Lower Tithonian and lower Berriasian brachiopods from the Márévár Limestone Formation, Zengővárkony (Mecsek Mountains Hungary), and remarks on their palaeoenvironment

A new collection provided some brachiopods assigned to Lacunosella hoheneggeri, Pygope diphya and P. janitor from the lower Tithonian (Micracanthoceras ponti Zone) and lower Berriasian (Calpionella Zone), and from the limestone succession at Zengővárkony, Mecsek Mountains, Hungary. This is the first taxonomic description and photographic documentation of these fossils. We provide reliable documentation of pygopid brachiopods from the Mecsek Mountains, known since 1880, but previously not described. For the moment, three pygopid brachiopod species are reliably reported from the Mecsek Mountains: Pygope diphya, P. janitor and Pygites diphyioides. The Lacunosella hoheneggeri described herein is the first record of Berriasian rhynchonellide brachiopods from the Mecsek Mountains. The lower Berriasian brachiopods may belong to a normal palaeoenvironment, with the usual size distribution.


Introduction
Berriasian brachiopods are scarce in the Western Tethys. Any new record increases our knowledge. However, Tithonian brachiopods are abundant, especially pygopid ones in the Tethyan faunal realm. After a long static period from the Triassic to the end of the Jurassic (Ager 1993: fig. 10.2), three distinctive genera evolved from the genus Nucleata.
These brachiopods remained without taxonomic descriptions until now, when the present authors revisited their reported localities. Before submitting this paper, we tried to find these pygopid brachiopods in the collection of the MGSH, Budapest. However, the pygopid brachiopods collected by Böckh (1880) and Vadász (1935) from the Mecsek Mountains are currently under revision by Attila Vörös, and were not available; there were no rhynchonellide brachiopods in the collections from the Berriasian of the Mecsek Mountains. The aim of this paper is to report, describe and document the rare Berriasian brachiopods from the Mecsek Mountains that have been known for decades (Böckh 1880, Vadász 1935, Vörös 1997), but only from faunal lists.

Geological setting
The Mecsek Mountains (Fig. 1) belong to the Tisza Mega-Unit (Haas and Péró 2004) as the northernmost unit of the domain, which is considered a microplate (Vörös 1993;Csontos and Vörös 2004). Late Jurassic development of the Mecsek Mountains is characterized by red, nodular, sometimes cherty and thin, ammonitico rosso-type Oxfordian and Kimmeridgian beds (Nagy 1964). In the Tithonian, the first indications of volcanic activity are discontinuous layers and beds of tuff. In the latest Jurassic and Berriasian continental rift type (Harangi 1994), volcanic activity halted carbonate sedimentation and produced an ankaramite-alkaline basaltic paleovolcano (Wein 1961;Császár 2002). The Upper Jurassic-Lower Cretaceous mixed volcano-sedimentary sequence seems to be continuous; however, Nagy (1964) indicated a discontinuity between the uppermost Tithonian and lowermost Berriasian. Contrary to this, a continuous Jurassic/Cretaceous boundary sequence has been suggested by Császár et al. (1990). Based on field observations, the present authors support the opinion of Császár et al. (1990). Related research is going on to define the J/K boundary beds in the Mecsek Mountains at Zengővárkony.

Studied sections
In the south-eastern part of the Mecsek Mountains in the abandoned quarry at Zengővárkony Böckh (1880) first reported Jurassic beds with pygopid brachiopods (Fig. 2). Böckh also collected ammonites from the abandoned quarry (called by him mészkemencék = lime kilns) that are housed in the collection of MGSH. The lime kilns of Zengővárkony are abandoned today. The small quarries traverse the succession (Fig. 3) from the Oxfordian (Nagy 1964) to the upper Berriasian (Grabowski et al. 2016). An artificial section was excavated during the current study between the lower Tithonian and upper Berriasian (Fig. 4). Some layers are recognized that have yielded pygopid specimens and a specimen of the ammonite Volanoceras volanense that indicates the lower Tithonian Micracanthoceras ponti Zone.
In a NW direction from the artificial section, there is a wall that would have been the quarry wall in the nineteenth century. Some sampling was done in the upper part that revealed a late Berriasian age on magnetostratigraphic sampling (Grabowski et al. 2016). 5-6 meters  Haas and Péró (2004), simplified below paleomagnetic sampling points of Grabowski et al. (2016), an early Berriasian section was found that provided other brachiopod specimens (Fig. 5). This part of the section is characterized by massive, pink-red-coloured micritic poorly stratified limestone beds. Thin sections from this bed revealed a rich calpionellid microfauna with Calpionella alpina prevailing that may indicate the lowermost Berriasian.

