For the purpose of this study the whole succession of the Skorków Lumachelle at Małogoszcz is subdivided into five units A-E (see Fig. 2). The general faunal and lithological characters of the succession were given in several older studies (Kutek, 1968; Kaźmierczak & Pszczółkowski, 1968; Seilacher et al., 1985; Machalski, 1996; Matyja et al., 2006; Matyja, 2011), all of them have been taken into account along with some new observations when prepared the following description.
Unit A consists of thick-bedded, soft bioclastic limestones with numerous internal moulds of various infaunal bivalves, including those of Pholadomya, often preserved in life-position. There occur also commonly epifaunal bivalves like Actinostreon, Trichites, Nanogyra and others, as well as various brachiopods and echinoids. The deposits attain 6.5 m in thickness. Their base is marked by the well-developed omission surface having character of hard-ground, and representing the successive stages of its development from soft- and firm-ground stages with numerous burrows (Thalassinoides and Rhizocorallium ) to bivalve and polychaete borings, and encrustation by serpulids of the hard-ground stage. This level marks the lower boundary of the Skorków Lumachelle (or lumachelle/coquina formation) with the underlying “sublithographic” limestones of the Buczyna Limestone Mbr. of the Spinkowa Góra Fm. (Wierzbowski, 2020). Ammonite occur rather commonly, especially of the family Ataxioceratidae: Ataxioceras (Parataxioceras) to “Orthosphinctes(Ardescia)”, Crussoliceras, Garnierisphinctes and Progeronia, and of the family Aulacostephanidae: Eurasenia, Involuticeras, Prorasenia, Rasenia (Pachypictonia) (see Kutek, 1968, 1994; Matyja, Wierzbowski, 2000; Wierzbowski, 2022; see also herein).
Unit B consists of oyster lumachelles about 2.5 m in thickness. The lumachelles are composed of densely packed shells of Actinostreon (“Lopha”, “Alectryonia”) with marked admixture of other bivalve shells, and those of diverse other groups – brachiopods, gastropods, echinoids; additionally are found remains of starfish, crinoids, fish and others. The fossils are commonly overgrown by epizoans (sponges, serpulids, bryozoans) and bored by lithophags. The deposit reveals the features of non-deposition and winnowing of finer particles, as well as temporary reworking. The latter is shown e.g., by the occurrence of multiphase growth of oysters from the elongated forms attached to seminfaunal bivalve shells to the cup-shaped forms all of them preserved in deposit, but commonly not in life position; it is also the case of occurrence of disoriented internal moulds of deep burrowing bivalves, and clasts of coral colonies. All these features indicate the residual lag type character of the discussed deposit. The ammonites are fairly common – but usually fragmentarily preserved. These are especially represented by Ataxioceratidae: mostly Crussoliceras, Garnierisphinctes, less commonly Progeronia, but to the virtual absence of Ataxioceras and “Orthosphinctes”, and somewhat less abundantly by Aulacostephanidae: Eurasenia, Rasenia, Prorasenia (see Kutek, 1968, 1994; Matyja, Wierzbowski, 2000; Wierzbowski, 2022, see also herein).
Unit C having only 1.75 m in thickness is developed as oncolitic limestone. Oncolites differ markedly in final size from less than millimeter to 3–4 cm, but the most commonly around 0.5-1 cm in diameter. The associated fauna is represented mostly by various bivalves, both infaunal to seminfaunal (often preserved in life position, such as Pleuromya) and epifaunal types (especially Nanogyra), associated with brachiopods, gastropods and echinoids. The ammonites occur fairly commonly. There is observed a marked domination of Ataxioceratidae: Crussoliceras, Garnierisphinctes, and Progeronia, and less common occurrence of Aulacostephanidae: mostly Prorasenia, subordinately Involuticeras and Eurasenia, but also of Aspidoceratidae: Pseudhimalayites and Psedowaagenia (see detailed comments below).
Stratigraphical and palaeobiogeographical interpretation of the ammonite faunas
The studied ammonite faunas contain besides the dominating Submediterranean-Mediterranean forms, also fairly commonly the Subboreal ones, as well as some of the strictly Mediterranean origin. Such a spectrum of ammonites enables not only the recognition of the various biostratigraphical zonations, but also makes possible correlation between the particular zonal schemes of different bioprovinces.
