Levels of changes in the genus Pinus Linné in the composition of Mesozoic and Cenozoic flora and vegetation as an additional criterion for the division of sediments by the Mesozoic and Cenozoic of Ukraine

The article presents an analysis of a large array of results of palynological studies of Mesozoic and Cenozoic sediments of Ukraine and adjacent regions of Belarus and Russia. Numerous literature data on the palynological characteristics of MesoCenozoic sediments and the materials of the authors are summarized according to the results of sporepollen analysis of Mesozoic and Cenozoic sediments within the main tectonic structures of Ukraine. It has been established that the genus Pinus (Pinaceae) is an integral part of the MesoCenozoic flora of Ukraine. Although, the participation in the flora and vegetation of the genus Pinus and its species diversity in different periods of geological time were different. Despite the long history and significant achievements of palynological research of MesoCenozoic sediments of Ukraine, no attention has been paid to the historical aspect of Pinus development in the MesoCenozoic flora. This work is presented as the first stem to fill this gap. The genus Pinus has a large stratigraphic range, but its species diversity and quantitative changes in the composition of Mesozoic and Cenozoic flora of different ages are markedly different. The analysis of these changes made it possible to trace the emergence and main levels at which the species composition was renewed and the role of Pinus in flora increased during the Mesozoic and Cenozoic. According to the results of the research, 5 levels of increasing the participation of the genus Pinus and changes in its species affiliation in the Mesozoic flora were established: Aalenian period of the Middle Jurassic (appearance of the first representatives of Pinus); Oxfordian time of the Late Jurassic; Valanginian – Early Barremian times of the Early Cretaceous; Albian time of the Early Cretaceous; Late Campanian time of the Late Cretaceous. 5 levels of increasing the role of Pinus and its species diversity for the flora and vegetation of the Cenozoic were also established: Oligocene time of the Paleogene, Konkianearly Sarmatian time of the Middle Miocene; early Pontian (Ivankov) time of the Late Miocene; early Kimmerian time (early Sevastopol) of the Early Pliocene and Martonosha time of the Early Neopleistocene. Certain levels have been traced for the similar age of Cenozoic flora of Belarus and Russia.


Introduction
Pinus is an integral part of the coniferous and mixed forests of the Northern Hemisphere. An important role in the modern vegetation of Ukraine also belongs to the genus Pinus, which refers mainly to Pinus sylvestris L. The forests of the western part of Ukraine (Carpathian region) also include Pinus cembra L. and Pinus mugo Turra.
Palynological studies of Mesozoic and Cenozoic sediments of Ukraine  The purpose of this study is to analyze and summarize a large array of literature materials and personal data of authors on palynological studies of Jurassic, Cretaceous, Paleogene, Neogene and Lower Quaternary sediments of Ukraine to identify levels of increasing role and species diversity of Pinus in Mesozoic and Cenozoic flora and the use of these levels for stratigraphic and correlation constructions.
The purpose of this study is to analyze and summarize a large array of literary materials and personal data of authors on palynological studies of Jurassic, Cretaceous, Paleogene, Neogene and Lower Quaternary sediments of Ukraine to identify levels of increasing role and species diversity of Pinus in Mesozoic and Cenozoic stratigraphic and correlation constructions.
The main research method was palynological: spore-pollen analysis. Stratigraphic, paleoecological and morphological methods are also used in the work.
The main problem in studying the flora of the Mesophyte is that there is currently no generally accepted classification for fossil spores and pollen of the Mesozoic. The issue of systematization and nomenclature of spores and pollen is one of the most relevant, unresolved in Mesophyte palynology. There are a large number of artificial systems that prevail today in the literature on the Mesozoic. As a result, the same taxa in different authors are listed under different generic and species names, and many already known species are described as new. An example of this is the genus Pinus. As an example, established and described by N. A. Bolkhovitina species Pinus divulgata subsequently described in the artificial classification as Pinuspollenites divulgatus. And there are many such examples. In this article, we used primary sources when the species is not re-described by artificial classification.
It is necessary to emphasize a number of important points regarding the reconstructions of the participation of the genus Pinus in the Cenozoic flora. The following factors were taken into account during the reconstruction of flora and paleovegetation. The high content of pine pollen in the spectra of certain sections of marine and continental sediments does not always provide an opportunity to reconstruct the level of increase of this genus in the vegetation within the entire region. In particular, it is necessary to take into account in which part of the marine paleobasin the section is located. Since the general increase in tree pollen is characteristic of deep-water sediments (Malyasova, 1976) and, accordingly, the most diverse composition of the spectra is characteristic of sediments of the central part of sea basins and the slope of the shelf. The spectra of shallow sediments are markedly depleted, and their composition is dominated by 1-2 components. A characteristic feature of these spectra is the significant presence of pollen from aquatic and coastal aquatic plants, which may change the ratio of the main groups of pollen in the spectra. Thus, some decrease in the role of pine pollen in the spectra of the Late Oligocene complex, which characterizes the Berekian deposits of some areas of northern Ukraine, is associated with an increase in the role of Taxodiaceae, which are usually markers of local conditions. N. O. Shchekina (1983) found that fossil spectra from Upper Oligocene -Miocene sediments of the southern part of Ukraine well reflect the distance of the section from the sea shore. The farther from the shore to the depths of the sea, the more gymnosperms with air sacs and the less pollen of angiosperms and gymnosperms without air sacs. When studying subaerial sediments, it is important to take into account the geomorphological location of sections, because in the composition of spore-pollen spectra from section sediments located on river terraces and steep coasts there is always an increased content of Pinus pollen (Sirenko, 2017 с). Therefore, during the reconstruction of the levels of Pinus changes in the Cenozoic flora, materials were analyzed from sections of age-old sediments located in different parts of Ukraine  Sirenko O. A.,Shevchuk O. A. Journ. Geol. Geograph. Geoecology,30(4),[741][742][743][744][745][746][747][748][749][750][751][752][753] and in different geomorphological conditions. Emphasis was made on changes in the species diversity of pines and the ratios in the composition of the pollen spectra of Pinus spp. subg. Haploxylon Koexne. and Pinus spp. subg. Diploxylon Koexne. Materials of palynological researches of Cenozoic deposits of adjacent regions of Belarus and Russia were taken into account for the purpose of establishment of levels which would be traced also in the specified territories.

