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-Phosphatized remnants of soft tissues inside the siphuncle tubes of Kachpurites fulgens. A) MSU 123/5, Eganovo locality. Remnants of cameral membranes are visible along the sides of the siphuncle tube. B) MSU 123/6 Eganovo locality. Abbreviations: sp ¼ septum; phl ¼ phosphatic coating on the internal surface of the chamber; st ¼ siphuncle tube; a? ¼ possible artery; se? ¼ possible siphuncle epithelium.
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Ammonoid soft tissues are rarely preserved and such findings are of considerable interest. Extremely little is known about the structure of ammonoid siphuncle soft-parts. Until now indisputable fossilized siphuncle soft tissues were known only in a few ammonoid genera. This article describes phosphatized soft tissues inside the siphuncle tubes of t...
Contexts in source publication
Context 1
... studied were collected by the author in the summers of 2013- 2015 at three localities: Eganovo (55832 0 08.28"N; 38803 0 10.47"E) and Mnevniki (55846 0 4.12"N; 37828 0 4.67"E) in the Moscow region and Cheremukha River (Mikhalevo-Ivanovskoe) (57857 0 25.68''N; 38843 0 7.36''E) in the Yaroslavl region (see map in Mironenko 2015b, fig.1). ...
Context 2
... connecting rings of siphuncle tubes are very often preserved within the phragmocone chambers of craspeditid ammonites in the Kachpurites fulgens Zone. The outer and inner surfaces of the connecting rings are covered with layers of fluorapatite (the formation of such layers is schematically shown in Barskov 1990, fig.1). Most often, the tubes are empty or contain remains of blood vessels in which the original structure is absent or very poorly distinguishable ( Fig. 1). ...
Context 3
... in the Kachpurites fulgens Zone. The outer and inner surfaces of the connecting rings are covered with layers of fluorapatite (the formation of such layers is schematically shown in Barskov 1990, fig.1). Most often, the tubes are empty or contain remains of blood vessels in which the original structure is absent or very poorly distinguishable ( Fig. ...
Context 4
... large central vessel and four smaller ones around it which were found in the cross-section of the siphuncle tubes of two Kachpurites specimens (Fig. 3) are entirely consistent with the data from Permian Akmilleria and Recent Nautilus which preserve a large central vein surrounded by four smaller arteries (in the case of Akmilleria only two are preserved) (Tanabe et al. 2000(Tanabe et al. , 2015. The large central vein is also visible in the phosphatized siphuncle of Paracanthoplites sp. ( Tanabe et al. 2015, fig.13.5a, 13.5b). ...
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Citations
... The membranes are phosphatized and based on EDX data, covered with apatite layers on both sides (see Zaton andMironenko 2015, fig. 5 andMironenko 2017, fig. 4 for EDX spectra of phosphatized structures from the same ammonites and localities). They are brown and often semi-transparent. ...
... The water in each chamber was captured in small volumes in direct contact with the siphuncle regardless of the position of the chamber in the shell. Studies of phosphatized remnants of siphuncle soft tissues of ammonoids indicate that the ammonoid siphuncle had fewer cells responsible for gas-liquid exchange than the siphuncle of modern nautilids (Tanabe et al. 2015;Mironenko 2017). Although this may suggest less effectiveness of ammonoid siphuncles, it can be assumed that the membranes which held water near the siphuncle significantly improved its efficiency. ...
