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Introduction

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Ostracoda is a class of the Crustacea, sometimes known as the seed shrimp because of their appearance. Some 50,000 extinct and extant species have been identified, grouped into several orders.

Ostracods are small crustaceans, typically around one mm in size, but varying between 0,2 to 3 mm, laterally compressed and protected by a bivalve-like, chitinous or calcareous valve or "shell". The hinge of the two valves is in the upper, dorsal region of the body.

Ecologically ostracods can be part of the zooplankton, or (most commonly) they are part of the benthos, living on or inside the upper layer of the sea floor. Some groups of ostracods are also found in fresh waters and in humid continental soils (normally in humid forests).

Ostracods are particularly useful for the biozonation of marine strata on a local or regional scale, and they are invaluable indicators of ancient shorelines, salinities and relative sea-floor depths. They have a long and well documented fossil record from the Cambrian to the present day. An outline microfaunal zonal scheme based on both foraminifera and ostracoda was compiled by M.B. Hart (1972).

Morphology

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The body of an ostracod is encased by two valves, which together form the duplicature. A distinction is made between the valve (hard parts) and the body with its appendages (soft parts).

Soft parts and ontogeny

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The body consists of a cephalon (head), separated from the thorax by a slight constriction. The segmentation is unclear. The abdomen is regressed or absent whereas the adult gonads are relatively large. There are 5-8 pairs of appendages. The branchial plates are responsible for oxygenation.

During the ontogeny the epidermis (containing mesodermal tissue invaginates ventrolaterally near the cephalon/thorax area. This invagination proceeds upwards and tailwards, until the whole animal is enveloped by a double tissue layer on both sides: this forms the duplicature. The dorsal region never becomes invaginated, and is called the isthmus. The mesodermal tissue in the duplicature develops into the vestibulum. The vestibulum makes contact with the body near the isthmus. It plays a role in oxygenation. In paleo-ecology, the size of the vestibulum can be cautiously interpreted as an environmental indicator. The two double tissue layers surrounding the animal each have an inner and an outer lamella, which surrounds the vestibulum. These lamellae are surrounded by a chitinous cuticle, that is secreted by the epidermal cells.

Like all arthropods, ostracods develop discontinually. Before reaching maturity 8 larval stages (instars) are passed.

Hard parts

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The epidermal cells may also secrete calcium carbonate after the chitinous layer is formed, resulting in a chalk layer enveloped by chitin. This calcification is not equally pronounced in all orders. During every instar transition, the calcified layer gets thicker. The outer lamella calcifies completely, while the inner lamella calcifies partially, with the rest remaining chitinous. The partial inner lamella calcification occurs when the ostracod becomes adult. The partial inner lamella calcification is most strongly developed frontally (see electron micrograph). The marginal zone is the area where inner and outer lamella meet, and includes part of the vestibulum. The edge of the marginal zone is called the fused zone, and in this area inner and outer lamella join. The fused zone can contain marginal pore canals. These, along with non-marginal pore canals (that are dispersed evenly along the ostracod's valve) connect the vestibulum to the outer world. The line of concrescence is the visible line between the vestibulum and the fused zone. In many cases, this line is wavering and follows the marginal pore canals. On the inner lamella, a selvage may be present.

Applications in paleo-ecology

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Environment-induced valve chemical composition

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Environment-induced valve morphology

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Use of ecological index-species

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Analysis of population structure

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Paleo-synecology:predation by drilling

