Revised Description of the Early Permian Recumbirostran “Microsaur” Nannaroter mckinziei Based on New Fossil Material and Computed Tomographic Data

MacDougall, Mark J.; Seeger, Robert C.; Gee, Bryan M.; Ponstein, Jasper; Jansen, Maren; Scott, Diane; Bevitt, Joseph J.; Reisz, Robert R.; Fröbisch, Jörg

doi:10.3389/fevo.2021.739316

Cited by 6 publications

(5 citation statements)

References 22 publications

(57 reference statements)

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“…The homodont dentition of small conical teeth is similar to that of other recumbirostrans such as the early-diverging Steenerpeton 34 , Diabloroter 29 and Odonterpeton 23 , though it is quite distinct from the multicuspid teeth in brachystelechids such as Batropetes (Glienke, 2015) and Carrolla 32 , 35 , and the bulbous dentition of Euryodus 33 . The tooth bases also exhibit a loosely infolded dentine, similar to that in other early reptiles with shallowly implanted teeth 36 and other recumbirostrans 24 .…”

Section: Descriptionsupporting

confidence: 60%

“…The new specimen was coded into the character-taxon matrix of Mann et al 23 , the most current matrix available for investigating recumbirostran phylogeny. The matrix was further updated with the addition of Tambaroter carrolli , another recrumbirostran from the Tambach Formation, and updated character codings for Nannaroter mckinziei were incorporated based on MacDougall et al 24 . Tambaroter was coded using the holotype, and only known specimen, MNG 14708.…”

Section: Methodsmentioning

confidence: 99%

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A new recumbirostran ‘microsaur’ from the lower Permian Bromacker locality, Thuringia, Germany, and its fossorial adaptations

MacDougall,

Jannel,

Henrici

et al. 2024

Sci Rep

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Several recumbirostran ‘microsaurs’ are known from early Permian sites across Germany, including the Tambach Formation in Thuringia, central Germany. The only ‘microsaur’ thus far described from the Tambach Formation was the ostodolepid recumbirostran Tambaroter carrolli. However, there is also the documented presence of an undescribed recumbirostran ‘microsaur’ at the well-known Bromacker locality. The Bromacker locality is highly recognized and best known for its very diverse and extremely well-preserved terrestrial tetrapod assemblage combined with the co-occurrence of an exceptional vertebrate ichnofossil record. Here we describe a second new recumbirostran taxon from the Tambach Formation, which is also the first from the Bromacker locality itself. Phylogenetic analysis indicates that the new taxon, Bromerpeton subcolossus gen. et sp. nov., is a brachystelechid recumbirostran, a group also known elsewhere in Germany. The following features differentiate Bromerpeton from the other members of the clade: the presence of 13 maxillary teeth, narrow postorbitals that do not substantially contribute to the postorbital region of the skull, the frontal does not contribute to the orbital margin, and the presence of five manual digits. This new recumbirostran ‘microsaur’ further adds to the unique ecosystem that is preserved at the Bromacker locality, granting us a better understanding of what was living underfoot the larger more well-known animals at the locality. Likewise, it expands our understanding of the evolution of recumbirostran ‘microsaurs’, especially with regards to digit and limb reduction within the clade.

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Section: Descriptionsupporting

confidence: 60%

Section: Methodsmentioning

confidence: 99%

A new recumbirostran ‘microsaur’ from the lower Permian Bromacker locality, Thuringia, Germany, and its fossorial adaptations

MacDougall,

Jannel,

Henrici

et al. 2024

Sci Rep

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“…The neurocranium remains a poorly sampled region, in large part because this is a historically difficult area to access and thus to code. It is hoped that additional tomographic work in temnospondyls (e.g., Robinson et al, 2005; Čerňanský et al, 2016; Arbez et al, 2017, 2022; Gee et al, 2019a; Gee, 2020a; Marsicano et al, 2021) will produce further clarity in the way that it has for ‘microsaurian’ lepospondyls (Maddin et al, 2011; Huttenlocker et al, 2013; Pardo et al, 2015; Szostakiwskyj et al, 2015; Pardo and Anderson, 2016; Gee et al, 2019b, 2020; MacDougall et al, 2021). There are also avenues for expanding certain characters that only capture generalized trends.…”

Section: Discussionmentioning

confidence: 99%

The disadvantage of derivation: conserved systematic flaws in primary data have repeatedly biased the phylogenetic inference of Temnospondyli (Tetrapoda, Amphibia)

