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= Conotubus =

Conotubus is a genus of tubular fossil found in Ediacaran period. Conotubus was first named by Zhang Lu Yi and Lin Shi Min. It is characterized by a hollow, flat cone-shaped tube, straight or naturally curved, with a clear distinction between the dorsal and abdominal parts. The dorsal part has wrinkles or folds that arch toward the caudal/end, and the fossil is usually pyritized. In subsequent studies, Zhang Luyi suggested that the anterior end might have a tentacle-like structure, and thus Hua et al. revised its features, suggesting that it is a conical tubular fossil composed of a series of interlocking funnels, and that the organism lived in a smooth inner tube, and that an  embryonic tube may have existed during growth as the diameter of the funnel body gradually expanded and the tube gradually assumed a conical shape with a closed beginning.

Conotubus was further defined by Cai et al. as a slightly curved tubular fossil with an open end and a rounded, closed end at the other end. No structures such as specialized cementation devices were observed, and the bluntly rounded closed end may have served to cement the tube body to the sediment. The pipe body is probably unmineralized and consists of a series of stacked barrel walls. Multiple layers of walls can be observed in cross-section because the body has a multi-layered wall stacking structure. In cross-section, the walls are circular. The newly added walls are stacked on top of each other with the older walls. Conotubus has a Body length 3-80mm, front end width 0.3-12mm, blunt tail end circle diameter: 0.1-4mm

Distribution
Conotubus was first found in Gaojiashan Lagerstätte. Except the discovery of Conotubus by Chen Mengguo et al. (1975) in the Gaojiashan section in Shaanxi Province, Simth et al. (2016) also found pyrite-conserved Conotubus in the Deep Springs Formation in Nevada, USA.

Fossil belt
conotubus-Gaojiashania Prololagena combination belt

Produced in the central part of the Gaojiashania section. Almost all layers have fossils, and the local layer section is extremely rich. On a specimen of 25×30cm², more than one hundred fossil right individuals of various forms and sizes are visible. This zone is the oldest fossil zone with mineralized walls, and it is the more prosperous development stage of the Gaojiashan Biota, dominated by Conotubus and bottle-shaped fossils Protolagena and Sicylagena, and large soft-bodied creepers (Gaojiashania, Ningqiangella. udaiella (MS) and macroscopic Chauria. Shouhsiani a. Vendotaenia) in symbiosis with them. Trypanosoma spp. are mainly distributed in this zone.

Taxonomy
Kingdom: Vermes

Phylum: Invertum phyli

Class: Invertae classis

Order: Incertei ordinis

Family: Incertae familiea

Genus: Conotubus Zhang et Lin gen. nov.

Type species: Conotubus hemiannulatus Zhang et Lin gen. et sp. nov.

Fossilizing
Conotubus found in Gaojianshan posit are mainly pyritized fossils. In terms of burial science, the Conotubus Gaojiashania-Protolagena assemblage is preserved by the predominant pyritization and has a perfect three-dimensional morphology. Allison (1988a) defined three different levels of preservation based on the amount of information lost during preservation of soft tissues, one of which is mineralized soft tissues. In this preservation method, only a small amount of fossil information is lost, and the three-dimensional morphology of fossils is intact and preserved with high accuracy. In this type of preservation, authigenic minerals usually precipitate before the decay of the organism, preserving soft tissues that are weakly resistant to decay. Conotubus tube bodies preserved in a fully mineralized soft-body mode. Pyrite precipitates prior to massive decay of the tube body, thus preventing collapse of the fossil.

Ecology
A detailed comparison with Cloudina suggests that the two have similarities in structure and lifestyle, inferring that the organic or weakly mineralized conotubus may be the predecessor of the mineralized Cloudina,

Conotubus fossils from the Gaojiashan Biota are characterized by in situ burial, and the beginning 1/3 one thirds of the fossil is often clearly bent or broken. The paleoecological features of this fossil are also presumed to be the insertion of the beginning tube body into the muddy substrate to anchor itself to the benthic life.

Considering their possible affinity with Cloudina, the two may have adopted a similar feeding mode. The mainstream view is that the beginning of the fossil tube body of Cloudina may be inserted into the microbial mat for filter-feeding life. Therefore, Conotubus might also perform similar paleoecological features.

Citation
■华洪,蔡耀平,闵筱,等. 埃迪卡拉纪末期管状动物的“大辐射”[J]. 西北大学学报（自然科学版）,2020,50(2):141-174. DOI:10.16152/j.cnki.xdxbzr.2020-02-001.

■CAI Y，SCHIFFBAUER J D，HUA Het al.，2012.Preservational  modes in the Ediacaran Gaojiashan Lagerstätte: pyritization,  alumino silicification，and carbonaceous compression. Paleogeography Palaeoclimatology Paleoecology

■骆劲舟,刘紫薇,任津杰,等. 埃迪卡拉纪末期Conotubus与Cloudina亲缘关系再研究——基于几何形态测量学的新证据[J]. 微体古生物学报,2019,36(3):205-214.

■林世敏, and 张运芬. "陕南震旦系上统高家山组发现的后生动物、遗迹化石和宏观藻类化石." 陕西地质 000.001(1986):9.

■华洪,张录易,张子福,等. 高家山生物群化石组合面貌及其特征[J]. 地层学杂志,2001,25(1):13-17. DOI:10.3969/j.issn.0253-4959.2001.01.003.

■蔡耀平, and 华洪. "陕西宁强埃迪卡拉纪晚期高家山生物群中黄铁矿化化石的成岩及风化过程." 古生物学报 47.2(2008):8.