Lubomir S. Metodiev

William Smith Meeting in Honor of J. H. Callomon, Sherborne Castle, September 30th - October 2nd 2015

Lubomir S. Metodiev Geological Institute, Bulgarian Academy of Sciences This work is based on the study of ammonites, which take part of the Bulgarian Academy of Sciences collections. Supplementary data on this material are available after a personal request at the following e-mail addresses: [email protected], [email protected].


The Callovian rocks have a relatively wide outcrop occurrence within the space of the Balkan Zone, which coincides with the Balkan Mts. Chain in Bulgaria. The latter forms the outermost part of the Alpine Orogen in this country and has WNW-ESE trend between the Moesian Platform from the north and the inner parts of the orogen from the south. It consists of thick Mesozoic rocks that are lying unconformably upon Godwanian Lower Palaeozoic siliciclastic sediments, high-grade metamorphic rocks and huge Late Palaeozoic acid intrusions.


Correlation scheme of the Lower-Middle Jurassic lithostratigraphic units from the Western Balkan Mts.

The Callovian Stage in Bulgaria typically corresponds to moderately expanded, and commonly gapped, finecarbonate-mudstone, pelagic- to hemipelagic facies with scattered ammonites, and only two areas in NW Bulgaria were found to contain a limited number of attractive outcrops, enclosing well-preserved and rich enough Callovian ammonites.

The Middle Jurassic rocks at the Zimevitsa Plateau, W Balkan Mts. (the red up-down arrow represents the approximate extent of the Callovian strata in the limbs of a prominent anticline structure).

William Smith Meeting in Honor of J. H. Callomon, Sherborne Castle, September 30th - October 2nd 2015 Usually, the Callovian ammonites can be found in highly condensed iron-ooidal-bioclastic limestones (including the field in which the Callovian Stage was found in Bulgaria, see below), and the ammonite assemblages in superposition are quite rare.

The Lower-Middle Callovian ammonite faunas from the condensed Fe-ooidal limestones of the Belogradchik Area.

The Bathonian-Callovian transition at the section near Gintsi Village includes hypercondensed Lower Callovian strata (30 cm-thick crinoidal limestones), showing very low rates of deposition, and keeping in-situ preserved ammonites that display a prolonged exposition on the sea-floor before burial.


Professor George Zlatarski (1854-1909) – the originator of the Jurassic stratigraphic studies in Bulgaria, and the title page of his monograph, in which the Jurassic System was introduced and subdivided into nine stages. However, the Callovian Stage was absent!

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Professor Stefan Bonchev Ivanov (1829-1947), and the first detailed geological map of NW Bulgaria published in 1919, in the work on which, the presence of the Callovian rocks was firstly indicated in Bulgaria (a red asterisk denotes the outcrop location discovered by the author). No Callovian were published again!

William Smith Meeting in Honor of J. H. Callomon, Sherborne Castle, September 30th - October 2nd 2015 Title page (left) and fossil plate (right) of the original paper of Bonchev and Popov, published in 1935, in which the Callovian Stage was introduced in Bulgaria. It is based on the discovery of highly condensed bed with many ammonites (abundant Macrocephalites and subordinate Pseudoperisphinctinae), located to the north of the town of Belogradchik. The Callovian Stage ‘celebrates’ 80 years in the Bulgarian Jurassic in 2015!

Fossil plate (left) and lithological column (right) of the same classical locality, revised in 1961 by Julius Stephanov. The latter author has found that the Callovian fossil-bearing bed keeps an incomplete Lower Callovian ammonite assemblage, which is lying directly on condensed Lower Bathonian strata. However, both works refer the Callovian Stage to the Upper Jurassic!

William Smith Meeting in Honor of J. H. Callomon, Sherborne Castle, September 30th - October 2nd 2015 After a few years, a new and more expanded fossiliferous Callovian sequence was discovered, and the Callovian Stage has found its true place into the set of the Jurassic stages in Bulgaria.

Lithological column of the upper Bathonian-Lower Oxfordian succession described by M. K. Howarth and J. Stephanov (left) and picture of cliffs of the Callovian-Oxfordian rocks (right) in the Nechinska Bara River valley (Western Fore-Balkan Mts.). This is the best development of the Callovian Stage in Bulgaria.

