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Introduction

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

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

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

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

Environment-induced valve chemical composition

Environment-induced valve morphology

Use of ecological index-species

Analysis of population structure

Paleo-synecology:predation by drilling

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German steam locomotive classification

More information Class until 1968, Class from 1968 ...
Class until 1968 Class from 1968 Original Whyte notation Operation Type Remarks Links
01.0-2001DRG standard design4-6-2S 36.20
01.0-2001DRG standard design rebuilt4-6-2S 36.20with Henschel-Mischvorwärmer
01.0-2001DRG standard design rebuilt4-6-2S 36.20with Hochleistungskessel
01.10DRG standard design4-6-2S 36.20de-streamlined
01.10011Rebuilt4-6-2S 36.20de-streamlined
01.10012Rebuilt4-6-2S 36.20de-streamlined with oil as fuel
03.0-2003DRG standard design4-6-2S 36.17, S 36.18
03.10DRG standard design4-6-2S 36.18de-streamlined
03.10Rekolok4-6-2S 36.18de-streamlined
05DRG standard design4-6-4S 37.19de-streamlined
10010New DB design4-6-2S 36.22partially streamlined
17.11-12Prussian S10.1, Bauart 19144-6-0S 35.17
18.1Württemberg C4-6-2S 36.16
18.3Baden IV h (1-3)4-6-2S 36.17
18.4-5Bavarian S3/64-6-2S 36.16, S 36.17, S 36.18partial DRG reproduction
18.6018Rekolok4-6-2S 36.18from Bavarian S3/6
23023New DB design2-6-2P 35.18
24DRG standard design2-6-0P 34.15
38.4Bavarian P3/5 H4-6-0P 35.15
38.10-40038Prussian P84-6-0P 35.17
39.0-2Prussian P102-8-2P 46.19
41DRG standard design2-8-2G 46.18/20
41041Rekolok2-8-2G 46.18
41042Rekolok2-8-2G 46.18with oil as fuel
42War locomotive2-10-0G 56.17
42.90War locomotive2-10-0G 56.18Converted BR 52 with Franco-Crosti-boiler
44044DRG standard design2-10-0G 56.20auch als ÜK (Übergangskriegslok) beschafft
44043DRG standard design2-10-0G 56.20with oil as fuel
45045DRG standard design2-10-2G 57.18/20
50050 - 053DRG standard design2-10-0G 56.15auch als ÜK (Übergangskriegslok) beschafft
50.40DRG standard design rebuilt2-10-0G 56.15with Franco-Crosti-boiler
52War locomotive2-10-0G 56.15
54.15-17Bavarian G3/4 H2-6-0G 34.16
55.0-6Prussian G7.10-8-0G 44.13
55.16-22Prussian G80-8-0G 44.14
55.25-56055Prussian G8.10-8-0G 44.17
56.1Prussian G8.32-8-0G 45.17
56.2-8Prussian G8.1 mit Laufachse0-8-0G 45.16Converted G8.1 by DRG
56.20-29Prussian G8.22-8-0G 45.17
57.5Bavarian G5/50-10-0G 55.17
57.10-35Prussian G100-10-0G 55.15
58.2-3Baden G12.1-72-10-0G 56.16
58.4Saxon XIII H2-10-0G 56.16
58.5Württemberg G122-10-0G 56.16
58.10-21Prussian G12.2-10-0G 56.16
59Württemberg K2-12-0G 67.16
61DRG standard design4-6-4St 37.18
62DRG standard design4-6-4Pt 37.20
64064DRG standard design2-6-2Pt 35.15
65065New DB design2-8-4Pt 47.17
66New DB design2-6-4Pt 36.16
70.0Bavarian Pt2/32-4-0Pt 23.14
70.1Baden Ig.1-22-4-0Pt 23.14, Pt 23.15partially DRG reproduction
71DRG standard design2-4-2Pt 24.15
74.0-3Prussian T 112-6-0Pt 34.16
74.4-13Prussian T 122-6-0Pt 34.17
75.0Württemberg T 52-6-2Pt 35.15
75.1-3Baden VI b.1-112-6-2Pt 35.14
75.4Baden VI c.1-72-6-2Pt 35.16
75.10-11Baden VI c.8-92-6-2Pt 35.16
76.0Prussian T104-6-0Pt 35.16
77.0Pfalz P52-6-4Pt 36.16
77.1Pfalz and Bavarian Pt3/62-6-4Pt 36.16
78.0-5078Prussian T18,
Württemberg T18		4-6-4Pt 37.17
78.10078DB rebuilt 3810-404-6-4Pt 37.17from Prussian P8
80DRG standard design0-6-0Gt 33.17
81DRG standard design0-8-0Gt 44.17
82082New DB design0-10-0Gt 55.18
85DRG standard design2-10-2Gt 57.20for the Höllentalbahn
86DRG standard design2-8-2Gt 46.15auch als ÜK (Übergangskriegslok) beschafft
87DRG standard design0-10-0Gt 55.17mit zahnradgekuppelten Endkuppelachsen
89.1Pfalz T30-6-0Gt 33.14
89.3Württemberg T30-6-0Gt 33.10, Gt 33.12
89.6Bavarian DII.II0-6-0Gt 33.15
89.7Bavarian R3/30-6-0Gt 33.15
89.8Bavarian R3/30-6-0Gt 33.16reproduction DRG
89.70-75Prussian T30-6-0Gt 33.10, Gt 33.11, Gt 33.12
91.3-18Prussian T9.32-6-0Gt 34.15
91.19Mecklenburg T42-6-0Gt 34.11, Gt 34.12, Gt 34.13
91.20Württemberg T92-6-0Gt 34.15
92.2-3Baden X b.1-70-8-0Gt 44.15, Gt 44.16
92.5-10Prussian T130-8-0Gt 44.15, Gt 44.16
92.20Pfalz R4/4, Bavarian R4/40-8-0Gt 44.16
93.0-4Prussian T140-8-0Gt 46.16
93.5-12093Prussian T14.10-8-0Gt 46.17
94.1Württemberg Tn0-10-0Gt 55.13
94.2-4Prussian T160-10-0Gt 55.15
94.5-17094Prussian T16.10-10-0Gt 55.17
95.0Prussian T202-10-2Gt 57.19
97.1Bavarian PtzL 3/40-6-2Z 34.15Cog locomotives
97.5Württemberg Hz0-10-0Z 55.15Cog locomotives newly designed by DRG
98.3Bavarian PtL 2/20-4-0L 22.11local locomotives Glaskasten
98.4-5Bavarian 0-8-0 XI0-6-2L 34.10, L 34.11local locomotives
98.5Bavarian PtL 3/40-6-2L 34.11local locomotives
98.6Pfalz 0-8-0 VIII0-6-2L 34.13local locomotives
98.8-9098Bavarian GtL 4/40-8-0L 44.11, L 44.12local locomotives z.T. reproduction der DRG
98.10Newly built by DRG0-8-2L 45.11local locomotives
98.11097rebuilt DRG - Bavarian GtL 4/50-8-2L 45.11local locomotives rebuilt aus bay. GtL 4/4
99099severalnarrow gauge locomotives
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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

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

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