珊瑚纲化石

珊瑚动物都是水媳型，全为海生，有单体和群体之分，营固着底栖生活。珊瑚动物口部周围的触手数目一般为4、6或8的倍数。

(一) 珊瑚的外骨骼

珊珊动物大多数具有钙质外骨骼，珊瑚虫体座落在外骨骼之上。虫体底部的边缘骨细胞分泌形成外骨骼的外壁和表壁，虫体底部周围的骨细胞分泌形成许多辐射状纵向分布的隔壁，底部中央的骨细胞则由下向上，随着珊瑚虫体的长大和阶段性地上移，分泌成一系列的横板。此外，还分泌有鳞板、泡沫板以及轴部构造等。

珊期外骨骼的最上部是珊瑚虫栖居的地方，般呈杯状凹陷，称为萼部。珊瑚虫的整个外骨骼称为珊瑚体。由单体珊瑚虫分泌成的外骨骼称为单体珊瑚；由群体珊明虫分泌的外骨骼称为复体珊期。

珊瑚纲中主要的化石类别有：四射珊瑚亚纲和横板珊瑚亚纲。

(二) 四射珊瑚亚纲(Tetracorallia)

1. 骨骼形态

四射珊瑚有单体和复体之分，单体珊瑚形状大多呈弯角锥状和近圆柱状，少数呈拖鞋状、方锥状、盘状等等。

复体珊瑚可分成丛状复体和块状复体两类。珊期个体外壁之间彼此分离的称为丛状复体，其中分离个体彼此近平行的称为笙状，个体间呈树枝状分离的称为枝状；珊期个体外壁之间彼此紧密相连的称为块状复体。

2. 骨骼构造

(1) 外壁和表壁

外壁和表壁是四射珊瑞的外围骨骼。在外壁面上，分布有纵向的隔壁沟和间隔壁脊。在外壁的表面盖有一层钙质膜状壁，称为表壁。表壁上有横向分布的细的生长纹和粗的生长皱,所以四射珊瑚又称皱壁珊瑚(Rugosa)。

(2) 隔壁的发生

隔壁是四射珊瑚体内呈辐射状纵向分布的板状骨骼，隔壁的发生有一定的顺序和部位，如一个单体珊瑚从其始端往上作一系列的横切面后，就能看到从珊瑚幼年期到老年期隔壁生长的全过程(图1)。

(3) 鳞板和泡沫板

鳞板是位于两片隔壁之间，形状和大小都比较规则的弯曲小板(图2)，鳞板分布在珊瑚体的边缘带，在纵切面上呈鳞片状，在横切面上呈近同心弧形排列在每两片隔壁之间，其凸面大多朝向珊瑚体外。有的珊瑚的二级隔壁很短,鳞板在两个一级隔壁之间形成交叉排列的“人”字形鳞板。鳞板在珊瑚体内的分布区称为鳞板带。

泡沫板是形状、大小不规则的泡沫状小板，一般也分布在珊瑚体的边缘带，在纵切面上与鳞板相似，但在横切面上呈泡沫状，其凸面朝向珊瑚体中央。泡沫板在珊瑚体内的分布区称为泡沫板带。隔壁分布在泡沫板带的内侧或呈刺状分布在泡沫板上。

(4) 横板

横板是珊瑚体内横向分布的薄板状骨骼，大多分布在珊瑚体的中部(图3)。在纵切面上，横板的分布一般呈近水平、上凸、下凹或呈马鞍形。横板的分布区称为横板带。

(5) 轴部构造

轴部构造有中轴和中柱两种。中轴是珊瑚体中央的实心轴状骨骼(图4)，由对隔壁在轴部加厚，或是由一级隔壁在轴部相交扭结或加厚而成。中柱是珊瑚体中央的一种疏松状的骨骼，它由内斜板、辐板和中板组成(图5):中板是由对隔壁伸人轴部,经分化而成的薄板，可与对隔壁相连或分离;辐板是由部分级隔壁伸入轴部，经分化而成的薄板，它们分布在中板的两侧；内斜板在横切面上，大致呈近同心状，分布在辐板之间。

3. 骨骼构造组合类型

根据四射珊瑚的横向构造(横板鳞板、泡沫板)和轴部构造的自然组合特点，骨骼构造的组合类型由简单到复杂分为单带型、双带型、三带型和特殊的泡沫型四类。从单带型，经双带型，到三带型是四射珊瑚的基本演化趋势。

(三) 横板珊瑚亚纲(Tabulata)

