菊石隔壁的作用

说明1：后面很多事情要处理，发布频率不会那么高了。之前写的几篇半成品由于要写完需要耗费大量时间精力，就先存为草稿等日后有空再说了。

说明2：翻译中有些是用自己的话说的，自己辨别。

说明3：初识缝合线的话请先看：https://zhuanlan.zhihu.com/p/84813950，此篇对初识者的作用不大。

很多人喜欢说缝合线（suture line），用缝合线，但缝合线实际上指气室隔壁与外壳相接处形成的纹路。而在很多情况下说的缝合线实际上应该是隔壁/隔板（septa）。同时，缝合线不只是菊石中存在，腹足类中那些接触线也是缝合线，有孔虫那些也是。(septa是septum的复数形式，下面不会特意区分了）

菊石隔板和缝合线对古生物学家们来说有着巨大的吸引力，很多研究者对菊石隔板和其皱状边缘的功能进行深入的研究。Westermann(1971, 1999)[1][2]、Kennedy和Cobban(1976)[3]、Hewitt和Westermann(1997, 2003)[4][5]以及Keupp(2000)[6]对所有可用的假说进行了概述。在此简要地重复这些，以阐明菊石复杂的隔板和仅局限于Lytoceratoidea的隔叶（septal lobe）的可能功能。

下面从生理（1-7）和机械性能（8-12）两个方面对其功能进行解释和简要讨论：

[1] Westermann GEG (1971) Form, structure and function of shell and siphuncle in coiled Mesozoic ammonoids. Life sciences contributions. R Ont Mus 78:1–39

[2] Westermann GEG (1999) Recent hypotheses on mechanical and metabolic functions of septal fluting and sutural complexity in post-carboniferous ammonoids. Ber Geol Bundesanst 46:120

[3] Kennedy WJ, Cobban WA (1976) Aspects of ammonite biology, biogeography, and biostratigraphy. Spec Pap Palaeontol 17:1–94

[4] Hewitt RA, Westermann GEG (1997) Mechanical significance of ammonoid septa with complex sutures. Lethaia 30:205–212

[5] Hewitt RA, Westermann GEG (2003) Recurrences of hypotheses about ammonites and Argonauta. J Paleontol 77:792–795

[6] Keupp H (2000) Ammoniten. paläobiologische Erfolgsspiralen. Thorbecke, Stuttgart

1. 复杂性和代谢率

隔板的形态反映了外套膜后方的形状，Newell（1949）[7] 认为其弯折有助于更好地呼吸，Pia（1923）[8] 认为是为了更好地产气。因此，缝合线的复杂程度应该与菊石代谢有关。代谢率通常被估计为耗氧率，但也可以被认为是浮力控制率或生物矿化率。缝合线复杂性反映代谢率的假设可以被以下事实所证伪:(i)隔壁的折叠方式远不能最理想地增加最大呼吸表面的表面积(如Hammer和Bucher 1999年所证明的那样[9]，它是最小面积的表面)，(ii)隔壁外套膜可能不直接接触海水，所有头足类动物都发育出鳃来呼吸;(iii)腔室的气体填充是通过体管提供的(Tanabe et al. 2015)[10]。

[7] Newell ND (1949) Phyletic size increase, an important trend illustrated by fossil invertebrates. Evolution 3:103–124

[8] Pia J (1923) Über die ethologische Bedeutung einiger Hauptzüge in der Stammesgeschichte der Cephalopoden. Ann Nat Mus Wien 36:50–73

[9] Hammer Ø, Bucher H (1999) Reaction-diffusion processes: application to the morphogenesis of ammonoid ornamentation. Geobios 32:841–852

[10] Tanabe K, Sasaki T, Mapes RH (2015) Soft-part anatomy of the siphuncle in ammonoids.

