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Fish/Tetrapod Communities in the Upper Devonian

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Fish/Tetrapod Communities in the Upper Devonian Fish/tetrapod Communities Examensarbete vid Institutionen för geovetenskaper in the Upper Devonian ISSN 1650-6553 Nr 301 Maxime Delgehier Fish/tetrapod Communities Vertebrate communities including tetrapods and fishes are known from a in the Upper Devonian limited number of Late Devonian localities from several areas worldwide. These localities encompass a wide variety of environments, from true marine conditions of the near shore neritic province, to fluvial or lacustrine conditions. These localities form the foundation for a number of data matrices from which three different sets of cluster analyses were made. The first set practices a strait forward taxonomical framework using present/absent data on species and genus level to test similarity between the various localities. The second set of analyses builds on the Maxime Delgehier first one with the integration of artificial hierarchies to compensate taxonomical biases and instead infer relationship. The third also builds on the previous ones, but integrates morphological data as indicators of relationships between taxa. From this, a critical review was made for each method which comes to the conclusion that the first analysis and the first artificial level of the second analysis provide the distinctions between Frasnian and Frasnian/Famennian locality whereas the second artificial level of the second analysis and the third analysis need to be improved. Uppsala universitet, Institutionen för geovetenskaper Examensarbete D/E1/E2/E, Geologi/Hydrologi/Naturgeografi /Paleobiologi, 15/30/45 hpISSN 1650-6553 Nr 301 Tryckt hos Institutionen för geovetenskaper, Geotryckeriet, Uppsala universitet, Uppsala, 2014. Examensarbete vid Institutionen för geovetenskaper ISSN 1650-6553 Nr 301 Fish/tetrapod Communities in the Upper Devonian Maxime Delgehier Supervisor: Henning Blom Copyright Maxime Delgehier and the Department of the Earth Sciences Uppsala University Published at Department of Earth Sciences, Geotryckeriet Uppsala University, Uppsala, 2014 Abstract Vertebrate communities including tetrapods and fishes are known from a limited number of Late Devonian localities from several areas worldwide. These localities encompass a wide variety of environments, from true marine conditions of the near shore neritic province, to fluvial or lacustrine conditions. These localities form the foundation for a number of data matrices from which three different sets of cluster analyses were made. The first set practices a strait forward taxonomical framework using present/absent data on species and genus level to test similarity between the various localities. The second set of analyses builds on the first one with the integration of artificial hierarchies to compensate taxonomical biases and instead infer relationship. The third also builds on the previous ones, but integrates morphological data as indicators of relationships between taxa. From this, a critical review was made for each method which comes to the conclusion that the first analysis and the first artificial level of the second analysis provide the distinctions between Frasnian and Frasnian/Famennian locality whereas the second artificial level of the second analysis and the third analysis need to be improved. Keywords: Palaeobiogeography, vertebrates, Tetrapods, Frasnian, Famennian Populärvetenskaplig sammanfattning Samhällen som innehåller ryggradsdjur, vilken innefattar såväl fiskar som landryggradsdjur (så kallade tetrapoder), är kända från flera lokaler av sen devonsk ålder runt om i världen. Dessa representerar också flera olika miljöer, vilket gör dessa till en bra grund för vår förståelse över hur ekologin påverkade de tidigaste tetrapoderna. Sammansättningen av ryggradsdjur i dessa lokaler ligger till grund för en jämförande analys där tre olika klusteranalyser har använts. Den första analysen använder närvaro/frånvaro-data av traditionellt etablerade arter och släkten för att på så sätt etablera likheten mellan de olika faunorna. Den andra analysen använder samma grundmetod, men dör art och släkten har ersatts av artificiella hierarkier för att på så sätt kompensera för taxonomisk bias och samtidigt ta hänsyn till andra antaganden om släktskapsförhållanden. Den tredje analysen ersätter namn och hierarkier med morfologiska karaktärer för att på så sätt få en annan och taxonomiskt oberoende test av likheterna mellan faunorna hos de olika lokalerna. Dessa tre analyser kunde sedan jämföras, med resultatet och slutsatsen att traditionell taxonomisk jämförelse och till viss del även artificiella hierarkier, ger bättre och mer tolkningsvänliga resultat där studien visar på en tydlig uppdelning i tid mellan lokalerna, medan den tredje metoden bör utvecklas ytterligare. Vertebrate communities including tetrapods and fishes are known from Late Devonian localities from several areas worldwide. These localities encompass a wide variety of environments. Their understanding is a key to understand ecologic pressure on these first tetrapods. The vertebrate communities from these localities are the base of data matrices from which three different cluster analyses were made. The first analysis is on forward taxonomical framework using present/absent data on the species and genus to test similarity between the various localities. The second builds on the previous one with the integration of artificial hierarchies to compensate taxonomical biases and instead infer relationship. The third analysis also builds on the previous ones, but integrates morphological data as indicators of relationships between taxa. From this, a critical review was made for each method which comes to the conclusion that the first analysis and the first artificial level of the second analysis provide the distinctions between Frasnian and Frasnian/Famennian localities whereas the second artificial level of the second analysis and the third analysis need to be improved. Keywords: Palaeobiogeography, vertebrates, Tetrapods, Frasnian, Famennian Table of Contents 1. Introduction ..................................................................................................................... 1 2. Aim .................................................................................................................................. 2 3. Background ..................................................................................................................... 2 4. Methodology ................................................................................................................. 12 5. Results ........................................................................................................................... 15 5.1 First analysis .............................................................................................................. 15 5.1.1 Species level ....................................................................................................... 15 5.1.2 Genus level ......................................................................................................... 17 5.2 Second analysis .......................................................................................................... 21 5.2.1 First artificial level ............................................................................................. 21 5.2.2 Second artificial level ......................................................................................... 24 5.3 Third analysis ............................................................................................................ 27 6. Discussion ..................................................................................................................... 30 7. Conclusion ..................................................................................................................... 35 8. Acknowledgements ....................................................................................................... 36 9. References ..................................................................................................................... 36 Appendix .................................................................................................................................. 47 1. Introduction Vertebrate communities including tettrapods and fishes are known from Late Devonian localities from several areas worldwide. These localities, sometimes referred to as tetrapod localities, provide vertebrate assemblages constituted by major groups of vertebrates as agnathans, placoderms, acanthodians, chondrichthyans, actinopterygians and sarcopterygians. These sites show thus a wide diversity of vertebrates in various palaeoenviironmental conditions (see Background). The study of the vertebrate faunas is also essential to understaannd what could be the selection pressures on these first tetrapodss, which represent a key event in the vertebrate evolution. Our understanding of this event, which popularly known as the ‘fish-tetrapod transition’ has progressed greatly since the discovery of Ichthyostega in Greenland by Säve-Söderberggh in 1932 with recent discoveries. There are at present only a few Upper Devonian tetrapod localities known (Figure 1): three Frasnian localities (in Scotland, China and Latvia), one Frasnian-Famennian locality (Australia) and seven Famennnnian localities (in Greenland, USA, Belgium, Latvia and Russia). Today there are twelve tetrapod genera and fourteen species described and even more if includingg the yet undescribed taxa that have been found (Lebedev & Clack,
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