A complex system of three-dimensional cameral membranes is known from the phragmocones of several ammonoid genera—both Paleozoic and Mesozoic. The origin and functions of these membranes remain mysterious, and their study is complicated by the absence of identical structures in modern cephalopods. Current hypotheses about the origin of cameral membranes and other organic structures of the phragmocone are mainly based on the study of Paleozoic, Triassic, and Cretaceous ammonoids. This paper examines the membranes of Subboreal Jurassic ammonites. The spatial arrangement and complexity of these membranes differ from those described earlier. It was previously assumed that three-dimensional membranes only appeared late in ammonoid ontogeny, at the end of the neanic stage. However, in the ammonites studied herein, such membranes are present starting from the second phragmocone chamber. In addition to membranes, we report other initially organic phragmocone structures of Jurassic ammonites: pseudosutures and drag lines. The discovery of a unique structure in the last phragmocone chamber of one specimen, which likely represents a fossilized set of pseudosepta, has led to a new hypothesis, that can explain the formation of all types of membranes and other initially organic phragmocone structures. According to this idea, all types of cameral sheets despite their different shapes, were formed during merging and subsequent dehydration of organic pseudosepta. Pseudosutures and drag lines are imprints of the pseudosepta margins.
... Although phosphatization represents one of many taphonomic processes that lead to exceptional preservation (Allison, 1988b;Briggs et al., 1993;Briggs and Wilby, 1996;Briggs, 2003;Butterfield, 2003;Xiao and Schiffbauer, 2009;Schiffbauer et al., 2014a;Muscente et al., , 2017, it receives much attention for its role in the preservation of cellular and subcellular details (Xiao and Knoll, 1999;Schiffbauer et al., 2012;. Phosphatization can lead to the preservation of coleoid gladii, mantle tissues, and ink sacs (Muscente et al., 2019;Sinha et al., 2021); arthropod carapaces (Waloszek, 2003;Muscente et al., 2019;Sinha et al., 2021); coprolites and bromalites Hawkins et al., 2018); vertebrate bones and soft tissues (Martill, 1988;Lindgren et al., 2018); and remains of mollusks (Wilby and Whyte, 1995;Mironenko, 2017), including their shells (Jurkowska and Kołodziej, 2013;Hoffmann et al., 2021). In the Posidonia Shale, apatite minerals Fig. 20. ...
Konservat-Lagerstätten—deposits with exceptionally preserved fossils of articulated multi-element skeletons and soft tissues—offer the most complete snapshots of ancient organisms and communities in the geological record. One classic example, the Posidonia Shale in southwestern Germany, contains a diverse array of fossils preserved during the ∼183 Ma Toarcian Oceanic Anoxic Event. Seminal work on this deposit led to the hypothesis that many Konservat-Lagerstätten were preserved in stagnant basins, where anoxic conditions limited soft tissue degradation. To date, however, no studies have thoroughly investigated the geomicrobiological processes that drove fossil mineralization in the Posidonia Shale. As a result, the role of anoxia in its exceptional preservation remains uncertain. Here, we address these issues by reviewing the geology of the Posidonia Shale; describing the mineralization of its fossils; and synthesizing novel and existing data to develop a new model for the paleoenvironment and taphonomy of the Lagerstätte. Although shells and carbonate skeletal elements were preserved as pyritized and carbonaceous fossils, non-biomineralized tissues were primarily preserved via phosphatization (transformation of remains into calcium phosphate minerals). Unambiguous examples of phosphatization include ammonite shells, crustacean carapaces, ichthyosaur remains, coprolites, and coleoid gladii, mantle tissues, and ink sacs. Phosphatized crustaceans and coleoids contain cracks filled with pyrite, sphalerite, and aluminosilicate minerals. Such cracks were likely generated during burial compaction, which fractured phosphatized tissues, exposed their organic matter to focused microbial sulfate reduction, and thereby led to formation of, and infilling by, sulfide and clay minerals. These observations indicate that phosphatization happened early in diagenesis, prior to burial compaction and microbial sulfate reduction, beneath (sub)oxic bottom water, and corroborate the hypothesis that the animals were preserved during ephemeral pulses of oxygenation in the basin and/or within environments located along boundaries of anoxic water bodies. Overall, our findings support the view that anoxic bottom water does not directly promote exceptional preservation; in fact, it may impede it. Konservat-Lagerstätten, particularly “stagnation deposits”, tend to form in (sub)oxic depositional environments with steep redox gradients and/or high sedimentation rates. Under these conditions, organisms are rapidly buried below the redox boundary, where their mineralization is promoted by focused geomicrobiological processes, and degradation is limited by the supply of oxidants in the microenvironments around them.