2. 快速控制浮力

曲折的隔壁增加了腔室中的可湿性壳基质表层(薄膜)，以支持更快地将液体输送到体管从而控制浮力(Mutvei 1967)[11];这一解释得到了Bayer [12] 对有机intracameral（内气室？）膜的发现(1975;另见2012，Seuss等人[13]和2015，Polizotto等人[14])和cameral膜的存在(Weitschat和Bandel 1991[15];Polizotto et al. 2015[16])的支持，但与之相矛盾的是:(i)隔壁面积最大化的非最佳结构；(ii)folioles（次级鞍）和lobules（次级叶）的低角度，可能阻碍(但加速)完全排空。然而，这一假设不能被完全否定，但它似乎不足以作为缝合复杂性进化的唯一解释。

[11] Mutvei H (1967) On the microscopic shell structure in some Jurassic ammonoids. Neues Jahrb Geol Paläontol Abh 129:157–166

[12] Bayer U (1975) Organische Tapeten im Ammoniten-Phragmokon und ihr Einfluß auf die Fossilisation. Neues Jahrb Geol Paläontol, Monatshefte 1975(1):12–25

[13] Seuss B, Mapes RH, Klug C, Nützel A (2012) Exceptional cameral deposits in a sublethally injured carboniferous orthoconic nautiloid from the Buckhorn Asphalt Lagerstätte in Oklahoma, USA. Acta Palaeontol Pol 57:375–390

[14] Polizzotto K, Landman NH, Klug C (2015) Cameral membranes, pseudosutures, and other soft tissue imprints in ammonoid shell. 

[15] Weitschat W, Bandel K (1991) Organic components in phragmocones of boreal Triassic ammonoids: implications for ammonoid biology. Paläontol Z 65:269–303

[16] Polizzotto K, Landman NH, Klug C (2015) Cameral membranes, pseudosutures, and other soft tissue imprints in ammonoid shell. 

3. 改善浮力调节能力

波纹形的凹槽使cameral液体可以通过表面张力储存，以改善浮力调节(Kulicki 1979[17];Kulicki和Mutvei,1988[18];Weitschat和Bandel,1991[19];Saunders,1995[20]);毫无疑问，表面张力将保持剩余的腔内液体，因此腔内水的横向移动将被最小化。

[17] Kulicki C (1979) The ammonite shell, its structure, development and biological significance. Palaeontol Pol 39:97–142

[18] Kulicki C, Mutvei H (1988) Functional interpretation of ammonoids septa. In: Wiedmann J, Kullmann J (eds) Cephalopods-present and past. Schweitzerbart, Stuttgart

[19] Weitschat W, Bandel K (1991) Organic components in phragmocones of boreal Triassic ammonoids: implications for ammonoid biology. Paläontol Z 65:269–303

[20] Saunders WB (1995) The ammonoid suture problem: relationships between shell and septum thickness and suture complexity in Paleozoic ammonoids. Paleobiology 21:343–355

4. 改变浮力

笛卡儿潜水者模型（Cartesian Diver Model）(Seilacher and Labarbera 1995[21];Seilacher & Gishlick 2015[22])假设最后一个隔壁保持未钙化直到下一个腔室周期开始;在这段时间里，隔壁外套膜后面的空间可能充满了气体，起着像鱼鳔一样的作用。封闭气体的体积可以通过横跨隔膜的缝合肌肉来调节，以改变浮力。这将允许菊石在水层中垂直移动，而不需要消耗大量的能量;虽然这是一个令人兴奋的假设，但它缺乏支撑(Jacobs 1996[23])，甚至可能与Seilacher的结合点模型（Tie-Point Model）相矛盾:假设lobule的形成是由肌肉的附着控制的，鞍的形成是由柔软的身体向前方向的拉动而简单地形成的，隔套（septal mantle）的可收缩纤维的附着将不是收缩或扩张充满气体的隔壁前空间的最佳选择;如果连接在缝合处的肌肉在相反的方向上发挥作用，则可以预期lobules和folioles的形状相似。在任何情况下，从近代的鹦鹉螺中了解到气壳的功能，并不是一个质量差的假设。

[21] Seilacher A, Labarbera M (1995) Ammonites as Cartesian Divers. Palaios 10:493–506

[22] Seilacher A, Gishlick AD (2015) Morphodynamics. CRC Press, London

[23] Jacobs DK (1996) Chambered cephalopod shells, buoyancy, structure and decoupling: history and red herrings. Palaios 11:610–614

5. 肌肉附着

一些人认为，隔壁凹陷促进了主要内收肌的附着(Seilacher 1975[23], 1988[24];Henderson，1984[25];Ebel，1992[26]);多组菊石的主要肌肉系统已被描述，且它们位于隔壁的前面(Doguzhaeva和Mutvei 1991[27],1996[28];Richter，2002[29];Klug et al.，2008[30];Richter和Fischer，2002[31])。因此，隔壁凹陷明显不用于插入头部牵缩肌或漏斗牵缩肌。