Main results and discussion Mesozoic
Representatives of the genus Pinus originated in the Middle Jurassic period and are clearly recorded according to O. A. Shevchuk is a part of flora of all regions of Ukraine (Carpathians, Dnipro-Donetsk depression, Ukrainian shield -Bajocian, Mountain Crimea -Aalenia).
Aalenian to Bathonian time is famous due to a large number of ancestral forms of Pseudopinus spp. and Protopinus spp. The most common species are Pseudopinus pectinella Bolch., Pseudopinus pergrandis Bolch., Pseudopinus contigua Bolch., Pseudopinus oblatinoides (Mal.) Bolch., Protopinus subluteus Bolch., Protopinus vastus Bolch., Protopinus scanicus Nilsson. At the border of Barremian and Aptian times, some single representatives of the ancestral forms of Pinus are noted, and then in the time range starting from the Cenomanian, they are not established (Fig. 2).
Pinuspollenites similis (Balme) M. Petr., P. minimus (Couper) Kemp., P. divulgatus Bolch. and Pinus pernobilis Bolch were noticed in the Middle Jurassic flora. Thus, as the first level of Pinus participation in the Mesozoic flora, it is possible to determine the Aalenian time.
Cenozoic flora, materials were analyzed from sections of age-old sediments located in different parts of Ukraine and in different geomorphological conditions. Emphasis was made on changes in the species diversity of pines and the ratios in the composition of the pollen spectra of Pinus spp. subg. Haploxylon Koexne. and Pinus spp. subg. Diploxylon Koexne. Materials of palynological researches of Cenozoic deposits of adjacent regions of Belarus and Russia were taken into account for the purpose of establishment of levels which would be traced also in the specified territories.  (Orlova-Turchyna, 1966;Voronova, Yanovska 1973, 1982, 1991Yanovska, 1973;Kuvaeva et all., 1973). A systematic description of species Pseudopinus spp., Protopinus spp. is given in the works of N.A. Bolkhovitina (Bolkhovitina, 1953). The results of palynological studies of Mesozoic sediments of Ukraine are compared with the materials of the study of similar age sediments of Russia and Sweden. (Chlonova, 1974;Vajda, 2001;Rostovtseva, 2014).

Representatives of the genus
Aalenian to Bathonian time is famous due to a large number of ancestral forms of Pseudopinus spp. and Protopinus spp. The most common species are Pseudopinus pectinella Bolch., Pseudopinus pergrandis Bolch., Pseudopinus contigua Bolch., Pseudopinus oblatinoides (Mal.) Bolch., Protopinus subluteus Bolch., Protopinus vastus Bolch., Protopinus scanicus Nilsson. At the border of Barremian and Aptian times, some single representatives of the ancestral forms of Pinus are noted, and then in the time range starting from the Cenomanian, they are not established (Fig. 2).
Pinuspollenites similis (Balme) M. Petr., P. minimus (Couper) Kemp., P. divulgatus Bolch. and Pinus pernobilis Bolch were noticed in the Middle Jurassic flora. Thus, as the first level of Pinus participation in the Mesozoic flora, it is possible to determine the Aalenian time.  Pinus pernobilis Bolch and Pinuspollenites divulgatus Bolch. played a significant role in the composition of the Late Jurassic flora of Ukraine (Fig. 3). The species composition of pines mostly remained  Pinus pernobilis Bolch and Pinuspollenites divulgatus Bolch. played a significant role in the composition of the Late Jurassic flora of Ukraine (Fig.  3). The species composition of pines mostly remained unchanged from Oxfordian to Tithonian, except for some new species Pinuspollenites verrucosus Zhang., Pinuspollenites spр. It is possible to establish the second level of increase in participation of Pinus by emergence of new types of pine as a part of flora of Oxfordian. 5 unchanged from Oxfordian to Tithonian, except for some new species Pinuspollenites verrucosus Zhang., Pinuspollenites spр. It is possible to establish the second level of increase in participation of Pinus by emergence of new types of pine as a part of flora of Oxfordian. At the turn of the Jurassic and Cretaceous periods, there was a decrease in the role of pine. During the Cretaceous, the role of Pinus in the flora grew from Valanginian to Barremian. The flora of this time is characterized by the greatest species diversity and number of pines: Pinus spp., Pinus incrassate Boch., P. vulgaris Boch., P. exeguus Boch., P. vulandjensis (Naum.) Bolch. P. exilioides Boch., P. insiguis (Naum.) Bolch., P. subcohcinua (Naum.) Bolch., Pinuspollenites divulgatus Bolch. Therefore, this interval can be considered a surge in the development of Pinus and attributed to the third level.
