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Phylogeny of the Branchiosauridae, with particular emphasis on the position of Leptorophus and Leptorophus rai- schi n. sp. 

Phylogeny of the Branchiosauridae, with particular emphasis on the position of Leptorophus and Leptorophus rai- schi n. sp. 

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A new branchiosaurid temnospondyl is described from an Early Permian lake deposit at Obermoschel, Germany. The new taxon has a triangular skull outline and shares derived features with Leptorophus, a genus formerly only known from the Permian of Saxony. The new species L. raischi is characterized by the following autapomorphies: (1) Interorbital di...

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... L. raischi in the analysis of SChoCh & Milner (2008) resulted in the same branchiosau- rid topology as in the original analysis, now with the two Leptorophus species forming sister taxa (see Appendix). The analysis was run in TNT (Traditional Search option, 45 characters, 20 taxa) and gave 8 equally parsimonious trees (91 steps, see consensus in Fig. 5). In particular, the Apateon and Melaner- peton clades are well supported, although their bases are not fully resolved. In the Melanerpeton clade, M. eisfeldi, M. sembachense, and M. humbergense form a polytomy with Leptorophus and Schoenfelderpe- ton. This indicates that Melanerpeton may form a grade. The Leptorophus-Schoenfelderpeton ...

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... Essentially, only the two areas with the best documentation of aquatic tetrapods can be compared: The Saar-Nahe Basin plus adjacent Sprendlinger Horst and Wetterau Basin and the Thüringer Wald Basin plus adjacent basins in Saxony. Mostly documented are closely related forms (Werneburg 1996;Schoch 2014). Their comparison reveals that only one stratigraphic level exists where two species occur in both regions: The discosauriscid Discosauriscus pulcherrimus occurs on the one hand in N4/N5 of the Saar-Nahe Basin (Winnweiler Abb. ...
... Vergleichen lassen sich im Wesentlichen nur die beiden Gebiete mit der besten Dokumentation aquatischer Tetrapoden: Das Saar-Nahe-Becken plus angrenzender Sprendlinger Horst und Wetterau-Becken und das Thüringer-Wald-Becken plus angrenzende sächsische Becken. Zumeist belegt sind nahe verwandte Formen (Werneburg 1996;Schoch 2014). Ihr Vergleich ergibt, dass nur ein stratigraphisches Niveau existiert, in dem zwei Arten in beiden Regionen auftreten: Der Discosauriscide Discosauriscus pulcherrimus kommt einerseits in N4/N5 des Saar-Nahe-Beckens (Winnweiler-Bank und Sobernheim-Bank) und andererseits in der oberen Oberen Oberhof-Formation des Thüringer Waldes (Oberer Protriton-Horizont) vor. ...
... 5: B7) vor. Neben den beiden gleichen Formen im SN und TW sind zahlreiche nahe verwandte Formen belegt (Werneburg 1996, Schoch 2014. Um auch diese biostratigraphisch zu nutzen, werden vor allem Vergesellschaftungs-Zonen (Assemblage-Zonen) verwendet (Tab. ...