[23] Seilacher A (1975) Mechanische simulation und funktionelle evolution des Ammoniten-Septums. Paläontol Z 49:268–286

[24] Seilacher A (1988) Why are nautiloid and ammonite sutures so different? Neues Jahrb Geol Paläontol Abh 177:41–69

[25] Henderson RA (1984) A muscle attachment proposal for septal function in Mesozoic ammonites. Palaeontology 27:461–486

[26] Ebel K (1992) Mode of life and soft body shape of heteromorph ammonites. Lethaia 25:179–193

[27] Doguzhaeva LA, Mutvei H (1991) Organization of the soft-body in Aconeceras (Ammonitina), interpreted on the basis of shell-morphology and muscle-scars. Palaeontol A 218:17–33

[28] Doguzhaeva LA, Mutvei H (1996) Attachment of the body to the shell in ammonoids. In: Landman NH, Tanabe K, Davis R (eds) Ammonoid paleobiology. Plenum, New York

[29] Richter U (2002) Gewebeansatz-Strukturen auf Steinkernen von Ammonoideen. Geol Beitr Hann 4:1–113

[30] Klug C, Meyer E, Richter U, Korn D (2008) Soft-tissue imprints in fossil and recent cephalopod septa and septum formation. Lethaia 41:477–492

[31] Richter U, Fischer R (2002) Soft tissue attachment structures on pyritized internal moulds of ammonoids. Abh Geol Bundesanst 57:139–149

6. 助于排空腔室

隔壁有助于在几乎任何深度排空腔室(Ward 1987[32]);这似乎是现实的原因，因为现代鹦鹉螺是这样使用腔室的。只有各种菊石分类群的内爆深度（implosion depths ）限制了这一点。然而，鹦鹉螺的隔壁只是轻轻弯折，因此，这种比较有点存疑。

[32] Ward PD (1987) The natural history of Nautilus. Allen and Unwin, Boston

7. 改善浮力逃避捕食或弥补壳的损伤

弯折的隔壁改善浮力控制，以逃避捕食(Daniel et al. 1997[33])，并有助于快速充满再生菊石壳室，以弥补壳的损失(Kröger 2001[34], 2002[35]);如果与现代鹦鹉螺的气壳功能(Ward 1979[36],1987[37])的实际比较是正确的，那么腔室排空是通过渗透实现的，因此可能太慢，无法帮助它们逃脱捕食者。为了在受到持续改变浮力的损伤后重新获得浮力控制能力，再次灌满（reflooding）可能已经足够快了。但是，这足以解释复杂性不断增加的强烈进化趋势吗?

[33] Daniel TL, Helmuth BS, Saunders WB, Ward PD (1997) Septal complexity in ammonoid cephalopods increased mechanical risk and limited depth. Paleobiology 23:470–481

[34] Kröger B (2001) Discussion—comments on Ebel’s benthic-crawler hypothesis for ammonoids and extinct nautiloids. Paläontol Z 75:123–125 

[35] Kröger B (2002) On the efficiency of the buoyancy apparatus in ammonoids: evidences from sublethal shell injuries. Lethaia 35:61–70

[36] Ward PD (1979) Cameral liquid in Nautilus and ammonites. Paleobiology 5:40–49

[37] Ward PD (1987) The natural history of Nautilus. Allen and Unwin, Boston

8. 软组织附着

隔壁帮助将柔软的身体连接到外壳上(von Buch,1829[38],1830[39];Suess,1865[40];Tate and Blake，1876[41];Steinmann，1888[42]，1925[43];Diener，1912[44];Spath,1919[45];Reyment 1955[46];Hengsbach，1978[47];Henderson，1984[48]);缝合线当然是一个临时的软组织附着部位，定期溶解发生转移(Klug et al. 2008[49])，但这种连接很可能不是很强。

[38] Buch Lv (1829) Note sur les ammonites. Annales des sciences naturelles par Audouin. Ad Brogniart et Dumas 17:267–275

[39] Buch Lv (1830) Note über Ammoniten. Jahrb Miner, Geognosie. Geol Petrefaktenk 1:397–398

[40] Suess E (1865) Über Ammoniten. Sitzungsber Math-Naturw Kl Kaiserl Akad Wissensch, Abt 1(52):71–89

[41] Tate R, Blake JF (1876) The Yorkshire lias. J. Van Vorst, London

[42] Steinmann G (1888) Vorläufige Mittheilung über die Organisation der Ammoniten. Ber Naturf Ges Freibg Breisgau 4:113–129