The ammonites of the family Ataxioceratidae are the typical Submediterranean (partly also Mediterranean) forms. Although “the family is still one of the most difficult to classify” ( Enay & Howarth, 2019, p. 112; see also discussion in chapter on evolution), its differentiation has became the basis for foundation of the Submediterranean zonations of the Lower Kimmeridgian, especially that established in south-eastern France, in the Jura Mts. in Switzerland, and in Swabian Alb and Franconian Alb in southern Germany (see e.g., Geyer, 1961; Atrops, 1982; Gygi, 2003; Enay et al., 2014), which is evidently recognizable in the area of central Poland (e.g., Kutek, 1968), including the section studied. The ammonites studied herein can be attributed to three different groups. The first of them recognized only in unit A in the Małogoszcz section is closely related to the genus Ataxioceras. It is represented by Ataxioceras (Parataxioceras) cf. planulatum (Quenstedt) (Fig. 3a), A. (P.) oppeli parvum Atrops (Fig. 3b), and “Orthosphinctes (Ardescia)” perayensis Atrops (Fig. 3c). The representatives of Ataxioceras are indicative of the semistriatum horizon, possibly beginning from its base as suggests occurrence of a form similar to A. planulatum characteristic of still older hypselocyclum horizon, of the upper part of the Lothari Subzone of the Hypselocyclum Zone in the accepted herein subdivision of Atrops (1982). The occurrence of “O”. perayensis, being a form of the Ataxioceras (Parataxioceras) oppeli group, possibly reduced in ontogenetic development due to the heterochrony, is indicative moreover of the topmost part of the Hypselocyclum Zone (Atrops, 1982; see also comments on evolution below). The stratigraphical interpretation of all these ammonites is consistent with the occurrence of Crussoliceras and Garnierisphinctes of the second group of Ataxioceratidae in the discussed ammonite fauna of unit A. Both these genera appear for the first time in the Submediterranean succession in the semistriatum horizon of the Hypselocyclum Zone (Atrops, 1982). Of the recognized here three species of that group – G. melliconense (Geyer) (Fig. 3d), Crussoliceras sayni (Camus et Thieuloy) (Fig. 4a), and Garnierisphinctes garnieri (Fontannes) (Fig. 4b)– the middle has been reported from the upper part of the Lothari Subzone (Gygi, 2003), whereas the level of appearance of the latter two has not been so far precisely recognized. The genus Progeronia of the third group of Ataxioceratidae is represented in unit A both by macroconchs: Progeronia (Progeronia) progeron (von Ammon) (Fig. 5a) and P. (P.) cf. eggeri (von Ammon), and microconch Progeronia (Hugueninsphinctes) breviceps (Quenstedt) (Fig. 5b). Although the appearance of Progeronia in the upper part of the Hypselocyclum Zone has been commonly recognized (e.g., Atrops, 1982), the reported new findings for the first time firmly prove the occurrence of the discussed species at that stratigraphical level.
The ammonites coming from unit B do not reveal the representatives of the first group related to the genus Ataxioceras. Instead there are commonly represented forms of two other groups of Ataxioceratidae: Crussoliceras and Garnierisphinctes ones, as well as that of the genus Progeronia. Unfortunately because of the taphonomic reasons (see above) the specimens are mostly incomplete and difficult for closer determination. The only recognized specifically forms are: Garnieriphinctes cf. garnieri (Fontannes) (Fig. 3e) and Crussoliceras cf. aceroides Geyer (Fig. 4c-d). Nevertheless, the assemblage is diagnostic of the lower part of the Divisum Zone – and may be treated as corresponding to the Crusoliensis or Tenuicostatum Subzone according to stratigraphical interpretation accepted herein (see e.g., Atrops, 1982; Enay et al., 2014).
It should be remembered, however, that in stratigraphical scheme of similar Submediterranean succession of southern Germany, the lower boundary of the Divisum Zone has been originally correlated with the level of the first occurrence of Crussoliceras and Garnierisphinctes (e.g., Geyer, 1961). According to that stratigrapical subdivision, the whole interval corresponding to unit A in the Małogoszcz section (compared with the upper part of the Lothari Subzone herein) would be correlated already with the lowest part of the Divisum Zone.
On the other hand, a markedly different ammonite succession is recognized in the coeval deposits of the Spanish sections of the Iberian Range, which can treated as representative of the western part of Submediterranean Province. It includes the occurrence there of a special ataxiocertid group distinguished as corresponding to the new genus Geyericeras, not known in other European areas. These ammonites define the aragoniense stratigraphical horizon occurring directly below the appearance of Crussoliceras indicating already the base of the Divisum Zone. The relevant correlation with SE France and eastern parts of the Submediterranean Province, including central Poland, strongly suggests the position of the aragoniense horizon directly below the upper part of the semistriatum horizon and the perayensis horizon (see Moliner & Olóriz, 2009, 2010; see also Moliner, 2009).
