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The marine conservation deposits of Monte San Giorgio (Switzerland, Italy): the prototype of Triassic black shale Lagerstätten
Swiss Journal of Palaeontology volume 143, Article number: 11 (2024)
Abstract
Marine conservation deposits (‘Konservat-Lagerstätten’) are characterized by their mode of fossil preservation, faunal composition and sedimentary facies. Here, we review these characteristics with respect to the famous conservation deposit of the Besano Formation (formerly Grenzbitumenzone; including the Anisian–Ladinian boundary), and the successively younger fossil-bearing units Cava inferiore, Cava superiore, Cassina beds and the Kalkschieferzone of Monte San Giorgio (Switzerland and Italy). We compare these units to a selection of important black shale-type Lagerstätten of the global Phanerozoic plus the Ediacaran in order to detect commonalities in their facies, genesis, and fossil content using principal component and hierarchical cluster analyses. Further, we put the Monte San Giorgio type Fossillagerstätten into the context of other comparable Triassic deposits worldwide based on their fossil content. The results of the principal component and cluster analyses allow a subdivision of the 45 analysed Lagerstätten into four groups, for which we suggest the use of the corresponding pioneering localities: Burgess type for the early Palaeozoic black shales, Monte San Giorgio type for the Triassic black shales, Holzmaden type for the pyrite-rich black shales and Solnhofen type for platy limestones.
Introduction
Since the pioneering work of Bernhard Peyer, who began his excavations in the Swiss canton of Ticino in 1924 (Lanz & Felber, 2020; Peyer, 1934), many books and articles have appeared about the conservation deposit of the Middle Triassic of Monte San Giorgio (for the dating of the section see Furrer et al., 2008); the latest comprehensive works are the volumes by Olivier Rieppel (2019) and by Heinz Lanz and Markus Felber (2020). Classically, the monographs (mostly published in the ‘Schweizerische Paläontologische Abhandlungen’, now the Swiss Journal of Palaeontology) on the vertebrates of this locality comprised the most important pioneering work. The rich fauna of fossil vertebrates provides a unique insight into the recovery of shallow marine ecosystems following the devastation of the largest mass extinction event in Earth history, the Permian–Triassic boundary mass extinction (Chen & Benton, 2012; Scheyer et al., 2014a). This fauna includes a broad array of remarkable marine reptiles (Figs. 1, 2), for which this Lagerstätte is arguably best known (e.g., Bürgin et al., 1989; Rieppel, 2019). In particular, the fascinating reptile Tanystropheus contributed to the fame of the Besano Formation (Fig. 1A). Originally known from fragmentary remains, mostly comprising highly elongated and hollow bones, these remarkable yet poorly understood remains led researchers to erroneous ideas about their systematic assignment (e.g., v. Meyer 1847–1855; Nopsca, 1923; Edinger, 1924). Only with the discovery of the spectacular skeletons excavated by Peyer at Monte San Giorgio did their correct identification become a possibility. Today, these elongate bones are known to be hyper-elongated cervical vertebrae that belonged to an extremely long necked, likely aquatic to semi-aquatic archosauromorph reptile (e.g., Beardmore & Furrer, 2017; Jaquier & Scheyer, 2017; Kuhn-Schnyder, 1959; Nosotti, 2007; Peyer, 1930, 1931a; Renesto, 2005; Spiekman & Mujal, 2023; Spiekman & Scheyer, 2019; Spiekman et al., 2020a, 2020b; Tschanz, 1986, 1988; Wild, 1973, 1980). Its terrestrial relative Macrocnemus was also studied by various authors (Herbst et al., 2021; Jaquier et al., 2017; Kuhn-Schnyder, 1962; Miedema et al., 2020; Nopcsa, 1930; Peyer, 1937; Premru, 1991; Renesto & Avanzini, 2002; Rieppel, 1989a; Saller, 2016).
Three important marine reptiles from the Middle Triassic of Monte San Giorgio with their reconstructions, recently crafted by Beat Scheffold. A Tanystropheus, PIMUZ T 2817. B Cyamodus, PIMUZ T58. C, Mixosaurus, PIMUZ T 4923 (top) and PIMUZ T 4376 (bottom)
To date, the fossil localities of Monte San Giorgio still represent the best-studied record of a Middle Triassic marine ecosystem worldwide, rich in marine reptiles, fishes, invertebrates, and plants (Fig. 3), which led to its recognition as a UNESCO World Heritage site in 2003 (Felber et al., 2004; https://whc.unesco.org/uploads/nominations/1090.pdf). Despite its long history, the relevance of the site is still increasing, both through continuing studies of the historical collections, and through comparisons to new abundant fossil material, especially also of marine reptiles, from contemporaneous sites on the eastern Tethys margin in what is now southern China (e.g., Benton et al., 2014).
Fossilized mollusks from the Middle Triassic of Monte San Giorgio (see Rieber, 1969, 1970, 1973; Pieroni, 2022). A, Proarcestes extralabiatus, internal mould. B, Repossia acutenodosa, silicified internal mould. C, Proarcestes extralabiatus, external mould. D, Phragmoteuthis ticinensis with complete arm crown, cephalic cartilage, oesophagus and ink sac. E, Daonella caudata. F, Pleuronautilus sp., internal mould
Besides Tanystropheus, there are of course other vertebrate fossils of scientific importance known from Monte San Giorgio (Figs. 1, 2, 4). These comprise, for example, the following vertebrate groups (for a more complete bibliography, see Albisetti & Furrer, 2022):
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The rauisuchian Ticinosuchus (e.g., Krebs, 1965; Lautenschlager & Desojo, 2011; Nesbitt, 2011; Pinna & Arduini, 1978);
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Placodonts (e.g., Kuhn, 1942; Kuhn-Schnyder, 1960; Neenan et al., 2014; Peyer, 1931b, 1931d; Pinna, 1992; Scheyer, 2010);
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Eosauropterygians (e.g., Beardmore & Furrer, 2016; Carroll & Gaskill, 1985; Cornalia, 1854; Hänni, 2004; Hugi, 2011; Hugi & Scheyer, 2012; Hugi et al., 2011; Kuhn-Schnyder, 1966, 1967, 1987; Mariani, 1923; Nosotti & Rieppel, 2003; Peyer, 1931c; Renesto, 1993; Rieppel, 1989b; Sander, 1988, 1989b);
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Thalattosaurs (e.g., Bastiaans et al., 2023a, 2023b; Klein et al., 2023; Kuhn, 1946a, 1946b, 1946c; Kuhn-Schnyder, 1988; Müller, 2005; Nopcsa, 1925; Peyer, 1936a, 1936b; Rieppel, 1987; Rieppel et al., 2005);
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Ichthyosaurs (e.g., Sander, 1989a; Brinkmann, 1996, 1998, 1999, 2004; Dal Sasso & Pinna, 1996; Maisch & Matzke, 1997, 1998; Maisch et al., 2006; Kolb et al., 2011; Pardo-Pérez et al., 2020; Renesto et al., 2020; Bindellini et al., 2021; Miedema et al., 2023), a recently prepared specimen is shown in Fig. 5;
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Chondrichthyans (e.g., Kuhn, 1946a; Mutter, 1998a, 1998b; Rieppel, 1981, 1982);
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Actinopterygians (e.g., Argyriou et al., 2016; Bürgin, 1990a, 1990b, 1992, 1995, 1999a, 1999b; Guttormsen, 1937; Kuhn, 1946b; Lombardo, 1999, 2013; Lombardo & Tintori, 2004; Lombardo et al., 2012; López-Arbarello et al., 2014, 2016, 2019; Maxwell et al., 2013, 2015; Mutter, 2001, 2004; Mutter & Herzog, 2004; Rieppel, 1985a, 1985b; Romano & Brinkmann, 2009; Scheyer et al., 2014a, 2014b; Schwarz, 1970; Tintori, 1990; Wilson et al., 2013);
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Sarcopterygians (e.g., Cavin et al., 2013, 2017a, 2017b; Ferrante & Cavin, 2023; Renesto & Stockar, 2018; Rieppel, 1980, 1985a, 1985b).
Reconstructions of some animals from Monte San Giorgio by Beat Scheffold. Note that not all of the depicted taxa may have co-occurred in time or in space (habitat depth, etc.). At Monte San Giorgio, the water depth was likely greater then shown in these images. A Meride Limestone (Ladinian). B Besano Formation (Anisian)
Exceptionally preserved ichthyosaur Mixosaurus cornalianus (Bassani, 1886). PIMUZ T 1839, Besano Formation, Monte San Giorgio (A). The skull of the specimen (C) is covered by a thin pyrite crust and in the pelvic region (B), some phosphatized soft-tissue remains are discernible. Mixosaurus belongs together with Neusticosaurus to the most common reptile fossils of the Besano Formation. This specimen was excavated in 1931 and prepared in 2019 by Christian Obrist
These materials gain increasing attention because of their usefulness for comparisons with related taxa from other Triassic localities. Especially in China, several localities have produced articulated skeletons, mostly of vertebrates, that resemble the Monte San Giorgio specimens not only morphologically, but also with respect to preservation and facies of the sedimentary matrix (e.g., Hu et al., 2011; Jiang et al., 2005, 2009, 2020; Li, 2006; Lu et al., 2018; Rieppel et al., 2000; Sun et al., 2016; Wang et al., 2008). This has revealed that there are numerous Triassic localities worldwide with more or less similar depositional conditions and thus fossil preservation as at Monte San Giorgio. Consequently, Monte San Giorgio has become a reference in research on this type of conservation deposits (cf. Arif et al., 2019; Benton et al., 2013, 2022; Frey et al., 2019; Seilacher, 1970, 1990; Seilacher et al., 1985).
Accordingly, we briefly outline the properties of the Besano Formation, Cava inferiore, Cava superiore, Cassina beds and the Kalkschieferzone of Monte San Giorgio. We compare these to those of other Triassic conservation deposits worldwide. For this purpose, we characterized the six Swiss Triassic conservation deposits and 39 other globally important Phanerozoic Lagerstätten including Ediacara using various sedimentological and palaeontological traits. These were then evaluated using multivariate analyses. The aims were (1) to identify similarities and differences of these Lagerstätten; (2) to identify the palaeoecological conditions in order (3) to better understand under which circumstances the various types of Lagerstätten have formed.
Methods
Here, we follow the approach of Frey et al. (2019) in using the questionnaire published by Seilacher et al. (1985) to compare marine conservation deposits starting with the Ediacaran through a variance–covariance principal component analysis. The variables included information (often absence/presence) on marine basin size, sedimentary facies, palaeolatitude (Fig. 6), thickness of the succession, duration of the time interval in which the exceptionally preserved fossils formed, sea level, sediment structures, pyrite in sediment, faunal composition, trace fossils, infauna, epibenthos, pelagic macrofossils, death marches, landing marks, soft parts, cuticles, roll marks, current alignment, aragonite, internal moulds (pyritic or other), concretions, deformation, carbonization, soft part preservation mode (phosphatization, pyritization, silicification or in clay minerals), and preservation by obrution, stagnation or microbial mats. For the analyses, we omitted ‘life position’, because this was uniformly coded as 0. The original dataset of Frey et al. (2019) included only 21 Lagerstätten.