The timing of pine diversification coincides with the evolution of angiosperms, and it is likely that competition between flowering plants and gymnosperms played a role in adaptation, which reduced species diversity and pine participation in the Late Barremian − Aptian period. In the Aptian period there was also a decrease in the participation and the role of the genus Pinus due to their displacement by other important members of the group of gymnosperms − in particular Cedrus.
By the middle of the Cretaceous period, morphological features identified two subgenera Pinus: Haploxylon and Diploxylon (Millar, 1998). Pines of two subgenera have also been reconstructed for the Albian flora of Ukraine (Fig. 4). Increasing the role of Pinus spp. as part of the flora, especially due to the representatives of the subgenus Diploxylon can be traced in the Albian period of the Volyn-Podilska plate, the Ukrainian Shield, the Dnipro-Donetsk basin and the Mountainous Crimea. According to M.A. Voronova, in the Albian period there are representatives of a new species Pinus aequalis (Naum.) Bolch. (Voronova, 1994). Therefore, the Albian period can be attributed to the fourth level of Pinus participation in the Mesozoic flora. No significant increase of the role of Pinus in the flora and vegetation composition of the Cenomanian-Santonian interval was recorded. The following species are characteristic of the Cenomanian flora of Donbas: Pinus concessa (Naum.) Bolch, P. trivialis Naum., P. subconcinua (Naum.) Bolch., P. At the turn of the Jurassic and Cretaceous periods, there was a decrease in the role of pine.
During the Cretaceous, the role of Pinus in the flora grew from Valanginian to Barremian. The flora of this time is characterized by the greatest species diversity and number of pines: Pinus spp., Pinus incrassate Boch., P. vulgaris Boch., P. exeguus Boch., P. vulandjensis (Naum.) Bolch. P. exilioides Boch., P. insiguis (Naum.) Bolch., P. subcohcinua (Naum.) Bolch., Pinuspollenites divulgatus Bolch. Therefore, this interval can be considered a surge in the development of Pinus and attributed to the third level.
The timing of pine diversification coincides with the evolution of angiosperms, and it is likely that competition between flowering plants and gymnosperms played a role in adaptation, which reduced species diversity and pine participation in the Late Barremian -Aptian period. In the Aptian period there was also a decrease in the participation and the role of the genus Pinus due to their displacement by other important members of the group of gymnosperms -in particular Cedrus.
By the middle of the Cretaceous period, morphological features identified two subgenera Pinus: Haploxylon and Diploxylon (Millar, 1998). Pines of two subgenera have also been reconstructed for the Albian flora of Ukraine (Fig. 4). Increasing the role of Pinus spp. as part of the flora, especially due to the representatives of the subgenus Diploxylon can be traced in the Albian period of the Volyn-Podilska plate, the Ukrainian Shield, the Dnipro-Donetsk basin and the Mountainous Crimea. According to M. A. Voronova, in the Albian period there are representatives of a new species Pinus aequalis (Naum.) Bolch. (Voronova, 1994). Therefore, the Albian period can be attributed to the fourth level of Pinus participation in the Mesozoic flora. 5 unchanged from Oxfordian to Tithonian, except for some new species Pinuspollenites verrucosus Zhang., Pinuspollenites spр. It is possible to establish the second level of increase in participation of Pinus by emergence of new types of pine as a part of flora of Oxfordian.  (2) At the turn of the Jurassic and Cretaceous periods, there was a decrease in the role of pine. During the Cretaceous, the role of Pinus in the flora grew from Valanginian to Barremian. The flora of this time is characterized by the greatest species diversity and number of pines: Pinus spp., Pinus incrassate Boch., P. vulgaris Boch., P. exeguus Boch., P. vulandjensis (Naum.) Bolch. P. exilioides Boch., P. insiguis (Naum.) Bolch., P. subcohcinua (Naum.) Bolch., Pinuspollenites divulgatus Bolch. Therefore, this interval can be considered a surge in the development of Pinus and attributed to the third level.
The timing of pine diversification coincides with the evolution of angiosperms, and it is likely that competition between flowering plants and gymnosperms played a role in adaptation, which reduced species diversity and pine participation in the Late Barremian − Aptian period. In the Aptian period there was also a decrease in the participation and the role of the genus Pinus due to their displacement by other important members of the group of gymnosperms − in particular Cedrus.
The fifth level of increase in the composition of pines in the Mesozoic flora, as well as a slight change in their species composition is timed to the end of the Campanian. The flora of the Late Cretaceous period is characterized by a significant participation of Pinus vulgaris Boch., P. subconcinua (Naum.) Bolch., P. concessa (Naum.) Bolch. Representatives of Pinus cf. minor Loudon appeared during the Campanian -Maastrichtian times.
