V ERTEBRATES A S B IOINDICATORS OF C LIMATE C HANGE

The use of living organisms for stratigraphy or as bioindicators of the state of the environment has been known since the 19 th century, but mainly for these studies the remains of invertebrate animals (in particular, molluscs) are used, and from vertebrates – mouse-like rodents. In the course of the work, certain species of vertebrates and invertebrates were selected, based on the presence of which in the material it is possible to reconstruct the climatic conditions in the historical past. Such information is very important for historians and archaeologists, since it allows them to better understand the living conditions of people in the historical past. The aim of our work is to identify species of vertebrates that are stenotopic in at least one factor and, on the basis of the findings of these species at archaeological sites, to make climatic reconstructions. Conclusions.


INTRODUCTION
The use of animals and their remains as indicators of the state of the environment has been known and studied for a long time.But the vast majority of animals that researchers focus on are, for the most part, invertebrates, fish, and small rodents.Other types of mammals are not often considered as bioindicators, the exception being the mammoth fauna complex.Birds and reptiles, too, usually do not fall into these species.In the past, people were much more dependent on natural conditions than they are now.Accordingly, such information is very important for historians and archaeologists, since it allows them to better understand the living conditions of people in the historical past.
Some species of vertebrates are stenotopic according to certain parameters, which allows us to use them for the reconstruction of paleoclimatic and paleoecological conditions, as well as for predicting changes in the future.
Paleoreconstructions of the climate based on the findings of representatives of various faunal complexes were made, among other things, by the famous paleontologist Pidoplichko 1 .In the 20 th century, the concept of "faunistic complexes" was developed, which was mainly used in paleontology 2 , and was also singled out for fish 3 .All this helps to make both paleoclimatic and paleoecological reconstructions.
In the literature there are separate references to the fact that the presence of certain species of animals can determine the natural conditions in which they lived.Thus, well-known zoologist Formozov 4 found that for many animal species, including medium and large vertebrates, the main limiting factor is not cold or the presence of water, but the maximum depth of snow cover in winter.
In the 1990s and in the 2010, climate reconstructions based on finds of animal bones were carried out by Е. Antipina 5 .Paleontologist L. Gorobets in his dissertation describes species such as capercaillie and black grouse as bioindicators 6 .
Species adapted to live in a wide range of natural conditions are called "eurybionts".Whereas species, the range of which is strictly limited by certain conditions (at least one of the factors), which are limiting for their distribution, are called "stenotopic".There is also such a thing as "ecological criterion of the species"these are all the environmental conditions that are necessary for a particular species.The environmental factor, which most strongly deviates from the optimum but is necessary for the survival of the species, is called limiting.Using the concepts of stenotopic species, ecological criteria and limiting factors, it becomes possible to reconstruct the climatic and ecological conditions of the past based on finds of animal bones.
Findings of animal bones as indicators for climate reconstruction in the historical past were used in some of his works by the well-known Ukrainian archaeozoologist O. Zhuravlev 7 .However, in most works, mainly individual species were considered and, for example, only mammals or birds.
Today, there is a need to generalize the available data, add new species to the list of bioindicators, and also make tables convenient for archaeologists to use.