Palaeogeographic map (modified after Scotese, 1997) with data from Brinkmann et al. (2010) and Benton et al. (2013). Note that most of the conservation deposits included here lie in tropical or moderate latitudes, while occurrences of disarticulated materials are also known from boreal to arctic regions (not differentiated here)
For this study, we added data of 34 localities to allow a global comparison of Triassic conservation deposits, which represents an incomplete but representative sample of known Lagerstätten (Tables 1, 2). Our list is not intended to be all inclusive for global Lagerstätten but was assembled with the intention of assessing the characteristics of the Triassic Monte San Giorgio in a global framework. For the Early Triassic, we included the Paris biota (Thaynes Fm) from Idaho, USA (Brayard et al., 2017; Doguzhaeva et al., 2018), the fauna from Kap Stosch, Greenland (Wordie Creek Fm; Brinkmann et al., 2010; Kear et al., 2016), the famous fish nodules from the Middle Sakamena Formation of Madagascar (Beltan, 1996; Brinkmann et al., 2010; Kogan & Romano, 2016), the ichthyosaur- and thalattosaur-bearing faunas of the Sulphur Mountain Formation from British Columbia and Alberta, Canada (Bastiaans et al., 2023a, 2023b; Neuman, 1992, 2015) and of the Vikinghøgda Formation in Svalbard (Hurum et al., 2018).
Since the various subunits of the Anisian and Ladinian strata at Monte San Giorgio bear different faunas, we discriminated between the Besano Formation, and the younger units Cava inferiore, Cava superiore, Cassina beds as well as the Kalkschieferzone (e.g., Stockar, 2010). For the Middle Triassic, we added several Chinese localities, which were highlighted as Konservat-Lagerstätten by Benton et al. (2013), being aware that there are several other important localities with articulated vertebrates in China. We assembled data for the localities Luoping, Yunnan (Guanling Fm; Hu et al., 2011), Panxian, Guizhou (Guanling Fm; Jiang et al., 2009), and Xingyi, Guizhou (Falang Fm; Lu et al., 2018). We complemented that list with some European Lagerstätten such as the Swiss Ducanfurgga (Prosanto Fm; Scheyer et al., 2017), which yielded some amazing vertebrate fossils recently (Cavin et al., 2017a, 2017b; Ferrante et al., 2023; Scheyer et al., 2017). Furthermore, we included data from the conservation deposits of the Prida Formation of Fossil Hill, Nevada (Kelley et al., 2016; Sander et al., 1994, 2021), Edgeøya, Svalbard (Botneheia Fm; Engelschiøn et al., 2023; Kear et al., 2016) and the Eosauropterygia-rich strata of the Gailtal in Carinthia (Partnach Fm; e.g., Rieppel, 1994; Tichy, 1998; Zapfe & König, 1980).
As far as the Late Triassic is concerned, we now included the Xiaowa Formation of Guanling, China (Jiang et al., 2005) as well as three European Lagerstätten. Austria has important conservation deposits of Late Triassic age, which received more attention recently. These are the Lunz Formation with the Polzberg biota (Lukeneder & Lukeneder, 2021, 2022, 2023) and the Seefeld Member of Wiestal (Hornung et al., 2019). From Italy, we included the Calcare di Zorzino (Tintori, 1992), which is renowned for the oldest pterosaurs and its splendid fish fauna. Of course, there are numerous more Triassic localities worldwide that yielded excellent fossils; a more comprehensive list was assembled by Brinkmann et al. (2010), but even this list needs an update.
As in Frey et al. (2019), we included the data of these 45 Lagerstätten listed in Tables 1 and 2 in principal component analyses on the variance–covariance matrix in PAST (Hammer et al., 2001). Eigenvalues are listed in Table 3. We then assembled data of the faunal composition and rough abundance estimates of the Triassic Lagerstätten in Table 4 with the eigenvalues in Table 5. We included rough estimates of relative abundances of most organism groups with a focus on eukaryotes, i.e. invertebrates are also included (for cephalopods, see, e.g., Airaghi, 1911; Rieber, 1969, 1970, 1973, 1974; Pieroni, 2022; Pohle et al. in press). Finer estimates of abundances can currently not be made since quantitative data are not available at the same precision for all localities and strata included in this analysis. We then ran another principal component analysis in PAST to compare the relative faunal composition of the Triassic sites (eigenvalues in Table 5). Additionally, we carried out hierarchical cluster analyses (paired group, Ward’s method) using the same datasets. The layout of all biplots was made with CorelDraw X8.
Results
Characteristics of the Konservatlagerstätten of Monte San Giorgio
Like several other Triassic conservation deposits, today’s Monte San Giorgio was located at the margin of the Tethys in a tropical latitude during the Middle Triassic (Fig. 6; see, e.g., Lu et al., 2018; Benton et al., 2013). Lithologically, the Besano Formation is dominated by light grey to dark grey dolomitized limestones and black shales (e.g., Arif et al., 2019; Bassani, 1886; Baumgartner et al., 2001; Bernasconi, 1994; Felber, 2006; Furrer, 1995, 2003, 2004; Röhl et al., 2001; Stockar et al., 2012). Most of the strata that yielded articulated vertebrate skeletons (sometimes with embryos or soft-tissue remains: Figs. 2B, 5) are thin-bedded and laminated black shales. In these respects, this Lagerstätte is quite similar to several of those from China (Guanling Fm of Luoping and Panxian, Falang Fm of Xingyi, Xiaowa Fm of Guanling; Benton et al., 2013). The fossiliferous Besano Formation is about 16 m thick and overlies the Salvatore Dolomite (Stockar, 2010). Above, the San Giorgio Dolomite and the Ladinian Meride Limestone follow; the latter contains further beds of Lagerstätten quality such as the Cava inferiore and superiore as well as the Cassina beds and the Kalkschieferzone (Stockar et al., 2010). Except for the somewhat more carbonatic Kalkschieferzone (hence the name), the other four units are dominated by finely laminated limestones and black shales (Stockar, 2010). Depending on the clay content, the fossils (including the bones) are flattened to varying degrees. This applies particularly to the articulated skeletons, although those preserved in carbonatic strata display three-dimensionally preserved bones, occasionally even undeformed. For a recent account of the fossil content with a focus on vertebrates, see Rieppel (2019).
Interestingly, the Besano Formation of Monte San Giorgio plotted somewhat separately from the other black shale deposits compared to the analysis of Frey et al. (2019) and in a different region than the other fossiliferous units at Monte San Giorgio (Fig. 7). In one of the cluster analyses (Fig. 8B), the Besano Formation formed a cluster with the Seefeld Member of Wiestal and the Cava superiore, while the other three units of Monte San Giorgio fell in a different place. In the PCA, the data points of all the Chinese Lagerstätten plot in the vicinity of the Cava inferiore and superiore, the Cassina beds and the Kalkschieferzone; this pattern was also found in the cluster analyses of Fig. 8. The data points of the classic black shales such as Holzmaden (Posidonia shale, Toarcian, Jurassic; Röhl et al., 2002), Bundenbach (Hunsrück slate, Emsian, Devonian; Bartels et al., 1998; De Baets et al., 2013) or Christian Malford (Oxford Clay, Jurassic; Wilby et al., 2008) lie in their own cluster (grey in Figs. 7, 8). In the PCA, the data point of the Besano Formation plots at the margin of the field of the Monte San Giorgio type conservation deposits and more or less between the fields occupied by Solnhofen type and the Holzmaden type Lagerstätten. This was expected considering that in all these deposits, flattened but articulated vertebrate skeletons are common, phosphatized soft-tissues are preserved, and pyritization occurs, albeit to differing extends (very common in the Hunsrück slate and the Posidonia shale while relatively rare in the Besano Formation: Fig. 5). Importantly, the facies of Monte San Giorgio is intermediate given the fact that it contains both laminated limestones and black shales. Accordingly, the Kalkschieferzone and Cava inferiore plot closer to the Solnhofen type in Fig. 7B. Fossil preservation, faunal composition (lack or scarcity of benthos), sedimentary facies, and the palaeogeographical setting suggest at least episodically anoxic conditions (Röhl et al., 2001; Stockar et al., 2012).
Classification of marine conservation deposits using a variation–covariation principal components analysis and the characterization of the Besano Formation of Monte San Giorgio (red margin). Data are listed in Tables 1 and 2. Modified after Frey et al. (2019). Note that among Triassic deposits, Monte San Giorgio, the Paris biota (Thaynes Fm) and Polzberg (Lunz Fm) are the only ones plotting close to the classic Black Shale Lagerstätten in A. A PCA 1 and 2; B PCA 2 and 3
Classification of marine conservation deposits using cluster analyses. A paired groups. B Ward’s method. Note how in both cases, the Solnhofen and Holzmaden type Lagerstätten cluster well
Triassic marine conservation deposits worldwide
As mentioned above, numerous Triassic localities with preservation modes similar to those known from the fossiliferous beds at Monte San Giorgio have been discovered in South China in the last decades (e.g., Benton et al., 2013; Li, 2006; Lu et al., 2018). Some are from the Early Triassic (Chaoxian, Nanzhang, Wuming, Yuan’an), several from the Middle Triassic (Dingxiao, Guiyang, Fuyuan, Luoping, Luxi, Panxian, Qingzhen, Renhuai, Xingyi) and at least three from the Late Triassic (Guanling, Nylamu, Tingri). Although fossil preservation surprisingly often resembles that of the Besano Formation of Monte San Giorgio (Xiaowa Fm of Guanling, Daye Fm of Guiyang, Guanling Fm of Panxian, Falang Fm of Xingyi), the overall taxonomic composition is similar but differs in key aspects (Table 4, Figs. 9, 10). Also, the respective abundances of the various vertebrate groups are not identical (Benton et al., 2013). The upper part of the Besano Formation yielded many fishes, Neusticosaurus (a pachypleurosaurid eosauropterygian) and Mixosaurus (an ichthyosaur), while some of the Chinese localities like the Xiaowa Fm of Guanling (Benton et al., 2013; Liu et al., 2013; Rieppel, 2019; Wang et al., 2008) are, e.g., rich in thalattosaurs. Furthermore, the huge pseudoplanktonic crinoid colonies of Traumatocrinus present at Guanling (Hagdorn et al., 2007) are unknown from the Alpine occurrences but are comparable to the driftwood crinoid colonies of Moroccocrinus of Late Devonian age from Morocco (Frey et al., 2018, 2019; Klug et al., 2003) and Seirocrinus found in the Jurassic Posidonia shale (e.g., Hess, 1999).
Classification of Triassic marine conservation deposits based on abundances of fossil groups using a variation–covariation principal components analysis and the characterization of the fossiliferous units of Monte San Giorgio (red margin). Data are listed in Table 4. Note the similarity in faunal composition of Monte San Giorgio and the Chinese Lagerstätten. The Paris biota (Thaynes Fm) and Polzberg (Lunz Fm) are special in being more invertebrate dominated. The fish localities overlap with those with abundant reptiles (e.g., Ducan). A PCA 1 and 2; B PCA 2 and 3. Reptiles in the graph stands for other reptile groups
Classification of Triassic marine conservation deposits based on abundances of fossil groups using a hierarchical cluster analysis and the characterization of the fossiliferous units of Monte San Giorgio (red margin). Data are listed in Table 4
In addition to the Chinese occurrences, well comparable conservation deposits of Triassic age with black shale characteristics in a broad sense (i.e. dark sediment, complete skeletons, poor in benthos, rich in clay) have been recognized in many other places. Examples for such deposits have been documented from Europe (eastern Switzerland, Ducan: Furrer, 2004; western Austria: Zapfe & König, 1980; Wachtler & Perner, 2018; Italy: Stefani et al., 1991; Slovakia: Čerňanský et al., 2018; Slovenia: Hitij et al., 2010), Asia (Spiti, India: Romano et al., 2016; Myanmar: San et al., 2019), and North America (Idaho: Brayard et al., 2017; Nevada: Romano et al., 2019).