[43] Steinmann G (1925) Beiträge zur Stammesgeschichte der Cephalopoden I. Argonauta und die Ammoniten. Z Indukt Abstamm- Vererb 36:350–416

[44] Diener C (1912) Lebensweise und Verbreitung der Ammoniten. Neues Jahrb Min Geol Paläontol 192:67–89

[45] Spath LF (1919) Notes on Ammonites. Geol Mag 56:27–35

[46] Reyment RA (1955) Some examples of homeomorphy in Nigerian Cretaceous ammonites. Geologisca Foren i Stockh Forh 77:567–594

[47] Hengsbach R (1978) Zur Sutur-Asymmetrie bei Anahoplites (Ammonoidea; Kreide). Senck leth 59:377–385

[48] Henderson RA (1984) A muscle attachment proposal for septal function in Mesozoic ammonites. Palaeontology 27:461–486

[49] Klug C, Meyer E, Richter U, Korn D (2008) Soft-tissue imprints in fossil and recent cephalopod septa and septum formation. Lethaia 41:477–492

9. 抵抗水压

凹槽加强了壳壁和最后形成的隔壁以抵抗静水压力(Buckland，1836[50]，他也接受了von Buch的想法;Owen，1843[51];Tate   and Blake，1876[52];Zittel 1884[53];Pfaff，1911[54];Nagao and Saito，1934[55];Reyment 1955[56];Westermann，1958[57],1971[58],1975[59];Seilacher 1975[60];Kennedy and Cobban，1976[61];Hewitt and Westermann，1997[62];Hassan等，2002[63];de Blasio，2008[64]);Jacobs(1990,1992,1996[65,66,67])回顾了所谓的“Buckland假说”。尽管隔膜褶边在增强耐压能力方面存在一定的功能限制，但在部分充满气体的气壳中存在这种壁很可能提供了一些流体静力支持，这反映在缝合线类似物（sutural approximation，这个没搞懂是啥）和壳体曲率之间的相关性中(Buckland 1836[50];Jacobs，1990[65],1996[67];contra Saunders 1995[20])。相比之下，褶边本身可能对这一功能贡献不大，并被认为与测深无关，和/或陆表海菊石和海洋菊石的栖息地深度没有重大差异(Olóriz和Palmqvist 1995[68];Olóriz等，1997[69],1999[70];Perez-Claros 2005[71])。然而，在先前列出的论文中，隔壁厚度没有被考虑在内。De Blasio(2008)[64]描述了缝合线褶皱的相关功能，即加固由于静水压力引起的壳体收缩，这可能决定浮力的损失。

[50] Buckland W (1836) Geology and mineralogy considered with reference to natural theology. Treatise VI. The bridgewater treatise on the power, wisdom, and goodness of god as manifested in the Creation. W. Pickering, London

[51] Owen R (1843) Lectures on the comparative anatomy and physiology of the invertebrate animals. p 392

[52] Tate R, Blake JF (1876) The Yorkshire lias. J. Van Vorst, London

[53] Zittel KA (1884) Cephalopoda. In: Zittel KA (ed) Handbuch der Palaeontologie. 1. Abth, 2. Band. R. Oldenbourg, Munich

[54] Pfaff E (1911) Über Form und Bau der Ammonitensepten und ihre Beziehungen zur Suturlinie. Jahrb Niedersächs Geol Ver (Geol Abt Nat Ges Hann) 4:207–223

[55] Nagao T, Saito R (1934) Peculiar septal features observed in ammonites of certain lytoceratid genera. Proc Imp Acad 10:357–360

[56] Reyment RA (1955) Some examples of homeomorphy in Nigerian Cretaceous ammonites. Geologisca Foren i Stockh Forh 77:567–59

[57] Westermann GEG (1958) The significance of septa and sutures in Jurassic ammonite systematics. Geol Mag 95:441–455

[58] Westermann GEG (1971) Form, structure and function of shell and siphuncle in coiled Mesozoic ammonoids. Life sciences contributions. R Ont Mus 78:1–39 

[59] Westermann GEG (1975) Model for origin, function and fabrication of fluted cephalopod septa. Paläontol Z 49:235–253

[60] Seilacher A (1975) Mechanische simulation und funktionelle evolution des Ammoniten-Septums. Paläontol Z 49:268–286