Article
Time indications for the correlation and calibration of the Rotliegend of Germany are integrated and presented in a new way. The correlations are based on the visual balance of bio- and ecostratigraphic indications and radio-isotopic age determinations (RIA), whereby confidence limits, equivalent to those of the RIA, are applied also for other time indications (conchostracans, aquatic tetrapods, fishes, insects, macroflora, and ecostratigraphic indications). In contrast, terrestrial tetrapods and their tracks, chemo- and sequence stratigraphy, and magnetic susceptibility did not contribute to correlations in the Rotliegend in Central Europe. The Illawarra Reversal of the Earth’ magnetic field (≈ 265 Ma) is fundamental for correlation and calibration. In general, however, the Regional Stratigraphic Scale is calibrated using U-Pb CA-ID-TIMS-RIA on zircon, Ar-Ar- and Rb-Sr-based RIA and, in addition, in the Early and Late Rotliegend using orbital-climatically controlled eccentricity cycles (≈ 100 ka, ≈ 400 ka). The boundary ages of the subgroups and of most formations are rounded to 0.5 Ma to avoid overinterpretation. Because of some inconsistent time indications alternative interpretations are also offered. The hitherto differing ages for the global Carboniferous-Permian boundary are the result of different dating methods: The ≈ 296 Ma in the Stratigraphic Tables of Germany 2002 and 2016 A (STG 2002; STG 2016 A) is an integrative age based on RIA from Central Europe, whereas the ≈ 299 Ma in the Global Stratigraphic Scales 2004 ff. and the STG 2016 B is based on a CA-ID-TIMS RIA on zircon from the southern Ural area. The age of ≈ 299 Ma is plausible from the perspective of the current Rotliegend RIA because the Rb-Sr age of 290.7 ± 0.9 Ma for the Donnersberg Formation (Lippolt & Hess 1989) has been replaced by the age of 294.5 ± 2.2 Ma, as recalculated in the present work. The updated time scale developed here will be integrated in the Stratigraphische Tabelle von Deutschland Kompakt 2022 (STDK 2022) and into the Stratigraphic Table of Germany Compact 2022 (STGC 2022). The age of the base of the Rotliegend in the Saar-Nahe Basin (SN, base Remigiusberg Formation and Glan Subgroup) is ≈ 299 Ma (U-Pb CA-ID-TIMS, zircon) resp. ≈ 300 Ma (Ar-Ar); the balanced compromise age of both is ≈ 299.5 Ma. In the Thüringer Wald (TW), the Rotliegend begins with the Ilmenau Formation (Subkommission Perm-Trias 2011) at ≈ 299.5 Ma (U-Pb CA-ID-TIMS). On the Flechtingen Block, at the southern margin of the Central European Basin, the oldest volcanic rock of the Altmark Subgroup is dated at 302 ± 3 Ma (U-Pb SHRIMP data). Accordingly, the Rotliegend in the STG 2002 and STG 2016 A starts at ≈ 302 Ma. However, the mean age calculated in the present work for the SHRIMP data of Breitkreuz & Kennedy (1999) is 298.6 ± 1.9 Ma, so that the base of the Altmark volcanic succession is here re-dated as ≈ 300.5 Ma. Thus, the ages of the present lithostratigraphic lower limits of the Rotliegend in northern Germany (CEB), in the TW and in the SN are, with ≈ 300.5 Ma to ≈ 299.5 Ma, only weakly diachronous if the nominal (face) values, which are both in the latest Carboniferous, are compared without the confidence intervals. For the first time, the Rotliegend of Germany is geochronologically subdivided into Early (≈ 300.5–295.5/294 Ma), Middle (≈ 295.5/294–266 Ma) and Late Rotliegend (≈ 266–257.5 Ma). The very long lasting Middle Rotliegend includes numerous and also extremely long stratigraphic gaps as a result of the amalgamation and the associated immense uplift of Pangaea in the area of Central and Western Europe. A very large stratigraphic gap in the Central European Basin (CEB) of ≈ 15 Ma(≈ 281–266 Ma, here called the Pangaea Gap) is supported by conchostracans, the Illawarra Reversal and the different palaeomagnetic properties of the sediments below and above the gap, which are discussed here for the first time. The Middle Rotliegend (duration of ≈ 29.5/28 Ma) is approx. twice as long as the Early (≈ 5.5/7 Ma) and Late Rotliegend (≈ 8.5 Ma) combined. The latter, however, contain the thickest successions in the Saar-Nahe