Materials and methods
Abbreviations. FO: first occurrence; L: length of the valve; W: width of the valve; H: height of the valve; h: length of the perforation on the ventral valve; hl: length of the perforation on surface of the dorsal valve according to Lukeneder (2002). Dimensions are given in mm. Measurements were acquired by a manual caliper. Measurements in brackets refer to estimated data due to poor preservation. The specimens are housed in the Palaeontological Collection of the Hungarian Natural History Museum, Budapest.
Institutional abbreviations. HNHM-Hungarian Natural History Museum, Budapest. Systematics of brachiopods follows the system of Williams et al. (1996).
Internal characters-As only one specimen was recovered, serial sections were not prepared.
Remarks. Although this species has extreme variability (Nekvasilová 1977: 67), the specimens of Remeš (1899: pl. 8, figs. 1, 2) may fall outside the variability (lack of strong ribs, not inflated shell, etc.). The dimensions of the present specimen (length and width) conform to the average dimensions taken from 1100 specimens (Nekvasilová 1977). Bujtor (2006) reported it also from Zengővárkony but from younger (upper Valanginian-lower Hauterivian) sediments. The younger population of L. hoheneggeri from the same locality presented a significant average size increase (Bujtor 2007: 192, fig. 4) of mean dimensions compared to the material from the type locality in Štramberk, Czech Republic (Nekvasilová 1977). However, the dimensions of the present specimen fall into the range of the Štramberk population of Nekvasilová (1977). The present specimen is most similar to the specimen of Barczyk (1979: pl. 2, fig. 4).
Stratigraphic and geographic distribution. Tithonian to Valanginian of SE France, Štramberk (Czech Republic), Hungary, Pieniny Klippen Belt (Poland), and the Ukrainian Carpathians.  Description. External characters: Shell large, adult, triangular shape, biconvex, laterally not inflated with elongated, teardrop shape foramen on the brachial valve placed close to the umbo. Ventral valve has a narrow ridge from the umbo to the perforation. Maximum width of the ridge is 5.5 mm, maximum height 2 mm. The internal moulds are partly covered by shell with a thickness of 0.3-0.5 mm. Lateral commissure is not seen, anterior commissure is straight. Umbo is big, erect, oval shaped. Both valves show fine growth lines throughout from the umbo to the anterior commissure. Where it is not covered by shell remains, fine and thin imprints of vascular myarium channels are preserved on the right side of the dorsal valve internal mould (specimen INV 2019.2815).
Internal characters-As only one complete specimen was recovered, serial sections were not prepared.
Remarks. Böckh (1880) noted that preservation is bad but he collected many specimens. We have only collected two specimens but with poor preservation. The present specimens agree most closely with the specimen of Barczyk (1972: pl. 4, fig. 2a) and Sulser (2016: fig. 8t) with the same narrow and elongated foramen. It differs from the specimen of Vörös and Dulai (2007) with its narrower and elongated foramen, less inflated ventral valve and less developed umbo.
The authorship of P. diphya is variously interpreted. Authors refer to Catullo or von Buch as the original author of the species; however in his original work, von Buch (1835) clearly referred to Fabio Colonna (cf. Dollfuss and Dautzenberg 1932: 312). Notwithstanding, according to Art. 3.2. of the International Code of Zoological Nomenclature "no name published before 1 January 1758 enters zoological nomenclature but information published before that day may be used". Therefore, von Buch must be credited as the author of the species; however, Fabio Colonna (or Fabius Columnae) could be indicated. We strongly suggest keeping Stratigraphic and geographic distribution. Stratigraphic distribution: FO of P. diphya is at the base of the lower Tithonian and it disappears by the end of the Berriasian (Dieni and Middlemiss 1981). It occurs in the western part of the Tethys, most commonly along the northern margin; however, it also appears along the southern margin of the Tethys, in Morocco (Somody 1992).
Stratigraphic and geographic distribution. Stratigraphic distribution: P. janitor FO is most probably in the Kimmeridgian and it disappears in the middle Barremian (Dieni and Middlemiss 1981). It has wide geographic distribution mainly in the western part of the Tethyan Realm with scarce occurrences in the Boreal Realm (East Greenland: Harper et al. 2005).