The ataxioceratid ammonites from unit C of the Małogoszcz section are still markedly dominated by Garnierishinctes and Crussoliceras, although the species are mostly different when compared with older units: Garnierisphinctes semigarnieri (Geyer) (Fig. 6a), G. championneti (Fontannes) (Fig. 6b), G. plebejus (Neumayr) (Fig. 6c), as well as Crussoliceras cf. lacertosum (Fontannes), C. cf. atavum (Schneid) – aceroides (Geyer). It is worth noting also the first occurrence of a form which possibly can be referred to the genus Tolvericeras; the corresponding specimens (Fig. 6d) are very similar to that described as “Tolvericeras (Tolvericeras) n. sp.” by Gygi (2003, Figs. 165–166) showing the polygyrate subdivision of ribs placed low in the whorl-side; this form was treated subsequently as taking the intermediate position between Garnierisphinctes and Tolvericeras (Enay et al., 2014, p. 327). Some representatives of Progeronia with well preserved specimen of Progeronia (Hugueninsphinctes) breviceps (Quenstedt) (Fig. 5c) are also recognized. The occurrence of several specimens of Aspidoceratidae represented mostly by Pseudohimalayites uhlandi (Oppel) unequivocally indicates that the whole ammonite assemblage from unit C corresponds already to the Uhlandi Subzone of the upper part of the Divisum Zone (see e.g., Geyer, 1961).
The last ataxioceratid ammonites coming from units D and E are dominated by representatives of Crussoliceras: C. cf. crusoliense (Fontannes); Garnierisphinctes: G. championneti (Fontannes); and Tolvericeras group; the representatives of the Progeronia group: Progeronia (Progeronia) cf. eggeri (von Ammon) (Fig. 5d) are less common. On the other hand, very numerously occur Aspidoceratidae represented almost exclusively by Psudhimalayites uhlandi (Oppel). These ammonites represent the upper parts of the Uhlandi Subzone of the Divisum Zone.
Several ammonites of the families Ataxioceratidae (such as Crussoliceras, Garnierisphinctes and Progeronia), as well as of Aspidoceratidae (mostly Pseudhimalayites) occurring in the studied succession of the Holy Cross Mts., central Poland, are in common with areas of the Mediterranean Province such as the Venetian Alps (see e.g., Pavia et al., 1987; Sarti, 1993; Caracuel et al., 1998), and the Central Appenines (Cecca et al., 1985; Cecca & Santantonio, 1986) in Italy, the Betic Cordillera in southern Spain (Olóriz, 1978), the Gerecse-Pils Moutains and the Bakony Mountains in Hungary (Főzy & Scherzinger, 2013; Főzy et al., 2022), the Romanian Carpathians (e.g., Grigore, 2000), and the Balkan Mts. in Bulgaria (Sapunov, 1979). This along with occurrence in the succession studied of some strictly Tethyan ammonites, such as Presimoceras, Idoceras and Nebrodites allows for recognition of the Mediterranean zonation (see Sarti, 1993; Caracuel et al., 1998, and correlations with older subdivisions).
The ammonites of the genus Presimoceras occur rarely in unit B of the Małogoszcz section. They are fragmentarily preserved, nevertheless they can be attributed to the P. herbichi group (Fig. 7g-h-i), being possibly close to P. nodulatum (Quenstedt). Such taxonomical interpretation indicates the correlation with the Mediterranean Herbichi Zone, additionally because of common occurrence of Crussoliceras - with its middle part – the Divisum Subzone (see Sarti, 1993). The occurrence of a single specimen of Idoceras balderum (Oppel) (Fig. 7k) in the discussed unit B suggests also similar correlation. Although the typical forms of I. balderum are commonly referred to the upper part of the Divisum Zone in Submediterranean Province (SE France, southern Germany, see e.g., Geyer, 1961; Atrops, 1982; see also Schweigert & Kuschel, 2017), some specimens coming from a lower part of the Divisum Zone in other areas (Swiss Jura Mts., Venetian Alps, Italy) are compared with that species as well (see e.g., Gygi & Persoz, 1986; Pavia et al., 1987; Sarti, 1993). The overlying deposits of unit C yielded a few specimens of Nebrodites including N. favaraenenis (Gemmellaro) (Fig. 7f) and N. cf. agrigentinus (Gemmellaro) (Fig. 7j), which together with appearance of Pseudhimalayites uhlandi (Oppel) indicate the upper part of the Herbichi Zone – the Uhlandi Subzone (see Sarti, 1993). Similarly, the co-occurrence of P. uhlandi with Nebrodites sp. and Taramelliceras (Taramelliceras) compsum (Oppel) (Fig. 7l) as recognized in still higher units units D and E indicates the presence of some upper parts of the Uhlandi Subzone (see Caracuel et al., 1998).