Basin and the Central European Basin, respectively, which are free of gaps in the basin centre, with ‘gaps’ being defined in this context as time spans of ≤ 100 ka and ≤ 400 ka, respectively. In the CEB, the Elbe Subgroup is cyclostratigraphically calibrated to 5.6 Ma. A gapless area in the Saar-Nahe Basin is the Glan Subgroup, which covers only 4 Ma and 3 Ma, respectively; correspondingly, its subunits G1 to G10 (Glan 1 to Glan 10), introduced here, last on average 0.4 Ma and 0.3 Ma, respectively. This results in a maximum accumulation rate of 870 Bubnoff (Bub, m/Ma, mm/ka) and of 1150 Bub, respectively, which can be explained by a maximum of tectonic activity along the Hunsrück Southern Border Fault. For the lower Nahe Subgroup (N1 to N5, Nahe 1 to Nahe 5), the maximum accumulation rates are ≈ 450–200 Bub and for the upper Nahe Subgroup (N6–N8), at an estimated duration of 12 Ma ≈ 125 Bub and ≈ 50 Bub at a duration of 30 Ma, respectively. In the Central European Basin the maximum accumulation rates are much lower compared to the Glan Subgroup, with 200 Bub in the Elbe Subgroup and ≈ 360 Bub in the Havel Subgroup (Fig. 27), although here the subsidence rate may have been higher than the accumulation rate, as the basin was ≈ 130 m below sea level at the end of Folge ro4 (Top of the Hannover Formation; this paper). We recommend (1) Bubnoff (Bub) as unit of measure of the accumulation rate and (2) the stratigraphic terminology of the Subkommission Perm-Trias (2011) and the STG 2016 A. We here propose that numerous tuffs of the Glan Subgroup could originate from volcanic centres of the TW, whereas so far only source areas south of the SN were discussed: On the one hand, the tuff-rich time of the upper Jeckenbach Subformation – Odernheim Formation (= Glan units 7 and 8 = G7/G8) seems to correlate with the volcanogenic Oberhof time in the TW and, on the other hand, the tuff-poor time of the Wahnwegen Formation – middle Jeckenbach Subformation (G2/G6) seems to correlate with the upper Ilmenau, Manebach, Goldlauter and lowest Oberhof formations, which are devoid of volcanic rocks in the TW. Should causality exist here, an additional and also precise criterion for correlation would be established. At present there are two variants: On the one hand, volcanism in the Oberhof Formation, according to RIA (U-Pb CA-ID-TIMS on zircon), begins ≈ 1.8 Ma earlier and ends ≈ 0.8 Ma earlier than in the Donnersberg Formation (Ar-Ar, Rb-Sr recalculated). On the other hand, the conchostracan Lioestheria pseudotenella in the TW, if considered equivalent to L. cf. pseudotenella in the SN, the ecostratigraphic and lithofacial indications and the aquatic tetrapod D. pulcherrimus, point to for a similar age of these magmatites. The Sobernheim Lens (SN, Nahe units N4/N5) with its fossils so important for correlations is here assigned to the Jakobsweiler Member (N4, upper Donnersberg Formation), to the Quartzite-Conglomerate (N5, in literature often Wadern) and to the lowermost Standenbühl Formation (N4/N5). The youngest time indication Co13, the conchostracan Lioestheria arroyoensis sp. nov. correlates the upper Standenbühl Formation (N8, Martens 2020, where N8 may be extremely long), roughly with the Arroyo Formation in Texas (≈ early Kungurian). The here favoured age of the Tambach Formation of ≈ 294–292 Ma is significantly higher than the ≈ 286–283 Ma of STG 2016 A and the ≈ 284–281 Ma of STG 2016 B. It is based on RIA R25 (Table 9; lower Rotterode Formation, 295.8 ± 0.4 Ma; Lützner et al. 2021), which is the youngest CA-ID-TIMS RIA in the TW, and the duration estimate of the Rotterode – Tambach gap. In the SN, the youngest RIA R29 (Rb/Sr) is from the Donnersberg Formation (294.5 ± 2.2 Ma, this paper). From here on until ≈ 265 Ma (Illawarra Reversal), the numerical ages of all Rotliegend units and their connection to the Global Stratigraphic Scale (GSS) are uncertain and therefore correlations between Central Europe and the global reference section in the southern Ural area, partly biostratigraphically via North America, vary greatly. In this contect, the „series“ Wolfcampian and Leonardian (standard Permian units