scholarly journals A quantitative taxonomic review of Fusichonetes and Tethyochonetes (Chonetidina, Brachiopoda)

2017 ◽  
Vol 91 (6) ◽  
pp. 1296-1305 ◽  
Author(s):  
Hui-ting Wu ◽  
G. R. Shi ◽  
Wei-hong He
Keyword(s):  
Cladistic Analysis ◽  
Species Classification ◽  
Triassic Boundary ◽  
Morphological Variations ◽  
Key Characteristics ◽  
Wide Range ◽  
Kolmogorov Smirnov ◽  
Morphological Variables ◽  
End Members ◽  
Permian Triassic Boundary

AbstractTwo middle Permian (Capitanian) to Early Triassic (Griesbachian) rugosochonetidae brachiopod genera, Fusichonetes Liao in Zhao et al., 1981 and Tethyochonetes Chen et al., 2000, have been regarded as two distinct taxa and used as such for a wide range of discussions including biostratigraphy, paleoecology, paleobiogeography, and the Permian-Triassic boundary mass extinction. However, the supposed morphological distinctions between the two taxa are subtle at best and appear to represent two end members of a continuum of morphological variations. In this study, we applied a range of quantitative and analytical procedures (bivariate plots, Kolmogorov-Smirnov test, categorical principle component analysis, and cladistic analysis) to a dataset of 15 quantified morphological variables, integrating both key external and internal characters, measured from 141 specimens of all well-known Fusichonetes and Tethyochonetes in order to test whether or not these two genera could be distinguished in view of the chosen characters. The results indicate that these two genera are morphologically indistinguishable and that the species classification previously applied to these two genera appears to represent polyphyletic groupings within the genus Fusichonetes. Consequently, Tethyochonetes is concluded to be a junior synonym of Fusichonetes. The diagnosis and key characteristics of Fusichonetes are clarified and refined based on a new suite of well-preserved specimens from the Permian−Triassic Xinmin section in South China.

DETERMINATION OF THE PERMIAN-TRIASSIC BOUNDARY IN AUSTRALIA FROM CARBON ISOTOPE STRATIGRAPHY

1994 ◽  
Vol 34 (1) ◽  
pp. 330 ◽  
Author(s):  
R. Morante ◽  
J.J. Veevers ◽  
A.S. Andrew ◽  
P.J. Hamilton
Keyword(s):  
Carbon Isotope ◽  
Isotope Composition ◽  
Time Correlation ◽  
Depositional Environments ◽  
Sedimentary Record ◽  
Triassic Boundary ◽  
Global Comparison ◽  
Wide Range ◽  
Isotope Stratigraphy ◽  
Permian Triassic Boundary

Significant excursions in the carbon isotope composition of organic matter from sedimentary sections across the Permian/Triassic boundary are documented from the Bonaparte, Canning, Carnarvon, Perth, and Bowen Basins. The analysed sections represent a wide range of depositional environments from marine to non-marine, among which precise time correlation is uncertain. The sense and magnitude of the isotopic excursions are comparable to those found elsewhere around the world from marine carbonates at this time. Early Triassic sediments consistently bear carbon more depleted in the carbon-13 isotope than do latest Permian sediments. The isotope excursion provides an isochronous global datum in the sedimentary record at the palaeontologically determined Permian/Triassic boundary. This carbon isotope chemostratigraphic scheme has application for:correlation between different depositional environments, at scales ranging from intrabasinal to global;comparison of sedimentation rates; andrecognition of lacunas in the sedimentary record.

Relationship between morphometrics and trophic levels in deep-sea fishes

2020 ◽  
Vol 637 ◽  
pp. 225-235 ◽  
Author(s):  
MA Ladds ◽  
MH Pinkerton ◽  
E Jones ◽  
LM Durante ◽  
MR Dunn
Keyword(s):  
Stable Isotopes ◽  
Trophic Level ◽  
Deep Sea ◽  
Strong Relationship ◽  
Ecosystem Model ◽  
Trophic Levels ◽  
Fish Size ◽  
Wide Range ◽  
Gape Size ◽  
Morphological Variables

Marine food webs are structured, in part, by predator gape size. Species found in deep-sea environments may have evolved such that they can consume prey of a wide range of sizes, to maximise resource intake in a low-productivity ecosystem. Estimates of gape size are central to some types of ecosystem model that determine which prey are available to predators, but cannot always be measured directly. Deep-sea species are hypothesized to have larger gape sizes than shallower-water species relative to their body size and, because of pronounced adaptive foraging behaviour, show only a weak relationship between gape size and trophic level. Here we present new data describing selective morphological measurements and gape sizes of 134 osteichthyan and chondrichthyan species from the deep sea (200-1300 m) off New Zealand. We describe how gape size (height, width and area) varied with factors including fish size, taxonomy (class and order within a class) and trophic level estimated from stable isotopes. For deep-sea species, there was a strong relationship between gape size and fish size, better predicted by body mass than total length, which varied by taxonomic group. Results show that predictions of gape size can be made from commonly measured morphological variables. No relationship between gape size and trophic level was found, likely a reflection of using trophic level estimates from stable isotopes as opposed to the commonly used estimates from FishBase. These results support the hypothesis that deep-sea fish are generalists within their environment, including suspected scavenging, even at the highest trophic levels.

HIGH PRECISION U-PB DATING OF THE PERMIAN-TRIASSIC BOUNDARY IN MARINE DEEP WATER SETTINGS

2016 ◽  
Author(s):  
Hugo Bucher ◽  
◽  
Björn Baresel ◽  
Morgane Brosse ◽  
Fabrice Cordey ◽  
...  
Keyword(s):  
High Precision ◽  
Deep Water ◽  
Triassic Boundary ◽  
Permian Triassic Boundary

scholarly journals Morphometric and Molecular Analyses of Ostertagia leptospicularis Assadov, 1953 from Ruminants: Species Diversity or Host Influence?

Animals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 182
Author(s):  
Anna Wyrobisz-Papiewska ◽  
Jerzy Kowal ◽  
Elżbieta Łopieńska-Biernat ◽  
Paweł Nosal ◽  
Iwona Polak ◽  
...  
Keyword(s):  
Host Species ◽  
Roe Deer ◽  
Bos Taurus ◽  
Capreolus Capreolus ◽  
Nematode Species ◽  
Molecular Techniques ◽  
Systematic Classification ◽  
Morphological Variations ◽  
Wide Range ◽  
Induced Changes

Ostertagia leptospicularis Assadov, 1953 was formally described in roe deer Capreolus capreolus and has been reported in a wide range of ruminants, including other Cervidae, as well as Bovidae. Nematode specimens derived from various host species exhibit morphological similarity; however, some differences can be observed. It is unclear if this is due to the differential reaction of one nematode species in different host species (i.e., host-induced changes) or because of distinct nematode species in these hosts (i.e., species complex). This paper focuses on specimens resembling O. leptospicularis f. leptospicularis and its closely related species (Ostertagia ostertagi f. ostertagi) collected from various hosts. Morphometric and molecular techniques were applied to assess host-induced changes in nematode morphology and to clarify its systematic classification. There was an overall effect of host species on measurements of nematodes resembling O. leptospicularis (both males and females), but the distinctiveness of the specimens from cattle Bos taurus were highlighted. The results obtained may suggest that the specimens of O. leptospicularis from cattle in Germany and cervids in central Europe belong to different strains. Furthermore, nematodes from the cervid strain appear to circulate within particular host species, which can be seen in the stated morphological variations.

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