Discussion
Pygopid brachiopods are frequently used for palaeobiogeographical analysis. Kázmér (1990Kázmér ( , 1993 proposed that the pairs of Pygope catulloi and P. diphya inhabited the nutrientpoor southern margin of Tethys, while P. janitor and Pygites diphyoides with a large central perforation inhabited the nutrient-rich northern margin of the Tethys. This assumption is rejected by Michalík (1996) on the basis that brachiopod distribution data did not support this pattern. However, later research may support this idea (Lukeneder 2002). Pygopids were also used as the marker ('Tethyan index' cf. Michalík 1992) of the Tethys; however, their presence in the Boreal Realm (Harper et al. 2005) did not fit into this assumption. Hence, it must be noted here that Ager and Walley (1977) considered a geographic range extension via the opening of the Atlantic Ocean. But other factors may interact, too. A Gulf Stream-type circulation may also have contributed to their extra-Tethyan distribution (Ager 1986;Sandy 1991).
Regarding the paleoecology of this group, it is also disputed. Although they are significant elements of the Tethyan basinal faunas (Ager 1976), their distribution was not only controlled by bathymetry and temperature (Michalík 1992), but by ocean currents, too (Ager 1994). Traditionally, pygopids are interpreted as deep-water organisms (Ager 1965(Ager , 1976. Today, pygopid brachiopods are rather considered as indicative of colder than warmer waters with eurybathic character. It is also suggested that pygopid brachiopods also occupy shallow water environments over seamounts (Ager 1993). On the other hand, in faunal assemblages, the increasing percentage of pygopids suggests deeper environments (Golonka and Krobicki 2001).
It is important to emphasize that in the Mecsek Mountains (but also in the Mecsek Tectonic unit) during the Berriasian volcanic activity intensified, Berriasian-Valanginian age pillow lavas are reported from the sequence, therefore the ocean floor was not quiescent, and undisturbed. It is remarkable, that beside the benthic brachiopods only nektonic animal remains (ammonites and calpionellids) and some microfossils (foraminifers) are recorded from the Tithonian-Berriasian beds in the Mecsek Mountains.
On the other hand, it is worth mentioning that the present specimen of Lacunosella hoheneggeri is remarkably smaller than those of the late Valanginian-early Hauterivian iron ore-related brachiopod fauna that is dominated by L. hoheneggeri (Bujtor 2006(Bujtor , 2007 from the same locality. But this is not surprising. The average mean dimensions of L. hoheneggeri are in line with the dimensions of the present specimen: Average L: 15.7 and average W: 16.3 mm (Bujtor 2007;Nekvasilová 1977). The dimensions of the present specimen fall into this range (see: Dimensions). This is further evidence that in normal conditions (e.g., at type locality of L. hoheneggeri in Štramberk, Czech Republic and the lower Berriasian at Zengővárkony), the length and width of this species is around 16 mm; while under special, nutrientrich conditions, it remarkably shifts to larger dimensions due to special ecological conditions (Bujtor and Vörös in press).

Conclusion
The first description and publication of pygopid brachiopods based on a new collection from the Mecsek Mountains (South Hungary) provides a solid foundation for any further palaeobiogeographic analysis, which has been based only on faunal lists during the past 140 years. The new field collection supported the presence of two pygopid species (Pygope diphya, P. janitor) in the region from where earlier researchers (Böckh 1880;Vadász 1935) quoted the presence of three pygopid species, which represent the Tithonian and the Berriasian. Based on previous (Bujtor 2006) and current research presented herein, three pygopid species are confirmed from the Upper Jurassic and Lower Cretaceous succession of the Mecsek Mountains: Pygope diphya, P. janitor and Pygites diphyoides. The new occurrence of Lacunosella hoheneggeri and its dimensions refer to normal ecological conditions as in its type locality in Štramberk, Czech Republic. the Österreichische-Ungarische Aktion Gesellschaft (Osztrák-Magyar Akció Alapítvány). The authors are thankful to the owner of the land, Mr. Ferenc Vogl for his kind permission to enter and collect on his land. The authors are indebted to Attila Vörös for his careful comments and suggestions on the early version of this paper. Our special thanks due to the reviewers, Donald A.B. MacFarlan (New Zealand), and Michael R. Sandy (University of Dayton, USA), Mike Reich (Editor-in-Chief) for their critical remarks and suggestions as well as correcting our English which significantly improved the quality of this paper.
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