Functional morphology, coaptation and palaeoecology of Hollardops (Trilobita, Acastidae), with descriptions of new species and two new genera from the Devonian of Morocco

IF 1.2 4区 地球科学 Q2 GEOLOGY
Allart P. VAN VIERSEN, Gerald J. Kloc
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引用次数: 1

Abstract

A group of asteropygine trilobites with 10 thoracic segments from the lower Emsian to lowermost Eifelian of western Europe and northwest Africa is deemed monophyletic. Available names for this clade are Hollardops Morzadec, 1997, Philipsmithiana Lieberman & Kloc, 1997, Modellops Lieberman & Kloc, 1997 and Pennarbedops Bignon & Crônier, 2013, the first of which has priority. Well-preserved Hollardops specimens from southern Morocco have revealed previously undescribed details of the mineralised exoskeleton that are interpreted here as coaptative and sensory devices. It is proposed that Hollardops, like many other asteropygines, practised a dual mode of coaptation: fully locked enrolment was alternated with a retracted pygidium, allowing temporary influx of oxygenated seawater and excretion through slits between the pygidial lappets. This putative ‘breathing device’ enabled the trilobite to remain enrolled for a longer period of time while maintaining vital body functions. A poor understanding of the problematic type species of Hollardops, H. mesocristatus (Le Maître, 1952), has clouded actual diversity in Algeria and Morocco. Hollardops klugi sp. nov. is the oldest known member of the genus and extends its confirmed stratigraphic range into the lower Emsian. Two species, H. kyriarchos sp. nov. and H. multatuli sp. nov., are recorded from just above the base of the upper Emsian. Additionally, H. angustifrons sp. nov., H. luscus sp. nov. and the first well-preserved specimens of H. boudibensis Morzadec, 2001 are recorded from the upper Emsian. The types of H. hyfinkeli (Lieberman & Kloc, 1997) and H. burtandmimiae (Lieberman & Kloc, 1997) are refigured and original species concepts reiterated. Feruminops Haas, 1968, including its junior subjective synonym Morzadecops Bignon & Crônier, 2013, from the lower Emsian of Morocco and Türkiye, may comprise the sister group of Hollardops. Additionally, the enrolment strategies and systematics of several other members of Asteropyginae are discussed. Platykardiapyge gen. nov. (type species: Metacanthina maderensis Morzadec, 2001) is erected for a group of Pragian–early Emsian asteropygines from Morocco, Spain and Türkiye with a widely heart-shaped pygidium and comparatively many pygidial pleurae, among other features. Bignonops gen. nov. (type species: Kayserops tamnrhertus Chatterton et al., 2006) is erected for some species previously included in Gandlops Bignon & Crônier, 2013. Minicryphaeus suavius sp. nov. is described from the lower Emsian of Morocco. The identity and generic affinity of the oldest known asteropygine, Ganetops gdoumontensis (Asselberghs, 1930) from the Pridolian of Belgium, are discussed.
摩洛哥泥盆纪Hollardops(三叶虫,蝗科)的功能形态、适应和古生态学,并附新种和两个新属的描述
在西欧和非洲西北部,一群具有10个胸椎节的asteropygine三叶虫被认为是单系的。这个分支的可用名称有Hollardops Morzadec, 1997年,Philipsmithiana Lieberman & Kloc, 1997年,Modellops Lieberman & Kloc, 1997年和Pennarbedops Bignon & Crônier, 2013年,其中第一个具有优先权。来自摩洛哥南部保存完好的霍拉多普斯标本揭示了先前未描述的矿化外骨骼细节,这里将其解释为适应和感觉装置。有人提出,Hollardops和许多其他asteropygines一样,采用了双重适应模式:完全锁定的入学与收缩的pygital交替进行,允许含氧海水暂时流入,并通过pygital lappets之间的缝隙排泄。这种假定的“呼吸装置”使三叶虫能够在维持重要身体功能的同时保持更长的时间。由于对有问题的Hollardops模式物种H. mesocristatus (Le matree, 1952)了解不足,阿尔及利亚和摩洛哥的实际多样性受到了影响。Hollardops klugi sp. 11 .是该属已知最古老的成员,并将其确定的地层范围扩展到下埃姆西亚。两个种,H. kyriarchos sp. nov和H. multatuli sp. nov,在上Emsian的底部上方被记录。此外,在上埃姆西亚地区还发现了11月的angustifrons .、11月的luscus .和2001年保存完好的Morzadec . boudibensis标本。H. hyfinkeli (Lieberman & Kloc, 1997)和H. burtandmimiae (Lieberman & Kloc, 1997)的类型被重新定义,并重申了原始物种概念。Feruminops Haas, 1968,包括其低级主观同义词Morzadecops Bignon和Crônier, 2013,来自摩洛哥和t rkiye的下Emsian,可能构成Hollardops的姐妹群。此外,本文还讨论了其他几个星尾科成员的招生策略和分类学。Platykardiapyge gen. 11 .(模式种:Metacanthina maderensis Morzadec, 2001)是一群来自摩洛哥、西班牙和土耳其的Pragian-early Emsian asteropygines,具有宽阔的心形胸肌和相对较多的胸肌,以及其他特征。Bignonops gen. 11 .(模式种:Kayserops tamnrhertus Chatterton et al., 2006)是在Gandlops Bignon & Crônier, 2013中先前收录的一些物种上建立的。小鳞鱼(Minicryphaeus suavius sp. 11 .)产于摩洛哥的Emsian河下游。本文讨论了来自比利时普里多利安的已知最古老的asteropyine, Ganetops gdoumontensis (Asselberghs, 1930)的身份和一般亲和力。
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来源期刊
Geologica Belgica
Geologica Belgica 地学-地质学
CiteScore
4.70
自引率
27.80%
发文量
8
审稿时长
>12 weeks
期刊介绍: Geologica Belgica is a Belgian journal that welcomes papers concerning all aspects of the earth sciences, with a particular emphasis on the regional geology of Belgium, North West Europe and central Africa. Papers not dedicated to the geology of Belgium, North West Europe and central Africa are only accepted when one of the authors is linked to a Belgian University or Institution. Thematic issues are highly appreciated. In this case, guest editors take in charge the selection of the manuscripts and the subject of the papers can be enlarged. The journal is in open access. Submitted manuscripts should be concise, presenting material not previously published. The journal also encourages the publication of papers from Belgian junior authors. Short letters are accepted. Papers written in English are preferred. Each mansucript will be reviewed by at least two reviewers.
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