Our principal components analysis shown in Fig. 9 allows a classification according to the abundance of (i) more pelagic groups such as ammonoids, fishes and ichthyosaurs; (ii) more neritic groups such as eosauropterygians or tanystrophaeids or (iii) generally invertebrates. Remarkably, the data points of Cava inferiore, Cava superiore, Cassina Beds and the Kalkschieferzone again plotted closer to each other than to the point of the Besano Formation. This pattern is also seen in the cluster analysis in Fig. 10. When regarding the PC1/PC2-plot, the Besano Formation-point is in the field of Lagerstätten with abundant invertebrates, while when regarding PC2 and PC3, it falls quite central in the neritic groups/ reptile-dominated field, possibly due to the abundance of eosauropterygians, thalattosaurs and placodonts. The other four units of Monte San Giorgio fall in their own field in the PC2/PC3-plot with other neritic animal-dominated Lagerstätten.
Discussion
In our principal component analysis presented in Fig. 7, it is remarkable how well especially the platy limestones (Solnhofen type) separate from all other marine Lagerstätten, at least in PC1 and PC2. The German localities plot even closer together within this field (lower right corner in Fig. 7A). They formed their own cluster in both cluster analyses (Fig. 8). The Palaeozoic localities of the Cambrian and Ordovician also fell in a quite well delineated field, which comprises all of the Burgess type both in the PCA and in one of the cluster analyses (Fig. 8A). Likewise, the classic black shale occurrences (Holzmaden type) plot close to each other in the PCA and in both cluster analyses (Fig. 8), while the Monte San Giorgio type organic-rich deposits are somewhat scattered in the PCA (Fig. 7), occupying a large but separate field, thus suggesting a somewhat variable palaeoenvironment. Remarkably, this includes occurrences of Early, Middle and Late Triassic age. It is worth mentioning that this pattern remained stable even after several changes in the matrix. Unsurprisingly, the localities of the Chinese Triassic included here lie quite close to each other in the PCA and the cluster analyses. It is also noteworthy that, in the PC2/PC3-plot (Fig. 7B), the field of the Triassic Monte San Giorgio type Lagerstätten overlaps the fields comprising the black shales deposits of the Holzmaden and the Burgess type as well as the platy limestones of the Solnhofen type. The data points of the only Proterozoic Lagerstätten Ediacara and the obrution deposit Gmünd (Psilonotenton) usually fall more or less separate from the other points both in the PCAs and the cluster analyses.
The peculiar grouping of Monte San Giorgio type Lagerstätten (Figs. 7A, 8A, 9B), is remarkable. We suggest that the highly unusual palaeoecological conditions needed to produce the sedimentary facies of these fossiliferous beds can be explained by the long-term effects of the Permian–Triassic boundary mass extinction (Benton, 2016; Burgess et al., 2014). This created a palaeoenvironment with low oxygen conditions, euxinia, and acidification (Galfetti et al., 2007; Goudemand et al., 2019; Payne et al., 2004, 2012; Romano et al., 2013) and other special conditions, that were unusually widespread throughout much of the Triassic. In turn, this is linked with low diversity benthos in many basins including a slow reef recovery (Benton, 2016).
In our second analysis, we focused on the faunal composition of the Monte San Giorgio type Lagerstätten. The Paris (Idaho; Thaynes Fm) and Polzberg biota (Austria; Lunz Fm) yield abundant and diverse invertebrates and plot near each other in both the PCA (Fig. 9) and the cluster analyses (Fig. 10). The other localities are distributed over the PCA-biplots according to whether their fauna is rather dominated by pelagic or neritic animals. A similar result was found in the cluster analyses, although the grouping differs somewhat (Fig. 10). In the PC1–PC2 plot, the Besano Formation of Monte San Giorgio is nested between the invertebrate dominated localities, while in the PC2–PC3 plot, it falls in the field with abundant thalattosaurs, placodonts and other more neritic animals, similar to some Chinese localities.
To some degree, the groupings correspond to our expectations, i.e. we knew that the localities of Madagascar (Sakamena Fm) and Ducanfurgga (Prosanto Fm) are fish-dominated while invertebrates are very common in the biotas of Polzberg (Lunz Fm) and Paris (Thaynes Fm). The question arises to what extent the results depend on the sampling effort and the quality of the documentation of discoveries. Particularly, the discovery of larger vertebrates may depend on larger excavations over longer time spans. Future excavations in other localities should optimally be bed-by-bed like many excavations at Monte San Giorgio and should document abundance data (specimen counts per bed per surface area or rock volume). Although the Besano Formation at Monte San Giorgio has become one Triassic marine conservation deposit out of many, it is the pioneer of this kind of deposit in the Triassic and will remain an important reference in the future. Accordingly, we consider it adequate to name this kind of Triassic conservation deposits ‘Monte San Giorgio type Lagerstätten’.
Conclusions
The conservation deposits of Anisian and Ladinian age of Monte San Giorgio, comprising the Besano Formation, Cava inferiore, Cava superiore, Cassina Beds, and the Kalkschieferzone, represent some of the first black shale conservation deposits of Triassic age that were thoroughly studied. Now, after a century of excavations and more than a century of research, these deposits begin to enjoy global scientific recognition (e.g., Etter, 2002a; Rieppel, 2019), and continue to produce valuable new information about the palaeobiology and evolution of Triassic vertebrates today.
With this paper, we want to highlight the key role of the conservation deposits of Monte San Giorgio: comparable to the pioneer role of the Burgess Shale for the Cambrian Lagerstätten or Solnhofen for the Mesozoic platy limestones, we highlight the pioneer role of the Besano Formation in particular as the prototype for Triassic Lagerstätten. Our simple comparison of 45 Fossillagerstätten worldwide employing principal component and hierarchical cluster analyses of 32 traits based on the list of Seilacher et al. (1985) confirm that the Besano Formation of Monte San Giorgio Lagerstätte is remarkably similar to other Triassic black shale deposits including, e.g., those of the Swiss Ducanfurgga and the South China block. The Triassic black shale deposits demonstrably occupy their own field separate from the Burgess type black shales, Solnhofen type platy limestones or Holzmaden type black shales. Accordingly, we introduce the term Monte San Giorgio type black shales.
The separate position of the Monte San Giorgio type organic-rich sediments can be explained by the mix of laminated limestones and black shales and the scarcity of benthics, as well as the rise of several new groups such as important clades of marine reptiles. This is to some extent very likely an effect of the long-term ecological impact of the Permian–Triassic boundary mass extinction and the recovery of marine biotas.
Concerning the fossil content of the Monte San Giorgio type Lagerstätten, we found the three main groups ‘pelagic dominated’, ‘neritic dominated’ and ‘invertebrate dominated’. For some of the included Lagerstätten, the position in the PCA-plots and the cluster analyses was expected, for some others we suspect that over the years, more vertebrates and particularly reptiles may be discovered with longer or increased collecting/sampling activities. Accordingly, the respective position might change in the future.
References
Airaghi, C. (1911). Ammoniti degli scisti bituminosi di Besano in Lombardia. Bollettino Della Società Geologica Italiana, 30, 1048–1050.
Albisetti, D., & Furrer, H. (2022). Bibliografia del Monte San Giorgio (p. 27). Fondazione del Monte San Giorgio.
Argyriou, T., Clauss, M., Maxwell, E. E., Furrer, H., & Sánchez-Villagra, M. R. (2016). Exceptional preservation reveals gastrointestinal anatomy and evolution in early actinopterygian fishes. Scientific Reports, 6, 18758. https://doi.org/10.1038/srep18758
Arif, S., Reitner, J., & Hoppert, M. (2019). Composition, diversity and functional analysis of the modern microbiome of the Middle Triassic Cava Superiore Beds (Monte San Giorgio, Switzerland). Scientific Reports, 9(1), 20394.
Arratia, G., Schultze, H.-P., Tischlinger, H., & Viohl, G. (2015). Solnhofen: Ein Fenster in die Jurazeit (p. 620). Pfeil.
Bartels, C., Briggs, D. E. G., & Brassel, G. (1998). The Fossils of the Hunsrück Slate. Marine Life in the Devonian. Cambridge Paleobiology Series, 3, 1–309.
Bassani, F. (1886). Sui fossili e sull’eta degli schisti bituminosi triasici di Besano in Lombardia. Atti Societa Italiana Di Scienze Naturali, 29, 15–72.
Bastiaans, D., Buffa, V., & Scheyer, T. M. (2023a). To glide or to swim? A reinvestigation of the enigmatic Wapitisaurus problematicus (Reptilia) from the Early Triassic of British Columbia. Canada. Royal Society Open Science, 10(11), 231171.
Bastiaans, D., Herbst, E. C., Van de Kamp, T., Zuber, M., & Scheyer, T. M. (2023). The first 3D cranial and myological reconstruction of the highly flattened remains of Askeptosaurus italicus (Diapsida: Thalattosauriformes). Abstracts of the International Congress of Vertebrate Morphology, 28. July-01. August 2023, Cairns, Australia.
Baumgartner, P. O., Bernoulli, D., & Martire, L. (2001). Mesozoic pelagic facies of the Southern Alps: Paleotectonics and paleoceanography. International Association of Sedimentologists, Davos: Field Trip Guide, Excursion A 1 (pp. 1–19).
Beardmore, S. R., & Furrer, H. (2016). Preservation of Pachypleurosauridae (Reptilia, Sauropterygia) from the Middle Triassic of Monte San Giorgio, Switzerland. Neues Jahrbuch Für Geologie Und Paläontologie, Abhandlungen, 280, 221–240.
Beardmore, S. R., & Furrer, H. (2017). Land or water: Using taphonomic models to determine the lifestyle of the Triassic protorosaur Tanystropheus (Diapsida, Archosauromorpha). Palaeobiodiversity and Palaeoenvironments, 98, 243–258.
Bernasconi, S. M. (1994). Geochemical and microbial controls on dolomite formation in anoxic environments: A case study from the middle Triassic (Ticino, Switzerland). Contributions to Sedimentology, 19, 1–109.
Beltan, L. (1996). Overview of systematics, paleobiology, and paleoecology of Triassic fishes of northwestern Madagascar. In G. Arratia & G. Viohl (Eds.), Mesozoic fishes—systematics and paleoecology (pp. 479–500). Verlag Dr. Friedrich Pfeil.
Benton, M. J. (2016). The Triassic. Current Biology, 26, R1214–R1218. https://doi.org/10.1016/j.cub.2016.10.060
Benton, M., Hu, S., Zhang, Q., Xie, T., Zhou, C., Wen, W., & Huang, J. (2022). Establishment of the Luoping Biota National Geopark in Yunnan, China. Geoconservation Research, 5, 261–284.
