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«To cite this version: Aihua Yuan. Latest Permian Deep-Water Ostracod (Crustacea) Fauna from South China. Pa- leontology. Universit´ Pierre et Marie ...»

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Step II: acidization and acid recycling All beakers 1, in which all samples are settled, are placed in the ventilate cabinet. According to the content of silica, generally 2% to 5% concentration of HF water solution was confected. During the process, the concentration can be changed according to the disaggregation status of samples.

First day: Samples in every beaker 1 are immerged with diluted HF solution.

Second day: The HF solution is very muddy and generally will not be recycled. If the sample contains much mud, it is necessary to gently rinse the meshy bag under the water. Then in the beaker 1, new diluted HF solution is poured to immerge the samples.

After about 12 hours: The excess HF solution is decanted to another container for recycling (considered as lower concentration e.g. half concentration in the next use). The meshy bag with samples is transferred to the beaker 2. The beaker 1 with the deposit is then filled with water (or add some soda ash) to reduce acidity so as to prevent destroying the fossils (water inpouring gently). The aggregate samples in beaker 2 are again immerged with new diluted HF solution.

After another 12 hours: The deposit in beaker 1 has sunk to the bottom. Pour out the water on the top of the deposit. Transfer the new deposits in beaker 2 to the beaker 1 and again fill with water. The aggregate samples in beaker 2 are immerged with the new diluted HF solution. Every 12 hours, this step is repeated until enough deposit is collected.

Step III: residua rinsing The deposits are sieved through 300 meshes. Gently transfer the residua in beaker 1 onto the sieve.

Immerge the bottom of the sieve into a large container (e.g. basin) filled with water. Shake the sieve gently with hand and accelerate the diffusion of the mud until the water flowing is clean. Transfer gently the residua into beaker 1. Place the beaker 1 in the heating-store or let it air-dry for picking.

According to our experiment, if not used for next sample rinsing, the sieve with residua was directly put in the heating-store. This way effectively avoids the conglutination between residua and beaker/pot. The residua can be completely and readily collected. The more important is that the destroy to fossils due to multi-transmit was greatly reduced.

Muddy rocks This method was introduced by Averbour in Wang (1987) for claystones and marlaceous rocks processing. Other than the former methods for calcareous and siliceous rocks disaggregating, the mechanism of this method is physical disaggregation under the force of chemical reaction. This method has been also widely used in conodont extracting.

38 Yuan Aihua: Latest Permian Deep-Water Ostracod (Crustacea) Fauna from South China 2008/5 Equipments: ventilated cabinet, beaker (plastic or vitreous), vitreous stick, 20 mesh and 300 mesh sieves, rubber gloves, respirator.

Chemicals: Na2S2O4 water-free powder, H2O2, blue methylene powder.

Step I: samples crushing.

Crush the samples properly. Although in the introduction of Averbour (1962) it is said that the rocks are not necessary to be crushed, it will accelerate the reaction after crushing, especially for a little hard mudstone. Place the crushed rocks into the beaker.

Step II: reaction Dissolve the Na2S2O4 water-free powder in another beaker to get 10% Na2S2O4 water solution (the vitreous stick is suggested for accelerating the dissolution). In the ventilated cabinet, pour the solution into the beaker with samples until immerge the samples. After about 30 minutes when the samples have been soaked by the Na2S2O4 solution (during this time, prepare for 15% H2O2 solution), pour the H2O2 solution into the beaker. The reaction between the two chemicals starts immediately. At the same time, heat and gas will be produced (sometimes smelly H2S volatizing). The force resulting from the reaction disaggregates the rocks and the samples become porridge-like.

Step III: rinsing Gently transfer the sample onto the battery of two sieves. For the residua on the 20 mesh sieve, the rinsing method is same as that for calcerous rocks. The residua on the 300 mesh sieve can be rinsed according to the method for siliceous rocks.

2.2.3 Picking, scanning and identifying

–  –  –

Mounting and photographing Equipments: scanning electronic microscope (SEM), sputter coater, copper stub, double-faced adhesive tape or latex, a fine writing brush, pieces of paper.