of the USA) played an important role. However, these lithostratigraphic units are at least unsuitabel as a reference system for large parts of North America, because they represent very variable time spans from region to region, similar with the “Lower Rotliegend” (“Autun”) and “Upper Rotliegend” (“Saxon”) of Central and Western Europe and therefore their assignement to the GSS is also very variable. This is due, among other things, to the fact that the Wolfcampian is often still understood as “lower Lower Permian”, although considerable parts of it are now placed in the Carboniferous, because as a result of the introduction of the Global Stratigraphic Section and Point (GSSP) for the base of the Asselian Stage (= global base of the Permian in the southern Ural area), the conventional regional Carboniferous-Permian boundaries shifted to an higher stratigraphic level and thus to a younger age in the USA, China and the Donbass (Fig. 14). If the 57 sedimentary cycles in the Ottweiler and Glan subgroups (Königer & Stollhofen 2001: mean duration 245 ka each) in the SN are orbital-climatically induced, these cycles can only be 100 ka cycles (short eccentricity). This is also supported by the 6 cycles in units G7 and G8 that have been described in detail in the literature, which are consistent with the duration of the Glan Subgroup of 3 Ma and (preferred) 4 Ma, respectively. The total duration to be expected from 57 cycles à ≈ 100 ka is ≈ 5.7 Ma in contrast to the duration determined here according to RIA of ≤ 8 Ma. One reason for the difference could be that in the Ottweiler und Glan subgroups there are cycles that have not been recorded so far. The time span of ≤ 8 Ma is also an outcome of the new estimate for the duration of the Cantabrian Gap (early Stephanian) in the Saar-Nahe Basin of ≈ 3.6 Ma that is clearly longer than proposed in the STG 2002 and STG 2016.
Article
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The origin of extant amphibians has been studied using several sources of data and methods, including phylogenetic analyses of morphological data, molecular dating, stratigraphic data, and integration of ossification sequence data, but a consensus about their affnities with other Paleozoic tetrapods has failed to emerge. We have compiled five datasets to assess the relative support for six competing hypotheses about the origin of extant amphibians: a monophyletic origin among temnospondyls, a monophyletic origin among lepospondyls, a diphyletic origin among both temnospondyls and lepospondyls, a diphyletic origin among temnospondyls alone, and two variants of a triphyletic origin, in which anurans and urodeles come from different temnospondyl taxa while caecilians come from lepospondyls and are either closer to anurans and urodeles or to amniotes. Our datasets comprise ossification sequences of up to 107 terminal taxa and up to eight cranial bones, and up to 65 terminal taxa and up to seven appendicular bones, respectively. Among extinct taxa, only two or three temnospondyl can be analyzed simultaneously for cranial data, but this is not an insuperable problem because each of the six tested hypotheses implies a different position of temnospondyls and caecilians relative to other sampled taxa. For appendicular data, more extinct taxa can be analyzed, including some lepospondyls and the finned tetrapodomorph Eusthenopteron, in addition to temnospondyls. The data are analyzed through maximum likelihood, and the AICc (corrected Akaike Information Criterion) weights of the six hypotheses allow us to assess their relative support. By an unexpectedly large margin, our analyses of the cranial data support a monophyletic origin among lepospondyls; a monophyletic origin among temnospondyls, the current near-consensus, is a distant second. All other hypotheses are exceedingly unlikely according to our data. Surprisingly, analysis of the appendicular data supports triphyly of extant amphibians within a clade that unites lepospondyls and temnospondyls, contrary to all phylogenies based on molecular data and recent trees based on paleontological data, but this conclusion is not very robust.