Some problem arises with interpretation in term of the Mediterranean zonation of the lowest part of the studied succession – unit A of the Małogoszcz section, corresponding in the Submediterranean subdivision to the uppermost part of the Hypselocyclum Zone and the upper part of the Lothari Subzone. The only ammonite of a strictly Mediterranean character coming from that stratigraphical interval is Nebrodites maccerimus (Quenstedt) (Fig. 7e), according to interpretation of the species by Ziegler (1959). Just that species was reported, however, from the boundary beds of the two Mediterranean zones – the Strombecki Zone and the Herbichi Zone or corresponding beds of the Divisum Zone (Caracuel et al., 1998; see also Olóriz, 1978; Sapunov, 1979). This, together with observations given above, suggests the discussed unit A corresponds most probably to the lowermost part of the Herbichi Zone.
The ammonite faunas of the family Aulacostephanidae commonly represented in the succession studied are indicative of the Subboreal Province. These ammonites numerously occurring in units A to B, less commonly in unit C, are mostly belonging to the genera Eurasenia and Involuticeras of the north-eastern European branch of the family, and rarely to the genus Rasenia (and its local ally Pachypictonia) related to its north-western European branch (Wierzbowski, 2022); both these groups of macroconchs occur together with their microconch counterparts of the genus Prorasenia. Some of these ammonites were presented and discussed previously: Rasenia (Pachypictonia) aff. indicatoria (Schneid), which seems to be related to Rasenia evoluta Spath (Wierzbowski, 2022, pl. 7), Eurasenia rolandi (Oppel) (Wierzbowski, 2022, pl. 10:4), and E. trimera (Oppel) (Wierzbowski, 2022, pl. 11: 4) as well as Involuticeras involutum (Quenstedt) (Wierzbowski, 2022, pl. 14: 2) – all of them from unit A; Eurasenia pendula (Schneid) (Wierzbowski, 2022, pl. 11: 2–3) – from unit B; and Eurasenia trimera (Oppel) (Wierzbowski, 2022, pl. 11: 5), possibly from unit C. In addition, several specimens of E. trimera (Oppel), E. trifurcata (Reinecke), E. pendula (Schneid), associated with Involuticeras, including I. crassicostatum (Geyer), along with common Prorasenia – especially P. quenstedti Schindewolf and P. witteana (Oppel), are reported from units A to C. On the other hand, some specimens of the genus Rasenia, including form similar to R. involuta Spath (Fig. 7a-b), have been recognized in units B and D-E (near the top of the section).
Summarizing, the ammonites of the genera Eurasenia and Involuticeras (associated with Prorasenia microconchs) occur in units A-C in the Małogoszcz section, indicating a stronger NE Subboreal influences, whereas NW Subboreal Rasenia are sporadically encountered nearly throughout the whole succession up to its top. Additionally, a few fragmentarily preserved specimens from unit E (and possibly its upper part), showing the ribbing similar to that of Eurasenia, reveal some weakening of ornamentation on the ventral side of whorls resembling thus younger genus Pararasenia (see Ziegler, 1962). They are especially similar to P. quenstedti Durand, differing in more elongated primary ribs, and in a weaker development of the ventral smooth band: thus, they are referred herein to as ? Pararasenia aff. quenstedti Durand (Fig. 7c-d). Moreover, in the upper part of the succession there appear rarely ammonites of the genus Rasenioides, representing a different branch of Aulacostephanidae, such as R. moeschi (Oppel), coming from the lowermost part of unit D, and illustrated by Matyja & Wierzbowski (2000, Fig. 4c) and Wierzbowski (2022, pl. 15:2A-B), and some other poorly preserved and difficult for closer determination specimens of that genus currently recognized in units D-E.
The stratigraphical interpretation of the discussed Subboreal ammonites in term of the Subboreal zonation indicates the correlation of the whole discussed succession with the NW European Cymodoce Zone. The occurrence of ammonites similar to Rasenia evoluta and R. involuta, strongly suggests the presence of the higher levels of that zone (see Birkelund et al., 1978, 1983). It should be remembered, however, that the highest part of the Cymodoce Zone was often treated in the past as an interval characterized by common occurrence of the fine-ribbed Rasenioides. In the studied succession at Małogoszcz, dominated by Submediterranean ammonites, the Subboreal Rasenioides ammonites are very rare, which precludes the precise differentiation of stratigraphical intervals corresponding to the Askepta Subzone, and/or Chatelaillonensis Subzone – both defined by occurrence of the Rasenioides faunas in northern European areas (see Birkelund et al., 1983; Hantzpergue, 1989, 1995). The former can be possibly correlated with the bulk of the succession studied from the Submediterranean horizon perayensis at its base, whereas the base of the latter subzone runs possibly somewhat lower, near the base of the semistriatum horizon, as resulted from wider biostratigraphical correlations of the Subboreal and Submediterranean sections (see Matyja, Wierzbowski, 2000; Comment et al., 2015).