横板珊瑚又名床板珊瑚，也是珊瑚纲中已经绝灭的一类,全为复体，可以造礁。其个体小，直径一般不超过5cm，常见有块状、丛状、树枝状、葡状、链状和枝块状等。

1.隔壁

横板珊瑚的隔壁不发育，一般不分组，没有序生现象，隔壁多呈刺状、鳞片状或脊状，少数呈板状(图8)。

2.横板

横板珊瑚的横板发达，也可分完整和不完整横板。完整横板呈水平倾斜或中央下四不完整横板呈交错状、泡沫状或漏斗状等(图9)。

3. 连接构造

分为孔、连接管和连接板。

（四）生态及地史分布

珊瑚动物营海生底栖生活，主要分布在海水清晰而温暖的正常浅海，它们以水中的细菌、单细胞浮游生物以及甲壳类、多毛类、棘皮动物等的幼虫为食。

珊瑚动物可分造礁和非造礁珊瑚两类。造礁珊瑚都是群体珊瑚，常与钙藻、水螅类、苔藓动物和海绵动物等造礁生物共生在一起。珊瑚礁是以珊瑚骨骼为主,并与层孔虫、苔藓虫、钙藻和古杯类等造礁生物和海百合、有孔虫、双壳类等喜礁生物共同堆积面成的。

四射珊瑚最早发现于中奥陶统，横板珊瑚最早发现于寒武系，均至二叠纪末绝灭。

以下为不同时期珊瑚礁的复原图：

1.- surface layer of live cyanobacteria.     2.- branched archaeocyates.      3.- Cup-shaped archaeocyates.
4.- Hancellorium.    5.- Oculitisiatus.    6.- traces left by an arthropod.     7.- solid cemented reef base.
The drawing is taken from D. Burney's "DINOSAURS Illustrated Encyclopedia". Moscow. AST-Astrel. 2003 ed. D.Sibbik.

1.- Nautiloides with straight shells.     2.- Nautiloides with spirally twisted shells.     3.- trilobites.
4.- gastropods.       5.- corals.       6.- sea lilies.
The drawing is taken from D. Burney's "DINOSAURS Illustrated Encyclopedia". Moscow. AST-Astrel. 2003 ed. D.Sibbik.

1,2,3.- different corals tabulates.     4.- Single coral rugosa.     5.- moss.
6.- trilobite.     7.- Brachiopod.     8.- sea lily.      9.- Nautiloidia.
The drawing is taken from D. Burney's "DINOSAURS Illustrated Encyclopedia". Moscow. AST-Astrel. 2003 ed. D.Sibbik.

参考：https://ammonit.ru/text/2504.htm

（五）珊瑚化石实例

1. Cycloseris  cyclolites

亚纲：Hexacorallia 六射珊瑚亚纲
目: Scleractinia  石珊瑚目
科：Fungiidae  石芝珊瑚科
属：Cycloseris  圆饼珊瑚属
种：cyclolites

Cycloseris是一种独居的盘状珊瑚。它们分布在印度-太平洋地区。它们栖息在较低的礁石斜坡，以及礁石之间有软沉积物的区域。它们能忍受浑浊的海水。Cycloseris属的珊瑚大多独居，自由生活，有些直径可达10厘米。圆盘要么是圆形的，要么是椭圆形的，中央的嘴被触角包围，可能是一个狭缝。珊瑚虫栖息在一个钙质的杯中，也就是珊瑚石中，只有在晚上才伸出触角进食。Cycloseris可能会与相关的Fungia属的标本混淆，但前者总是自由生活，即使是在幼体时，而后者有一个疤痕，表明它们年轻时附着在哪里。

Genus Cyclolites Lamarck, 1801

Type species. Cyclolites elliptica Lamarck, 1801 (="porpite elliptique… Guettard, 1770, mem. Vol. 2, p. 342, pl. 21, fig. 17, 18.").

