Budoš Limestone
Stratigraphic range: Lower Toarcian ~
Duga Valley, where the southernmost Budoš Limestone emerges
Type	Geological formation
Thickness	50–60 m (160–200 ft)[1]
Lithology
Primary	Limestones alternated with green marls and calcareous stone
Other	Lithified limestone
Location
Coordinates	42°59′30″N 18°54′20″E / 42.99167°N 18.90556°E / 42.99167; 18.90556
Region	Nikšić
Country	Montenegro
Type section
Named for	Budoš Mountain
Named by	Pantić
Year defined	1952[1]
Budoš Limestone (Montenegro)

The Budoš Limestone ("Budos Mountain Limestone", also known as Briska Breccia^[2]) is a geological formation in Montenegro, dating to 180 million years ago, and covering the Toarcian stage of the Jurassic Period. It has been considered an important setting in Balkan paleontology, as it represents a unique terrestrial setting with abundant plant material, one of the few know from the Toarcian of Europe.^[3] It is the regional equivalent to the Toarcian units of Spain such as the Turmiel Formation, units like the Azilal Formation of Morocco and others from the Mediterranean such as the Posidonia Beds of Greece and the Marne di Monte Serrone of Italy.^[4] In the Adriatic section, this unit is an equivalent of the Calcare di Sogno of north Italy, as well represents almost the same type of ecosystem recovered in the older (Pliensbachian) Rotzo Formation of the Venetian region, know also for its rich floral record.^[5]

Description

The Toarcian paleogeography of Montenegro was characterised by two major units, mostly found in the Dinarides: the High Karst Zone, representing a Carbonate Platform, concretely the Adriatic-Dinaric Carbonate Platform and the Budva Basin, that represented a pelagic setting where ammonites are abundant. The previous Pliensbachian Platform suffered in the Toarcian a partial flooding, with the carbonate facies recovered at W of Nikšić, NE of Podgorica and in the Rumija Mt remaining as environments close to the marginal part.^[4] The Budva basin evolution in the Toarcian was marked by the changes in the sea level, developing a distally steepened ramp until the Lower Toarcian, and an accretionary rimmed platform in younger layers.^[6] The Adriatic-Dinaric Carbonate Platform is well measured at the Mount Rumija where the transitional facies between the platform setting and the deeper pelagic environment is seen, recovering a lateral transition from a lagoonal environment exposed in Seoce to the platform edge, exposed in Tejani (called Tejani section), and finally the deeper water environment, called Livari section can be observed at the own Mount Rumija.^[7]

The Seoce Section is likely linked with the Budoš Limestone depositional setting, found mostly on the mountain of the same name on the Dinarides near Nikšić. The main unit is lithologically almost identical to the major fossiliferous levels of the Rotzo Formation, composed by bituminous limestones and marly limestones (fenestrate limestones and tempestites) with several episodes of emersions, all of coastal origin and rich in plant detritus and leaf remains, connected to the typical Lithiotis reefs found in the Pliensbachian-Toarcian carbonate platforms in the Adriatic region.^[5] The Budoš Limestone was delimited as younger than the Rotzo Formation due to its floral composition and the fact is overlain by the Late Toarcian-Aalenian greenish local claystone-limestone layers.^[5]

The unit is mostly known by its rich macroflora, the most complete and only known of the Mediterranean Toarcian realm, with several characteristics, such as the abundant presence of thermophilic Bennettitales and the dominance of the Seed Fern Pachypteris, that grew on semi-arid climates.^[8] Most of the research of the flora was done by Pantic between 1952 & 1981, recovering abundant Macroflora and Palynomorphs. Several genera where recovered, such as Coniopteris (Dicksoniaceae), Lindleycladus (Krassiloviaceae) and Elatides (Taxodiaceae).^[9]

Ecosystem

The Budoš Limestone was developed in a coastal setting with marine ingressions, likely a Mangrove-type environment