Article
Full-text available
The origin of extant amphibians has been studied using several sources of data and methods, including phylogenetic analyses of morphological data, molecular dating, stratigraphic data, and integration of ossification sequence data, but a consensus about their affinities with other Paleozoic tetrapods has failed to emerge. We have compiled five datasets to assess the relative support for six competing hypotheses about the origin of extant amphibians: a monophyletic origin among temnospondyls, a monophyletic origin among lepospondyls, a diphyletic origin among both temnospondyls and lepospondyls, a diphyletic origin among temnospondyls alone, and two variants of a triphyletic origin, in which anurans and urodeles come from different temnospondyl taxa while caecilians come from lepospondyls and are either closer to anurans and urodeles or to amniotes. Our datasets comprise ossification sequences of up to 107 terminal taxa and up to eight cranial bones, and up to 65 terminal taxa and up to seven appendicular bones, respectively. Among extinct taxa, only two or three temnospondyl can be analyzed simultaneously for cranial data, but this is not an insuperable problem because each of the six tested hypotheses implies a different position of temnospondyls and caecilians relative to other sampled taxa. For appendicular data, more extinct taxa can be analyzed, including some lepospondyls and the finned tetrapodomorph Eusthenopteron, in addition to temnospondyls. The data are analyzed through maximum likelihood, and the AICc (corrected Akaike Information Criterion) weights of the six hypotheses allow us to assess their relative support. By an unexpectedly large margin, our analyses of the cranial data support a monophyletic origin among lepospondyls; a monophyletic origin among temnospondyls, the current near-consensus, is a distant second. All other hypotheses are exceedingly unlikely according to our data. Surprisingly, analysis of the appendicular data supports triphyly of extant amphibians within a clade that unites lepospondyls and temnospondyls, contrary to all phylogenies based on molecular data and recent trees based on paleontological data, but this conclusion is not very robust.
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The origin of extant amphibians has been studied using several sources of data and methods, including phylogenetic analyses of morphological data, molecular dating, stratigraphic data, and integration of ossification sequence data, but a consensus about their affinities with Paleozoic tetrapods has failed to emerge. We have compiled five datasets to assess the relative support for six competing hypotheses about the origin of extant amphibians: a monophyletic origin among temnospondyls, a monophyletic origin among lepospondyls, a di-phyletic origin among both temnospondyls and lepospondyls, a diphyletic origin among temnospondyls alone, and two variants of a triphyletic origin, in which anurans and urodeles come from different temnospondyl taxa while caecilians come from lepospondyls and are either closer to anurans and urodeles or to amniotes. Our datasets comprise ossification sequences of up to 107 terminal taxa and up to eight cranial bones, and up to 65 terminal taxa and up to seven appendicular bones, respectively. Among extinct taxa, only two or three temnospondyl can be analyzed simultaneously for cranial data, but this is not an insuperable problem because each of the six tested hypotheses implies a different position of temnospondyls and caecilians relative to other sampled taxa. For appendicular data, more extinct taxa can be analyzed, including some lepospondyls and the finned tetrapodomorph Eusthenopteron, in addition to temnospondyls. The data are analyzed through maximum likelihood, and the AICc (corrected Akaike Information Criterion) weights of the six hypotheses allow us to assess their relative support. By an unexpectedly large margin, our analyses of the cranial data support a monophyletic origin among lepospondyls; a monophyletic origin among temnospondyls, the current near-consensus, is a distant second. All other hypotheses are exceedingly unlikely according to our data. Surprisingly, analysis of the appendicular data supports triphyly of extant amphibians within a clade that unites lepospondyls and temno-spondyls, contrary to all phylogenies based on molecular data and recent trees based on paleontological data, but this conclusion is not very robust.
Article
Nanobamus macrorhinus Schoch and Milner, 2014 is a small amphibamiform temnospondyl from the early Permian Arroyo Formation of Texas. It is most readily characterized by an elongate and partially subdivided naris. This condition is superficially reminiscent of that seen in the coeval trematopids, the group to which N. macrorhinus was originally referred to under an interpretation of the holotype as a larval form. This was discounted by later workers, but the amphibamiform affinities of the specimen were not formalized until recently. The specimen has never been described in the context of its amphibamiform affinities and remains poorly characterized, never having been sampled in a phylogenetic analysis. Here we present a complete, updated osteological description of N. macrorhinus , including an improved characterization of its unique mosaic of plesiomorphic and apomorphic features and clarification of the taxon's autapomorphies. Our analysis of the taxon's phylogenetic position within Amphibamiformes shows that N. macrorhinus was recovered as diverging after basal amphibamiforms, e.g., the micropholids, and before derived amphibamiforms, e.g., the amphibamids. This is supported by the unique mixture of retained plesiomorphies, e.g., nonforeshortened postparietals and an oval choana, and apomorphies, e.g., a narrow interorbital region and slender palatal rami of the pterygoid. These results reflect the complexity of terrestrial amphibamiform diversity and provide further insight into the evolutionary history of the lissamphibian stem in terrestrial environments.