William Smith Meeting in Honor of J. H. Callomon, Sherborne Castle, September 30th - October 2nd 2015 A three-fold substage (zonal) subdivision was adopted by Howarth and Stephanov (1965), and it is still in use. The zonal units are too broad, with roughly defined stratigraphy and limits, and placed in inverted commas in order to emphasize that they are conditional. The ammonite taxa that were selected for typifying the zones or erected as indices do not seem reliable as they exhibit a high degree of taxonomic uncertainty or too extended stratigraphical ranges, and some of them might be facies-bound, while others are even unusual in Bulgaria. The Bulgarian Callovian ammonite scheme is provisional, pending revision and refinement, to bring it into the line with current European practice.

William Smith Meeting in Honor of J. H. Callomon, Sherborne Castle, September 30th - October 2nd 2015 The Bathonian Homoeoplanulites and Choffatia It is the Late Bathonian Oxycerites oppeli The Bathonian genus Prevalia – the plausible derivation link between the latest Bathonian Zigzagiceratinae and – examples from the Upper Bathonian ancestors of the Biochron time when the first forerunners the earliest Bathonian Pseudoperisphinctinae! Callovian Pseudoperisphinctinae! of the Pseudoperisphinctinae may have appeared from Procerites or Siemiradzkia ancestors! Choffatia vicenti Mangold Homoeoplanulites bugesiacus (Dominjon)

Choffatia praecursor Mangold

Prevalia thressa (Stephanov) Prevalia bassae (Stephanov) Homoeoplanulites sp. Siemiradzkia berthae (Lissajous)

Prevalia pseudoperspicua Prevalia paragracilis (Besnosov) (Stephanov)

Choffatia vicenti Mangold

Prevalia prevalensis (Stephanov)

Prevalia gr. detorta (de Grossouvre)

Homoeoplanulites mouterdei Mangold, Martin & Prieur Choffatia richei Mangold

Homoeoplanulites gr. pseudoannularis (Lissajous) Choffatia vicenti Mangold

The earliest record of the subfamily Pseudoperisphinctinae in Bulgaria is that of Homoeoplanulites [M + m] and Choffatia [M +m], which appear near the base, occur throughout the upper Bathonian, and continue ranging across the Bathonian/Callovian boundary.

William Smith Meeting in Honor of J. H. Callomon, Sherborne Castle, September 30th - October 2nd 2015 Choffatia perdagata (Waagen) Choffatia recupeoi (Gemmellaro)

Homoeoplanulites difficilis (Buckman) Homoeoplanulites madani (Spath)

Macrocephalites spp. Homoeoplanulites balinensis (Neumayr) Homoeoplanulites furculus (Neumayr)

Choffatia neumayri (Siemiradzki)

Choffatia transitoria (Spath) Homoeoplanulites funatus (Oppel)

Choffatia composita (Mangold)

Choffatia cf. pseudofunata (Teisseyre)

After a few levels of a relative scarcity at the basal beds of the Callovian strata, Homoeoplanulites [M + m] and Choffatia [M + m] display equally prominent abundance nearly the top-half of the Lower Callovian, but Choffatia become much more common, whilst Homoeoplanulites tend to decrease in the assemblages and disappear probably around the Lower/Middle Callovian boundary.


Elatmites prahecquensis Mangold

Indosphinctes luceyensis Mangold

Indosphinctes petaini (Lemoine)

Indosphinctes rusticus Spath

Indosphinctes zelleri (Petitclerc)

Elatmites aff. gracililobatus (Buckman)

Indosphinctes choffati (Parona and Bonarelli)

Elatmites nikitinoensis (Sazonov) Elatmites gr. graciosus (Siemiradzki)

Elatmites steinmanni (Parona and Bonarelli)

Elatmites sp.

Elatmites revili Mangold

Elatmites calloviensis (Loczy)

The levels of maximum dispersal of the Lower Callovian Homoeoplanulites and Choffatia coincide with the advent of an abundance of other striking members of the subfamily Pseudoperisphinctinae in Bulgaria – Indosphinctes [M] and Elatmites [m].


