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| synonyms = }} ''Mongolitubulus'' is a form genus encapsulating a range of ornamented conical small shelly fossils of the Cambrian period. It is potentially synonymous with ''Rushtonites'', ''Tubuterium'' and certain species of ''Rhombocorniculum'', and owing to the similarity of the genera,〔〔 〕 they are all dealt with herein. Organisms that bore ''Mongolitubulus''-like projections include trilobites, bradoriid arthropods and hallucigeniid lobopodians. == Morphology == The fossils consist of round, slender, pointed, spines with a slight curvature,〔 and are covered with short rhomboid processes that spiral around the spine surface, forming a regular mosaic with a 60° angle of intersection.〔 Spines very from sub-millimetric up to two centimetres in length, but do not show any growth lines, suggesting that they were moulted and replaced.〔 Species are defined on the basis of the ornamentation, which may of course be convergent. Spines of ''Rhombocorniculum cancellatum'' have a similar surface ornamentation and are also curved, sometimes in two dimensions to form a 'screw'; they had an inner and outer organic layer that surrounded a layer of pillar-like apatite crystals; these enclosed a honeycomb-like structure of narrow edge-parallel chambers. This genus is a useful biostratigraphic marker of the Lower Cambrian. The rhomboid ornament uniformly covers all the spine, with the exception (in some cases) of the smooth-surfaced tip. ''Mongolitubulus'' has a comparable structure; phosphatic fossils show that there was a smooth outer layer about 2–3.5 µm thick, a 10–15 µm-thick inner layer comprising axis-parallel fibres that are each ~1 µm wide, and a large cavity in the centre of the spine.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mongolitubulus」の詳細全文を読む スポンサード リンク
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