Benton, M. J., Zhang, Q., Hu, S., Chen, Z.-Q., Wen, W., Liu, J., Huang, J., Zhou, C., Xie, T., Tong, J., & Choo, B. (2013). Exceptional vertebrate biotas from the Triassic of China, and the expansion of marine ecosystems after the Permo-Triassic mass extinction. Earth-Science Reviews, 137, 85–128. https://doi.org/10.1016/j.earscirev.2013.05.014
Bindellini, G., Wolniewicz, A. S., Miedema, F., Scheyer, T. M., & Dal Sasso, C. (2021). Cranial anatomy of Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio, Italy/Switzerland: Taxonomic and palaeobiological implications. PeerJ, 9, 1–66. https://doi.org/10.7717/peerj.11179
Brayard, A., Krumenacker, J., Botting, J. P., Jenks, J., Bylund, K. G., Fara, E., Vennin, E., Olivier, N., Goudemand, N., Saucède, T., Charbonnier, S., Romano, C., Doguzhaeva, L., Thuy, B., Hautmann, M., Stephen, D. A., Thomazo, C., & Escarguel, G. (2017). Unexpected Early Triassic marine ecosystem and the rise of the Modern evolutionary fauna. Science Advances, 3, e1602159. https://doi.org/10.1126/sciadv.1602159
Briggs, D. E. G., Erwin, D. H., & Collier, F. J. (1994). The Fossils of the Burgess Shale (p. 238). Smithsonian Books.
Brinkmann, W. (1996). Ein Mixosaurier (Reptilia, Ichthyosauria) mit Embryonen aus der Grenzbitumenzone (Mitteltrias) des Monte San Giorgio (Schweiz, Kanton Tessin). Eclogae Geologicae Helvetiae, 89, 1321–1344.
Brinkmann, W. (1998). “Sangiorgiosaurus” n.g.-eine neue Mixosaurier-Gattung (Mixosauridae, Ichthyosauria) mit Quetschzähnen aus der Grenzbitumenzone (Mitteltrias) des Monte San Giorgio (Schweiz, Kanton Tessin). Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 207, 125–144.
Brinkmann, W. (1999). Ichthyosaurus cornalianus Bassani, 1886 (currently Mixosaurus cornalianus; Reptilia, Ichthyosauria): Proposed designation of a neotype. Case 3122. Bulletin of Zoological Nomenclature, 56, 247–249.
Brinkmann, W. (2004). Mixosaurier (Reptilia, Ichthyosauria) mit Quetschzähnen aus der Grenzbitumenzone (Mitteltrias) des Monte San Giorgio (Schweiz, Kanton Tessin). Schweizerische Paläontologische Abhandlungen, 124, 1–84.
Brinkmann, W., Romano, C., Bucher, H., Ware, D., & Jenks, J. (2010). Palaeobiogeography and stratigraphy of advanced gnathostomian fishes (Chondrichthyes and Osteichthyes) in the Early Triassic and from selected Anisian localities (Report 1863–2009). Zentralblatt Für Geologie Und Paläontologie, 2, 765–812.
Burgess, S. D., Bowring, S., & Shen, S. (2014). High-precision timeline for Earth’s most severe extinction. Proceedings of the National Academy of Sciences, 111, 3316–3321. https://doi.org/10.1073/pnas.1317692111
Bürgin, T. (1990a). Der Schuppenpanzer von Habroichthys minimus, einem ungewöhnlichen Strahlenflosser (Actinopterygii; Peltopleuriformes) aus der Mittleren Trias der Südalpen. Neues Jahrbuch Für Geologie Und Paläontologie, Abhandlungen, 1990(11), 647–658.
Bürgin, T. (1990b). Reproduction in Middle Triassic actinopterygians; complex fin structures and evidence of viviparity in fossil fishes. Zoological Journal of the Linnean Society, 100, 379–391.
Bürgin, T. (1992). Basal ray-finned fishes (Osteichthyes; Actinopterygii) from the middle Triassic of Monte San Giorgio (Canton Tessin, Switzerland): Systematic palaeontology with notes on functional morphology and palaeoecology. Schweizerische Paläontologische Abhandlungen, 114, 1–164.
Bürgin, T. (1995). Actinopterygian fishes (Osteichthyes; Actinopterygii) from the Kalkschieferzone (Uppermost Ladinian) near Meride (Canton Ticino, Southern Switzerland). Eclogae Geologicae Helvetiae, 88, 803–826.
Bürgin, T. (1999a). Middle Triassic marine fish faunas from Switzerland. Mesozoic Fishes, 2, 481–494.
Bürgin, T. (1999b). New actinopterygian fishes (Osteichthyes) from the lower Meride Limestones (Lower Ladinan) of Acqua del Ghiffo (Monte San Giorgio, Southern Switzerland). In: 3rd International symposium on lithographic limestones. Rivista Museo civico Scienze Naturali “Enrico Caffi“, Suppl. al Vol. 20, 57–62.
Bürgin, T., Rieppel, O., Sander, P. M., & Tschanz, K. (1989). The fossils of Monte San Giorgio. Scientific American, 260, 74–81.
Carroll, R. L., & Gaskill, P. (1985). The nothosaur Pachypleurosaurus and the origin of plesiosaurs. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 309(1139), 343–393.
Cavin, L., Furrer, H., & Obrist, C. (2013). New coelacanth material from the Middle Triassic of eastern Switzerland, and comments on the taxic diversity of actinistians. Swiss Journal of Geosciences, 106, 161–177.
Cavin, L., Mennecart, B., Obrist, C., Costeur, L., & Furrer, H. (2017a). Heterochronic evolution explains unusual body shape in a Triassic coelacanth from Switzerland. Scientific Reports, 7(13695), 1–7. https://doi.org/10.1038/s41598-017-13796-0
Cavin, L., Mennecart, B., Obrist, C., Costeur, L., & Furrer, H. (2017b). Heterochronic evolution explains novel body shape in a Triassic coelacanth from Switzerland. Scientific Reports, 7, 13695. https://doi.org/10.1038/s41598-017-13796-0
Čerňanský, A., Klein, N., Soták, J., Olšavský, M., Šurka, J., & Herich, P. (2018). A Middle Triassic pachypleurosaur (Diapsida: Eosauropterygia) from a restricted carbonate ramp in the Western Carpathians (Gutenstein Formation, Fatric Unit): Paleogeographic implications. Geologica Carpathica, 69, 3–16. https://doi.org/10.1515/geoca-2018-0001
Charbonnier, S. (2009). Le Lagerstätte de La Voulte: Un environnement bathyal au Jurassique (p. 272). Publications scientifiques du Muséum Paris.
Chen, Z.-Q., & Benton, M. J. (2012). The timing and pattern of biotic recovery following the end-Permian mass extinction. Nature Geoscience, 5, 375–383. https://doi.org/10.1038/ngeo1475
Cornalia, E. (1854). Notizie zoologiche sul Pachypleura edwardsii Cor. Nuovo sauro acrodonte degli strati triasici di Lombardia. Giornale Dell’istituto Lombardo Di Scienze, Lettere Ed Arti, 6, 45–56.
Dal Sasso, C., & Pinna, G. (1996). Besanosaurus leptorhynchus n. gen. n. sp., a new shastasaurid ichthyosaur from the Middle Triassic of Besano (Lombardy, N. Italy). Paleontologia Lombarda, Ns., 4, 1–23.
De Baets, K., Klug, C., Korn, D., Bartels, C., & Poschmann, M. (2013). Emsian Ammonoidea and the age of the Hunsrück Slate (Rhenish Mountains, Western Germany). Palaeontographica A, 299, 1–114.
Dietl, G., & Schweigert, G. (2001). Im Reich der Meerengel. Pfeil Verlag.
Doguzhaeva, L. A., Brayard, A., Goudemand, N., Krumenacker, L. J., Jenks, J. F., Bylund, K. G., Fara, E., Olivier, N., Vennin, E., & Escarguel, G. (2018). An Early Triassic gladius associated with soft tissue remains from Idaho, USA—a squid-like coleoid cephalopod at the onset of Mesozoic Era. Acta Palaeontologica Polonica, 63, 341–355.
Du, Y., Song, H., Dal Corso, J., Wang, Y., Zhu, Y., Song, H., Tian, L., Chu, D., Huang, J., & Tong, J. (2023). Paleoenvironments of the Lower Triassic Chaohu Fauna, South China. Palaeogeography, Palaeoclimatology, Palaeoecology, 617, 1–10. https://doi.org/10.1016/j.palaeo.2023.111497
Edinger, T. (1924). Rückenmark im Wirbelkörper! Anatomischer Anzeiger, 57, 515–519.
Engelschiøn, V. S., Roberts, A. J., With, R., & Hammer, Ø. (2023). Exceptional X-Ray contrast: Radiography imaging of a Middle Triassic mixosaurid from Svalbard. PLoS ONE, 18(5), e0285939. https://doi.org/10.1371/journal.pone.0285939
Ehiro, M. (2022). Latest Olenekian (Early Triassic) Ammonoids from the Uppermost Part of the Osawa Formation (Inai Group) in the South Kitakami Belt, Northeast Japan. Paleontological Research, 26, 137–157. https://doi.org/10.2517/PR200027
Etter, W. (2002a). Monte San Giorgio: Remarkable Triassic marine vertebrates. In D. J. Bottjer, W. Etter, J. W. Hagadorn, & C. M. Tang (Eds.), Exceptional Fossil Preservation (pp. 221–242). Columbia University Press.
Etter, W. (2002b). La Voulte-sur-Rhône: Exquisite cephalopod preservation. In D. J. Bottjer, W. Etter, J. W. Hagadorn, & C. M. Tang (Eds.), Exceptional fossil preservation (p. 403). Columbia University Press.
Felber, M. (2006). Il Monte San Giorgio (p. 222). Edizioni Casagrande: Dai fossili alla lavorazione artistica della pietra.
Felber, M., Furrer, H., & Tintori, A. (2004). The Triassic of Monte San Giorgio in the World Heritage List of UNESCO: An opportunity for science, the local people and tourism. Eclogae Geologicae Helvetiae, 97, 1–2.
Ferrante, C., & Cavin, L. (2023). Early Mesozoic burst of morphological disparity in the slow-evolving coelacanth fish lineage. Scientific Reports, 13, 11356. https://doi.org/10.1038/s41598-023-37849-9
Forey, P. L., Yi, L., Patterson, C., & Davies, C. E. (2003). Fossil fishes from the Cenomanian (Upper Cretaceous) of Namoura, Lebanon. Journal of Systematic Palaeontology, 1, 227–330.
Frey, L., Pohle, A., Rücklin, M., & Klug, C. (2019). Fossil-Lagerstätten and preservation of vertebrates and invertebrates from the Devonian of Morocco (eastern Anti-Atlas). Lethaia, 53, 242–266. https://doi.org/10.1111/let.12354
Frey, L., Rücklin, M., Korn, D., & Klug, C. (2018). Late Devonian and Early Carboniferous alpha diversity, ecospace occupation, vertebrate assemblages and bio-events of southeastern Morocco. Palaeogeography, Palaeoclimatology, Palaeoecology, 496, 1–17.
Furrer, H. (1995). The Kalkschieferzone (Upper Meride Limestone; Ladinian) near Meride (Canton Ticino, Southern Switzerland) and the evolution of a Middle Triassic intraplatform basin. Eclogae Geologicae Helvetiae, 88, 827–852.
Furrer, H. (2003). Der Monte San Giorgio im Südtessin -Vom Berg der Saurier zur Fossil-Lagerstätte internationaler Bedeutung. Neujahrsblatt Der Naturforschenden Gesellschaft Zürich, 206, 1–64.