Cyclolites was originally described as "Polypier libre, orbiculaire ou elliptique, convexe et lamelleux en–dessus, applati en desous avec des lignes circulaires concentriques. Il constitue une seule étoile lamelleuse" (Lamarck, 1801, p. 369), presenting four species according to the next order: C. numismalis, C. hemisphaerica, C. elliptica and C. cristata. Milne Edwards and Haime (1849) named C. elleptica [sic] Lamarck as only example of Cyclolites, which we regard as the first secondary designation of C. elliptica as type species for this genus. Alloiteau (1957, p. 331–332) presented a strong reasoning for this selection: Cyclolites as defined by Lamarck is a very polyphyletic group and only appropriate to be used as describing the overall shape of these corals: cyclolitoid, meaning hemispheroid corallite with a flat base, considered to be discoid to cupolate shaped. Cyclolites numismalis, as the first in the list of Lamarck's species, could be regarded as the type species of Cyclolites, but is a junior synonym of the Silurian rugose coral Madrepora porpita Linnaeus, 1767. This would make Palaeocyclus Milne Edwards and Haime, 1849, having the same type species, a junior synonym of Cyclolites. The second species of Lamarck, C. hemisphaerica, was suspected by Alloiteau to be a badly drawn C. elliptica, which was the third species of Lamarck. The last one, C. cristata, became the type species of Aspidiscus Kœnig, 1825. The type specimen(s) of C. elliptica are considered to be lost. To avoid confusion Alloiteau suggested that the main part of the Cretaceous "Cyclolites" were to be reassigned to Cunnolites. Alloiteau (1957) created Cunnolites barrerei as a replacement for C. elliptica and selected a specimen from coll. Depéret (lab. Geol. de Sorbonne) as "Neoholotype", supposedly from Coustouges, France, which is near Perpignan. Cyclolites as a genus name was reestablished by Löser (2009, p. 133) with Faujas de Saint–Fond, 1799 as author of the genus, since in Faujas (1799) referred directly to Lamarck (1801, p. 369) and this would mean that, if the date of publication of Faujas would have been correct, the name would indeed be first published, completely with description in Faujas and the author would have become "Lamarck in Faujas (1799)". However, Pasteur (1802), who translated Faujas (1799) into the Dutch language, stated that the first part of the Dutch translation was published only after the first five parts of Faujas had been published. The reference to Cyclolites and to Lamarck occurred in the second part of the Dutch translation (Pasteur, 1804), meaning that those references occurred in the parts of the French original that were published after 1802, so that Lamarck (1801) remains the correct author and year of publication of the generic name Cyclolites.

Cyclolites differs with Funginella in having perforations in their septa. Funginella? isfahanensis differs also from Cyclolites/Cunnolites species in being a lot smaller in its adult stage.

以上英文参考：http://www.thefossilforum.com/index.php?/topic/61029-interesting-coral-morocco/

时期：白垩纪；  产地：Ait Hani，Morocco（图11）

现生珊瑚：

2. Cycloseris barcelonensis (Oppenheim,1911) Funginellastraea barcelonensis (Alloiteau)

Period: Paleogene 古第三纪
Epoch-Stage-Strata: Middle Eocene 中始新世
Era: Cenozoic 新生代
Age: Bartonian 巴尔顿阶
Common name: fossil coral
Comments: complete,excellent quality,natural,no restoration,solitary coral
Location: South of Europe

3. Pattalophyllia sinuosa (Achiardi,1867)

Period: Paleogene
Epoch-Stage-Strata: Middle Eocene
Era: Cenozoic
Age: Bartonian
Common name: fossil coral
Comments: complete,excellent quality,natural,no restoration,solitary coral
Location: South of Europe

4. Tarbellastraea conoidea.(REUS,1871)

亚纲：Hexacorallia 六射珊瑚亚纲
目: Scleractinia  石珊瑚目
科：Merulinidae  绳纹珊瑚科

Period: Neogene 新第三纪
Epoch-Stage-Strata: Middle Miocene 中新世中期
Era: Cenozoic
Age: Badenian (about 13-15 million years)  中新世
Location: pr. Baranya Hosszúhetény (Hungary) 匈牙利

5. Agaricia lukavatcensis (Oppenheim,1923)

目: Scleractinia  石珊瑚目
科：Agariciidae  莲珊瑚科(菌珊瑚科)

Period: Paleogene
Epoch-Stage-Strata: Eocene
Era: Cenozoic
Age: Bartonian 巴尔顿阶
Common name: fossil coral
Location: South of Europe

6. Aulosmilia archiaci

亚纲：Hexacorallia 六射珊瑚亚纲
目: Scleractinia  石珊瑚目
亚目：Faviina
科：Meandrinidae
属：Aulosmilia Alloiteau 1952

产地:Santa Maria, Lerida, Spain

时期:Upper Cretaceous, Santonian 圣通阶，距今约 0.96 亿年

7. Actinocyathus sp 辐杯珊瑚

目: 十字珊瑚目 Stauriida
科：轴珊瑚科 Axophyllidae
属：辐杯珊瑚属 Actinocyathus d'Orbigny, 1849
产地：Assa Zag area in the far south of Morocco
时期：Pennsylvanian subperiod of the Carboniferous Period（323.2 to 298.9 MYA）

注：In North America, the Mississippian and Pennsylvanian periods are used instead of the Carboniferous Period, which covers that same time frame in other parts of the world.