At the boundary of the Cretaceous and Paleogene both the number and the species of pines decreased.

Cenozoic
Studies show that that a significant place in the composition of the Cenozoic flora belonged to the genus Pinus, especially in the Late Oligocene, Early and Middle Miocene flora.
The role of Pinus in the flora grew from the Early to the Late Paleogene (Stotland, 1974). The beginning of the dominance of this genus corresponds to the Eocene-Oligocene boundary. However, the largest species diversity of Pinus is typical for the Oligocene. The flora of this period is characterized by a significant participation of Pinus spp. subg. Haploxylon, and among them − Pinus sect. Mirabilis. Anan. At the same time, it should be noted that the dominant role in the pine forests of Ukraine belonged to the subgenus Diploxylon. However, according to N.O. Schekina (1986), the number of representatives of this subgenus increased from the Oligocene by the end of the Pliocene, and the presence of Pinus subg. Haploxylon decreased accordingly in this direction. According to the study of Paleogene and Neogene sediments of the north-western part of the Dnipro-Donetsk depression, as the part of the Late Oligocene flora Pinus subg. Haploxylon recorded a significant involvement (Sirenko, 2003 b). The dominance of pines in the Late Oligocene flora of the south-eastern slope of the Voronezh anteclisis is indicated by V.G. Shpul (2005). According to T.B. Rylova (2001) in the Late Oligocene flora of Belarus is also dominated by various species of Pinus, but they belong largely to the subgenus Haploxylon. Analyzing the materials regarding the increasing role of representatives of thermophilic species Pinus subg. Haploxylon in the Oligocene flora of the north-western part of the Dnipro-Donetsk depression (Sirenko, 2003 b) and Belarus in comparison with other regions of Ukraine, it is possible to assume that the number of representatives of this subgenus in the composition of the same age flora increases in the western direction and may be associated with an increase in humidity. We have observed the same pattern for the Pliocene and Early Neopleistocene flora of Ukraine and Belarus (Sirenko, 2017 c).
Thus, the Oligocene time can be determined as the first significant level of Pinus participation in the Cenozoic flora. This level is clearly visible, both for the flora of different parts of Ukraine and for adjacent regions. The following representatives of Pinus are typical for the Oligocene flora: Pinus cembraeformis Zakl., P. cf. protocembrae Zakl., P. cf. sibirica Mayr. P. cf. singularts Mayr., P cf. koraiensis Sieb. at Succ., P. cf. cristata Panova, Pinus sect. Mirabilis Anan., that according to the classification of O.A. Ananova (1974)  The fifth level of increase in the composition of pines in the Mesozoic flora, as well as a slight change in their species composition is timed to the end of the Campanian. The flora of the Late Cretaceous period is characterized by a significant participation of Pinus vulgaris Boch., P. subconcinua (Naum.) Bolch., P. concessa (Naum.) Bolch. Representatives of Pinus cf. minor Loudon appeared during the Campanian -Maastrichtian times.
At the boundary of the Cretaceous and Paleogene both the number and the species of pines decreased.

Cenozoic
Studies show that that a significant place in the composition of the Cenozoic flora belonged to the genus Pinus, especially in the Late Oligocene, Early and Middle Miocene flora.
The role of Pinus in the flora grew from the Early to the Late Paleogene (Stotland, 1974). The beginning of the dominance of this genus corresponds to the Eocene-Oligocene boundary. However, the largest species diversity of Pinus is typical for the Oligocene. The flora of this period is characterized by a significant participation of Pinus spp. subg. Haploxylon, and among them -Pinus sect. Mirabilis. Anan. At the same time, it should be noted that the dominant role in the pine forests of Ukraine belonged to the subgenus Diploxylon. However, according to N. O. Schekina (1986), the number of representatives of this subgenus increased from the Oligocene by the end of the Pliocene, and the presence of Pinus subg. Haploxylon decreased accordingly in this direction. According to the study of Paleogene and Neogene sediments of the northwestern part of the Dnipro-Donetsk depression, as the part of the Late Oligocene flora Pinus subg. Haploxylon recorded a significant involvement (Sirenko, 2003 b). The dominance of pines in the Late Oligocene flora of the south-eastern slope of the Voronezh anteclisis is indicated by V. G. Shpul (2005). According to T. B. Rylova (2001) in the Late Oligocene flora of Belarus is also dominated by various species of Pinus, but they belong largely to the subgenus Haploxylon. Analyzing the materials regarding the increasing role of representatives of thermophilic species Pinus subg. Haploxylon in the Oligocene flora of the north-western part of the Dnipro-Donetsk depression (Sirenko, 2003 b) and Belarus in comparison with other regions of Ukraine, it is possible to assume that the number of representatives of this subgenus in the composition of the same age flora increases in the western direction and may be associated with an increase in humidity. We have observed the same pattern for the Pliocene and Early Neopleistocene flora of Ukraine and Belarus (Sirenko, 2017 c).
