to anchor the body to the surface when pulling it forward. The living forms can withdraw their pharynx and introvert deeply into the body, which can be demonstrated only for the pharynx in the Lower Cambrian forms. Details of the arrangement and number of pharynx and introvert spines are considered useful features for a systematic positioning for the Lower Cambrian taxa. The structures themselves might have evolved, however, earlier than in the scalidophoran ground pattern and probably characterised already the stem species of cycloneuralian nemathelminths because of the presence of similar features in both taxa of the Nematoida, the nematomorphs (in the larvae) and the nematodes (circum-oral sensilla). Introverts with rings of six scalids in Nematoida opposite to rings of multiples of four or five in Scalidophora indicate a possible position of the fossil taxa close to the Scalidophora. We argue that the loricate Cambrian taxa (the fourth set) are derivatives of the stem lineage of the Loricifera. This implies that minute size, slight bilateralisation, a specific piercing apparatus developed along the evolutionary path of these animals toward life in the interstitial, characterise the crown group. Reconstructing the life habits of the fossil taxa, it seems to us that the forms investigated by us were most likely epi- or inbenthic, living in muddy sedimentary environments. A vertical burrowing into the sediment does not seem very likely, while a predatory life is plausible also for the Cambrian nemathelminths. We furthermore discuss the significance of these fossils with regard to the systematic status of the Nemathelminthes. (c) 2007 Elsevier B.V. All tights reserved. |
关键词 | Cycloneuralia Introverta Life Habit Scalids Segmentation Feeding Locomotion |
DOI | 10.1016/j.palaeo.2007.03.019 |
语种 | 英语 |
关键词[WOS] | Cambrian Chengjiang Lagerstatte ; Sw China ; Priapulids Priapulida ; Palaeoscolecid Worms ; Gene-sequences ; South China ; Arthropods ; Kinorhyncha ; Loricifera ; Larvae |
WOS研究方向 | Physical Geography ; Geology ; Paleontology |
WOS类目 | Geography, Physical ; Geosciences, Multidisciplinary ; Paleontology |
WOS记录号 | WOS:000250694700015 |
出版者 | ELSEVIER SCIENCE BV |
文献类型 | 期刊论文 |
条目标识符 | http://ir.nigpas.ac.cn/handle/332004/85 |
专题 | 中国科学院南京地质古生物研究所 其他 |
通讯作者 | Maas, Andreas |
作者单位 | 1.Univ Ulm, Sect Biosystemat Documentat, D-98081 Ulm, Germany 2.Chinese Acad Sci, Nanjing Inst Geol & Palaeontol, Nanjing 210008, Peoples R China 3.Univ Bonn, Inst Palaeontol, D-53115 Bonn, Germany |
推荐引用方式 GB/T 7714 | Maas, Andreas,Huang, Diying ,Chen, Junyuan ,et al. Maotianshan-Shale nemathelminths - Morphology, biology, and the phylogeny of Nemathelminthes[J]. PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY,2007,254(1-2):288-306. |
APA | Maas, Andreas,Huang, Diying ,Chen, Junyuan ,Waloszek, Dieter,&Braun, Andreas.(2007).Maotianshan-Shale nemathelminths - Morphology, biology, and the phylogeny of Nemathelminthes.PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY,254(1-2),288-306. |
MLA | Maas, Andreas,et al."Maotianshan-Shale nemathelminths - Morphology, biology, and the phylogeny of Nemathelminthes".PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY 254.1-2(2007):288-306. |
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