Macrocephalites ?macrocephalus (Schlotheim) “breccia” Macrocephalites septifer (Buckman) [M + m]

Macrocephalites cf. jacquoti (Douvillé) Macrocephalites cf. dolius (Buckman)

Macrocephalites cf. herveyi (Sowerby)

Macrocephalites gr. liberalislophopleurus (Buckman)

Macrocephalites gracilis Spath [M + 2m]

Macrocephalites versus (Buckman)

Macrocephalites cf. subtrapezinus (Waagen)

Macrocephalites lamellosus (Sowerby) [M]

From the time of discovery of the Callovian in Bulgaria, Macrocephalites faunas were considered to be the main age-defining fossils of the Lower Callovian. Indeed they are, but will have to be reassessed both in terms of ranges and taxa, and weighed with the other coeval faunas.


Bullatimorphites bullatus (d’Orbigny)

Sigaloceras calloviense (J. Sowerby) - a pathological specimen showing entirely different ornament on the two sides

Hecticoceras hecticum (Reinecke) Reineckeia sp.

Zieteniceras pseudolunula (Elmi)

Oxycerites mamertensis (Waagen)

Rehmannia cf. grossouvrei (Petitclerc)

Even rare, some other key-examples of age-diagnostic ammonite genera (e.g. Bullatimorphites, Sigaloceras, Reineckeia, Oxycerites, Zieteniceras, Hecticoceras s.s., Rehmannia) also occur, and taken together with the Pseudoperisphinctinae, these faunas could serve for the obtaining of more reliable faunal spectra and finer stratigraphical discrimination of the Lower Callovian than that attained previously.


Putealiceras punctatum (Stahl) Sublunuloceras gr. discoides (Spath)

Pseudopeltoceras gr. famulum (Spath)

Rossiensiceras multicostatum (de Tsytovitch) Brightia gr. nodosum (Bonarelli)

Lunuloceras gr. lonsdalii (Pratt)

Orbignyiceras trezeense Gérard & Contaut

Zieteniceras zieteni (de Tsytovitch)

MIDDLE CALLOVIAN

Glyptia submatheyi (Lee)

Peltomorphites athletoides (Lahusen) UPPER CALLOVIAN

The range of the Pseudoperisphinctinae rapidly declines in the Middle, and especially in the Upper Callovian, and they became strongly subordinate to the high diversity of morphologies referred to Hecticoceras (s.l.). The latter faunas generally define the boundaries of the Middle Callovian, but they still remain unclear in terms of their taxonomical limits and stratigraphical ranges. The Upper Callovian is limited between the advents of the earliest members of the Aspidoceratidae (Pseudopeltoceras and Peltomorphites, respectively).

William Smith Meeting in Honor of J. H. Callomon, Sherborne Castle, September 30th - October 2nd 2015 Choffatia gr. poculum (Leckenby)

Flabellisphinctes villanyensis (Till)

Flabellia tuberosus Mangold

Binatisphinctes cf. hammulatus (Buckman)

Binatisphinctes gr. rjazanensis (Teisseyre)

Binatisphinctes comptoni (Pratt) Kosmoceras cf. bigoti (Douvillé)

Binatisphinctes rossicus (Siemiradzki)

Paralcidia aperta Spath

Choffatia trina (Buckman) Orionoides [nucleus]

Alligaticeras aff. rotifer (Brown)

Within this framework, the Middle-Upper Callovian Pseudoperisphinctinae yielded a faunal set that is composed of Flabellisphinctes [M] and Flabellia [m], followed upwards by Binatisphinctes [M + m] and scattered Choffatia [M + m], as well as by rare Kosmoceratidae and Oppeliidae. Approximately at the mid-Upper Callovian levels, the incoming of the subfamily Perisphinctinae (Alligaticeras and Orionoides) was recorded. The Middle-Upper Callovian ammonite record from Bulgaria reminds to that given by Cox (1988) from UK!


The conclusion that can be drawn from the above stated evidence is that at least valuable indications were newly obtained and deeper faunal discrimination seems possible, but much work is still needed!