Changes in environment versus evolutionary development of ammonites
The stratigraphical interval corresponding to the upper part of the Hypselocyclum Zone and to the Divisum Zone (or in a broader sense to the whole Divisum Zone) of the uppermost Lower Kimmeridgian represents one of the most prominent faunal turnover in the whole Upper Jurassic. It is markedly correlated with changes in the depositional environment as based on sedimentological data. The main reasons of changes were of climatic and tectonic nature resulting from sea-level oscillations, and/or opening of new sea-routs. It should be remembered that the deepest faunal changes generally occurred during the transgressions, whereas endemism was rather related to dominance of the shallow-water environments (Atrops & Ferry, 1989; Hanzpergue, 1995; Wierzbowski, 2022).
The stratigraphical interval discussed herein corresponded in the Submediterranean Province to decline of the shallow-water carbonate platforms due to progress of a large transgression. This resulted from the tectonic subsidence of the wide shallow-water carbonate areas including that of the Holy Cross Mountains in central Poland: at the boundary between the COK and the LUK tectono-stratigraphic sequences (Kutek, 1994) which corresponds to the boundary between the Buczyna Mbr. of the Spinkowa Góra Fm., and the Skorków Lumachelle of the Coquina Fm. in the Małogoszcz section (Wierzbowski, 2020). The progress of the transgression is well shown in the section studied by several sedimentological observation summarized by Matyja et al. (2006), and by analysis of the geochemical data, mostly oxygen and carbon composition of shells of various oysters by Wierzbowski (2019). A similar tectonic phenomenon is observed in the development of the Banné Member of the Lower Reuchenette Fm. in the Jura Mountains of northern Switzerland which marks the change from an older flat carbonate platform topography into that of a “prominent basin and swell morphology” (Jank et al., 2006). In addition, the climatic oscillations had also a marked influence on sea-level changes, especially those of longer duration related to 100-kyr and 405-kyr eccentricity cycles. Such a study to attempt to recognize the climatic cycles was presented on the basis of detailed geochemical analysis of the Early Kimmeridgian pelagic deposits of the south-eastern France having a good ammonite stratigraphy (Boulila et al., 2008; see also Atrops, 1982). It resulted in recognition of three main eccentricity cycles within deposits strictly coeval to those studied herein and showing similar assemblage of ammonites: beginning with the important transgressive level corresponding to minimum of 405-kyr MS cycle developed at the base of the whole succession (Min. 4 in Fig. 2 of Boulila et al., 2008), and the following two minima of 100-kyr cycles. The duration of the whole stratigraphical interval corresponding to the broadly treated Divisum Zone can be estimated as 260 to 300 kyr (Boulila et al., 2008).
The overall transgression at the decline of the Early Kimmeridgian attained its very high level in central Poland (and south-eastern France) at the end of the Hypselocyclum Chron – during the semistriatum and perayenis horizons, when the transgressive deposits of a basal part of the Skorków Lumachelle (denoted herein as unit A, see Fig. 2) completely covered the earlier shallow-water carbonate platform deposits. This level additionally corresponds to the minimum (Min. 4 after Boulila et al., 2008) of the 405-kyr eccentricity cycle: it marks the minimum of the magnetic susceptibility (MS), and corresponds to enhanced carbonate production, showing the maximum insolation, which appears to have induced a very high sea-level according to the model proposed by Boulila et al. (2008, 2010).
The transgression in the Submediterranean Province controlled both by climatic and synsedimentary tectonics resulted in a marked exchange of the ammonite faunas (Fig. 8). The extinction of the older lineage of typical Submediterranean ammonites Ataxioceratinae, corresponding to decline of the genus Ataxioceras, was associated with the appearance of new members of the family Ataxioceratidae, such as genera Crussoliceras and Garnierisphinctes, beginning a new evolutionary stage of their development (see Atrops & Ferry, 1989; Enay & Howarth, 2019). The former lineage is represented in the studied interval of the uppermost Hypselocyclum Zone of the Submediterranean Province, from south-eastern France to central Poland, by the last smaller-sized forms of the genus Ataxioceras, both micro- and macroconchs (Atrops, 1982). The final, somewhat isolated microconch member of that lineage is “Orthosphinctes (Ardescia)” perayensis Atrops. This form has been sometimes treated as the end-member of the separate Ardescia lineage (or even Lithacosphinctes lineage; see Moliner & Olóriz, 2010), but it can be also considered as the final member of the small-sized Ataxioceras (Parataxioceras) oppeli group, originated due to the heterochrony process. It may be concluded thus, it is possibly a small-sized form developed due to progenesis as shown by its ornamentation very similar to that of the inner whorls of its direct forerunner – the subspecies A. (P.) oppeli parvum Atrops (see also Atrops, 1982, p. 228, Fig. 53).