[61] Kennedy WJ, Cobban WA (1976) Aspects of ammonite biology, biogeography, and biostratigraphy. Spec Pap Palaeontol 17:1–94    

[62] Hewitt RA, Westermann GEG (1997) Mechanical significance of ammonoid septa with complex sutures. Lethaia 30:205–212

[63] Hassan MA, Westermann GEG, Hewitt RA, Dokainish MA (2002) Finite element analysis of simulated ammonoid septa (extinct Cephalopoda): septal and sutural complexities do not reduce strength. Paleobiology 28:113–126

[64] De Blasio FV (2008) The role of suture complexity in diminishing strain and stress in ammonoid phragmocones. Lethaia 41:15–24

[65] Jacobs DK (1990) Sutural pattern and shell stress in Baculites with implications for other cephalopod shell morphologies. Paleobiology 16:336–348 

[66]Jacobs DK (1992) The support of hydrostatic load in cephalopod shells—adaptive and ontogenetic explanations of shell form and evolution from Hooke 1695 to the present. Evol Biol 26:287–349 

[67] Jacobs DK (1996) Chambered cephalopod shells, buoyancy, structure and decoupling: history and red herrings. Palaios 11:610–614

[68] Olóriz F, Palmqvist P (1995) Sutural complexity and bathymetry in ammonites: fact or artifact? Lethaia 28:167–170

[69] Olóriz F, Palmqvist P, Pérez-Claros JA (1997) Shell features, main colonized environments, and fractal analysis of sutures in Late Jurassic ammonites. Lethaia 30:191–204 

[70] Olóriz F, Palmqvist P, Pérez-Claros JA (1999) Recent advances in morphometric approaches to covariation of shell features and the complexity of suture lines in Late Jurassic ammonites, with reference to the major environments colonized. In: Olóriz F, Rodríguez-Tovar FJ (eds) Advancing research on living and fossil cephalopods. Kluwer Academic, New York

[71] Pérez-Claros JA (2005) Allometric and fractal exponents indicate a connection between metabolism and complex septa in ammonites. Paleobiology 31:221–232

10. 承受软体施加的压力

褶边(Frilling)帮助最后的隔壁承受通过软体施加到壳壁上的压力(Pfaff 1911[54]);这一假设可能有一定的真实性，因为新形成的隔壁的非矿化或不完全矿化膜可能更紧密地保留在褶皱缝合线中，从而允许更大的压力梯度在气壳和柔软部分之间建立(Klug et al. 2008[49])。

11. 增加总重以控制浮力

隔壁增加了壳体的整体重量以控制浮力(Reyment 1958[72];Teichert 1967[73]);毫无疑问，隔层增加了重量，但据推测，这不是隔壁的主要功能，因为额外的压载物可以通过简单地增加其他地方的外壳厚度来增加。此外，当低密度腔体填料也被考虑在内时，这个概念就显得不太合理了。

[72] Reyment RA (1958) Some factors in the distribution of fossil Cephalopods. Acta Universitatis Stockholmiensis—Stockholm contributions. Geology 1:97–184

[73] Teichert C (1967) Major features of cephalopod evolution. Essays in paleontology and stratigraphy. Spec Pub 2:162–210

12. 身体与壳体连接

Lewy(2002,2003[74、75])认为，复杂的凹槽间隔是软体和壳体之间更强连接的结果(临时保持系统，没有肌肉附着)。这导致Lewy(2002)[74]假设，隔壁边缘凹槽的复杂性越大，菊石就越能承受身体和漂浮着的壳体之间的牵引力，因此，菊石捕食和与其他生物竞争就更有侵略性;这一假设完全缺乏来自软组织或肌肉印记的证据(Doguzhaeva和Mapes 2015[76];Klug and Lehmann 2015[77])。

[74] Lewy Z (2002) The function of the ammonite fluted septal margins. J Paleontol 76:63–69 [75] Lewy Z (2003) Reply to Checa and to Hewitt and Westermann. J Paleontol 77:796–798

[76] Doguzhaeva LA, Mapes RH (2015) Muscle scars in ammonoid shells.

[77] Klug C, Lehmann J (2015) Soft part anatomy of ammonoids: reconstructing the animal based on exceptionally preserved specimens and actualistic comparisons.

假缝合线 & 拖线/拖带 & 体管膜

内容很多，暂且不提，仅放图于此。