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Templates I created

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Template:Scale model

Template:Infobox rail transport by country

Template:scale model

Template:notsportcycling

Template:bicycle racing

Class until 1968 Class from 1968 Original Whyte notation Operation Type Remarks Links
01.0-2 001 DRG standard design 4-6-2 S 36.20
01.0-2 001 DRG standard design rebuilt 4-6-2 S 36.20 with Henschel-Mischvorwärmer
01.0-2 001 DRG standard design rebuilt 4-6-2 S 36.20 with Hochleistungskessel
01.10 DRG standard design 4-6-2 S 36.20 de-streamlined
01.10 011 Rebuilt 4-6-2 S 36.20 de-streamlined
01.10 012 Rebuilt 4-6-2 S 36.20 de-streamlined with oil as fuel
03.0-2 003 DRG standard design 4-6-2 S 36.17, S 36.18
03.10 DRG standard design 4-6-2 S 36.18 de-streamlined
03.10 Rekolok 4-6-2 S 36.18 de-streamlined
05 DRG standard design 4-6-4 S 37.19 de-streamlined
10 010 New DB design 4-6-2 S 36.22 partially streamlined
17.11-12 Prussian S10.1, Bauart 1914 4-6-0 S 35.17
18.1 Württemberg C 4-6-2 S 36.16
18.3 Baden IV h (1-3) 4-6-2 S 36.17
18.4-5 Bavarian S3/6 4-6-2 S 36.16, S 36.17, S 36.18 partial DRG reproduction
18.6 018 Rekolok 4-6-2 S 36.18 from Bavarian S3/6
23 023 New DB design 2-6-2 P 35.18
24 DRG standard design 2-6-0 P 34.15
38.4 Bavarian P3/5 H 4-6-0 P 35.15
38.10-40 038 Prussian P8 4-6-0 P 35.17
39.0-2 Prussian P10 2-8-2 P 46.19
41 DRG standard design 2-8-2 G 46.18/20
41 041 Rekolok 2-8-2 G 46.18
41 042 Rekolok 2-8-2 G 46.18 with oil as fuel
42 War locomotive 2-10-0 G 56.17
42.90 War locomotive 2-10-0 G 56.18 Converted BR 52 with Franco-Crosti-boiler
44 044 DRG standard design 2-10-0 G 56.20 auch als ÜK (Übergangskriegslok) beschafft
44 043 DRG standard design 2-10-0 G 56.20 with oil as fuel
45 045 DRG standard design 2-10-2 G 57.18/20
50 050 - 053 DRG standard design 2-10-0 G 56.15 auch als ÜK (Übergangskriegslok) beschafft
50.40 DRG standard design rebuilt 2-10-0 G 56.15 with Franco-Crosti-boiler
52 War locomotive 2-10-0 G 56.15
54.15-17 Bavarian G3/4 H 2-6-0 G 34.16
55.0-6 Prussian G7.1 0-8-0 G 44.13
55.16-22 Prussian G8 0-8-0 G 44.14
55.25-56 055 Prussian G8.1 0-8-0 G 44.17
56.1 Prussian G8.3 2-8-0 G 45.17
56.2-8 Prussian G8.1 mit Laufachse 0-8-0 G 45.16 Converted G8.1 by DRG
56.20-29 Prussian G8.2 2-8-0 G 45.17
57.5 Bavarian G5/5 0-10-0 G 55.17
57.10-35 Prussian G10 0-10-0 G 55.15
58.2-3 Baden G12.1-7 2-10-0 G 56.16
58.4 Saxon XIII H 2-10-0 G 56.16
58.5 Württemberg G12 2-10-0 G 56.16
58.10-21 Prussian G12. 2-10-0 G 56.16
59 Württemberg K 2-12-0 G 67.16
61 DRG standard design 4-6-4 St 37.18
62 DRG standard design 4-6-4 Pt 37.20
64 064 DRG standard design 2-6-2 Pt 35.15
65 065 New DB design 2-8-4 Pt 47.17
66 New DB design 2-6-4 Pt 36.16
70.0 Bavarian Pt2/3 2-4-0 Pt 23.14
70.1 Baden Ig.1-2 2-4-0 Pt 23.14, Pt 23.15 partially DRG reproduction
71 DRG standard design 2-4-2 Pt 24.15
74.0-3 Prussian T 11 2-6-0 Pt 34.16
74.4-13 Prussian T 12 2-6-0 Pt 34.17
75.0 Württemberg T 5 2-6-2 Pt 35.15