Furrer, H. (2004). So kam der Fisch auf den Berg—Eine Broschüre zur Sonderausstellung über die Fossilfunde am Ducan. Bündner Natur-Museum Chur und Paläontologisches Institut und Museum der Universität Zürich. 32.
Furrer, H., Schaltegger, U., Ovtcharova, M., & Meister, P. (2008). U-Pb zircon age of volcaniclastic layers in Middle Triassic platform carbonates of the Austroalpine Silvretta nappe (Switzerland). Swiss Journal of Geosciences, 101, 595–603.
Galfetti, T., Bucher, H., Brayard, A., Hochuli, P. A., Weissert, H., Guodun, K., Atudorei, V., & Guex, J. (2007). Late Early Triassic climate change: Insights from carbonate carbon isotopes, sedimentary evolution and ammonoid paleobiogeography. Palaeogeography, Palaeoclimatology, Palaeoecology, 243, 394–411.
Goudemand, N., Romano, C., Leu, M., Bucher, H., Trotter, J. A., & Williams, I. S. (2019). Dynamic interplay between climate and marine biodiversity upheavals during the early Triassic Smithian-Spathian biotic crisis. Earth-Science Reviews, 195, 169–178.
Grogan, E. D., & Lund, R. (2002). The geological and biological environment of the Bear Gulch Limestone (Mississippian of Montana, USA) and a model for its deposition. Geodiversitas, 24, 295–315.
Guttormsen, S. E. (1937). Beitrage zur Kenntnis des Ganoidengebisses, insbesondere des Gebisses von Colobodus. Schweizerische Paläontologische Abhandlungen, 56, 1–41.
Hagdorn, H., Wang, X., & Wang, C. (2007). Palaeoecology of the pseudoplanktonic Triassic crinoid Traumatocrinus from Southwest China. Palaeogeography, Palaeoclimatology, Palaeoecology, 247, 181–196.
Hammer, Ø., Harper, D. A. T., & Ryan, P. D. (2001). PAST: Palaeontological statistics software package for education and data analysis. Palaeontologia Electronica, 4, 1–9.
Hänni, K. (2004). Die Gattung Ceresiosaurus. Ceresiosaurus calgagnii Peyer und Ceresiosaurus lanzi n. sp. (Lariosauridae, Sauropterygia). PhD Thesis. Paläontologisches Institut und Museum, University of Zürich, Zürich. 146.
Hemleben, C., & Freels, D. (1977). Algen-laminierte und gradierte Plattenkalke in der Oberkreide Dalmatiens (Jugoslawien). Neues Jahrbuch Für Geologie Und Paläontologie, Abhandlungen, 154, 61–93.
Herbst, E. C., Lautenschlager, S., Bastiaans, D., Miedema, F., & Scheyer, T. M. (2021). Modeling tooth enamel in FEA comparisons of skulls: comparing common simplifications with biologically realistic models. iScience, 24, 103182. https://doi.org/10.1016/j.isci.2021.103182
Hess, H. (1999). Lower Jurassic Posidonia Shale of Southern Germany. In H. Hess, W. I. Ausich, C. E. Brett, & M. J. Simms (Eds.), Fossil crinoids (pp. 183–196). Cambridge University Press.
Hitij, T., Žalohar, J., Celarc, B., Križnar, M., Renesto, S., & Tintori, A. (2010). The kingdom of Tethys: The fossilized world of Triassic vertebrates from the Kamniško-Savinjske Alps. Scopolia, 5, 1–212.
Hornung, T., Kogan, I., Moosleitner, G., Wolf, G., & van der Wielen, J. (2019). The Norian fish deposits of Wiestal (“Seefeld Member”, Northern Calcareous Alps, Salzburg, Austria)—taxonomy and palaeoenvironmental implications. Austrian Journal of Earth Sciences, 112, 125–165. https://doi.org/10.17738/ajes.2019.0008
Hu, S.-X., Zhang, Q.-Y., Chen, Z.-Q., Zhou, C.-Y., Lu, T., Xie, T., Wen, W., Huang, Y.-J., & Benton, M. J. (2011). The Luoping biota: Exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction. Proceedings of the Royal Society B, 278, 2274–2282. https://doi.org/10.1098/rspb.2010.2235
Hugi, J. (2011). The long bone histology of Ceresiosaurus (Sauropterygia, Reptilia) in comparison to other eosauropterygians from the Middle Triassic of Monte San Giorgio (Switzerland/Italy). Swiss Journal of Palaeontology, 130, 297–306.
Hugi, J., & Scheyer, T. M. (2012). Ossification sequences and associated ontogenetic changes in the bone histology of pachypleurosaurids from Monte San Giorgio (Switzerland/Italy). Journal of Vertebrate Paleontology, 32, 315–327.
Hugi, J., Scheyer, T. M., Sander, P. M., Klein, N., & Sánchez-Villagra, M. R. (2011). Long bone microstructure gives new insights into the life of pachypleurosaurids from the Middle Triassic of Monte San Giorgio, Switzerland/Italy. Comptes Rendus Palevol, 10, 413–426.
Hurum, J. H., Engelschiøn, V. S., Økland, I., Bratvold, J., Ekeheien, C. P., Roberts, A. J., Delsett, L. L., Hansen, B. B., Mørk, A., Nakrem, H. A., Druckenmiller, P. S., & Hammer, Ø. (2018). The history of exploration and stratigraphy of the Early to Middle Triassic vertebrate-bearing strata of Svalbard (Sassendalen Group, Spitsbergen). Norwegian Journal of Geology, 98, 165–174.
Jaquier, V. P., Fraser, N. C., Furrer, H., & Scheyer, T. M. (2017). Osteology of a new specimen of Macrocnemus aff. M. fuyuanensis (Archosauromorpha, Protorosauria) from the Middle Triassic of Europe: implications for species recognition and paleogeography of tanystropheid protorosaurs. Frontiers in Earth Science, 5, 91. https://doi.org/10.3389/feart.2017.00091
Jaquier, V. P., & Scheyer, T. M. (2017). Bone histology of the Middle Triassic long-necked reptiles Tanystropheus and Macrocnemus (Archosauromorpha, Protorosauria). Journal of Vertebrate Paleontology, 37, e1296456. https://doi.org/10.1080/02724634.2017.1296456
Jiang, D., Motani, R., Hao, W., Rieppel, O., Sun, Y., Tintori, A., Sun, Z., & Schmitz, L. (2009). Biodiversity and sequence of the Middle Triassic Panxian marine reptile fauna, Guizhou Province, China. Acta Geologica Sinica, English Edition, 83, 451–459.
Jiang, D., Motani, R., Li, C., Hao, W., Sun, Y., Sun, Z., & Schmitz, L. (2005). Guanling Biota: A marker of Triassic biotic recovery from the end-Permian extinction in the ancient Guizhou Sea. Acta Geologica Sinica, English Edition, 79, 715–859.
Jiang, D.-Y., Motani, R., Tintori, A., Rieppel, O., Ji, C., Zhou, M., Wang, X., Lu, H., & Li, Z.-G. (2020). Evidence supporting predation of 4-m marine reptile by Triassic megapredator. iScience, 23(9), 10147. https://doi.org/10.1016/j.isci.2020.101347
Kear, B. P., Lindgren, J., Hurum, J. H., Milan, J., & Vajda, V. (2016). An introduction to the Mesozoic biotas of Scandinavia and its Arctic territories. In B. P. Kear, J. Lindgren, J. H. Hurum, J. Milan, & V. Vajda (Eds.), Mesozoic biotas of Scandinavia and its Arctic territories (Vol. 434, p. 15). Geological Society, Special Publications.
Kelley, N. P., Motani, R., Embree, P., & Orchard, M. J. (2016). A new Lower Triassic ichthyopterygian assemblage from Fossil Hill, Nevada. PeerJ, 4(e1626), 1–16. https://doi.org/10.7717/peerj.1626
Klein, N., Sander, P. M., Liu, J., Druckenmiller, P. S., Metz, E., Kelley, N. P., & Scheyer, T. M. (2023). Comparative bone histology of two thalattosaurians (Diapsida: Thalattosauria) Askeptosaurus italicus from the Alpine Triassic (Middle Triassic) and a Thalattosauroidea indet. from the Carnian of Oregon (Late Triassic). Swiss Journal of Palaeontology, 142, 1–20. https://doi.org/10.1186/s13358-023-00277-3
Krebs, B. (1965). Ticinosuchus ferox nov. gen. nov. sp. Ein neuer Pseudosuchier aus der Trias des Monte San Giorgio. Schweizerische Paläontologische Abhandlungen, 81, 1–140.
Klug, C., Rücklin, M., Meyer-Berthaud, B., & Soria, A. (2003). Late Devonian pseudoplanktonic crinoids from Morocco. Neues Jahrbuch für Geologie und Mineralogie, Monatshefte, 2003(3), 153–163.
Kogan, I., & Romano, C. (2016). Redescription of Saurichthys madagascariensis Piveteau, 1945 (Actinopterygii, Early Triassic), with implications for the early saurichthyid morphotype. Journal of Vertebrate Paleontology, 36, 1–22. https://doi.org/10.1080/02724634.2016.1151886
Kolb, C., Sánchez-Villagra, M. R., & Scheyer, T. M. (2011). The palaeohistology of the basal ichthyosaur Mixosaurus (Ichthyopterygia, Mixosauridae) from the Middle Triassic: Palaeobiological implications. Comptes Rendus Palevol, 10, 403–411.
Kuhn, E. (1942). Über einen weiteren Fund von Paraplacodus broilii PEYER aus der Trias des Monte San Giorgio. Eclogae Geologicae Helvetiae, 35, 174–183.
Kuhn, E. (1946a). Der Schädel von Askeptosaurus italicus Nopcsa. Eclogae Geologicae Helvetiae, 39, 363.
Kuhn, E. (1946b). Über Acrodus-Funde aus dem Grenzbitumenhorizont der anisischen Stufe der Trias des Monte San Giorgio (Kanton Tessin). Ecologae Geologicae Helvetiae, 38, 662–673.
Kuhn, E. (1946c). Über einen Fund von Birgeria aus der Trias des Monte San Giorgio (Kanton Tessin). Eclogae Geologicae Helvetiae, 39, 363–364.
Kuhn-Schnyder, E. (1959). Hand und Fuss von Tanystropheus longobardicus (Bassani). Eclogae Geologicae Helvetiae, 52, 921–941.
Kuhn-Schnyder, E. (1960). Über Placodontier. Paläontologische Zeitschrift, 34, 91–102.
Kuhn-Schnyder, E. (1962). Ein weiterer Schädel von Macrocnemus bassanii Nopcsa aus der anisischen Stufe der Trias des Monte San Giorgio (Kt. Tessin, Schweiz). Paläontologische Zeitschrift, 1962, 110–133.
Kuhn-Schnyder, E. (1966). Der Schädel von Paranothosaurus amsleri Peyer aus dem Grenzbitumenhorizont der anisisch-ladinischen Stufe der Trias des Monte San Giorgio (Kanton Tessin, Schweiz). Eclogae Geologicae Helvetiae, 59, 517–540.
Kuhn-Schnyder, E. (1967). Das Problem der Euryapsida. Mitteilungen aus dem Paläontologischen Institut der Universität Zürich, 49, 335–348.