... Accordingly, these are the most widely reported organic hard components of soft tissues (Closs, 1967a(Closs, , 1967bHollingworth & Hilton, 1999;Klug & Jerjen, 2012;Klug & Lehmann, 2015;Klug et al., , 2016Klug et al., , 2021Kruta et al. 2011Kruta et al. , 2020Landman et al., 2010;Lehmann, 1981;Lehmann & Weitschat, 1973;Mapes et al., 2019;Tanabe, Kruta, et al., 2015;Wippich & Lehmann, 2004). Besides, a few records exist for the presence of ammonoid gills (Klug et al., 2021;Lehmann, 1985;Lehmann & Weitschat, 1973;Mironenko, 2015), and siphuncle (Mironenko, 2017 and references therein; Tanabe et al., 1982Tanabe et al., , 2000Tanabe, Sasaki, et al., 2015). The siphuncle is a long, segmented soft tissue that begins at the rear soft body. ...
... The fossil record of soft tissue remains is restricted to localities and strata with exceptional preservational conditions. EDS spectra revealed the presence of large amounts of phosphate and fluorine in the shell (Fig. 3d, e, see Tanabe et al., 2000 andMironenko, 2017 for similar EDS spectra). Furthermore, the siphuncular remains also contain high amounts of phosphate, thus suggesting the taphonomic process of phosphatization as responsible agent for the exceptional preservation of the herein described early Albian ammonites. ...
Findings of ammonoid soft tissues are extremely rare compared to the rich fossil record of ammonoid conchs ranging from the Late Devonian to the Cretaceous/Paleogene boundary. Here, we apply the computed-tomography approach to detect ammonoid soft tissue remains in well-preserved fossils from the Early Cretaceous (early Albian) of NE-Germany of Proleymeriella . The ammonites were found in glauconitic–phosphatic sandstone boulders. Analyses of the high-resolution Ct-data revealed the presence of cameral sheets, the siphuncular tube wall, and the siphuncle itself. The siphuncle is a long, segmented soft tissue that begins at the rear end of the body chamber and comprises blood vessels. Chemical analyses using energy-dispersive spectroscopy (EDS) showed that all preserved soft tissues were phosphatized and are now composed of fluorapatite. The same holds true for preserved shell remains that locally show the nacreous microstructure. We provide a short description of these soft tissue remains and briefly discuss the taphonomic pathway.
... Phosphatization is the main type of preservation of soft-bodied marine animals including coleoids, in all currently known Konservat-Lagerstätten localities, such as Jurassic Posidonia Shales, Oxford Clay Formation, Solnhofen Plattenkalks, etc., their bodies are phosphatized (Donovan & Fuchs 2016). Soft tissues of ammonites, such as their mantle and muscle fragments (Mironenko 2015;Klug et al. 2021b) and siphuncle blood vessels (Tanabe et al. 2000;Mironenko 2017), are also replaced with phosphatic minerals, although the preservation of ammonite bodies is usually incomplete, with very rare exceptions (Klug et al. 2021b). ...
The first well-preserved soft-body imprint of a fossil squid was discovered from the Lower Oligocene of the Krasnodar region, Russia. The squid is perfectly preserved, with many details of its body available for study, such as imprints of eyes and head, a pair of statoliths, jaws, and stomach contents. Statoliths of this squid are the first finds of in situ statoliths in fossil non-belemnoid coleoids, and their shape is characteristic of the genus Loligo (family Loliginidae). Although some Mesozoic coleoids were previously classified as teuthids, these finds remain controversial and the squid described herein is the first unquestionable representative of fossil Teuthida known to date. It should be noted that the squid is preserved not due to phosphatization, which is typical for fossil coleoids, but by pyritization and carbonization. Numerous fish remains in the stomach contents of the squid indicate its piscivorous diet. A small cutlassfish Anenchelum angustum, which was buried together with the squid and whose bones are located near the squid's jaws, sheds light on the circumstances of the death of this animal. Most likely, the squid suffocated in the anoxic bottom waters, where it drowned along with its last prey (distraction sinking).
