The homalonotid trilobite Burmeisteria Salter, 1865 in the Lower Devonian of Argentina: new data in the context of southwestern Gondwana

2020 ◽  
Vol 94 (3) ◽  
pp. 498-512
Author(s):  
Juan José Rustán ◽  
Beatriz G. Waisfeld ◽  
N. Emilio Vaccari
Keyword(s):  
Defensive Behavior ◽  
Lower Devonian ◽  
Central Western Argentina ◽  
Argentine Precordillera ◽  
Upper Silurian ◽  
Pore Canals ◽  
Marine Basins ◽  
Ventral Process ◽  
Stratigraphic Interval

AbstractThe homalonotid trilobite Burmeisteria Salter, 1865 is revised from material from the Lower Devonian of central western Argentina (the Talacasto Formation in the Precordillera Basin). In contrast to other closely related Devonian marine basins from South America (mainly Bolivia, Brazil and Uruguay), the only species recognized in Argentina include Burmeisteria herschelii (Murchison, 1839) and B. notica (Clarke, 1913). New observations on the structure of the carapace indicate that structures sometimes interpreted as granules with taxonomic meaning are, in fact, taphonomic characters that represent the fillings of pore canals exposed by decortication. The antero-ventral process of the rostral plate may be a locking device during enrollment, which allowed long-term defensive behavior with a minimum of muscular energy. Burmeisteria is an upper Silurian to Middle Devonian endemic representative of southwestern Gondwanan (Malvinokaffric) basins. In the Argentine Precordillera Basin, this genus is virtually restricted to a sandy, Pragian, stratigraphic interval capped by a marker bed first reported by Keidel in 1921.

Chronometric calibration of mid-Ordovician to Tournaisian conodont zones: a compilation from recent graphic-correlation and isotope studies

1992 ◽  
Vol 129 (6) ◽  
pp. 709-721 ◽  
Author(s):  
Barry G. Fordham
Keyword(s):  
High Resolution ◽  
High Precision ◽  
Time Scale ◽  
Lower Devonian ◽  
New South ◽  
Upper Ordovician ◽  
South Wales ◽  
Isotope Studies ◽  
Stratotype Section ◽  
Upper Silurian

AbstractThree available graphic-correlation analyses are used to calibrate mid-Palaeozoic conodont zonations: Sweet's scheme for the mid- to Upper Ordovician; Kleffner's for the mid- to Upper Silurian; and Murphy & Berry's for the lower and middle Lower Devonian. The scheme of Sweet is scaled by applying the high-precision U-Pb zircon date of Tucker and others for the Rocklandian and linked with that of Kleffner by scaling the graptolite sequence of the Ordovician-Silurian global stratotype section to fit two similarly derived dates from this sequence. The top of Kleffner's scheme, all of Murphy & Berry's, as well as standard zones to the Frasnian are calibrated by using tie-points of the latest Cambridge-BP time-scale (GTS 89). However, the recent microbeam zircon date by Claoué-Long and others for the Hasselbachtal Devonian-Carboniferous auxiliary stratotype is used to calibrate the standard Famennian zones. Also the similarly derived but preliminary determination reported by Roberts and others from the Isismurra Formation of New South Wales is tentatively taken as the top of the Tournaisian and so used to calibrate Tournaisian zones. Despite the considerable extrapolation required to compile these schemes and their inherent errors, the resultant time-scale closely agrees with other dates of Tucker and others from the Llanvirn as well as the GTS 89 Homerian-Gorstian tie-point. This suggests that stratigraphic methods can be usefully applied to geochronometry. The Llandovery appears to have lasted longer (16 m. y.) than usually envisaged and the Ordovician-Silurian boundary may need to be lowered to approximately 443.5 Ma. Certainly, chrons varied widely in duration and further stratigraphic studies to estimate their relative durations as well as high-resolution dating for their calibration will be crucial to more accurate biochronometries.

Synchronology

1985 ◽  
Vol 309 (1138) ◽  
pp. 11-27 ◽  
Keyword(s):  
Sea Level ◽  
Quantitative Methods ◽  
Lower Devonian ◽  
Practical Interest ◽  
Radiometric Dating ◽  
Vertebrate Evolution ◽  
Significant Evidence ◽  
Red Sandstone ◽  
Level Curves ◽  
Upper Silurian

Radiometric dating cannot as yet approach the resolution obtainable in Silurian and Devonian biostratigraphy. Progress towards achievement of a global standard for the Wenlock and Emsian interval (against which evolution and environment must be seen) is reviewed. In biostratigraphical correlation with this standard certain groups are especially useful. Correlation between marine Upper Silurian and Lower Devonian rocks and their equivalents in the Old Red Sandstone magnafacies presents particular problems and yet the latter provides significant evidence of plant and vertebrate evolution at this time. The recognition of widespread physical events such as volcanic episodes may sometimes prove useful. Sea level curves seldom provide a precise synchronology not achievable through biostratigraphy. Quantitative methods of correlation are so far of theoretical rather than practical interest.

scholarly journals Feasibility of Preparing Nesting Box and Luring Large Solitary Carpenter Bee, Xylocopa Valga

2017 ◽  
Vol 61 (2) ◽  
pp. 263-267
Author(s):  
Michał Schulz ◽  
Radosław Ścibior ◽  
Kamil Badurowicz ◽  
Aleksandra Łoś ◽  
Milena Bajda ◽  
...  
Keyword(s):  
Social Behavior ◽  
Defensive Behavior ◽  
Solitary Bees ◽  
Solitary Bee ◽  
Carpenter Bee ◽  
South Eastern ◽  
Drill Bits ◽  
Carpenter Bees ◽  
Long Term Observation

Abstract Xylocopa valga, commonly called the carpenter bee and the largest bee with metallicviolet hair cover, is extremely rarely observed in Poland. We hypothesize that a stable and possibly long-term population of X. valga can be maintained in Poland through the creation of suitable nesting conditions. X. valga has been observed since the spring of 2014 in Wisznice (south-eastern Poland). A nesting box made out of 25 wooden blocks with drilled holes was hung about 2.5 meters above the ground. X. valga were interested in the blocks made of willow wood but did not nest in the beech, alder and pine. The carpenter bees chose holes made with drill bits of 10, 15, 20 mm in diameter and a length of 10, 15 and 20 cm. X. valga flying in the same direction most often visited the flora taxa: Aquilegia vulgaris, Ballota nigra, Consolida ajacis, Delphinium consolida, Deutzia scabra, Catalpa spp., Wisteria spp., Robinia ambigua, Stachys spp. and Trifolium pretense. X. valga is a solitary bee, but unlike most other solitary bees it demonstrates aspects of social behavior. It was observed to display cohabitative behavior involving the use of a single hole by more than one female. The females showed aggressive defensive behavior and if approached too closely started buzzing loudly. The information obtained during the long-term observation shows that X. valga can be maintained in partly artificial conditions to increase and stabilize the bee population.

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