When discussing the phylogenetical position of the genus Crussoliceras the most commonly interpretation given (Hantzpergue, 1989; see also Enay et al., 2014) suggested its origin from the Early Kimmeridgian Lithacosphinctes due to growth heterochrony – mostly progenesis and neoteny. The genus Lithacosphinctes as interpreted recently (e.g., Moliner & Olóriz, 2010) includes both micro- and macroconchs corresponding to “the most conservative lineage” among the Early Kimmeridgian Submediterranean Ataxioceratinae: according to such interpretation the genus comprises also some evolute, smaller-sized microconch species occurring in the lower part of the Lothari Subzone, at the end of the lineage, and attributed previously to the Orthosphinctes (Ardescia) inconditus group (see Atrops, 1982), but excluding “O. (A.)” perayensis as shown herein (see above). However, in accordance to that, there does not exist any link in the Submediterranean successions, both stratigraphical and morphological nature, between the older Lithacosphinctes group, and the younger well-developed Crussoliceras group. It is the reason that the proposed lineage of evolutionary development from the indigenous Submediterranean genus Lithacosphinctes to the suddenly appearing genus Crussoliceras is not accepted herein. It should be remembered that according to Moliner (2010), the genus Garnierisphinctes has been treated as descendent of a special group of the genus Ardescia (recognized as the separate genus, composed both of micro-and macroconchs), and moreover it was suggested that the genus Progeronia evolved from Garnierisphinctes during the late Divisum Chron. Also that interpretation is not accepted because of the stratigraphical reasons – the occurrence of the typical representatives of the genus Progeronia in much older deposits of the Early Kimmeridgian (see assemblage of unit A herein, see also e.g., Sarti, 1993).
The new ammonite genera – Crussoliceras, Garnierisphinctes and Progeronia which appeared during discussed transgression at the end of the Hypselocyclum Chron have had possibly their roots in the Mediterranean areas. Such an opinion was expressed already by Pavia et al. (1987) who suggested affinity of Crussoliceras to the Mediterranean Passendorferiinae, which interpretation has been, however, partly questioned by Enay et al. (2014). The Mediterranean origin of the discussed genera can be, however, additionally supported by the occurrence of the genera Progeronia and possibly Crussoliceras deep in the Mediterranean Strombecki Zone – correlated with some lower parts of the Submediterranean Hypselocyclum Zone, markedly below the Lothari Subzone (see e.g., Sarti, 1993). The principal reason for suggesting that representatives of the genera Crussoliceras and Garnierisphinctes have been originated from Mediterranean migrants is, however, that there are not known their earlier Submediterranean forerunners. Somewhat different situation is with the genus Progeronia only, because there are known some forms occurring in older deposits of the Submediterranean succession which seem similar to typical representatives of the genus – e.g., such as “Orthoshinctes (Ardescia)” enayi Atrops occurring at the narrow interval between the lower and middle parts of the Platynota Zone from SE France to central Poland (Atrops, 1982; see also Wierzbowski, 2017). The open problem is, however, if they represent the fragmentarily recognized members of a single (?Mediterranean) lineage, or the local offshoots of Ataxioceratidae developed during the transgressive episodes. A generally poor knowledge on details of the succession (and their precise dating) yielding ammonites referred to as Orthosphinctes, Crussoliceras and Progeronia (e.g., Pavia et al., 1987; Sarti, 1993) in the crucial intervals of the Lower Kimmeridgian (mostly the Strombecki Zone) in the Mediterranean sections prevents the detailed recognition of the evolutionary development of the discussed lineages.
The evolutionary development of ammonites of the family Aulacostephanidae proceeded a different way. In central Poland, in the area of Burzenin, north-west of the Holy Cross Mountains, in the deposits of open-marine environment of the middle part of the Hypselocyclum Zone (i.e. older than studied herein), was noted a marked increase in number, and in morphological development of representatives of the family (Wierzbowski, 2017). These ammonites belonged here to two different groups: that showing a more heavily-ribbed shells and representing possibly a more shallow-water environment such as Eurasenia and Involuticeras, and another one composed of Vineta to Balticeras and the first Rasenioides showing more subdued ribbing, exploring possibly more-open marine, nektonic environment (Wierzbowski, 2022). The overall transgression at the end of the Hypselocyclum Chron brought the heavily-ribbed Aulacostephanidae into flooded area of the shallow-water carbonate platform of the Holy Cross Mountains. Their share within the whole ammonite fauna of unit A in the Małogoszcz section ranges even up to about 35%. On the other hand, the aulacostephanids of the second group were totally absent in this area.