For further identication, choose the well-preserved specimens for photography. When mounting the specimens, orient them according to the anterior-posterior to profit the next step. And ensure to choose enough characteristic specimens for each species (if it is possible) and orient them in different views. At the same time of mounting, draw the outline of the stub as well as the sketch figure of the specimens (this will avoid confusion if you do scanning rotation) and label the distinguished character (complete carapace or left or right valve, in lateral or ventral or dorsal or end view) (e.g. Tab. 2-2-B).

Then the stub is coated with gold or carbon in vacuum status for several minutes. Carefully hold the stub and gently stick it on the stage of SEM for photography. Microfossils are generally scanned under strict work condition of vacuum (lower than 5e-3 atomospheric pressure) and high voltage (20 kV).

Tab. 2-2-B Data sheet used during ostracod scanning Photo number Amount of the same carapaces Amount of the same valves Bed number Remarks Identifying The identification is a very complex work. It is the most important step of paleontological research.





No machine is enabled to accomplish that. Researchers can not only rely on the fossils themselves, but consider the geological time, environment and region.

In the practical operation, print the photos and primarily classify them in high level. Then identify them group by group. The first step is to orientate, measure and describe the specimens (principles see 2.1.4). The next is to compare the specimens with those similar in as many related literatures as possible (principles see 2.1.5). When referring to the literature, making detailed record would save much time for writing the synonymy (derivation, namer, time, geological age, occurrences, environment, literatures etc.) and the later discussing. Each identified species should be described in certain format. There are not unified format for descriptions. Generally speaking, a regular systematic description should contain the items of material, description, measurements/dimensions, remarks and occurrence. In new taxa, derivation, diagnosis and type (holotype, paratype…) should be designated.

40 Yuan Aihua: Latest Permian Deep-Water Ostracod (Crustacea) Fauna from South China 2008/5

§2.3 Systematic descriptions

In this work, 43 genera and 128 species were identified, including 1 new genus (Denticupachydomella n.gen.) and 4 new species (Bairdia dongpanensis Yuan & Crasquin-Soleau, 2007, Spinomicrocheilinella anterocompressa Yuan & Crasquin-Soleau, 2007, Denticupachydomella spinosa n.gen. n.sp. and Pseudobythocypris guiqianensis n.sp.). It should be pointed out that the new genus and the latter two new species are proposed here. The proposition will be valid only after published in a research journal.

As mentioned above, the taxonomic classification of Moore (1961) is followed here. The new taxa after 1961 are mainly referred to the literatures of their original derivation.

Remarks:

For completely presenting the faunas, all the species from the Dongpan Section are also included in the systematic descriptions, but only with the specific name and the plate number. The detailed descriptions see the Appendix 3.

The main involved abbreviations in the following systematic descriptions:

RV: right valve; LV: left valve AB: anterior border; PB: posterior border;

DB: dorsal border; ADB: anterodorsal border; PDB: posterodorsal border;

VB: ventral border; AVB: anteroventral border; PVB: posteroventral border;

L: maximum length; H: maximum height; H/L: ratio of maximum height to maximum length CA: cardinal angle; ACA: anterior cardinal angle; PCA: posterior cardinal angle;

–  –  –

Remarks: Compared with the specimens from the Wuchiapingian strata of Hydra Island, Greece (Sohn, 1978), the PCA of the specimen here is less distinct, the hinge line shorter and curvature radius of PB smaller. Due to the poor preservation, the groove bordered by tubercles along free margins was not observed in the specimen here.

Occurrence: Latest Permian. Guangxi (bed LQ16, Dalong Formation of Liuqiao Section), South China.

–  –  –

2007 Kirkbya cf.sp.A sensu Becker & Wang, 1992; Yuan et al.: p. 170, pl.1, fig.1.

Occurrence: Latest Permian. Guangxi (bed 03DP3, Dalong Formation of Dongpan section), South China.

–  –  –

Material: One valve.

Measurements: L=1024µm, H=560µm, H/L=0.55.

Remarks: Compared with Kirkbya wymani Kellett, 1933 from the Early Permian of Kansas, here the specimen does not present the depressed area below the lobe and has not the anteroventral node. Note that I consider that the shoulder is posterior, so the orientation of the specimens in Kellett (1933, p.91, pl.15, figs 23-32) should be reversed.

Occurrence: Latest Permian. Guangxi (bed LQ9, Dalong Formation of Liuqiao Section), South China.