Thus, the Oligocene time can be determined as the first significant level of Pinus participation in the Cenozoic flora. This level is clearly visible, both for the flora of different parts of Ukraine and for adjacent regions. The following representatives of Pinus are typical for the Oligocene flora: Pinus cembraeformis Zakl., P. cf. protocembrae Zakl., P. cf. sibirica Mayr. P. cf. singularts Mayr., P cf. koraiensis Sieb. at Succ., P. cf. cristata Panova, Pinus sect. Mirabilis Anan., that according to the classification of O. A. Ananova (1974)  Pinus also played a significant role in the flora of the Early and Middle Miocene. The species composition of pines has largely remained unchanged since the Oligocene, with the exception of some species (for example, Pinus cf. koraiensis Sieb. at Succ. was practically absent in the Miocene flora, and P. cf. cristata Panova after the Karaganian time of the Middle Miocene, was only a single representative of the dendroflora of the middle Sarmatian time).
The second level of significant increase in the composition of pines in the Cenozoic flora, as well as a marked change in their species composition is timed to the end of the Middle Miocene (Konkian and, especially, early Sarmatian times). Pinus baileyana Trav., P. veronica Anan., P. gigantea Anan. appear at the Konkian time. The flora of early Sarmatian times has the greatest species diversity and number of pines: Pinus mirabilis (Rudolf.) Anan, P. baileyana, P. Ruthenica, P. veronica Anan., P. minutus Zakl. (Korallova, 1962;Syabryaj, Shchekina, 1983;Shchekina, 1979). According to N. O. Shchekina in the early Sarmatian pine forests of the subgenus Diploxylon belonged to the Sula, Banksia, Taeda sections (Shchekina, 1979). Similar patterns of flora have been observed for the territory of the North-Eastern Priazovye and the Lower Don (Ananova, 1974). According to V. G. Shpul (1990), the flora of the late Ivlinsky and early Gurivsky times of Middle Miocene of the Volga-Hopper interfluve, which correspond to the Konkian and early Sarmatian in Ukraine, is dominated by various Pinus, similar in composition to the Konkian and early Sarmatian of Ukraine. This level can also be traced for the Miocene flora of Belarus (late Burnosky time) (Palinozone brns5) (Rylova, 2001(Rylova, , 2002, which corresponds to the early Sarmatian in Russia. Regarding the participation of Haploxylon and Diploxylon in the flora, the materials of different researchers differ slightly. In particular, N. O. Shchekina (1979) in the characterization of sporepollen complexes corresponding to the lower Sarmatian sediments of Ukraine indicated the predominance of pollen of the subgenus Diploxylon (which was up to 40 %), as well as a slightly lower content of pollen Pinus subg Haploxylon (without specifying its percentage). Instead, O. M. Ananova (1974), in characterizing the similar age complexes of the southern part of the Russian plain, noted the predominance of pollen Pinus subg. Haploxylon, which belonged to 5 species (including Pinus mirabilis and Pinus tertiaria) in contrast to the three species Pinus subg Diploxylon. This conclusion is confirmed by the materials of V. G. Shpul according to the characteristics of the Lamkinska series of the Oka-Don plain (spore-pollen complex III, which corresponds to the Lower Sarmatian deposits of Russia and Ukraine) (Shpul, 2004). The common thing to all analyzed materials is that the flora of early Sarmatian times differed significantly in the number of pine and their species diversity. Pinus also played a significant role in the flora of the Early and Middle Miocene. The species composition of pines has largely remained unchanged since the Oligocene, with the exception of some species (for example, Pinus cf. koraiensis Sieb. at Succ. was practically absent in the Miocene flora, and P. cf. cristata Panova after the Karaganian time of the Middle Miocene, was only a single representative of the dendroflora of the middle Sarmatian time).
The second level of significant increase in the composition of pines in the Cenozoic flora, as well as a marked change in their species composition is timed to the end of the Middle Miocene (Konkian and, especially, early Sarmatian times). Pinus baileyana Trav., P. veronica Anan., P. gigantea Anan. appear at the Konkian time. The flora of early Sarmatian times has the greatest species diversity and number of pines: Pinus mirabilis (Rudolf.) Anan, P. baileyana, P. Ruthenica, P. veronica Anan., P. minutus Zakl. (Korallova, 1962;Syabryaj, Shchekina, 1983;Shchekina, 1979). According to N.O. Shchekina in the early Sarmatian pine forests of the subgenus Diploxylon belonged to the Sula, Banksia, Taeda sections (Shchekina, 1979). Similar patterns of flora have been observed for the territory of the North-Eastern Priazovye and the Lower Don (Ananova, 1974). According to V.G. Shpul (1990), the flora of the late Ivlinsky and early Gurivsky times of Middle Miocene of the Volga-Hopper interfluve, which correspond to the Konkian and early Sarmatian in Ukraine, is dominated by various Pinus, similar in composition to the Konkian and early Sarmatian of Ukraine. This level can also be traced for the Miocene flora of Belarus (late Burnosky time) (Palinozone brns5) (Rylova, 2001(Rylova, , 2002, which corresponds to the early Sarmatian in Russia. Regarding the participation of Haploxylon and Diploxylon in the flora, the materials of different researchers differ slightly. In particular, N.O. Shchekina (1979) in the characterization of spore-pollen complexes corresponding to the lower Sarmatian sediments of Ukraine indicated the predominance of pollen of the subgenus Diploxylon (which was up to 40%), as well as a slightly lower content of pollen Pinus subg Haploxylon (without specifying its percentage). Instead, O.M. Ananova (1974), in characterizing the similar age complexes of the southern part of the Russian plain, noted the predominance of pollen Pinus subg. Haploxylon, which belonged to 5 species (including Pinus mirabilis and Pinus tertiaria) in contrast to the three species Pinus subg Diploxylon. This conclusion is confirmed by the materials of V.G. Shpul according to the characteristics of the Lamkinska series of the Oka-Don plain (spore-pollen complex III, which corresponds to the Lower Sarmatian deposits of Russia and Ukraine) (Shpul, 2004). The common thing to all analyzed materials is that the flora of early Sarmatian times differed significantly in the number of pine and their species diversity.  