... Large volumes of phosphate in the body chamber of Upper Jurassic ammonites from Central Russia were produced during the decay of organic tissues -either ammonite body or organic debris (Zatoń and Mironenko, 2015). Phosphatic minerals usually cover all soft tissues remnants of these ammonites such as organic parts of ammonite jaws and siphuncle blood vessels (Mironenko, 2014;2017b). However, there is no organic debris or ammonite soft-tissue remnants in the studied shell and phosphatic minerals concentrate around the hermit crabthese facts are pieces of evidence in favor of a version that phosphate was produced during the decay of the hermit crab tissues, whereas it should be noted that the mold can also decay. ...
The discovery of a hermit crab (superfamily Paguroidea) preserved in the likely immature shell of an ammonite, Craspedites nekrassovi is reported from the Upper Jurassic of Moscow, Russia. This is the oldest undoubtable symmetrical hermit crab to date which is known from non-reefal environments. This new occurrence combined with the documentation of numerous sublethal and lethal injuries on ammonite shells in the same beds (probably produced by such paguroids), all suggest that the hermit crabs not only lived in ammonite shells but also hunted these animals. The proportion of damaged shells (including healed ones) varies in different Upper Jurassic ammonite genera from 1.2% in Kachpurites up to 9.3% in Craspedites. Among damaged Kachpurites only 6.25% survived attacks whereas among Craspedites the percentage of survivors was 87.5%. These data imply that Craspedites likely lived near the sea bottom and often encountered hermit crabs, whereas Kachpurites likely lived in the water column.
... Аптихи были найдены в келловейских отложениях в карьере Михайловцемент в Рязанской области (Рогов, 2004 a), в оксфордских отложениях у д. Рыбаки в Московской области (Rogov, Mironenko, 2016;Mironenko, 2017a, Рис. 5) и в волжских отложениях в Среднем Поволжье (Рогов, 2004 b), а также в карьере Еганово в Московской области и Карамышевская набережная на территории Москвы (Мироненко, 2014). Оксфордские и волжские аптихи были обнаружены в жилых камерах аммонитов, которым они принадлежали, что позволило сравнить размер аптихов с диаметром устья аммонитов. ...
Ammonoidea is a subclass of cephalopod mollusks that existed in the seas from the end of the Devonian to the very end of the Cretaceous. Due to the beauty and variety of the forms of ammonoid shells, they have become the subject of collecting, whereas their rapid evolution and widespread distribution made them an important tool for biostratigraphy. However, in spite of the abundance of ammonoid shells in Paleozoic and Mesozoic deposits, their popularity among professional and amateur paleontologists as well as their significance for stratigraphy, ammonoids themselves had remained highly enigmatic creatures until recently. However, in the last two decades the situation has improved significantly. New findings of well-preserved ammonoid shells shed light on the structure of the muscular system of ammonoids and areas of attachment of soft tissues to the shell, the structure of the siphuncle soft tissues, the digestive system and the jaw apparatus. A detailed study of the embryonic development of modern cephalopods and the latest discoveries in the evolution of the entire Cephalopoda allowed us to draw conclusions about the structure of those parts of the ammonoid soft body that have not yet been found in the fossil state. At present, it can be considered as proven that the ammonoids had well-developed eyes, a complex system of retractor muscles, a powerful hyponome and a wrinkle layer, similar to the black layer of Nautilida, which played an important role in the swimming and manoeuvrability of ammonoids. Ammonoids, like other cephalopods, initially had ten arms. The soft tissues of the siphuncle were similar to those of modern Nautilus, although they differed in some details. This publication summarizes current data on the anatomical structure of ammonoids, including those based on the findings made by the author in the Jurassic localities of Central Russia. It also discusses the paleobiology of ammonoids, such as in vivo orientation of their shells in the water, the mechanism of the swimming and ammonoid reproduction.
