Ben Creisler
Some recent non-dino papers:
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Free pdf:
Jonathan D. Kennedy, Petter Z. Marki, ÂJon Fjeldsà & Carsten Rahbek (2020)
Peripheral ecoâmorphology predicts restricted lineage diversification and endemism among corvoid passerine birds
Global Ecology and Biogeography (2020)
doi: https://doi.org/10.1111/geb.13194
https://onlinelibrary.wiley.com/doi/10.1111/geb.13194
Across a variety of taxonomic scales, species diversity is unevenly distributed among its constituent units, and clades with few species are more common than expected assuming homogeneous rates of speciation and extinction among lineages. In order to explain the prevalence of speciesâpoor families among a global and speciesârich radiation of passerine birds, we test whether these groups share common ecoâmorphological, geographical and phylogenetic attributes.
Location
Global.
Time period
Late Oligocene to the present day.
Major taxa studied
The Corvides (c. 790 species).
Methods
We obtained 10 linear measurements of external morphology for 782 species of corvoid passerines. Using these measurements as a proxy for species ecology, we assessed the positioning of corvoid families in ecoâmorphological trait space and how these factors were associated with their species richness and rates of lineage diversification. Subsequently, we compared these same characteristics (species richness, morphological positioning and rates of lineage diversification) between families that are currently endemic to the Australasian ancestral area of the Corvides with those that have dispersed and diversified throughout other continental and insular landmasses.
Results
Families with low species richness and rates of diversification tend to occupy the most peripheral positions in ecoâmorphological trait space, with almost all of these groups being endemic to Australasia. The peripheral ecoâmorphological positioning of the Australasian groupings is generally greater than expected upon accounting for differences in phylogenetic isolation and heterogeneity in rates of trait evolution, implying that speciesâpoor corvoid families repeatedly evolved towards marginal areas of morphospace.
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Free pdf:
Susanna KÃmmell, Fernando Abdala, Judyth Sassoon, and Virginia Abdala (2020)
Evolution and identity of synapsid carpal bones.
Acta Palaeontologica Polonica (in press)
doi:https://doi.org/10.4202/app.00709.2019
http://app.pan.pl/article/item/app007092019.html
To date there is little information on carpal bone homology in late Palaeozoic and Mesozoic Synapsida. Crucial to the understanding of homology in synapsid carpal elements is the fact that different nomenclatures are used for the carpals of non-mammaliamorph Synapsida (Gegenbauerâs canonical nomenclature) and Mammaliaformes (mammalian nomenclature). The homologies of the carpals of non-mammaliamorph synapsids and mammals were established early last century and have not been reviewed since then. Here we provide a detailed study of the carpal bones of synapsids ranging in age from the early Permian to Late Cretaceous. The mammaliamorph lunate, previously considered the homologue of the intermedium of non-mammaliamorph synapsids, is interpreted here as homologous to their lateral centrale. We interpret the single mammaliamorph centrale as a homologue of the medial centrale of non-mammaliamorph synapsids. In some synapsid specimens, we found that one or two centralia are fused to the radiale (e.g., the gorgonopsian Arctognathus and tritylodontid Bienotheroides), supporting a digging habit. A third centrale is present in the therocephalian Theriognathus, very likely an abnormal duplication. An additional medial bone in a biarmosuchian was interpreted as a prepollex/ sesamoid. A cartilaginous prepollex/sesamoid may also have been present in several non-mammaliamorph synapsids, which have an open space proximal to distal carpal I. Distal carpal V is completely lost in dicynodonts and it is mainly fused to distal carpal IV in the adult stage of most other therapsid groups, but showed a delayed development in most non-mammaliamorph cynodonts. In mammaliamorphs, distal carpal V is not present. Our observations provide an updated revision of synapsid carpal homologies, mainly on the basis of position and anatomical contacts and also taking into account the results of embryological studies.
Evolution and identity of synapsid carpal bones.
Acta Palaeontologica Polonica (in press)
doi:https://doi.org/10.4202/app.00709.2019
http://app.pan.pl/article/item/app007092019.html
To date there is little information on carpal bone homology in late Palaeozoic and Mesozoic Synapsida. Crucial to the understanding of homology in synapsid carpal elements is the fact that different nomenclatures are used for the carpals of non-mammaliamorph Synapsida (Gegenbauerâs canonical nomenclature) and Mammaliaformes (mammalian nomenclature). The homologies of the carpals of non-mammaliamorph synapsids and mammals were established early last century and have not been reviewed since then. Here we provide a detailed study of the carpal bones of synapsids ranging in age from the early Permian to Late Cretaceous. The mammaliamorph lunate, previously considered the homologue of the intermedium of non-mammaliamorph synapsids, is interpreted here as homologous to their lateral centrale. We interpret the single mammaliamorph centrale as a homologue of the medial centrale of non-mammaliamorph synapsids. In some synapsid specimens, we found that one or two centralia are fused to the radiale (e.g., the gorgonopsian Arctognathus and tritylodontid Bienotheroides), supporting a digging habit. A third centrale is present in the therocephalian Theriognathus, very likely an abnormal duplication. An additional medial bone in a biarmosuchian was interpreted as a prepollex/ sesamoid. A cartilaginous prepollex/sesamoid may also have been present in several non-mammaliamorph synapsids, which have an open space proximal to distal carpal I. Distal carpal V is completely lost in dicynodonts and it is mainly fused to distal carpal IV in the adult stage of most other therapsid groups, but showed a delayed development in most non-mammaliamorph cynodonts. In mammaliamorphs, distal carpal V is not present. Our observations provide an updated revision of synapsid carpal homologies, mainly on the basis of position and anatomical contacts and also taking into account the results of embryological studies.