Kuhn-Schnyder, E. (1987). Die Triasfauna der Tessiner Kalkalpen. XXVI. Lariosaurus-lavizzarii new species (Reptiplia; Sauropterygia). Schweizerische Paläontologische Abhandlungen, 110, 1–24.
Kuhn-Schnyder, E. (1988). Bemerkungen zur Ordnung der Thalattosauria (Reptilia). Eclogae Geologicae Helvetiae, 81, 879–886.
Lanz, H., & Felber, M. (2020). Wissenschaftliche Grabungen, Landschaften und Menschen im Gebiet des Monte San Giorgio – Aufnahmen 1924–1936. Geologia Insubrica, 14, 1–110.
Lautenschlager, S., & Desojo, J. B. (2011). Reassessment of the Middle Triassic rauisuchian archosaurs Ticinosuchus ferox and Stagonosuchus nyassicus. Paläontologische Zeitschrift, 85, 357–381.
Li, J. (2006). A brief summary of the Triassic marine reptiles of China. Vertebrata PalAsiatica, 44, 99–108.
Li, Q., & Liu, J. (2020). An Early Triassic sauropterygian and associated fauna from South China provide insights into Triassic ecosystem health. Communications Biology, 3(63), 1–11. https://doi.org/10.1038/s42003-020-0778-7
Liu, J., Zhao, L. J., Li, C., & He, T. (2013). Osteology of Concavispina biseridens (Reptilia, Thalattosauria) from the Xiaowa Formation (Carnian), Guanling, Guizhou, China. Journal of Paleontology, 87, 341–350.
Lombardo, C. (1999). Sexual dimorphism in a new species of the actinopterygian Peltopleurus from the Triassic of northern Italy. Palaeontology, 42, 741–760.
Lombardo, C. (2013). A new basal actinopterygian fish from the Late Ladinian of Monte San Giorgio (Canton Ticino, Switzerland). Swiss Journal of Geosciences, 106, 219–230.
Lombardo, C., & Tintori, A. (2004). New Perleidiforms from the Triassic of the Southern Alps and the revision of Serrolepis from the Triassic of Wüttemberg (Germany). Mesozoic Fishes, 3, 179–196.
Lombardo, C., Tintori, A., & Tona, D. (2012). A new species of Sangiorgioichthys (Actinopterygii, Semionotiformes) from the Kalkschieferzone of Monte San Giorgio (Middle Triassic; Meride, Canton Ticino, Switzerland). Bollettino Della Societa Paleontologica Italiana, 51, 203–212.
Long, J., & Trinajstic, K. (2018). A review of recent discoveries of exceptionally preserved fossil fishes from the Gogo sites (Late Devonian, Western Australia). Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 108, 111–117.
López-Arbarello, A., Bürgin, T., Furrer, H., & Stockar, R. (2016). New holostean fishes (Actinopterygii: Neopterygii) from the Middle Triassic of the Monte San Giorgio (Canton Ticino, Switzerland). PeerJ, 4, e2234. https://doi.org/10.7717/peerJ.2234
López-Arbarello, A., Bürgin, T., Furrer, H., & Stockar, R. (2019). Taxonomy and phylogeny of Eosemionotus Stolley, 1920 (Neopterygii: Ginglymodi) from the Middle Triassic of Europe. Palaeontologia Electronica, 22(1), 1–64. https://doi.org/10.26879/904
López-Arbarello, A., Stockar, R., & Bürgin, T. (2014). Phylogenetic relationships of the Triassic Archaeosemionotus Deecke (Halecomorphi, Ionoscopiformes) from the ‘Perledo Fauna.’ PLoS ONE, 9(10), 1–64.
Lu, H., Jiang, D.-Y., Motani, R., Ni, P.-G., Sun, Z.-Y., Tintori, A., Xiao, S.-Z., Zhou, M., Ji, C., & Fu, W.-L. (2018). Middle Triassic Xingyi Fauna: Showing turnover of marine reptiles from coastal to oceanic environments. Palaeoworld, 27, 107–116. https://doi.org/10.1016/j.palwor.2017.05.005
Lukeneder, A., & Lukeneder, P. (2021). The Upper Triassic Polzberg palaeobiota from a marine Konservat-Lagerstätte deposited during the Carnian Pluvial Episode in Austria. Scientific Reports, 11(16644), 1–14. https://doi.org/10.1038/s41598-021-96052-w
Lukeneder, A., & Lukeneder, P. (2023). New data on the marine Upper Triassic palaeobiota from the Polzberg Konservat-Lagerstätte in Austria. Swiss Journal of Palaeontology, 142, 1–14. https://doi.org/10.1186/s13358-023-00269-3
Lukeneder, P., & Lukeneder, A. (2022). Mineralized belemnoid cephalic cartilage from the late Triassic Polzberg Konservat-Lagerstätte (Austria). PLoS ONE, 17(4), e0264595. https://doi.org/10.1371/journal.pone.0264595
Maisch, M. W., & Matzke, A. T. (1997). Mikadocephalus gracilirostris n. gen., n. sp., a new ichthyosaur from the Grenzbitumenzone (Anisian-Ladinian) of Monte San Giorgio (Switzerland). Paläontologische Zeitschrift, 71, 267–289.
Maisch, M. W., & Matzke, A. T. (1998). Observations on Triassic ichthyosaurs. Part II: A new ichthyosaur with palatal teeth from Monte San Giorgio. Neues Jahrbuch für Geologie und Paläontologie-Monatshefte, 1998(1), 26–41.
Maisch, M. W., Matzke, A. T., & Brinkmann, W. (2006). The otic capsule of the Middle Triassic ichthyosaur Mixosaurus from Monte San Giorgio (Switzerland): New evidence on the braincase structure of basal ichthyosaurs. Eclogae Geologicae Helvetiae, 99, 205–210.
Mariani, E. (1923). Su un nuovo esemplare di “Lariosaurus balsami, CUR.” Trovato negli scisti di Perledo sopra Varenna (Lago di Como). Atti Della Società Italiana Di Scienze Naturali, 62, 1–8.
Martin, E. L. O., Pittet, B., Gutiérrez-Marco, J.-C., Vannier, J., El Hariri, K., Lerosey-Aubril, R., Masrour, M., Nowak, H., Servais, T., Vandenbroucke, T. R. A., Van Roy, P., Vaucher, R., & Lefebvre, B. (2016). The Lower Ordovician Fezouata Konservat-Lagerstätte from Morocco: Age, environment and evolutionary perspectives. Gondwana Research, 34, 274–283. https://doi.org/10.1016/j.gr.2015.03.009
Maxwell, E. E., Argyriou, T., Stockar, R., & Furrer, H. (2018). Re-evaluation of the ontogeny and reproductive biology of the Triassic fish Saurichthys (Actinopterygii: Saurichthyidae). Palaeontology, 18, 559–574.
Maxwell, E. E., Furrer, H., & Sánchez-Villagra, M. R. (2013). Exceptional preservation demonstrates a new mode of axial skeleton elongation in early ray-finned fishes. Nature Communications, 4, 2570. https://doi.org/10.1038/ncomms357010.1038/ncomms3570
Maxwell, E. E., Romano, C., Wu, F., & Furrer, H. (2015). Two new species of Saurichthys (Actinopterygii: Saurichthyidae) from the Middle Triassic of Monte San Giorgio, Switzerland, with implications for character evolution in the genus. Zoological Journal of the Linnean Society, 173, 887–912. https://doi.org/10.1111/zoj.12224
Meyer, H. V. (1855). Die Saurier des Muschelkalkes mit Rücksicht auf die Saurier aus buntem Sandstein und Keuper. In H. Keller (Ed.), Zur Fauna der Vorwelt, zweite Abtheilung (pp. 1–167). Heinrich Keller.
Miedema, F., Klein, N., Blackburn, D. G., Sander, P. M., Maxwell, E. E., Griebeler, E. M., & Scheyer, T. M. (2023). Heads or tails first? Evolution of fetal orientation in ichthyosaurs, with a scrutiny of the prevailing hypothesis. BMC Ecology and Evolution, 23(12), 1–13. https://doi.org/10.1186/s12862-023-02110-4
Miedema, F., Spiekman, S. N. F., Fernandez, V., Reumer, J. W. F., & Scheyer, T. M. (2020). Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography. Scientific Reports, 10(1), 12412. https://doi.org/10.1038/s41598-020-68912-4
Müller, J. (2005). The anatomy of Askeptosaurus italicus from the Middle Triassic of Monte San Giorgio and the interrelationships of thalattosaurs (Reptilia, Diapsida). Canadian Journal of Earth Sciences, 42, 1347–1367.
Mutter, R. J. (1998a). Tooth variability and reconstruction of dentition in Acrodus sp. (Chondrichthyes, Selachii, Hybodontoidea) from the Grenzbitumenzone (Middle Triassic) of Monte San Giorgio (Ticino, Switzerland). Geologia Insubrica, 3, 23–31.
Mutter, R. J. (1998b). Zur systematischen Stellung einiger Bezahnungsreste von Acrodus georgii sp. nov. (Selachii, Hybodontoidea) aus der Grenzbitumenzone (Mittlere Trias) des Monte San Giorgio (Kanton Tessin, Schweiz). Eclogae Geologicae Helvetiae, 91, 513–519.
Mutter, R. J. (2001). The skull of Colobodontidae sensu Andersson 1916 (emended) (Actinopterygii: Perleidiformes). Geologia Insubrica, 6, 65–78.
Mutter, R. J. (2004). The “perleidiform” family Colobodontidae: A review. Mesozoic Fishes, 3, 197–208.
Mutter, R. J., & Herzog, A. (2004). A new genus of Triassic actinopterygian with an evaluation of deepened flank scales in fusiform fossil fishes. Journal of Vertebrate Paleontology, 24, 794–801.
Neenan, J., Li, C., Rieppel, O., Bernardini, F., Tuniz, C., Muscio, G., & Scheyer, T. M. (2014). Unique method of tooth replacement in durophagous placodont marine reptiles, with new data on the dentition of Chinese taxa. Journal of Anatomy, 224, 603–613. https://doi.org/10.1111/joa.12162
Nesbitt, S. J. (2011). The early evolution of archosaurs: Relationships and the origin of major clades. American Museum of Natural History, Bulletin, 352(292), 1–292.
Neuman, A. G. (1992). Lower and Middle Triassic Sulphur Mountain formation, Wapiti Lake, British Columbia. 1. Summary of geology and fauna. Royal British Columbia Museum Contributions to Natural Science, 16, 1–12.
Neuman, A. G. (2015). Fishes from the Lower Triassic portion of the Sulphur Mountain Formation in Alberta, Canada: geological context and taxonomic composition. Canadian Journal of Earth Sciences, 52, 557–568. https://doi.org/10.1139/cjes-2014-0165
Nopsca, F. B. (1923). Neubeschreibung des Trias-Pterosauriers Tribelesodon. Paläontologische Zeitschrift, 5, 161–181.
Nopcsa, F. B. (1925). Askeptosaurus, ein neues Reptil der Trias von Besano. Zentralblatt für Mineralogie, Geologie und Paläontologie, 8, 265–267.
Nopcsa, F. B. (1930). Notizen über Macrocnemus Bassanii nov. gen. et spec. Centralblatt Für Mineralogie, Geologie und Paläontologie B, 1930, 252–255.