It was considered initially that this flora grew in a continental setting, appearing on deposits that resemble modern inland deposition on ferric soils, thus, in a large inland valley with semi-arid conditions but with nearby large water bodies such as lakes.^[10] Latter however, was interpreted that this flora developed on an island setting in the Dinaric Carbonate Platform, likely linked with the exposed layers of Seoce. This setting would be made of the emerged Budoshi High, representing an island flora; a humid belt would have existed along the shore, while coniferous vegetation would have prevailed in the drier interior.^[11] The Budoš flora, as well Rumija and Seoce lithiotis facies were made after the Livari Supersequence created a massive lagoon in the inner ramp.^[6] A common facies in the 3 locations shows about 1–2 m thick lagoon parasequences, from lithiotis rich subtidal packstone to shallower wackestone, where the lagoonal shale facies recovering the flora deposited.^[6]

The main consensus is that the layers rich in flora belong to a Bahamian-type Mangrove system developed on a coastal setting with a nearby arid inland setting dominated by Cheirolepidiaceae conifers and Bennettites, that was either a submarine intraoceanic carbonate platform or part of a large landmass. The Mangrove system was mostly composed of seed ferns bearing the leaf genus Pachypteris linked with complex root systems that cover most of the layers, developed over and linked with the local aberrant bivalve (Lithiotis) reefs and evolved as a belt around the coast, yet is unknown how far reached.^[10] The inland setting was dry and with common wildfire activity, as proven by the great amount of charcoal recovered in some of the layers.^[10] The Lithiotis layers are intercalated by oolitic and oncolitic layers of likely subtidal origin, with several coastal cycles measured, such as development of lagoons and complete flooding of the vegetation levels, as well small coal-dominated sections. The ingression-regression trend allowed the development of the local mangroves.^[10]

The same type of ecosystem was also recovered more recently on slightly older (Late Pliensbachian) rocks on Albania, with also great dominance of the genus Pachypteris linked with root systems along Lithiotis reefs, with evidence of catastrophic events which “killed” the flora.^[12] These types of layers have been vinculated with the early evolution of crabs.^[13]