–  –  –

2007 Kirkbya sp.1; Yuan et al.: p. 170, pl.1, figs 4-6.

Occurrence: Latest Permian. Guangxi (beds 03DP3 and 03DP5, Dalong Formation of Dongpan section), South China.

–  –  –

Material: One valve.

Measurements: L=933µm, H=533µm, H/L=0.57.

Remarks: The strong hollow spine, obliquely downward pointed at the anterodorsal part, could lead to attribute the specimen to the genus Tubulikirkbya Kozur, 1985a. But the tubule-like spine here is not formed by the prolongation of the two marginal ridges, which is one of generic characteristics of the genus Tubulikirkbya.

Occurrence: Latest Permian. Guangxi (bed LQ7, Dalong Formation of Liuqiao Section), South China.

Kirkbya sp.3 Pl. 1, fig. 8

Material: One valve.

Measurements: L=883µm, H=517µm, H/L=0.58.

Remarks: According to the distinct kirkbyan pit surrounded by a rim, this specimen is assigned to the genus Kirkbya Jones, 1859.

Occurrence: Latest Permian. Guangxi (bed LQ16, Dalong Formation of Liuqiao Section), South China.

–  –  –

Remarks: In Kozur (1985a, p.33, pl.8, fig.1), the specimen, assigned to Kellettina ultima, has two faintely connected lobes and the kirkbyan pit just below the lobe at the mid-hight of the carapace. So I think that assignation of the former specimens to Aurikirkbya should be more reasonable. The present specimen here strongly resembles Aurikirkbya ultima (Kozur, 1985a) from the Late Permian (Abedahian) of Hungary by the sub-rectangular outline, reticulation and marginal rim. Compared with Aurikirkbya ultima (Kozur, 1985a), the specimen here has the AB and PB with larger curvature radius and well-developed marginal rim along whole free margins and the reticulation only around two lobes.

Occurrence: Latest Permian. Guangxi (bed LQ16, Dalong Formation of Liuqiao Section), South China.

–  –  –

2007 Aurikirkbya sp.1; Yuan et al.: p. 171, pl.1, fig.2.

Occurrence: Latest Permian. Guangxi (bed 03DP2, Dalong Formation of Dongpan Section), South China.

–  –  –

Material: One valve.

Measurements: (without the lobe) L=551µm, H=303µm, H/L=0.55.

Remarks: Compared with other Aurikirkbya species, the present specimen has a very obtuse CA. Due to the incomplete preservation of the other CA, it does not allow precise orientation and identification.

Occurrence: Latest Permian. Guangxi (bed LQ16, Dalong Formation of Liuqiao Section), South China.

–  –  –

2007 Nodokirkbya ? cf. striatoreticulata Kozur, 1991a; Yuan et al.: p. 171-173, pl.1, fig.3.

Material: One valve.

Measurements: L=825µm, H=405µm, H/L=0.49.

Remarks: The main character of the present specimen is the presence of two carinae which do not converge at the CA. They form the step-like appearance, between which there are rows of reticulations.

The inner carina projects beyond the DB. Although the two carinae are not well preserved, for each carina along their margins, the base of hollow tubercles can be clearly recognized. One broken hollow spine is present on the anterodorsal part. According to the characters above, this specimen is assigned to the genus Tubulikirkbya Kozur, 1985a, but is poorly preserved so that some characters can not be observed. Compared with the other Tubulikirkbya species, the present specimen has the peculiar type of carinae and ornamentation.

Occurrence: Latest Permian. Guangxi (bed LQ16, Dalong Formation of Liuqiao Section), South China.

–  –  –

Material: One valve.

Measurements: L=1200µm, H=612µm, H/L=0.51.

Remarks: Although this specimen is poorly preserved, the prominent sub-central and posterior nodes could be recognized, which make it be assigned to the family Amphissitidae Knight, 1928. The posterior denticules give an appearance of Neoamphissites costatus Becker & Wang, 1992 from the Late Permian of Sichuan and Fujian and Amphissites biambonaria Hao, 1992a from the Late Permian of Guizhou, South China (we think these two species should be one). But here the specimen has not the three carinae on the lateral surface.

Occurrence: Latest Permian. Guangxi (bed LQ35, Dalong Formation of Liuqiao Section), South China.

–  –  –

Material: One valve.

Measurements: (without the lobe) L=624µm, H=271µm, H/L=0.43.



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