Similar features of distribution of ammonites of the family Aulacostephanidae have been observed also in other shallow-water areas of the Western European Shelf, corresponding to the so-called “Western European Swell” (Hantzpergue, 1989; Hantzpergue et al., 1997; see also Enay et al., 2014). A sudden appearance of ammonites of the genus Eurasenia, along and above the occurrence of Ataxioceras of A. lothari group, “coincided with a maximum sea-level rise” (Hantzpergue, 1995, p. 247). The horizons aulsnisa and manicata as defined on the basis of Eurasenia in the Western European Shelf can be just correlated with the semistriatum horizon of the upper part of the Hypselocyclum Zone of the Submediterranean zonation (Hantzpergue, 1989; Matyja & Wierzbowski, 2000).
On the other hand, a sudden development of the genus Rasenioides representing the second group of Aulacostephanidae took place in the areas of northern and north-western Europe corresponding to the Subboreal Province, or representing the transitional areas between Submediterranean and Subboreal provinces. The dominance of these ammonites is observed e.g., in England (Birkelund et al., 1983), where their appearance defines the base of the Askepta Subzone correlated with the upper part of the Subboreal Cymodoce Zone, but also in a similar stratigraphical position in the Peri-Baltic Syneclise from the north-eastern Poland to Lithuania (e.g., Wierzbowski et al., 2015). In Aquitaine (Hantzpergue, 1989; Hantzpergue et al., 1997), the appearance of Rasenioides defines the base of the askeptus horizon within the Chatelaillonensis Subzone – which is located directly above the aulsnisa-manicata horizons with Eurasenia. The crucial for correlation of the discussed aulacostephanid (Subboreal) and the ataxioceratid (Submediterranean) zonations appeared the data from boreholes in the Zalesie Anticline in northern Poland studied by the present author. The recognized here (Matyja & Wierzbowski, 2000, Figs. 3–4) nearly coeval occurrence of early Rasenioides and “Orthosphinctes (Ardescia)” perayensis Atrops indicates, the correlation of the lowermost part of the Askepta Subzone or askeptus horizon of the Chatelaillonensis Subzone in Subboreal or transitional areas of the northern Europe with the perayensis horizon of the uppermost part of the Hypselocylum Zone of the Submediterranean Province. It should be remembered, however, that the occurrence of “O.(A.)” perayensis along with late representatives of the genus Rasenioides transitional to Aulacostephanoides, as reported in archival materials from core Kcynia IG-IV in northern Poland (Matyja & Wierzbowski, 2000, Fig. 2), suggests also a local higher upward range of that species. Anyway, the sudden invasion of the the Subboreal Rasenioides to the north, coincided possibly in time with a sudden spread across the Submediterranean Province of ammonites of the Mesogean affinity – such as Crussoliceras, Garnierisphinctes and Progeronia, as discussed above.
Unit B in the Małogoszcz section has clearly the regressive character as indicated by its lithological characteristics (see above). The assemblage of ammonites consists mostly of Ataxioceratidae (Crussoliceras, Garnierisphinctes and Progeronia) and to lesser degree of the heavily-ribbed Aulacostephanidae (Eurasenia, Prorasenia, rare Rasenia), showing thus a marked similarity to that of unit A, but without Ataxioceras. The younger ammonite assemblage of unit C reveals, however, a markedly different character.
The most important new faunal elements in ammonite assemblage of unit C are the suddenly appearing fairly numerous Aspidoceratidae, especially those of the genus Pseudhimalayites with the species P. uhlandi (Oppel). The roots of the genus were possibly in the Western Tethyan areas, or even far outside, thus a wide distribution of this genus in many European sections was an effect of migration (see e.g., Schweigert, 1997). The species P. uhlandi associated with many other Tethyan ammonites, such as various species of Nebrodites, occurs commonly in the Western Tethyan areas, and their foreland – in the Submediterranean Province, defining everywhere the upper part of the Divisum Zone or of the Herbichi Zone – the Uhlandi Subzone (e.g., Geyer, 1961, Sarti, 1993; Caracuel et al., 1998). Even in the studied Submediterranean succession at Małogoszcz – some representatives of various species of Nebrodites have been encountered along with P. uhlandi in unit C. Additionally, the not numerous Aulacostephanidae are markedly impoverished here, both in number and in presence of heavily-ribbed forms. All these data strongly suggests a transgressive character of unit C. It should be remembered that the deposits of the Uhlandi Subzone are treated as transgressive in character in many areas of Europe (e.g., Marques & Olóriz, 1992). This high sea-level can be correlated possibly with the minimum of 100-kyr eccentricity cycle (see Boulila et al., 2008, 2010).