The next level of increase in the role of Pinus was traced at the end of the Miocene (Novorossiysk time of the Pontian of the southern part of Ukraine and Ivankiv time -in Northern Ukraine). This period is characterized by the dominance of pines in the flora, as well as their significant species diversity. It should be noted that the species of pines typical for the flora of the Konkian and early Sarmatian times, namely: P. baileyana, P. ruthenica, P. veronica, are no longer typical for the early Pontian flora. Pinus mirabilis Anan. is singly noted only in the dendroflora of the Kerch Peninsula . The flora of these stages was dominated by representatives of the subgenus Diploxylon: Pinus sp. sect. Eupitys Spach (dominated) P. sp. sect. Sula Mayr., P. sp. sect. Taeda, P. sp. sect. Pseudostrobus., P. sp. sect. Banksia Mayr., P. longifoliaformis Zakl., but the role of Pinus spp. subg. Haploxylon. in the composition of forests was still quite significant: P. pusillus., P. sp. sect. Pinus also played a significant role in the flora of the Early and Middle Miocene. The species composition of pines has largely remained unchanged since the Oligocene, with the exception of some species (for example, Pinus cf. koraiensis Sieb. at Succ. was practically absent in the Miocene flora, and P. cf. cristata Panova after the Karaganian time of the Middle Miocene, was only a single representative of the dendroflora of the middle Sarmatian time).
The second level of significant increase in the composition of pines in the Cenozoic flora, as well as a marked change in their species composition is timed to the end of the Middle Miocene (Konkian and, especially, early Sarmatian times). Pinus baileyana Trav., P. veronica Anan., P. gigantea Anan. appear at the Konkian time. The flora of early Sarmatian times has the greatest species diversity and number of pines: Pinus mirabilis (Rudolf.) Anan, P. baileyana, P. Ruthenica, P. veronica Anan., P. minutus Zakl. (Korallova, 1962;Syabryaj, Shchekina, 1983;Shchekina, 1979). According to N.O. Shchekina in the early Sarmatian pine forests of the subgenus Diploxylon belonged to the Sula, Banksia, Taeda sections (Shchekina, 1979). Similar patterns of flora have been observed for the territory of the North-Eastern Priazovye and the Lower Don (Ananova, 1974). According to V.G. Shpul (1990), the flora of the late Ivlinsky and early Gurivsky times of Middle Miocene of the Volga-Hopper interfluve, which correspond to the Konkian and early Sarmatian in Ukraine, is dominated by various Pinus, similar in composition to the Konkian and early Sarmatian of Ukraine. This level can also be traced for the Miocene flora of Belarus (late Burnosky time) (Palinozone brns5) (Rylova, 2001(Rylova, , 2002, which corresponds to the early Sarmatian in Russia. Regarding the participation of Haploxylon and Diploxylon in the flora, the materials of different researchers differ slightly. In particular, N.O. Shchekina (1979) in the characterization of spore-pollen complexes corresponding to the lower Sarmatian sediments of Ukraine indicated the predominance of pollen of the subgenus Diploxylon (which was up to 40%), as well as a slightly lower content of pollen Pinus subg Haploxylon (without specifying its percentage). Instead, O.M. Ananova (1974), in characterizing the similar age complexes of the southern part of the Russian plain, noted the predominance of pollen Pinus subg. Haploxylon, which belonged to 5 species (including Pinus mirabilis and Pinus tertiaria) in contrast to the three species Pinus subg Diploxylon. This conclusion is confirmed by the materials of V.G. Shpul according to the characteristics of the Lamkinska series of the Oka-Don plain (spore-pollen complex III, which corresponds to the Lower Sarmatian deposits of Russia and Ukraine) (Shpul, 2004). The common thing to all analyzed materials is that the flora of early Sarmatian times differed significantly in the number of pine and their species diversity.  Cembrae., P. sp. sect. Strobus. This level is well traced both within Ukraine (Shchekina, 1979) and Russia (Taman Peninsula) (Ananova, Volkova, Zubakov, etc., 1985). The next level of increase in the participation and species diversity of Pinus in the flora corresponds to the early Kimmerian Pliocene of southern Ukraine and the early Sevastopolsky time of northern Ukraine. Within the southern and northern parts of platform Ukraine and within the Kerch Peninsula at this time the forest type of vegetation prevailed, the dominant role in the forests belonged to pines, in species composition close to the forests of early Pontian time: Pinus spр. subg. Diploxylon, P. sp. sect. Banksia, P. sp. sect. Eupitys, P. sp. sect. Taeda, P. sp. sect. Sula, P. longіfoliaformis, P. minutus Zakl., P. sp. sect. Cembrae, P. sp. sect. Strobus. It should be noted that P. sp. sect. Taeda, P. minutus are no longer typical for the flora of the Late Pliocene and Pleistocene of Ukraine. This level is also observed for the early Kimmerian flora of Russia (Taman Peninsula) (Filippova, 2002).