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Free pdf:
Michael D. Cherney, Jeffrey A. Wilson Mantilla, Iyad Zalmout, Mohammed Sameh M. Antar, and Philip D. Gingerich (2020)
New Specimens of the Late Eocene Turtle Cordichelys (Pleurodira: Podocnemididae) From Wadi Al Hitan and Qasr El-Sagha in the Fayum Province of Eqypt.
Contributions from the Museum of Paleontology, University of Michigan 33(2): 29-64
https://deepblue.lib.umich.edu/handle/2027.42/163364
https://deepblue.lib.umich.edu/bitstream/handle/2027.42/163364/ContributionsVol33No2_Lo_Res.pdf
Podocnemidid turtles in the subtribe Stereogenyina are diagnosed by a unique, partially developed secondary palate that consists of a pair of lateral flanges, each formed by the maxilla and palatine, separated by a midline cleft. Two monospecific stereogenyine genera, Stereogenys and Cordichelys, overlap temporally and spatially in the upper Eocene deposits of the Fayum Depression in Egypt. The taxonomic history of these genera is complicated and intertwined, and the two species (St. cromeri and C. antiqua) may be more closely related than their long history of generic separation suggests. Here we describe two new specimens of Cordichelys--a skull and shell from the lower Priabonian Birket Qarun Formation and a complete skull from the overlying middle Priabonian of the Qasr el-Sagha Formation. We also attribute to Cordichelys a mandible that previously had been tentatively identified as Stereogenys. These specimens along with previously described Cordichelys materials reveal substantial morphological variation within the currently monotypic genus. Presence of Cordichelys in the Birket Qarun Formation corroborates previous interpretations of a marine habitat for these turtles. Meanwhile, the reconstructed shell of the new Birket Qarun specimen reveals moderate doming and an ovoid outline that contrast with previous interpretations of its shape as "flat" and "cordiform."Â
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Free pdf
Free pdf
Kunio Kaiho, Md. Aftabuzzaman, David S. Jones & Li Tian (2020)
Pulsed volcanic combustion events coincident with the end-Permian terrestrial disturbance and the following global crisis.
Geology (advance online publication)
doi: https://doi.org/10.1130/G48022.1
https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G48022.1/592427/Pulsed-volcanic-combustion-events-coincident-withÂ
Eruption of the Siberian Traps large igneous province (LIP) is thought to have triggered the Permian-Triassic biological crisis, the largest of the Phanerozoic mass extinctions. Mercury concentration enrichments have been widely used as a proxy for volcanic inputs to sediments, especially for ancient LIP eruptions. However, detailed correlations of magmatic pulses with extinction events in the terrestrial and marine realms are not fully resolved. Here we use paired coronene (a six-ring polycyclic aromatic hydrocarbon, a high-temperature combustion proxy) and mercury spikes as a refined proxy for LIP emplacement. In records from stratigraphic sections in south China and Italy, we identify two sets of paired coronene-mercury spikes accompanied by land plant biomarker spikes, followed by a rapid decrease coinciding with terrestrial ecological disturbance and extinction of marine metazoans. Each short-term episode is likely caused by high-temperature combustion of sedimentary hydrocarbons during initial sill emplacement of the Siberian Traps LIP. These data indicate that discrete volcanic eruptions could have caused the terrestrial ecosystem crisis followed by the marine ecosystem crisis in ~60 k.y., and that the terrestrial ecosystem was disrupted by smaller global environmental changes than the marine ecosystem.
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Free pdf:
Yu Pei, Jan-Peter Duda & Joachim Reitner (2020)
Sedimentary factories and ecosystem change across the Permian-Triassic Critical Interval (P-TrCI): insights from the Xiakou area (South China).
PalZ (advance online publication)
doi: https://doi.org/10.1007/s12542-020-00530-x
https://link.springer.com/article/10.1007/s12542-020-00530-x
The Permian-Triassic mass extinction included a potentially catastrophic decline of biodiversity, but ecosystem change across this event remains poorly characterized. Here we reconstruct sedimentary factories and ecosystem change across the Permian-Triassic Critical Interval (P-TrCI) in the Xiakou area (South China). Six microfacies (MF) were classified. The succession begins with a eukaryote-controlled carbonate factory (MF-1) that passes upward into an organomineralization-dominated carbonate factory (MF-2-3). Organic-rich marls atop these units reflect carbonate factory collapse (MF-4). Organomineralization-driven carbonate formation restarts prior to the Permian-Triassic boundary (MF-5) and subsequently develops into a mixed carbonate factory where organomineralization and biomineralization are almost equally important (MF-6). MF-1 reflects oxygenated shallow water environments. In contrast, MF-2-6 were all deposited in somewhat deeper environments, some of which episodically exhibited elevated salinities, oxygen depletion, and, possibly, euxinic conditions. Our results demonstrate that distinct changes in carbonate production styles, biodiversity, and environmental conditions are not synchronous at Xiakou. Furthermore, the Xiakou record is strikingly different to that of other localities, even from the same area (e.g., the Global Stratotype Section and Point section at Meishan). Together, these findings highlight the enormous complexity of the P-TrCI and calls simplified views of the Permian-Triassic mass extinction into question.
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