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DOI	10.1016/j.palaeo.2020.109848
	On the origin of hyolith helens
	Skovsted C.B.; Martí Mus M.; Zhang Z.; Pan B.; Li L.; Liu F.; Li G.; Zhang Z.
发表日期	2020
ISSN	0031-0182
卷号	555
英文摘要	Helens, the curved lateral spines inserted between the conch and operculum of some hyoliths, are a unique morphological adaptation characterizing the order Hyolithida. These structures are paired, movable and had a mechanical function, probably related to orienting the hyolith conch and lifting its aperture above the sea floor. We show that helens are intimately associated with the hyolith opercula and are structurally comparable to the rod like units that constitute the clavicles, internal wall-like structures of the hyolithid operculum that probably evolved to secure the operculum from lateral displacement in the conch aperture. In some early Cambrian hyolith taxa that lack helens, such as Paramicrocornus, new clavicle rods are added in the gap separating the clavicles from the cardinal processes, the same position where helens are inserted in later hyolithids. We also show that the size of incipient helens at the earliest ontogenetic stage matches the size of the clavicles in associated opercula. We propose that helens are modified clavicle rods that were detached from the operculum and developed into lateral spines through allometric growth during early ontogeny. Further, we suggest a four-step model for the evolution of hyolithid hyoliths from orthothecid ancestors: 1, Externally fitting operculum; 2, Stabilizing, radially arranged structures on the inside of the operculum; 3, Ligula and folded operculum; 4, Detachment of clavicle rods and origin of helens. © 2020 The Authors
英文关键词	Cambrian; Clavicles; Evolution; Hyolithida; Operculum; Orthothecida
语种	英语
scopus关键词	adaptation; biostratigraphy; Cambrian; fossil record; growth response; morphology; ontogeny; shellfish; Hyolithidae; Ligula
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/150405
作者单位	Department of Palaeobiology, Swedish Museum of Natural History, Box 50007, Stockholm, SE-104 05, Sweden; Shaanxi Key Laboratory of Early Life and Environments, State Key Laboratory of Continental Dynamics and Department of Geology, Northwest University, Xi'an, 710069, China; Área de Paleontología, Universidad de Extremadura, Avenida de Elvas s/n, Badajoz, 06006, Spain; Department of Biological Sciences, Macquarie University, North Ryde, Sydney, NSW 2109, Australia; State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, 210008, China
推荐引用方式 GB/T 7714	Skovsted C.B.,Martí Mus M.,Zhang Z.,et al. On the origin of hyolith helens[J],2020,555.
APA	Skovsted C.B..,Martí Mus M..,Zhang Z..,Pan B..,Li L..,...&Zhang Z..(2020).On the origin of hyolith helens.Palaeogeography, Palaeoclimatology, Palaeoecology,555.
MLA	Skovsted C.B.,et al."On the origin of hyolith helens".Palaeogeography, Palaeoclimatology, Palaeoecology 555(2020).