Increasing of the role of Pinus spp. as a part of flora, especially at the expense of representatives of the subgenus Diploxylon is traced in the early Kuyalnik time of the Late Pliocene of the southern part of Ukraine and the Kyzylyar and early Bogdanivka time of its northern and northeastern parts. It should be noted that analogues of the spore-pollen complex from Kyzylyar sediments have not been established among the complexes that characterize the lagoon-marine sediments of Ukraine.
In the Neogene section of the Trans Asov massif, there is a break in sedimentation between the Kimmerian and Kuyalnik deposits (Semenenko, 1987). The composition of the dendroflora changed dramatically during the Kuyalnik time. The main component of forests was Pinus spр. subg. Diploxylon, heat-loving species of the subgenus Haploxylon were almost completely absent. This level correlates well with the level of dominance of pine and the general impoverishment of the flora of the early Sokolsky time (SPC VII) of the Middle Volga region. (Linkina, 2006). In the early Bogdanivka time, there was also an increase in the role of pines in the dendroflora, but in the forests dominated by Pinus spр. subg. Diploxylon, a few members of the subgenus Haploxylon already appear. A similar pattern is inherent in the dendroflora of the early Kuyalnik time of southern Ukraine, as well as the middle Sokolsky time (SPC VIII) of the Middle Volga region (Linkina, 2006) and the early Sukhodolsky time of the Volga-Hopper interfluve (SPC X) (Shpul, 1991). Thus, the established regularity of significant impoverishment of the dendroflora of the Late Pliocene of Ukraine, which also concerns its main component -the genus Pinus, is well compared with that for the European part of Russia. According to A. O. Velichko and co-authors (2011) in the landscape of the territory of the European part of Russia clearly records the cooling at the turn of 3.4 million years, which is probably traced in Ukraine in the Kyzylyar time. Although, given the lack of analogues of Kyzylyar sediments in the marine context of the Pliocene of Ukraine at this stage of research, we consider it appropriate to identify a combined Kyzylyar early-Bogdanivka level of changes in the role of Pinus in the dendroflora, which generally corresponds to the early Kuyalnik stage of the Black Sea region of Ukraine and the early Akchagylian stage of the Caspian region of Russia.
Increasing of the role of Pinus spp. as a part of flora, especially at the expense of representatives of the subgenus Diploxylon is traced in the early Kuyalnik time of the Late Pliocene of the southern part of Ukraine and the Kyzylyar and early Bogdanivka time of its northern and northeastern parts. It should be noted that analogues of the spore-pollen complex from Kyzylyar sediments have not been established among the complexes that characterize the lagoon-marine sediments of Ukraine. In the Neogene section of the Trans Asov massif, there is a break in sedimentation between the Kimmerian and Kuyalnik deposits (Semenenko, 1987). The composition of the dendroflora changed dramatically during the Kuyalnik time. The main component of forests was Pinus spр. subg. Diploxylon, heat-loving species of the subgenus Haploxylon were almost completely absent. This level correlates well with the level of dominance of pine and the general impoverishment of the flora of the early Sokolsky time (SPC VII) of the Middle Volga region. (Linkina, 2006). In the early Bogdanivka time, there was also an increase in the role of pines in the dendroflora, but in the forests dominated by Pinus spр. subg. Diploxylon, a few members of the subgenus Haploxylon already appear. A similar pattern is inherent in the dendroflora of the early Kuyalnik time of southern Ukraine, as well as the middle Sokolsky time (SPC VIII) of the Middle Volga region (Linkina, 2006) and the early Sukhodolsky time of the Volga-Hopper interfluve (SPC X) (Shpul, 1991). Thus, the established regularity of significant impoverishment of the dendroflora of the Late Pliocene of Ukraine, which also concerns its main component − the genus Pinus, is well compared with that for the European part of Russia. According to A.O. Velichko and co-authors (2011) in the landscape of the territory of the European part of Russia clearly records the cooling at the turn of 3.4 million years, which is probably traced in Ukraine in the Kyzylyar time. Although, given the lack of analogues of Kyzylyar sediments in the marine context of the Pliocene of Ukraine at this stage of research, we consider it appropriate to identify a combined Kyzylyar early-  A significant increase in the role of Pinus in the composition of flora and vegetation is also recorded in the Kryzhanivka time of the Eopleistocene. However, due to the fact that in Kryzhanivka time there was a fairly pronounced zonation of plant cover and the established pattern was not observed for all regions of Ukraine, we consider it acceptable not to allocate this level as a benchmark.