Fossil content

Flora

Palynology

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Stratigraphic position	Material	Notes	Images
Nannoceratopsis[9]	Nannoceratopsis cf. gracilis	Budos Mountain	Cysts	A Dinoflajellate, member of the family Nannoceratopsiaceae. It is a genus related with Marine deposits.
Scrinocassis[9]	Scrinocassis sp.	Budos Mountain	Miospores	Dubious Genus with affinities with Scriniocassiaceae. Brackish Green Algae, related to lagoonar water bodies
Porcellispora[9]	Porcellispora longdonensis	Budos Mountain	Miospores	Dubious Genus with affinities with Bryophyta
Aratrisporites[9]	Aratrisporites sp	Budos Mountain	Miospores	Affinities with Isoetaceae. This genus is usually found in situ found related to genera such as Cyclostrobus, Lycostrobus and Annalepis.
Foveosporites[9]	Foveosporites vissheri Foveosporites sp."	Budos Mountain	Miospores	Affinities with the family Lycopodiaceae inside Lycopodiopsida. Lycopod spores, related with herbaceous to arbustive flora common on humid environments	Extant Lycopodium specimens. Genera like Foveosporites probably come from a similar plant
Densoisporites[9]	Densoisporites "sp. A" Densoisporites "sp. B" Densoisporites "sp. C"	Budos Mountain	Miospores	Affinities with the Selaginellaceae inside Lycopsida. Herbaceous Lycophyte flora, similar to ferns, related to humid settings.	Extant Selaginella, typical example of Selaginellaceae. Genera like Densoisporites probably came from a similar or related plant
Calamospora[9]	Calamospora sp.	Budos Mountain	Miospores	Affinities with the Calamitaceae inside Equisetales. Horsetails, herbaceous flora related to high humid environments, flooding tolerant plants.	Recosntruction of the Genus Calamites, found associated with Calamospora
Styxisporites[9]	Styxisporites sp	Budos Mountain	Miospores	Uncertain Fern Miospores whose affinity cannot be concreted beyond Pteridophytes.
Ischyosporites[9]	Ischyosporites sp.	Budos Mountain	Miospores
Verrucosisporites[9]	Verrucosisporites "sp. A" Verrucosisporites "sp. B"	Budos Mountain	Miospores
Deltoidospora[9]	Deltoidospora minor	Budos Mountain	Miospores
Skarbysporites[9]	Skarbysporites sp.	Budos Mountain	Miospores
Murospora[9]	Murospora cf. bicolateralis	Budos Mountain	Miospores
Klukisporites[9]	Klukisporites variegatus Klukisporites neovariegatus	Budos Mountain	Miospores	Affinities with the family Lygodiaceae inside Polypodiopsida. Climbing fern spores	Example of extant Lygodium, Klukisporites come probably from similar genera or maybe a species from the genus
Monolites[9]	Monolites couperi	Budos Mountain	Miospores	Affinities with the Polypodiaceae inside Polypodiales. Ferns of several sizes, from both dry land and near water environments.	Example of extant Drynaria specimens, Leptolepidites come probably from similar genera
Leptolepidites[9]	Leptolepidites macroverrucosus Leptolepidites cf. crassibalteus	Budos Mountain	Miospores	Affinities with the family Dennstaedtiaceae inside Polypodiales. Forested areas Fern Spores	Example of extant Dennstaedtia specimens, Leptolepidites come probably from similar genera
Granulatisporites[9]	Granulatisporites "sp. A" Granulatisporites "sp. B" Granulatisporites "sp. C"	Budos Mountain	Miospores	Affinities with Dipteridaceae inside Pteridophyta. Fern spores related to freshwater ponds.	Example of extant Dipteris specimens, Granulatisporites come probably from similar genera
Duplexisporites[9]	Duplexisporites problematicus	Budos Mountain	Miospores	Affinities with the family Cyatheaceae inside Cyatheales. Arboreal Fern Spores	Example of extant Cyathea, Duplexisporites come probably from similar genera
Obtusisporites[9]	Obtusisporites sp	Budos Mountain	Miospores
Concavisporites[9]	Concavisporites cf. kaiseri Concavisporites "sp. A" Concavisporites "sp. B" Concavisporites cf. Gleichenia unbonatus	Budos Mountain	Miospores	Affinities with the genus Gleichenia inside Gleicheniaceae. Tropical Ferns related to humid ferric soils.	Example of extant Gleichenia, Concavisporites come probably from similar genera
Matonisporites[9]	Matonisporites cf. phlebopteroides	Budos Mountain	Miospores	Affinities with the genus Matoniaceae inside Gleicheniales. Ferns of several sizes, from both dry land and near water environments.
Vitreisporites[9]	Vitreisporites pallidus	Budos Mountain	Pollen	Pollen from the Family Caytoniaceae inside Caytoniales. Caytoniaceae are a complex group of Mesozoic Fossil floras, that can be related to both Peltaspermales and Ginkgoaceae.
Cycadopites[9]	Cycadopites "sp. A" Cycadopites "sp. B" Cycadopites cf. follicularis	Budos Mountain	Pollen	Affinities with the family Cycadaceae inside Cycadales.	Extant Cycas platyphylla. Cycadopites maybe come from a related plant
Bennettiteaepollenites[9]	Bennettiteaepollenites sp.	Budos Mountain	Pollen	Affinities with Bennettitaceae inside Bennettitales. Abundant and Dry environment indicator
Callialasporites[9]	Callialasporites sp.	Budos Mountain	Pollen	Affinities with the family Araucariaceae inside Pinales. Conifer pollen from medium to large arboreal plants	Extant Araucaria. Callialasporites maybe came from a related plant
Classopollis[9]	Classopollis cf. chateaunovi Classopollis "sp. A" Classopollis "sp. B" Classopollis "sp. C" Classopollis meyeriana Classopollis cf. simplex	Budos Mountain	Pollen	Affinities with the Hirmeriellaceae inside Pinopsida. Dominant Palynological residue, indicator of Dry conditions
Podocarpidites[9]	Podocarpidites sp.	Budos Mountain	Pollen	Affinities with the Podocarpaceae inside Pinopsida. Conifer pollen from medium to large arboreal plants	Extant Podocarpus. Podocarpidites maybe come from a related plant
Cerebropollenites[9]	Cerebropollenites macroverrucosus	Budos Mountain	Pollen	Affinities with both Sciadopityaceae and Miroviaceae inside Pinopsida. This Pollen resemblance with extant Sciadopitys suggest that Miroviaceae can be an extinct lineage of sciadopityaceaous-like plants.[14]	Extant Sciadopitys. Cerebropollenites likely come from a related plant
Pityosporites[9]	Pityosporites sp	Budos Mountain	Pollen	Affinities with the family Pinaceae inside Pinopsida. Conifer pollen from medium to large arboreal plants	Extant Tsuga Cone, example of the Abietoideae. Pinaceae Pollen like Pityosporites likely come from a similar plant

