{"title":"The Middle Ordovician conodonts Eoplacognathus robustus Bergström and E. lindstroemi (Hamar): Taxonomy and apparatus reconstruction","authors":"S. Heredia, Ana Mestre","doi":"10.5027/ANDGEOV46N3-3189","DOIUrl":null,"url":null,"abstract":"The Middle-Upper Ordovician Ponón Trehué Formation cropping out in the San Rafael Block (Argentina) provided a large collection of conodonts which have been published years ago. The species Eoplacognathus robustus and Eoplacognathus lindstroemi recovered from these strata have been revised and restudied. In this contribution we describe M and S elements that were assigned previously to Baltoniodus prevariabilis and Baltoniodus variabilis as belonging to the E. robustus and E. lindstroemi apparatuses. The morphological characters of the P, S and M elements as part of these late Eoplacognathus apparatus were analyzed and support the proposal of a new reconstruction of it. We have compared this apparatus with the Baltoniodus apparatus and suggest the inclusion of the Eoplacognathus genus into the Balognathidae family. The new architecture of the Eoplacognathus apparatus is comparable to the genus Lenodus. This analysis improves the knowledge about this index conodont group allowing a new insight on the evolution, phylogeny and paleobiology of this linage.","PeriodicalId":49108,"journal":{"name":"Andean Geology","volume":null,"pages":null},"PeriodicalIF":0.9000,"publicationDate":"2019-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Andean Geology","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.5027/ANDGEOV46N3-3189","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOLOGY","Score":null,"Total":0}
引用次数: 2
Abstract
The Middle-Upper Ordovician Ponón Trehué Formation cropping out in the San Rafael Block (Argentina) provided a large collection of conodonts which have been published years ago. The species Eoplacognathus robustus and Eoplacognathus lindstroemi recovered from these strata have been revised and restudied. In this contribution we describe M and S elements that were assigned previously to Baltoniodus prevariabilis and Baltoniodus variabilis as belonging to the E. robustus and E. lindstroemi apparatuses. The morphological characters of the P, S and M elements as part of these late Eoplacognathus apparatus were analyzed and support the proposal of a new reconstruction of it. We have compared this apparatus with the Baltoniodus apparatus and suggest the inclusion of the Eoplacognathus genus into the Balognathidae family. The new architecture of the Eoplacognathus apparatus is comparable to the genus Lenodus. This analysis improves the knowledge about this index conodont group allowing a new insight on the evolution, phylogeny and paleobiology of this linage.
San Rafael地块（阿根廷）中上奥陶世Ponón Trehué组提供了多年前出版的大量牙形石。对从这些地层中恢复的Eoplaconagnathus robustus和Eoplacanagnathus lindstroemi物种进行了修订和重新研究。在这篇文章中，我们描述了以前分配给前变巴尔托诺杜和可变巴尔托诺杜属的M和S元素，它们属于粗壮E.robustus和林氏E.lindstroemi装置。分析了作为这些晚期始氏器一部分的P、S和M元素的形态特征，并支持对其进行新的重建的建议。我们将该器与Baltoniodus器进行了比较，并建议将始氏器属纳入Balognatidae科。Eoplancognathus装置的新结构可与Lenodus属相媲美。这一分析提高了对该指数牙形石群的了解，从而对该谱系的进化、系统发育和古生物学有了新的认识。
期刊介绍：
This journal publishes original and review articles on geology and related sciences, in Spanish or English, in three issues a year (January, May and September). Articles or notes on major topics of broad interest in Earth Sciences dealing with the geology of South and Central America and Antarctica, and particularly of the Andes, are welcomed.
The journal is interested in publishing thematic sets of papers and accepts articles dealing with systematic Paleontology only if their main focus is the chronostratigraphical, paleoecological and/or paleogeographical importance of the taxa described therein.
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