Units D and E in the Małogoszcz section yielded numerous specimens of Pseudhimalayites uhlandi (Oppel). Unfortunately the distribution of these specimens in the succession cannot be traced in details mostly because of lack of precise location of the particular finds. It is only the topmost part of unit E recognized which shows a marked concentration of the Pseudhimalayites shells, some of them attaining large sizes. In a similar stratigraphical position has been found also a few specimens of Phylloceratidae of giant sizes (about 0.5 m in diameter), interpreted herein as the allochtonous elements which appearance has been possibly related to the post-mortem drift of shells from the Tethyan areas (thus not taken into account in the diagram of distribution of the ammonite genera in the succession – see Fig. 2). It seems highly probable that the concentration of all these shells at the top of unit E resulted from a very high sea-level. This may correspond to the minimum of the next 100-kyr eccentricity cycle well documented in the late Divisum Subchron (see Boulila et al., 2008, 2010). This level corresponds possibly also to the balderum horizon (or subzone) as marked by common occurrence of the Tethyan form Idoceras balderum (Oppel) well documented at the top of the Uhlandi Subzone of the Divisum Zone in the Submediterranean areas of southern Germany to south-eastern France (see e.g., Hantzpergue et al., 1997). Such stratigraphical interpretation can be also confirm by finding in the Małogoszcz section, at the top of unit E, of a single specimen of Taramelliceras (Taramelliceras) compsum (Oppel) of the Tethyan origin.
Some changes in ammonites of the family Ataxioceratidae seen already in unit C, recognized also in units D-E include the emerging of the new genus Tolvericeras. The genus as interpreted by Enay et al. (2014) derived possibly from Garnierisphinctes and Crussoliceras. The rare specimens discovered in the Małogoszcz succession show a marked similarity to “ Tolvericeras n. sp.” in Gygi (2003, p. 144, Figs. 165–166) coming from the Divisum Zone of northern Switzerland, showing independently some similarity to Garnierisphinctes. On the other hand, the units C-D-E yielded also numerous specimens of Crussoliceras [C. cf. crusoliense (Font.)], Garnierisphinctes [G. plebejus (Neumayr and G. championneti (Neum., G. semigarnieri (Geyer] and less common Progeronia [ P. (P.) eggeri (von Ammon), P. (H.) breviceps (Quenstedt)].
The recognized changes within family Aulacostephanidae in units D-E of the Małogoszcz section include especially the rare occurrences of the advanced morphologically representatives of the genus Rasenioides, such as R. moeschi (Oppel). Their appearance, already at the base of unit D, can be treated as a manifestation of “southern drift” of the genus which developed earlier in the Subboreal Province (see Wierzbowski, 2022; see also comments above): this phenomenon resulted possibly from appearance in the succession studied of marly facies resembling the “Virgulian Facies” of north-western Europe suitable for development of the Subboreal fauna (cf. Hantzpergue, 1995). On the other hand, the local occurrence of a special group of aulacostephanids intermediate between some Eurasenia and Pararasenia has been recognized in upper parts of unit E. They show heavy ornamentation on the whorl side characteristic of both Eurasenia and Pararasenia, but reveal an incipient obliteration of ribbing in the ventral side of whorls typical of the genus Pararasenia. The specimen (Fig. 7c-d) studied resembles the heavily ribbed species Pararasenia quenstedti Durand (cf. Ziegler, 1962) reported in younger beds of the earliest Late Kimmeridgian in the Małogoszcz section (Kutek, 1968).
Two specimens coming from units B and D-E (Fig. 7a-b) are representatives of NW European Subboreal genus Rasenia. They show a weakly involute to weakly evolute coiling, rather distant primary ribs, and a high number of secondary ribs (the secondary/primary rib ratio equals 5.0 at about 50 mm diameter). The specimens belong to Rasenia involuta Spath, a very characteristic species commonly encountered in southern England where the specimens coming from (e.g., Birkelund et al., 1983, Fig. 3A-D) are very similar to the specimens studied. It is worth noting that all these specimens resemble also the heavily-ribbed form referred to as Rasenioides ecolisnus (Hantzpergue, 1989, pl. 35: c-f). It should be remembered that the latter is treated as a form which begins a side branch of the Rasenioides lineage, leading in its evolutionary development to origin of a more heavily-ribbed forms of the genus Aulacostephanoides (Hantzpergue, 1989, Figs. 130,133), or marking the transition to the genus Aulacostephanus (Borreli, 2014, Fig. 2). The possible phylogenetical link between late Rasenia involuta, and some early forms of Aulacostephanoides/Aulacostephanus (as suggested herein) can be thus considered as an alternative proposal for the lineage (assuming the phylogenetical affinity between R. involuta and R. ecolisnus), which developed independently of that leading from the densely-ribbed Rasenioides to the typical Aulacostephanoides (cf. Borreli, 2014).