Nosotti, S. (2007). Tanystropheus longobardicus (Reptilia, Protorosauria): Re-interpretations of the anatomy based on new specimens from the Middle Triassic of Besano (Lombardy, northern Italy). Memorie Della Società Italiana Di Scienze Naturali e Del Museo Civico Di Storia Naturale Di Milano, 35, 1–88.
Nosotti, S., & Rieppel, O. (2003). “Eusaurosphargis dalsassoi” N. Gen. N. Sp., a new, unusual diapsid reptile from the Middle Triassic of Besano (Lombardy, N Italy). Memorie Societa Italiana Scienze Naturali, 16, 1–33.
Pardo-Pérez, J. M., Kear, B. P., & Maxwell, E. E. (2020). Skeletal pathologies track body plan evolution in ichthyosaurs. Scientific Reports, 10(4206), 1–7. https://doi.org/10.1038/s41598-020-61070-7
Payne, J. L., & Clapham, M. E. (2012). End-Permian mass extinction in the oceans: An ancient analog for the twenty-first century? Annual Review of Earth and Planetary Sciences, 40, 89–111.
Payne, J. L., Lehrmann, D. J., Wei, J., Orchard, M. J., Schrag, D. P., & Knoll, A. H. (2004). Large perturbations of the carbon cycle during recovery from the end-Permian extinction. Science, 305, 506–509.
Peyer, B. (1930). Tanystropheus longobardicus Bass. sp. Vorläufige Mitteilung. Centralblatt für Mineralogie etc., 8, 336–337.
Peyer, B. (1931a). Die Triasfauna der Tessiner Kalkalpen II. Tanystropheus longobardicus Bass. Sp. Abhandlungen Der Schweizerischen Paläontologischen Gesellschaft, 50, 9–110.
Peyer, B. (1931b). Die Triasfauna der Tessiner Kalkalpen III. Placodontia. Schweizerische Paläontologische Abhandlungen, 51, 1–25.
Peyer, B. (1931c). Die Triasfauna der Tessiner Kalkalpen. IV. Peyer, B. 1931. Ceresiosaurus calcagnii nov. gen. nov. spec. Abhandlungen der Schweizerischen Paläontologischen Gesellschaft, 62, 1–87.
Peyer, B. (1931d). Paraplacodus broilii nov. gen. nov. sp., ein neuer Placodontier aus der Tessiner Trias: Vorläufige Mitteilung. Centralblatt für Mineralogie und Paläontologie B, 1931, 570–573.
Peyer, B. (1934). Zehn Jahre Tessiner Fossiliengrabung des Zoologischen Museums der Universität Zürich. Verhandlungen der Schweizerischen Naturforschenden Gesellschaft, 115, 257–261.
Peyer, B. (1936a). Die Triasfauna der Tessiner Kalkalpen. X. Clarazia schinzi nov. gen. nov. spec. Schweizerische Paläontologische Abhandlungen, 57, 1–61.
Peyer, B. (1936b). Die Triasfauna der Tessiner Kalkalpen. XI. Heschleria ruebeli nov. gen. nov. spec. Schweizerische Paläontologische Abhandlungen, 58, 1–48.
Peyer, B. (1937). Die Triasfauna der Tessiner Kalkalpen. XII Macrocnemus Bassanii Nopcsa. Schweizerische Paläontologische Abhandlungen, 59, 1–140.
Pieroni, V. (2022). Middle Triassic Nautilida from the Besano Formation of Monte San Giorgio, Switzerland. Swiss Journal of Palaeontology, 141, 21. https://doi.org/10.1186/s13358-022-00263-1
Pinna, G. (1992). Cyamodus hildegardis Peyer, 1931 (Reptilia, Placodontia). Memorie Della Societa Italiana Di Science Naturali e Del Museo Civico Di Storia Naturale Di Milano, 26, 2–21.
Pinna, G., & Arduini, P. (1978). Un nuovo esemplare di Ticinosuchus ferox Krebs, rinvenuto nel giacimento Triassico di Besano in Lombardia. Natura - Società Italiana Di Scienze Naturali, Museo Civico Di Storia Naturale Di Milano, 69, 73–80.
Pohle, A. & Klug, C. Orthoceratoid and coleoid cephalopods from the Middle Triassic of Switzerland with an updated taxonomic framework for Triassic Orthoceratoidea. Swiss Journal of Palaeontology, 143, 30 (in press)
Premru, E. (1991). Beschreibung eines neuen Fundes von Macrocnemus bassanii Nopcsa (Reptilia, Squamata, Prolacertiformes) aus der Grenzbitumenzone (Anis/Ladin) des Monte San Giorgio (Besano, I) (p. 57). Diplomarbeit Universität Zürich.
Renesto, S. (1993). A juvenile Lariosaurus (Reptilia, Sauropterygia) from the Kalkschieferzone (Uppermost Ladinian) near Viggiu (Varese, Northern Italy). Rivista Italiana Di Paleontologia e Stratigrafia, 99, 199–212.
Renesto, S. (2005). A new specimen of Tanystropheus (Reptilia Protorosauria) from the Middle Triassic of Switzerland and the ecology of the genus. Rivista Italiana Di Paleontologia e Stratigrafia, 11, 377–379.
Renesto, S., & Avanzini, M. (2002). Skin remains in a juvenile Macrocnemus bassanii Nopcsa (Reptilia, Prolacertiformes) from the Middle Triassic of northern Italy. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 224, 31–48.
Renesto, S., Dal Sasso, C., Fogliazza, F., & Ragni, C. (2020). New findings reveal that the Middle Triassic ichthyosaur Mixosaurus cornalianus is the oldest amniote with a dorsal fin. Acta Palaeontologica Polonica, 65, 511–522. https://doi.org/10.4202/app.00731.2020
Renesto, S., & Stockar, R. (2018). First record of a coelacanth fish from the Middle Triassic Meride Limestone of Monte San Giorgio (Canton Ticino, Switzerland). Rivista Italiana Paleontologia e Stratigrafia, 124, 639–653.
Rieber, H. (1969). Daonellen aus der Grenzbitumenzone der mittleren Trias des Monte San Giorgio (Kanton Tessin, Schweiz). Eclogae Geologicae Helvetiae, 62, 657–683.
Rieber, H. (1970). Phragmoteuthis? ticinensis n. sp., ein Coleoidea-Rest aus der Grenzbitumenzone (Mittlere Trias) des Monte San Giorgio (Kanton Tessin, Schweiz). Paläontologische Zeitschrift, 44, 32–40.
Rieber, H. (1973). Die Triasfauna der Tessiner Kalkalpen. XXII. Cephalopoden aus der Grenzbitumenzone (Mittlere Trias) des Monte San Giorgio (Kanton Tessin, Schweiz). Schweizerische Paläontologische Abhandlungen, 93, 1–96.
Rieber, H. (1974). Breviconoteuthis breviconus Reis, ein Phragmoteuthide aus der Mittleren Trias des Monte San Giorgio, Kanton Tessin, Schweiz. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 7, 415–421.
Rieppel, O. (1980). A new coelacanth from the Middle Triassic of Monte San Giorgio, Switzerland. Eclogae Geologicae Helvetiae, 73, 921–939.
Rieppel, O. (1981). The hybodontiform sharks from the Middle Triassic of Monte San Giorgio, Switzerland. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 161, 324–353.
Rieppel, O. (1982). A new genus of shark from the Middle Triassic of Monte San Giorgio, Switzerland. Palaeontology, 25, 399–412.
Rieppel, O. (1985a). Die Triasfauna der Tessiner Kalkalpen. XXV. Die Gattung Saurichthys (Pisces, Actinopterygii) aus der mittleren Trias des Monte San Giorgio, Kanton Tessin. Schweizerische Paläontologische Abhandlungen, 108, 1–103.
Rieppel, O. (1985b). A second actinistian from the Middle Triassic of Monte San Giorgio, Kanton Tessin, Switzerland. Eclogae Geologicae Helvetiae, 78, 707–713.
Rieppel, O. (1987). Clarazia and Hescheleria: A re-investigation of two problematical reptiles from the Middle Triassic of Monte San Giorgio (Switzerland). Palaeontographica Abteilung A, 195, 101–129.
Rieppel, O. (1989a). The hind limb of Macrocnemus bassanii (Nopcsa) (Reptilia, Diapsida): Development and functional anatomy. Journal of Vertebrate Paleontology, 9, 373–387.
Rieppel, O. (1989b). A new pachypleurosaur (Reptilia: Sauropterygia) from the Middle Triassic of Monte San Giorgio, Switzerland. Philosophical Transactions of the Royal Society of London B, 323, 1–73.
Rieppel, O. (1994). Lariosaurus balsami Curioni (Reptilia, Sauropterygia) aus den Gailtaler Alpen. Carinthia II, 184, 345–356.
Rieppel, O. (2019). Mesozoic sea dragons: Triassic marine life from the ancient tropical lagoon of Monte San Giorgio (Life of the Past) (p. 256). Indiana University Press.
Rieppel, O., Liu, J., & Bucher, H. (2000). The first record of a thalattosaur reptile from the Late Triassic of southern China (Guizhou Province, PR China). Journal of Vertebrate Paleontology, 20, 507–514.
Rieppel, O., Müller, J., & Liu, J. (2005). Rostral structure in Thalattosauria (Reptilia, Diapsida). Canadian Journal of Earth Sciences, 42, 2081–2086.
Röhl, H. J., Schmid-Röhl, A., Furrer, H., Frimmel, A., Oschmann, W., & Schwark, L. (2001). Microfacies, geochemistry and palaeoecology of the Middle Triassic Grenzbitumenzone from Monte San Giorgio (Canton Ticino, Switzerland). Geologia Insubrica, 6, 1–13.
Röhl, A., Schmid-Röhl, H. J., Oschmann, W., Frimmel, A., & Schwark, L. (2002). Palaeoenvironmental reconstruction of Lower Toarcian epicontinental black shales (Posidonia Shale, SW Germany): Global versus regional control. Geobios, 35, 13–20.
Romano, C., & Brinkmann, W. (2009). Reappraisal of the lower actinopterygian Birgeria stensioei Aldinger, 1931 (Osteichthyes; Birgeriidae) from the Middle Triassic of Monte San Giorgio (Switzerland) and Besano (Italy). Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 252, 17–31.
Romano, C., Goudemand, N., Vennemann, T. W., Ware, D., Schneebeli-Hermann, E., Hochuli, P. A., Brühwiler, T., Brinkmann, W., & Bucher, H. (2013). Climatic and biotic upheavals following the end-Permian mass extinction. Nature Geoscience, 6, 57–60.
Romano, C., López-Arbarello, A., Ware, D., Jenks, J. F., & Brinkmann, W. (2019). Marine Early Triassic Actinopterygii from the Candelaria Hills (Esmeralda County, Nevada, USA). Journal of Paleontology, 93, 971–1000. https://doi.org/10.1017/jpa.2019.18
Romano, C., Ware, D., Brühwiler, T., Bucher, H., & Brinkmann, W. (2016). Marine Early Triassic Osteichthyes from Spiti, Indian Himalayas. Swiss Journal of Palaeontology, 135, 275–294.
