A reappraisal of the morphology and systematics of <i>Extuaspis megista</i>, a brachythoracid arthrodire from the Early Devonian of Yunnan, China

doi:10.1080/14772019.2025.2455751

IVPP-IR

	*A reappraisal of the morphology and systematics of Extuaspis megista, a brachythoracid arthrodire from the Early Devonian of Yunnan, China*
	Xue, Qinyuan 1,2; Wang, Junqing 1; Zhu, Min1,2 ; Zhu, You-an 1,2
	2025-12-31
发表期刊	JOURNAL OF SYSTEMATIC PALAEONTOLOGY
ISSN	1477-2019
卷号	23 期号:1 页码:16
通讯作者	Zhu, Min(zhumin@ivpp.ac.cn) ; Zhu, You-an(zhuyouan@ivpp.ac.cn)
摘要	Exutaspis megista Y.-H. Liu and Wang 1981, discovered in the Lower Devonian Jiucheng Formation of Yunnan Province, south-western China, has been under phylogenetic contention since it was first described. Initially placed within Phlyctaeniidae, it was later suggested to be a member of Brachythoraci. Here, we re-examine the morphology of Exutaspis in detail, including the visceral surface of the skull roof and the dorsal aspect of the neurocranium, using the holotype and an additional specimen. Our redescription shows that Exutaspis possesses characters commonly seen in brachythoracids, such as an unbifid posterior postorbital process, the presence of a lateral consolidated arch and a developed nuchal thickening. Further, its morphology aligns closely with that of buchanosteoids, a cosmopolitan group of brachythoracids, particularly in the outline of the preorbital plates and in the dorsal profile of the neurocranium. To further elucidate the phylogenetic position of Exutaspis, we composed an updated matrix that contains 174 characters and 86 taxa, incorporating brachythoracids and comprehensively sampling arthrodires. The maximum parsimony analysis and Bayesian inference both recovered Exutaspis within the monophyletic Buchanosteoidea as the sister group of Goodradigbeeon australianum. The increasing knowledge of the diversity in the basal array of brachythoracids and their characters, such as the visceral consolidated structures on their skull roofs, provides important insight into the rise of brachythoracids from small bottom-feeders to fast-swimming giants.
关键词	Placodermi Arthrodira Brachythoraci Buchanosteoidea phylogeny
DOI	10.1080/14772019.2025.2455751
关键词[WOS]	PLACODERM FISHES ; SOUTH CHINA ; EUBRACHYTHORACID ARTHRODIRES ; ASPINOTHORACID ARTHRODIRE ; WEE JASPER ; GOGO ; OHIO ; AUSTRALIA ; REDESCRIPTION ; ACTINOLEPIDA
收录类别	SCI
语种	英语
资助项目	National Natural Science Foundation of China ; [42272028]
项目资助者	National Natural Science Foundation of China
WOS研究方向	Evolutionary Biology ; Paleontology
WOS类目	Evolutionary Biology ; Paleontology
WOS记录号	WOS:001426709700001
出版者	TAYLOR & FRANCIS LTD
引用统计
文献类型	期刊论文
条目标识符	http://119.78.100.205/handle/311034/24373
专题	中国科学院古脊椎动物与古人类研究所
通讯作者	Zhu, Min; Zhu, You-an
作者单位	1.Chinese Acad Sci, Inst Vertebrate Paleontol & Paleoanthropol, CAS Key Lab Vertebrate Evolut & Human Origins, Beijing 100044, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100044, Peoples R China
推荐引用方式 GB/T 7714	Xue, Qinyuan,Wang, Junqing,Zhu, Min,et al. A reappraisal of the morphology and systematics of Extuaspis megista, a brachythoracid arthrodire from the Early Devonian of Yunnan, China[J]. JOURNAL OF SYSTEMATIC PALAEONTOLOGY,2025,23(1):16.
APA	Xue, Qinyuan,Wang, Junqing,Zhu, Min,&Zhu, You-an.(2025).A reappraisal of the morphology and systematics of Extuaspis megista, a brachythoracid arthrodire from the Early Devonian of Yunnan, China.JOURNAL OF SYSTEMATIC PALAEONTOLOGY,23(1),16.
MLA	Xue, Qinyuan,et al."A reappraisal of the morphology and systematics of Extuaspis megista, a brachythoracid arthrodire from the Early Devonian of Yunnan, China".JOURNAL OF SYSTEMATIC PALAEONTOLOGY 23.1(2025):16.