75.1-3 Baden VI b.1-11 2-6-2 Pt 35.14
75.4 Baden VI c.1-7 2-6-2 Pt 35.16
75.10-11 Baden VI c.8-9 2-6-2 Pt 35.16
76.0 Prussian T10 4-6-0 Pt 35.16
77.0 Pfalz P5 2-6-4 Pt 36.16
77.1 Pfalz and Bavarian Pt3/6 2-6-4 Pt 36.16
78.0-5 078 Prussian T18,
Württemberg T18
4-6-4 Pt 37.17
78.10 078 DB rebuilt 3810-40 4-6-4 Pt 37.17 from Prussian P8
80 DRG standard design 0-6-0 Gt 33.17
81 DRG standard design 0-8-0 Gt 44.17
82 082 New DB design 0-10-0 Gt 55.18
85 DRG standard design 2-10-2 Gt 57.20 for the Höllentalbahn
86 DRG standard design 2-8-2 Gt 46.15 auch als ÜK (Übergangskriegslok) beschafft
87 DRG standard design 0-10-0 Gt 55.17 mit zahnradgekuppelten Endkuppelachsen
89.1 Pfalz T3 0-6-0 Gt 33.14
89.3 Württemberg T3 0-6-0 Gt 33.10, Gt 33.12
89.6 Bavarian DII.II 0-6-0 Gt 33.15
89.7 Bavarian R3/3 0-6-0 Gt 33.15
89.8 Bavarian R3/3 0-6-0 Gt 33.16 reproduction DRG
89.70-75 Prussian T3 0-6-0 Gt 33.10, Gt 33.11, Gt 33.12
91.3-18 Prussian T9.3 2-6-0 Gt 34.15
91.19 Mecklenburg T4 2-6-0 Gt 34.11, Gt 34.12, Gt 34.13
91.20 Württemberg T9 2-6-0 Gt 34.15
92.2-3 Baden X b.1-7 0-8-0 Gt 44.15, Gt 44.16
92.5-10 Prussian T13 0-8-0 Gt 44.15, Gt 44.16
92.20 Pfalz R4/4, Bavarian R4/4 0-8-0 Gt 44.16
93.0-4 Prussian T14 0-8-0 Gt 46.16
93.5-12 093 Prussian T14.1 0-8-0 Gt 46.17
94.1 Württemberg Tn 0-10-0 Gt 55.13
94.2-4 Prussian T16 0-10-0 Gt 55.15
94.5-17 094 Prussian T16.1 0-10-0 Gt 55.17
95.0 Prussian T20 2-10-2 Gt 57.19
97.1 Bavarian PtzL 3/4 0-6-2 Z 34.15 Cog locomotives
97.5 Württemberg Hz 0-10-0 Z 55.15 Cog locomotives newly designed by DRG
98.3 Bavarian PtL 2/2 0-4-0 L 22.11 local locomotives Glaskasten
98.4-5 Bavarian 0-8-0 XI 0-6-2 L 34.10, L 34.11 local locomotives
98.5 Bavarian PtL 3/4 0-6-2 L 34.11 local locomotives
98.6 Pfalz 0-8-0 VIII 0-6-2 L 34.13 local locomotives
98.8-9 098 Bavarian GtL 4/4 0-8-0 L 44.11, L 44.12 local locomotives z.T. reproduction der DRG
98.10 Newly built by DRG 0-8-2 L 45.11 local locomotives
98.11 097 rebuilt DRG - Bavarian GtL 4/5 0-8-2 L 45.11 local locomotives rebuilt aus bay. GtL 4/4
99 099 several narrow gauge locomotives

Templatefactory

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James Cameron

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James Cameron
Films

Piranha II: The Spawning (1981) | The Terminator (1984) | Aliens (1986) | The Abyss (1989) | Terminator 2: Judgment Day (1991) | True Lies (1994) | Titanic (1997) | Dark Angel (series) (2000) | Ghosts of the Abyss (documentary) (2002) | Aliens of the Deep (documentary) (2005) |

Creationist welcome template

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Welcome again, Phlebas/sandbox. It appears you are a creationist, but thank you for your contributions anyway. I sincerely hope you like the place and decide to stay. Here are a few good links for newcomers like yourself:

Stone Age

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This period is part of the Stone Age.
Paleolithic
:Lower Palaeolithic
:Middle Palaeolithic
:Upper Palaeolithic
Mesolithic
Neolithic