San, K. K., Fraser, N. C., Foffa, D., Rieppel, O., & Brusatte, S. L. (2019). The first Triassic vertebrate fossils from Myanmar: Pachypleurosaurs in a marine limestone. Acta Palaeontologica Polonica, 64, 357–362. https://doi.org/10.4202/app.00594.2019
Saller, F. (2016). Anatomia, paleobiologia e filogenesi di Macrocnemus bassanii Nopcsa 1930 (Reptilia, Protorosauria). Dottorato di ricerca in Scienze della terra, 27 Ciclo. Università di Bologna. https://doi.org/10.6092/unibo/amsdottorato/7449.
Sander, P. M. (1988). A fossil reptile embryo from the Middle Triassic of the Alps. Science, 239, 780–783.
Sander, P. M. (1989a). The large ichthyosaur Cymbospondylus buchseri, sp. nov., from the Middle Triassic of Monte San Giorgio (Switzerland), with a survey of the genus in Europe. Journal of Vertebrate Paleontology, 9, 163–173.
Sander, P. M. (1989b). The pachypleurosaurids (Reptilia: Nothosauria) from the Middle Triassic of Monte San Giorgio (Switzerland) with the description of a new species. Philosophical Transactions of the Royal Society of London B, 325, 561–670.
Sander, P. M., Griebeler, E. M., Klein, N., Velez Juarbe, J., Wintrich, T., Revell, L. J. & Schmitz, L. (2021). Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans. Science, 374, 1578, 1–16.
Sander, P. M., Rieppel, O. C., & Bucher, H. (1994). New marine vertebrate fauna from the Middle Triassic of Nevada. Journal of Paleontology, 68, 676–680.
Scheyer, T. M. (2010). New interpretation of the postcranial skeleton and overall body shape of the placodont Cyamodus hildegardis Peyer, 1931 (Reptilia, Sauropterygia). Palaeontologia Electronica, 13(2), 15A.
Scheyer, T., Neenan, J. M., Bodogan, T., Furrer, H., Obrist, C., & Plamondon, M. (2017). A new, exceptionally preserved juvenile specimen of Eusaurosphargis dalsassoi (Diapsida) and implications for Mesozoic marine diapsid phylogeny. Scientific Reports, 7(4406), 1–22. https://doi.org/10.1038/s41598-017-04514-x
Scheyer, T. M., Romano, C., Jenks, J., & Bucher, H. (2014a). Early Triassic marine biotic recovery: the predators’ perspective. PLoS ONE, 9(3), e88987. https://doi.org/10.1371/journal.pone.0088987
Scheyer, T. M., Schmid, L., Furrer, H., & Sánchez-Villagra, M. R. (2014b). An assessment of age determination in fossil fish: The case of the opercula in the Mesozoic actinopterygian Saurichthys. Swiss Journal of Palaeontology, 133, 243–257.
Schwarz, W. (1970). Die Triasfauna der Tessiner Kalkalpen. XX. Birgeria Stensiöi Aldinger. Schweizerische Paläontologische Abhandlungen, 89, 1–93.
Scotese, C. R. (1997). Paleogeographic Atlas, PALEOMAP progress report 90–0497 (p. 37). Department of Geology, University of Texas at Arlington.
Seilacher, A. (1970). Begriff und Bedeutung der Fossil-Lagerstätten. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 1970, 34–39.
Seilacher, A. (1990). Taphonomy of fossil-Lagerstätten. In D. E. G. Briggs & P. R. Crowther (Eds.), Palaeobiology: a synthesis (pp. 266–270). Blackwell.
Seilacher, A., Reif, W.-E., & Westphal, F. (1985). Sedimentological, ecological and temporal patterns of fossil Lagerstätten. Philosophical Transactions of the Royal Society of London B, 311, 5–23.
Selden, P., & Nudds, J. (2012). Evolution of fossil ecosystems (p. 304). Boca Raton: CRC Press.
Spiekman, S. N. F., & Mujal, E. (2023). Decapitation in the long-necked Triassic marine reptile Tanystropheus. Current Biology, 33, R699–R709.
Spiekman, S. N. F., Neenan, J. M., Fraser, N. C., Fernandez, V., Rieppel, O., Nosotti, S., & Scheyer, T. M. (2020a). Aquatic habits and niche partitioning in the extraordinarily long-necked Triassic reptile Tanystropheus. Current Biology, 30(19), 1–7. https://doi.org/10.1016/j.cub.2020.07.025
Spiekman, S. N. F., Neenan, J. M., Fraser, N. C., Fernandez, V., Rieppel, O., Nosotti, S., & Scheyer, T. M. (2020b). The cranial morphology of Tanystropheus hydroides (Tanystropheidae, Archosauromorpha) as revealed by synchrotron microtomography. PeerJ, 8(2), e10299. https://doi.org/10.7717/peerj.10299
Spiekman, S. N. F., & Scheyer, T. M. (2019). A taxonomic revision of the genus Tanystropheus (Archosauromorpha, Tanystropheidae). Palaeontologia Electronica, 22.3.80, 1–46. https://doi.org/10.26879/1038
Stefani, M., Arduini, P., Garassino, A., Pinna, G., Teruzzi, G., & Trombetta, G. L. (1991). Palaeoenvironment of extraordinary fossil biotas from the Upper Triassic of Italy. Atti Della Societa Italiana Di Scienze Naturali e Del Museo Civico Di Storia Naturale Di Milano, 132, 309–335.
Stockar, R. (2010). Facies, depositional environment, and palaeoecology of the Middle Triassic Cassina beds (Meride Limestone, Monte San Giorgio, Switzerland). Swiss Journal of Geosciences, 103, 101–119. https://doi.org/10.1007/s00015-010-0008-2
Stockar, R., Baumgartner, P. O., & Condon, D. (2012). Integrated Ladinian bio-chronostratigraphy and geochrononology of Monte San Giorgio (Southern Alps, Switzerland). Swiss Journal of Geosciences, 105, 85–108. https://doi.org/10.1007/s00015-012-0093-5
Sun, Z., Jiang, D., Ji, C., & Hao, W. (2016). Integrated biochronology for Triassic marine vertebrate faunas of Guizhou Province, South China. Journal of Asian Earth Sciences, 118, 101–110. https://doi.org/10.1016/j.jseaes.2016.01.004
Tang, C. M. (2002). Monte Bolca: An Eocene fishbowl. In D. J. Bottjer, W. Etter, J. W. Hagadorn, & C. M. Tang (Eds.), Exceptional fossil preservation (pp. 365–377). Columbia University Press.
Tichy, K. (1998). Ein Neufund von Neusticosaurus toeplitschi (Nopcsa, 1928) (Reptilia, Sauropterygia) aus den Partnachschichten der Gailtaler Alpen, Kärnten. Carinthia II, 188, 519–530.
Tintori, A. (1990). Dipteronotus olgiatii n. sp. (Actinopterygii, Perleidiformes) from the Kalkschieferzone of Ca’del Frate (N. Italy). Atti Ticinensi Di Scienze Della Terra, 33, 191–197.
Tintori, A. (1992). Fish taphonomy and Triassic anoxic basins from the alps: A case history. Rivista Italiana Paleontologia e Stratigrafia, 97, 393–408.
Tschanz, K. (1986). Funktionelle Anatomie der Halswirbelsäule von Tanystropheus longobardicus (Bassani) aus der Trias (Anis/Ladin) des Monte San Giorgio (Tessin) auf der Basis vergleichend morphologischer Untersuchungen an der Halsmuskulatur rezenter Echsen. PhD thesis, University of Zurich, Zurich, Switzerland.
Tschanz, K. (1988). Allometry and heterochrony in the growth of the neck of Triassic prolacertiform reptiles. Palaeontology, 31, 997–1011.
Van Roy, P., Orr, P. J., Botting, J. P., Muir, L. A., Vinther, J., Lefebvre, B., el Hariri, K., & Briggs, D. E. G. (2010). Ordovician faunas of Burgess Shale type. Nature, 465, 215–218.
Wachtler, M., & Perner, T. (2018). Some new and exciting Triassic Archosauria from the Dolomites (Northern Italy). Dolomythos Museum, Oregon Institute of Geological Research.
Wang, X., Bachmann, G. H., Hagdorn, H., Sander, P. M., Cuny, G., Chen, X., Wang, C., Chen, L., Cheng, L., Meng, F., & Xu, G. (2008). The Late Triassic black shales of the Guanling area, Guizhou Province, south-west China: A unique marine reptile and pelagic crinoid fossil lagerstätte. Palaeontology, 51, 27–61. https://doi.org/10.1111/j.1475-4983.2007.00735.x
Ware, D., Jenks, J. F., Hautmann, M., & Bucher, H. (2011). Dienerian (Early Triassic) ammonoids from the Candelaria Hills (Nevada, USA) and their significance for palaeobiogeography and palaeoceanography. Swiss Journal of Geosciences, 104, 161–181.
Wilby, P. R., Duff, K., Page, K., & Martin, S. (2008). Preserving the unpreservable: A lost world rediscovered at Christian Malford, UK. Geology Today, 24, 95–98.
Wild, R. (1973). Die Triasfauna der Tessiner Kalkalpen XXII. Tanystropheus longobardicus (Bassani) (Neue Ergebnisse). Schweizerische Paläontologische Abhandlungen, 95, 1–162.
Wild, R. (1980). Die Triasfauna der Tessiner Kalkalpen. XXIV. Neue Funde von Tanystropheus (Reptilia, Squamata). Schweizerische Paläontologische Abhandlungen, 102, 1–43.
Wilson, L. A. B., Furrer, H., Stockar, R., & Sánchez-Villagra, M. R. (2013). A quantitative evaluation of evolutionary patterns in opercle bone shape in Saurichthys (Actinopterygii: Saurichthyidae). Palaeontology, 56, 901–915.
Xian-Guang, H., Siveter, David J., Siveter, Derek J., Aldridge, R. J., Pei-Yun, C., Gabbott, S. E., Xiao-Ya, M., Purnell, M. A. & Williams, M. (2003). The Cambrian fossils of Chengjiang, China: the flowering of early animal life. Wiley, Hoboken N.J.
Zapfe, H. & König, H. (1980). Neue Reptilienfunde aus der Mitteltrias der Gailtaler Alpen (Kärnten, Österreich). Sitzungsberichte der Österreichischen Akademie der Wissenschaften. Mathematisch-naturwissenschaftliche Klasse, Abt. I, 189, 65–82.
Acknowledgements
Christian Obrist (Rickenbach) prepared the specimen in Fig. 5. We thank Adriana Lopez-Arbarello (Munich) and two anonymous reviewers for their constructive criticism, which helped to significantly improve the manuscript. Merle Greif (Zürich) kindly took the photo of the phragmoteuthid.
Funding
DB and TMS were supported by the Swiss National Science Foundation SNSF (project no. 31003A_179401). SNFS is funded by the Deutsche Forschungsgemeinschaft DFG (project no. SCHO 791/7-1 to Rainer Schoch).
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CK, BS and TMS had the idea for this study. BS made the models in Fig. 1 and the illustrations in Fig. 4. Data were collected by CK, DB, SNFS and TMS. The photos and other figures were made by CK. Parts of the text were written by all authors. All authors agreed on the final version of the text.
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Klug, C., Spiekman, S.N.F., Bastiaans, D. et al. The marine conservation deposits of Monte San Giorgio (Switzerland, Italy): the prototype of Triassic black shale Lagerstätten. Swiss J Palaeontol 143, 11 (2024). https://doi.org/10.1186/s13358-024-00308-7
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DOI: https://doi.org/10.1186/s13358-024-00308-7