The next level of increasing the role of Pinus in the dendroflora is timed to the first warm stage of the Early Neopleistocene (Martonosha). The vegetation type of the central, north-eastern and western parts of Ukraine was dominated by forest vegetation. Pines played a dominant role in the dendroflora of all, without exception, regions of Ukraine: Pinus spp. subg. Diploxylon (prevailed), P. spp. sect Eupitys, P. longifoliaformis, P. spp. sect. Strobus, P. spp. sect. Cembrae. This level is well traced both for the territory of Ukraine and adjacent regions of Russia (Tregub, Starodubtseva, 2005) and is characterized by the most significant representation of the genus Pinus in the Early Neopleistocene flora, its diversity and noticeable presence of Haploxylon.

Сonclusions
The genus Pinus has a large stratigraphic range, but its species diversity and quantitative changes in the composition of different ages of Mesozoic and Cenozoic flora differ markedly. The analysis of these changes makes it possible to trace the emergence and the main levels at which the species composition was renewed and its role in the flora increased during the Mesozoic and Cenozoic.
The Mesozoic flora has 5 levels, which characterize the increase in the participation of the genus Pinus at different ages, among which the two levels are most pronounced. In particular, the appearance of the first representatives of Pinus, the Aalenian time (Middle Jurassic), is clearly recorded in the flora of the territory of Ukraine. Also, an important moment in the development of Mesozoic flora -the Albian time (Еarly Cretaceous), when the representatives of Pinus split into two generic groups -subgenus Haploxylon and Diploxylon. The traced levels can be used as benchmarks for stratigraphic divided of Mesozoic and Cenozoic sediments of Ukraine and their correlation with the similar sediments of other regions.

Acknowledgment
The article highlights the results of research funded by the budget program «Substantiation of the boundaries of regional and local stratigraphic units of the Phanerozoic of Ukraine for geological maps of the new generation» (KPKVK 6541030).

9
Bogdanivka level of changes in the role of Pinus in the dendroflora, which generally corresponds to the early Kuyalnik stage of the Black Sea region of Ukraine and the early Akchagylian stage of the Caspian region of Russia. A significant increase in the role of Pinus in the composition of flora and vegetation is also recorded in the Kryzhanivka time of the Eopleistocene. However, due to the fact that in Kryzhanivka time there was a fairly pronounced zonation of plant cover and the established pattern was not observed for all regions of Ukraine, we consider it acceptable not to allocate this level as a benchmark.
The next level of increasing the role of Pinus in the dendroflora is timed to the first warm stage of the Early Neopleistocene (Martonosha). The vegetation type of the central, north-eastern and western parts of Ukraine was dominated by forest vegetation. Pines played a dominant role in the dendroflora of all, without exception, regions of Ukraine: Pinus spp. subg. Diploxylon (prevailed), P. spp. sect Eupitys, P. longifoliaformis, P. spp. sect. Strobus, P. spp. sect. Cembrae. This level is well traced both for the territory of Ukraine and adjacent regions of Russia (Tregub, Starodubtseva, 2005) and is characterized by the most significant representation of the genus Pinus in the Early Neopleistocene flora, its diversity and noticeable presence of Haploxylon.

Сonclusions
The genus Pinus has a large stratigraphic range, but its species diversity and quantitative changes in the composition of different ages of Mesozoic and Cenozoic flora differ markedly. The analysis of these changes makes it possible to trace the emergence and the main levels at which the species composition was renewed and its role in the flora increased during the Mesozoic and Cenozoic.
The Mesozoic flora has 5 levels, which characterize the increase in the participation of the genus Pinus at different ages, among which the two levels are most pronounced. In particular, the appearance of the first representatives of Pinus, the Aalenian time (Middle Jurassic), is clearly recorded in the flora of the territory of Ukraine. Also, an important moment in the development of Mesozoic flora − the Albian time (Еarly Cretaceous), when the representatives of Pinus split into two generic groups − subgenus Haploxylon and Diploxylon. 5 levels of increasing the role of Pinus and its species diversity for the flora and vegetation of the Cenozoic were also established: Oligocene time of the Paleogene, Konkian-early Sarmatian time of the Middle Miocene; early Pontian (Ivankiv) time of the Late Miocene; early Kimmerian time (early Sevastopol) of the Early Pliocene and Martonosha time of the Early Neopleistocene.
Participation of representatives of Pinus spp. subg. Haploxylon and Pinus spp. subg. Diploxylon in the composition of the Cenozoic flora was different. In general, the tendency to reduce the role of pines of the subgenus Haploxylon in the composition of flora from the Paleogene to the Pliocene, established by N.O. Schekina (1986) is traced, but at certain stages of nature development (early Sarmatian and early Pontian of Miocene, early Kimmerian of Pliocene) recorded an increase in the number of representatives of this subgenus and its species diversity compared to the older flora.
A comparison of the composition of the Cenozoic flora of Ukraine and the adjacent regions of Belarus and Russia indicates the existence of a pattern of growth of the role of Pinus in the composition of forests from southwest to east and northeast.
The determined levels of changes in the composition of Pinus in the development of Mesozoic and Cenozoic flora are well traced not only within different regions of Ukraine, but also typical for the flora of adjacent regions of Belarus and Russia.
The traced levels can be used as benchmarks for stratigraphic divided of Mesozoic and Cenozoic sediments of Ukraine and their correlation with the similar sediments of other regions.