Gee

2022

Preprint

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Phylogenetic analyses and their resultant tree topologies underlie paleobiological studies. Regardless of the type of study, the relationships of focal taxa are foundational, whether implemented in a qualitative or a quantitative framework. This reliance places a premium on the continued refinement of both phylogenetic methods and inference. Temnospondyls are a diverse clade of non-amniote ('amphibian') tetrapods whose phylogenetic relationships have been extensively explored due to their speciose nature, widespread occurrence in Paleozoic and Mesozoic paleoenvironments, and putative relationship to extant amphibians. Despite being studied by a diversity of workers, there is only one dataset that is widely employed to test the broad-scale relationships of Temnospondyli, that of Schoch (2013). This dataset has been reused in several high-profile studies testing the question of lissamphibian origins, and the original resultant topology has been widely adopted by taxonomic specialists and non-specialists alike. However, close examination of this matrix reveals discernible patterns of problematic codes related to non-homology, dependency, and unsubstantiated data (e.g., codes for postcranial characters for taxa with no known postcrania). These patterns, in conjunction with their prevalence, warrant a thorough survey of the entire matrix and subsequent reanalysis of its various forms to test whether previously published findings regarding the relationships of temnospondyls and the origins of lissamphibians are substantiated. A thorough reassessment of this matrix and several of its high-profile derivates revealed that the phylogeny of temnospondyls is more poorly known than depicted by the literature and that certain hypotheses of lissamphibian origins within Temnospondyli lack phylogenetic support.

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“…This precludes the need for physical dissection and/or preparation of specimens, which is relevant when describing structures from rare or fragile material ( e.g. , Metscher, 2009 ; Haszprunar et al, 2011 ; Deans et al, 2012 ; Beutel et al, 2019 ; Willsch et al, 2020 ; MacDougall et al, 2021 ; Stillwell et al, 2020 ). In palaeontology, 3D data has been used widely in the visualisation of fossils preserved in amber ( Lak et al, 2008 ; Perrichot et al, 2008 ; Riedel et al, 2012 ; Xing et al, 2016a ; Xing et al, 2016b ; Xing et al, 2018 ; Daza et al, 2020 ; Bolet et al, 2021 ) and also in the examination of fossils that are still surrounded in their original rock matrix ( Moreau et al, 2014 ; Schwarzhans et al, 2018 ; Reid et al, 2019 ; Mayr et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

An earliest Triassic age forTasmaniolimulusand comments on synchrotron tomography of Gondwanan horseshoe crabs

Bicknell

Brougham

Bevitt

2022

PeerJ

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Constraining the timing of morphological innovations within xiphosurid evolution is central for understanding when and how such a long-lived group exploited vacant ecological niches over the majority of the Phanerozoic. To expand the knowledge on the evolution of select xiphosurid forms, we reconsider the four Australian taxa: Austrolimulus fletcheri, Dubbolimulus peetae, Tasmaniolimulus patersoni, and Victalimulus mcqueeni. In revisiting these taxa, we determine that, contrary to previous suggestion, T. patersoni arose after the Permian and the origin of over-developed genal spine structures within Austrolimulidae is exclusive to the Triassic. To increase the availability of morphological data pertaining to these unique forms, we also examined the holotypes of the four xiphosurids using synchrotron radiation X-ray tomography (SRXT). Such non-destructive, in situ imaging of palaeontological specimens can aid in the identification of novel morphological data by obviating the need for potentially extensive preparation of fossils from the surrounding rock matrix. This is particularly important for rare and/or delicate holotypes. Here, SRXT was used to emphasize A. fletcheri and T. patersoni cardiac lobe morphologies and illustrate aspects of the V. mcqueeni thoracetronic doublure, appendage impressions, and moveable spine notches. Unfortunately, the strongly compacted D. peetae precluded the identification of any internal structures, but appendage impressions were observed. The application of computational fluid dynamics to high-resolution 3D reconstructions are proposed to understand the hydrodynamic properties of divergent genal spine morphologies of austrolimulid xiphosurids.

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Revised Description of the Early Permian Recumbirostran “Microsaur” Nannaroter mckinziei Based on New Fossil Material and Computed Tomographic Data

Cited by 6 publications

References 22 publications

A new recumbirostran ‘microsaur’ from the lower Permian Bromacker locality, Thuringia, Germany, and its fossorial adaptations

A new recumbirostran ‘microsaur’ from the lower Permian Bromacker locality, Thuringia, Germany, and its fossorial adaptations

The disadvantage of derivation: conserved systematic flaws in primary data have repeatedly biased the phylogenetic inference of Temnospondyli (Tetrapoda, Amphibia)

An earliest Triassic age forTasmaniolimulusand comments on synchrotron tomography of Gondwanan horseshoe crabs

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