Ryoji Wani's research while affiliated with Yokohama National University and other places

... The analyses of ontogenetic trajectories of septal spacing enable us to recognise the system of chamber formation throughout the animal's ontogeny. The documented ontogenetic trajectories of septal spacing in ammonoids (Kulicki 1974;Lehmann 1976;Bucher & Guex 1990;Bucher 1997;Dommergues 1988;Mignot 1993;Landman & Waage 1993;Bucher et al. 1996;Polizzotto et al. 2007;Kraft et al. 2008;Paul 2011;Arai & Wani 2012;Zell & Stinnesbeck 2016;Iwasaki et al. 2020;Beck et al. 2021;Kawakami et al. 2022) have been mostly analysed using two-dimensional measurements (rotational angles or linear distance between two succeeding septa). Such analyses of ontogenetic trajectories of septal spacing with twodimensional measurements coincide with ontogenetic events (hatching, maturity;Callomon 1963;Crick 1978;Landman 1987, Tanabe et al. 1993Landman & Waage 1993;Landman et al. 1996;Bucher et al. 1996;Davis et al. 1996;Klug 2004;Klug et al. 2007;Arai & Wani 2012;Kawakami et al. 2022) and the transitions between ontogenetic stages (e.g. ...

... Numerous examples are found in ammonoids dating back to the Devonian (Tanabe et al., 2015a;Klug et al., 2016). They are rarer in the Nautilida, but a few specimens are usable for shape analysis (Klug et al., 2021a). In Coleoids, beaks are found from the end of the Lower Jurassic (Nixon, 2015;Klug et al., 2021b). ...

... possibly caused by unfavourable ecological circumstances, pathologies or injuries, has rarely been studied (Bayer, 1977;Kraft et al., 2008;Lehmann, 1975). However, recent studies show that intermediate septal crowding is far from being a special case, but can be observed almost regularly in ammonoids (Arai & Wani, 2012;Bucher et al., 1996;Iwasaki et al., 2020;Kraft et al., 2008;Tajika et al., 2015Tajika et al., , 2020Zell & Stinnesbeck, 2016). ...

... The www.nature.com/scientificreports/ process of biomineralization has been previously described in detail for the rotaliid foraminifera Ammonia beccarii 38 . The calcification stages of A. beccarii, in particular the calcification between organic layers 38 , resembles structures seen at nanoplastic incorporation sites investigated here (Supplementary Figs. 3 and 4). ...

... This interpretation agrees with observations of membrane probes labeling thin ectoplasmic layer that most likely isolated the crystals from the surrounding water during mineralization (32). Recent ultrastructural SEM investigations also document another globothalamean species (Ammonia) that revealed isolation of calcification sites by two external organic layers, i.e., inner and outer organic layers, entrapping the POS (41,42). These external layers, actively involved in calcification during the chamber formation, truly represent inner and outer lamellipodial structures identified in A. lessonii. ...

... The globopodium has a granular, compact inner, and a less dense, translucent, outer portion 31 . An array of rhizopodial strands radiates from the surface of the globopodial bulge and forms a protective outer sphere [31][32][33] . Calcification starts at the periphery of the translucent section of the globopodium within a network of globopodial/rhizopodial filaments, the POS 21,31-33 . ...

... Knowledge about intraspecific variation during ontogeny is also very scarce for the majority of organisms and there are very few papers showing specific patterns. Tajika et al. (2018) demonstrated that conchs of Nautilus pompilius show high variation early in ontogeny and again shortly before maturity and supposed these peaks in variation to be related to certain growth stages. In intertidal oribatid mites, growth only happens when animals molt into the next stage and our results do not indicate any obvious ontogenetic pattern. ...

... During this phase, passive dispersal via ocean currents is plausible, which in the absence of geographic or oceanographic barriers could lead to development of genetic cohesion among well-connected populations. However, this is strongly dependent on the amount of time juvenile ammonoids spent in the plankton Villanueva et al. 2016;Wani 2017). There are currently no reliable estimates for growth rates in ammonoids, but rapid growth (reaching maturity in <5 years) is likely , which might suggest limited dispersal potential in the plankton. ...

... (3) The septal interspace L s (corresponds to the terms chamber height, chamber length or septal distance, as used in other coleoid studies; e.g. Jeletzky, 1966;Fuchs et al., 2013;Wani et al., 2018), measured as the distance between consecutive septa along the external (dorsal) spiral; the septal expansion rate (SER) was calculated as the relative increase of L s from septum to septum. (4) The whorl interspace ratio (WIR), calculated continuously from the protoconch to the last chamber based on the extracted outline data (this is shown for one point in Fig. 3). ...

... Therefore, the functionality of the buoyancy apparatus might be more affected or completely lost as shown by Tsujino & Shigeta (2012). So, in a hypothetic scenario, the phragmocone was perforated and filled with seawater; in this state, the organism could not have retained its neutral buoyancy (Maeda & Seilacher, 1996;Tsujino & Shigeta, 2012;Wani & Gupta, 2015) and eventually succumbed (i.e., by starvation, hypoxia, or thermal and/or osmotic shock). The ballasting would not have allowed postmortem transport enabling the retention of the structures observed on the specimen (Yacobucci, 2018). ...