Reassessment of historic ‘microsaurs’ from Joggins, Nova Scotia, reveals hidden diversity in the earliest amniote ecosystem

@article{Mann2020ReassessmentOH,
  title={Reassessment of historic ‘microsaurs’ from Joggins, Nova Scotia, reveals hidden diversity in the earliest amniote ecosystem},
  author={Arjan Mann and Bryan M. Gee and Jason D. Pardo and David Marjanovi{\'c} and Gabrielle Ruth Adams and Ami S. Calthorpe and Hillary C. Maddin and Jason S. Anderson},
  journal={Papers in Palaeontology},
  year={2020},
  volume={6}
}
‘Microsaurs’ are traditionally considered to be lepospondyl non‐amniotes, but recent analyses have recovered a subset of ‘microsaurs’, the fossorially adapted Recumbirostra, within Amniota. This novel conclusion highlights the need for additional work to evaluate these competing hypotheses with the aim of refining the phylogenetic position of ‘microsaurs’. Of particular importance in this regard is the placement of potential close relatives of recumbirostrans to determine whether they support… 
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Cranial anatomy and systematics of Dendrerpeton cf. helogenes (Tetrapoda, Temnospondyli) from the Pennsylvanian of Joggins, revisited through micro‐CT scanning
The Joggins Fossil Cliffs constitute an upper Carboniferous (Pennsylvanian) locality in Nova Scotia (Canada). This site, known for the rich record of fossils preserved in the palaeoenvironment in…
Joermungandr bolti, an exceptionally preserved ‘microsaur’ from the Mazon Creek Lagerstätte reveals patterns of integumentary evolution in Recumbirostra
The Carboniferous Pennsylvanian-aged (309–307 Ma) Mazon Creek Lagerstätte produces some of the earliest fossils of major Palaeozoic tetrapod lineages. Recently, several new tetrapod specimens…
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  • 2021
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An examination of local species richness (alpha diversity) of synapsids and reptiles during the Pennsylvanian and Cisuralian at different spatial scales shows that these taxonomic revisions have substantial impacts on relative diversity patterns of synapid and reptiles.
A Mississippian (early Carboniferous) tetrapod showing early diversification of the hindlimbs
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A new East Kirkton tetrapod with an unusual hindlimb morphology reminiscent of that of several stem- and primitive crown amniotes is named and described, with a unique ilium with two slender and elongate processes and a 5-digit pes with a long, stout metatarsal IV and a greatly elongate digit IV.
Evolutionary Change in Locomotion Close to the Origin of Amniotes Inferred From Trackway Data in an Ancestral State Reconstruction Approach
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It is demonstrated that steps in early amniote locomotion evolution can be addressed by applying methods of ancestral state reconstruction on trackway data – a novel approach in tetrapod ichnology.
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The well-defined isometry, and particularly, the high interrelation between metatarsals and phalanges permit us to suggest that the mesosaur hind limb is subject to notable modularity, which would position them as more basal amniotes than previously thought.
The Making of Calibration Sausage Exemplified by Recalibrating the Transcriptomic Timetree of Jawed Vertebrates
TLDR
The present work reevaluate all thirty calibrations in detail, present the current state of knowledge on them with its various uncertainties, rerun the dating analysis, and conclude that calibration dates cannot be taken from published compendia or other secondary or tertiary sources without risking strong distortions to the results.
Phylogeny, function and ecology in the deep evolutionary history of the mammalian forelimb
TLDR
This work quantitatively compared the forelimb shapes of the multiple fossil synapsid radiations to a broad sample of extant Mammalia representing a variety of divergent locomotor ecologies and indicates that eachsynapsid radiation explored different areas of morphospace and arrived at functional solutions that reflected their distinctive ancestral morphologies.
Carboniferous tetrapod biostratigraphy, biochronology and evolutionary events
  • S. Lucas
  • Geography, Environmental Science
    Special Publications
  • 2021
Abstract Tetrapod (amphibian and amniote) fossils of Carboniferous age are known almost exclusively from the southern part of a palaeoequatorial Euramerican province. The stratigraphic distribution…
Can We Reliably Calibrate Deep Nodes in the Tetrapod Tree? Case Studies in Deep Tetrapod Divergences
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It is found that node priors for amphibians and tetrapods show high phylogenetic lability and different phylogenetic treatments identifying disparate taxa as the earliest representatives of these crown groups, and it is suggested that sampling outside of classic European and North American sections may dramatically change the timelines of tetrapod evolution.
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