Plant remains

Genus	Species	Location	Material	Notes	Images
Equisetites[1][9]	Equisetites columnaris Equisetites sp.	Budos Mountain	Isolated Stems	Affinities with Equisetaceae inside Sphenopsida. Near water plants, associated with static freshwater ponds and other humid environments.	Example of Equisetites specimen
Coniopteris[1][9]	Coniopteris sp	Budos Mountain	Isolated pinnae	A Fern of the family Polypodiales inside Polypodiidae. Common cosmopolitan Mesozoic fern genus. Recent research has reinterpreted it a stem group of the Polypodiales (Closely related with the extant genera Dennstaedtia, Lindsaea, and Odontosoria).[15]	Coniopteris specimen
Pachypteris[1][9]	Pachypteris sp	Budos Mountain	Isolated pinnae	Affinities with Umkomasiaceae inside Peltaspermopsida. Large Tree ferns associated to humid conditions. The dominant floral remain over the mangrove-type layers
Caytonia[1][9]	Caytonia sp.	Budos Mountain	Pollen Organs	Affinities with Caytoniales inside Peltaspermopsida. Reproductive organ of the Peltaspermales, with berry like cupules with numerous small seeds arrayed along axes.
Otozamites[1][9]	Otozamites beani Otozamites cf. gramineus Otozamites tenuatus Otozamites sp.	Budos Mountain	Isolated leaflets	Affinities with Williamsoniaceae inside Bennettitales. Cycadales-Like medium sized trees. The most abundant flora on the Budos Mountain Limestone.	Otozamites specimen
Ptilophyllum[1][9]	Ptilophyllum pectinoides Ptilophyllum cf. pecten	Budos Mountain	Isolated leaflets	Affinities with Williamsoniaceae inside Bennettitales.	Ptilophyllum specimen
Zamites[1][9]	Zamites sp.	Budos Mountain	Isolated leaflets	Affinities with Williamsoniaceae inside Bennettitales.	Zamites specimen
Eretmophyllum[1][9]	Eretmophyllum sp.	Budos Mountain	Branched shoots	Affinities with Ginkgoales inside Ginkgoopsida. Ginko Relatives with a more wider leaf, representing among the best specimens found on the mediterranean realm.
Brachyphyllum[1][9]	Brachyphyllum crucis	Budos Mountain	Branched shoots	Affinities with Araucariaceae or Hirmeriellaceae inside Pinales.	Example of Brachyphyllum specimen
Pagiophyllum[1][9]	Pagiophyllum kurri	Budos Mountain	Branched shoots	Affinities with Araucariaceae or Hirmeriellaceae inside Pinales.	Example of Pagiophyllum specimen
Lindleycladus[1][9]	Lindleycladus lanceolatus	Budos Mountain	Branched shoots	Affinities with Krassiloviaceae inside Voltziales.
Elatides[1][9]	Elatides williamsoni	Budos Mountain	Branched shoots	Affinities with Cupressaceae inside Coniferales. Leaves from Arbustive to Arboreal Coniferous trees.	Elatides specimens

See also

• List of fossiliferous stratigraphic units in Italy
• Toarcian turnover
• Toarcian formations

References