Histology of the galeaspid dermoskeleton and endoskeleton, and the origin and early evolution of the vertebrate cranial endoskeleton

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	Histology of the galeaspid dermoskeleton and endoskeleton, and the origin and early evolution of the vertebrate cranial endoskeleton
	Wang, NZ; Donoghue, PCJ; Smith, MM; Sansom, IJ; wwangnz@hotmail.com; phil.donoghue@bristol.ac.uk; moya.smith@kcl.ac.uk; i.j.sansom@bham.ac.uk
刊名	J VERTEBR PALEONTOL
	2005
卷号	25 期号:4
关键词	Jawed Vertebrates Scales Mineralization Fish Cartilage Biostratigraphy Perichondrium Osteichthyes Phylogeny Agnathans
ISSN号	0272-4634
英文摘要	The histological composition of the galeaspid cephalothoracie skeleton has been much debated: here we attempt to resolve this through the analysis of well-preserved remains of galeaspids from Yunnan Province, and Tarim Basin. Xinjiang Uygur Autonomous Region, China. Our results indicate that the galeaspid dermoskeleton is dominantly composed from an acellular laminar bone in which the mineral is organised into cylindrical crystal bundles that are arranged into three orthogonal sets with associated extrinsic fiber spaces, a unique histology for which the term L gleaspedin is coined. This is permeated by a coarse vascular plexus that divides the dermoskeleton into upper and lower zones, and the upper zone into distinct tesserae, which, like the bounding vascular network, are polygonal in outline. The outer surface of the dermoskeleton is ornamented by a series of tubercles centered oil tesserae, the latter composed partly from galeaspedin, and partly from a capping layer of microspherulitic, acellular bone, similar to the limiting layer of bone of elasmoid scales. Neither dentine nor enameloid is present, nor do the tissue compositions or their arrangement indicate an odontogenic origin. The endoskeleton is composed of an outer zone of globular calcified cartilage in contact with the dermoskeleton through a poorly mineralized intermediate zone. The inner zone is finely laminated, resulting from progressive zones of calcification embracing the calcospherites in a direction away from the dermoskeleton. There is no persuasive histological evidence for the presence of appositional perichondral bone. As in osteostracans, the galeaspid endoskeleton is interpreted as all expanded neurocranium. However, the presence of a calcified cartilaginous neurocranium in galeaspids in the absence of a perichondral bone layer indicates that these two histogenic components have distinct evolutionary origins. The presence of perichondral bone is a synapomorphy of osteostracans and jawed vertebrates, while the presence Of a mineralized neurocranium unites galeaspids to this clade (possibly also including pituriaspids).
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公开日期	2013-11-27
内容类型	期刊论文
源URL	[http://119.78.100.205/handle/311034/5030]
专题	古脊椎动物与古人类研究所_图书馆1
通讯作者	wwangnz@hotmail.com; phil.donoghue@bristol.ac.uk; moya.smith@kcl.ac.uk; i.j.sansom@bham.ac.uk
推荐引用方式 GB/T 7714	Wang, NZ,Donoghue, PCJ,Smith, MM,et al. Histology of the galeaspid dermoskeleton and endoskeleton, and the origin and early evolution of the vertebrate cranial endoskeleton[J]. J VERTEBR PALEONTOL,2005,25(4).
APA	Wang, NZ.,Donoghue, PCJ.,Smith, MM.,Sansom, IJ.,wwangnz@hotmail.com.,...&i.j.sansom@bham.ac.uk.(2005).Histology of the galeaspid dermoskeleton and endoskeleton, and the origin and early evolution of the vertebrate cranial endoskeleton.J VERTEBR PALEONTOL,25(4).
MLA	Wang, NZ,et al."Histology of the galeaspid dermoskeleton and endoskeleton, and the origin and early evolution of the vertebrate cranial endoskeleton".J VERTEBR PALEONTOL 25.4(2005).