辐杯珊瑚，又名放线杯珊瑚、辐环珊瑚，是一属已灭绝的珊瑚，生存于石炭纪的浅海中。群体大小不一，从扁平到圆形都有，由单体以粗劣的蜂窝状形式紧密地排列在一起而组成。萼为凹形，中间有突出部分。隔膜很薄，长短不一。中轴突出的结构很复杂，由一系列倾斜度很大的疱状小骨板所组成，这些骨板呈圆锥状围绕着一个很小的中心骨板，并且还被隔膜骨板切分。隔膜数目众多，在珊瑚单体内部形成一个宽大的外部区域，具有体型很大且不规则的明显特征。横板为扁平状或凹形。珊瑚单体有很薄的外壁及纤细的脊。

8. Thamnopora

纲: Anthozoa，Ehrenberg 1834 珊瑚纲
亚纲：Tabulata，Milne-Edwards and Haime 1850，横板珊瑚亚纲
目: Favositida，Wedekind 1937
亚目：Favositina，Wedekind 1937
超科：Pachyporicae，Gerth 1921
科：Pachyporidae，Gerth 1921
属：Thamnopora，Steininger 1831

9. Heliophyllum 日射脊板珊瑚

纲: Anthozoa，Ehrenberg 1834 珊瑚纲
亚纲：Rugosa
目: Stauriida，Verrill 1865  (Mid Ordovician - Late Permian)
亚目：CyathophyllinaNicholson 1889
超科：Pachyporicae，Gerth 1921
科：Zaphrentidae，Milne-Edwards and Haime 1850

The Rugosa or "rugose corals" (referring to their wrinkled appearance), also known as "horn corals" were an important group of Paleozoic organisms. Both solitary and colonial forms are known, but the former are more common. Solitary rugosans usually have a horn shaped (hence the alternative term, "horn corals"), while the colonial types commonly have hexagonal corallites. The skeleton is made of calcite and is generally quite massive. Solitary rugose corals range in size from a few millimeters in diameter and in length to 14 centimeters in diameter and a height of close to one meter. Some colonies may be 4 meters in diameter. Like modern corals (e.g. sea anemones, which can be observed in intertidal rock pools), the coral animal (or polyp) fed by using tentacles to capture and sweep organisms into their mouths

As a very general rule, rugose coral have stronger radial septa than they do transverse platforms. The septa radiate out from the center. Rugose corals have both major and minor septa.  Rugose corals differ from other corals by the pattern by which they add septa through their ontogeny (development and growth). Both solitary and colonial rugosans have this distinctive septal insertion pattern, which gives most rugose corals bilateral symmetry. The six prosepta are added first, including the cardinal septum and counter septum, which are at 180 degrees from one another. . After this the major septa (metasepta) are inserted serially in four positions; minor septa short and inserted between major septa, probably serially also. It is this four-fold developmental pattern that gives rugose corals their alternative name of tetracorals (tetra meaning four).

 New corallites may bud asexually, although they also reproduced sexually. The buds have four septa. As the corallite grows, the septa begin to spread further apart, and new septa are added, generally, four septa at a time are added to maintain a rigid structure.

The growth lines on the coral span its length from the calice (top) to the base. Rugose corals generally added a new layer of growth each day a new wrinkle), and the days in the Paleozoic year have been determined through counting growth rings on rugose corals. It is now known for example that the Devonian period had a year of 400 days (in the past the Earth rotated more quickly around it's axis; this rotation is being gradually but continually slowed by the tidal "brake" exerted by the moon's gravity).

Classification of the Rugose corals is provisional and will no doubt be revised as more detailed investigation of the microstructure of the different groups is made. The present arrangement (from the Treatise of Invertebrate Paleontology) has three suborders:

suborder Streptelasmatina (Ordovician to Late Permian) - includes both solitary and colonial types. The tabulae are domed (convex upward). The periphery of the corallum has either a stereozone or a dissepimentarium. Examples include Streptelasma, Heliophyllum.

suborder Columnariina (Ordovician—Permian). Usually colonial, rarely solitary forms. Examples: include Spongophyllum and Lonsdaleia. The septa are thin, the tabulae flat, depressed or downwardly convex

suborder Cystiphyllina (Ordovician—Devonian). Solitary or colonial forms. The septa are large with complex microstructure. A wide dissepimentarium or a stereozone is present. Examples include Cystiphyllum, Calceola, and Goniophyllum.

▲ An alternative classification has instead two orders, and elevates the Rugosa from ordinal to subclass ranking:

Subclass Rugosa

  1.Order Stauriida (Mid Ordovician - Late Permian)

  2. Order Cystiphyllida (Mid Ordovician - Mid Devonian)

（六）相关网址

1.  https://www.fossilshells.nl/Miscel/cnidaria013.html

2. https://ammonit.ru/text/2504.htm

3. https://www.fossilien.de/seiten/korallen/nattheim.htm

4. https://www.fossilplanet.com/en/catalogue/fossil-coral/

5. https://www.mindat.org/taxon-8489523.html