Martinelli, A. G., Francischini, H., Dentzien-Dias, P. C., Soares, M. B., and C. L. Schultz. 2016.
The oldest archosauromorph from South America: postcranial remains from the Guadalupian (mid-Permian) Rio do Rasto Formation (Paraná Basin), southern Brazil. Historical Biology.
DOI:10.1080/08912963.2015.1125897
http://www.tandfonline.com/doi/full/10.1080/08912963.2015.1125897
Abstract - In this contribution, we report a distal portion of a left humerus that likely belongs to an indeterminate basal archosauromorph from the Guadalupian (mid-Permian) Rio do Rastro Formation (Paraná Basin) of southern Brazil. A precise taxonomy of the fragmented and isolated humerus UFRGS-PV-0546-P is not warranted at generic nor familiar level but, likely, this specimen belongs to an Archosauromorpha due to the lack of both the entepicondylar and the ectepicondylar foramina. The narrow distal end of the humerus, the rounded radial and ulnar condyles, and the moderately developed supinator process with a shallow ectepicondylar groove (not notched) are features reminiscent of tanystropheids rather than that of other archosauromorphs. This material likely represents the first and oldest Permian archosauromorph from South America and indicates the presence of this lineage before the P/T boundary.
Showing posts with label Permian. Show all posts
Showing posts with label Permian. Show all posts
The Early Evolution of Synapsids
Brocklehurst, N., Kammerer, C. F., and J. Frobisch. 2013. The early evolution of synapsids, and the influence of sampling on their fossil record. Paleobiology 39:470-490. DOI: 10.1666/12049
Abstract - Synapsids dominated the terrestrial realm between the late Pennsylvanian and the Triassic.
Their early evolution includes some of the first amniotes to evolve large size, herbivory, and macropredators. However, little research has focused on the changes in diversity occurring during this early phase in their evolutionary history, with more effort concentrating on later events such the Permo-Triassic extinction. Here we assess synapsid diversity, at both the species and genus levels, between the Carboniferous (Moscovian) and the Middle Permian (Capitanian). A raw, taxic diversity (richness) estimate is generated, and we use two separate methods to correct for sampling biases in this curve. To remove the effect of anthropogenic sampling bias, we apply a recently published modification of the residual diversity method, and then generate a supertree, using matrix representation with parsimony to infer ghost lineages and obtain a phylogenetic diversity estimate. The general diversity pattern reflects the initial diversification of synapsids in the late Pennsylvanian and early Cisuralian, which was followed by an extinction event during the Sakmarian. Diversity recovered during the Artinskian and Kungurian, coinciding with the radiation of Caseidae, although other families begin to decline. A second extinction event occurred across the Kungurian/Roadian boundary, in which Edaphosauridae and Ophiacodontidae died out although Caseidae and Therapsida diversified. The sampling-corrected curves reveal further extinction during the Roadian, although therapsids were again unaffected. Pelycosaurian-grade synapsids survived during the Wordian and Capitanian, but were a minor part of an otherwise therapsid-dominated fauna. Evidence of significant anthropogenic sampling bias calls
into question previous diversity studies that have not employed sampling correction.
Abstract - Synapsids dominated the terrestrial realm between the late Pennsylvanian and the Triassic.
Their early evolution includes some of the first amniotes to evolve large size, herbivory, and macropredators. However, little research has focused on the changes in diversity occurring during this early phase in their evolutionary history, with more effort concentrating on later events such the Permo-Triassic extinction. Here we assess synapsid diversity, at both the species and genus levels, between the Carboniferous (Moscovian) and the Middle Permian (Capitanian). A raw, taxic diversity (richness) estimate is generated, and we use two separate methods to correct for sampling biases in this curve. To remove the effect of anthropogenic sampling bias, we apply a recently published modification of the residual diversity method, and then generate a supertree, using matrix representation with parsimony to infer ghost lineages and obtain a phylogenetic diversity estimate. The general diversity pattern reflects the initial diversification of synapsids in the late Pennsylvanian and early Cisuralian, which was followed by an extinction event during the Sakmarian. Diversity recovered during the Artinskian and Kungurian, coinciding with the radiation of Caseidae, although other families begin to decline. A second extinction event occurred across the Kungurian/Roadian boundary, in which Edaphosauridae and Ophiacodontidae died out although Caseidae and Therapsida diversified. The sampling-corrected curves reveal further extinction during the Roadian, although therapsids were again unaffected. Pelycosaurian-grade synapsids survived during the Wordian and Capitanian, but were a minor part of an otherwise therapsid-dominated fauna. Evidence of significant anthropogenic sampling bias calls
into question previous diversity studies that have not employed sampling correction.
Amazing Preservation of a Permian Forest Redux
Here is the abstract and link (open access) to the previously mentioned article. It is too bad that with instantaneous preservation of a Permian ecosystem that no animals are mentioned as found. I also mistakenly stated in my previous post that the site was in China. It is actually from Mongolia.
Wang, J., Pfefferkorn, H. W., Zhang, Y., and Z. Feng. 2012. Permian vegetational Pompeii from Inner Mongolia and its implications for landscape paleoecology and paleobiogeography of Cathaysia. PNAS, published online before print. doi: 10.1073/pnas.1115076109
Abstract - Plant communities of the geologic past can be reconstructed with high fidelity only if they were preserved in place in an instant in time. Here we report such a flora from an early Permian (ca. 298 Ma) ash-fall tuff in Inner Mongolia, a time interval and area where such information is filling a large gap of knowledge. About 1,000 m2 of forest growing on peat could be reconstructed based on the actual location of individual plants. Tree ferns formed a lower canopy and either Cordaites, a coniferophyte, or Sigillaria, a lycopsid, were present as taller trees. Noeggerathiales, an enigmatic and extinct spore-bearing plant group of small trees, is represented by three species that have been found as nearly complete specimens and are presented in reconstructions in their plant community. Landscape heterogenity is apparent, including one site where Noeggerathiales are dominant. This peat-forming flora is also taxonomically distinct from those growing on clastic soils in the same area and during the same time interval. This Permian flora demonstrates both similarities and differences to floras of the same age in Europe and North America and confirms the distinct character of the Cathaysian floral realm. Therefore, this flora will serve as a baseline for the study of other fossil floras in East Asia and the early Permian globally that will be needed for a better understanding of paleoclimate evolution through time.
Amazing Preservation of a Permian Forest
The upcoming issue of PNAS has an article documenting amazing preservation of a Permian paleobotanical locality in China, the result of rapid burial by volcanic ash. The actual article is not up yet but you can read about the study here.
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