MATERIAL AND METHODS
The aim of our work is to identify species of vertebrates that are stenotopic in at least one factor and, on the basis of the findings of these species at archaeological 1 Пидопличко И.Г.Фауна Ольвии (по раскопкам 1935-1937 гг.).Природа. 1938. № 11-12. С. 113-116. 2  sites, to make climatic reconstructions.On the graphs, the height of the sinusoids reflects the level of temperature change conditionally: calibration in degrees was not carried out, however, the height of the sinusoid along the Y axis will be greater where cooling or warming was greater compared to other periods.This was done to visualize the results of reconstructions and to facilitate data comparison.
During 2006-2022, we examined zooarchaeological material from more than 85 archaeological sites (more than 184,000 remains of animal origin), from the Neolithic to the late Middle Ages.In terms of the amount of researched material, the most representative are the results of the research of Olbia and the multi-layered site of Ratniv-II.
The remains of mammals and birds were determined by comparing bone fragments with specimens of modern and subfossil species from the collection of the National Natural Science Museum of the National Academy of Sciences of Ukraine.The degree of fragmentation was determined according to the method of E. Antipinova8 , the age of the sawdust -according to G. Klevezal9 .The fishes were identified by comparing bones and scales with modern specimens from the author's comparative osteological collection.In those cases where it was possible, the exact age of the fish was determined by the scales and vertebrae of the fish.Systematics and types of fish names, given according to Y. Movchan's reference guide10 .
To determine the size of subfossil bones, they were measured with a caliper to the nearest 0.1 mm according to the method of von Drisch11 .Statistical processing was performed in the PAST program.
In addition, we analyzed the conditions necessary for the life of the most common species of vertebrates, as well as a number of birds, reptiles, mollusks, and even plants.In this paper, the patterns we describe refer to the territory of Europe, including Ukraine.We did not carry out similar studies for other territories.Similar reconstructions, but by different methods, are made by climatologists and paleobotanists (or archaeobotanists).
A prerequisite for correct reconstructions is the origin of the studied animal bones directly from the study area.Because there are situations (for example, archaeologists find a bone carving workshop) in which there are many deer antlers.But they can be brought from other places and are unsuitable for reconstructions of the local paleoclimate.At the end of the reconstruction, we compared our conclusions with the data obtained for these territories by scientists of these specialties.
The method described by us has shown good results, with its help it is possible to trace climate changes -global changes in warm and cold periods, forests by steppes, as well as the species composition of some tree species and grasses.Like any reconstruction, this method does not give a 100% match.The most accurate reconstruction is given by complex analysis based on all available sources of information.

RESULTS
As a result of the analysis of all the data, we identified a number of species for which it is possible to carry out paleoreconstructions. Thus, the bones of the European roe deer (Capreolus capreolus, Linnaeus, 1758) in the materials testify to the presence of woody vegetation of soft species, representatives of such genera as Willow (Salix), Populus (Populus) and Alnus (Alnus) during the studied period.In addition, one of the main limiting factors for the species is the maximum depth of the snow cover in winter (it cannot exceed 25 cm, maximum -up to 30 cm) 12 .The species is found both in the forest-steppe and in the forest zone, but on the edge of the forest.Beaver (Castor fiber, Linnaeus, 1758) also indicates the presence of soft rocks in the floodplain, and depending on the hydrological regime, it can either build a hut and a dam, or dig holes in the bank.The species itself can also directly affect the state of the reservoir.Table 1 shows the most relevant species for the territory of Ukraine.Predominantly, wild vertebrate species are the best bioindicators.Although some domestic species are also suitable for this -for example, domestic sheep (Ovis aries, Linnaeus, 1758), which require open spaces and grassy vegetation.
European elk (Alces alces, Linnaeus, 1758) in the first line indicates the presence of forests, often broad-leaved, and with interspersed conifers.Either for the presence of young coniferous forests.Also, the species gravitates to wet places, mainly to swampy areas.The maximum depth of the snow cover in winter for this observation should be 80 cm.Wild boar (Sus scrofa, Linnaeus, 1758) in the material indicate that the maximum depth of the snow cover was no more than 40 cm -oak, or oak-hornbeam) forest.For the red deer (Cervus elaphus, Linnaeus, 1758), the maximum depth of the winter cover storage is 40 cm 13 .One of the main intermediary factors for the european pound turtle (Emys orbicularis, Linnaeus, 1758) is the average winter temperature, which should not be below +2.6°C 14 .The indicator species also include the wood grouse (Tetrao urogallus, Linnaeus, 1758) and the hazel grouse (Tetrastes bonasia, Linnaeus, 1758), which are typical forest species.The wood grouse primarily prefers coniferous forests, while the latter prefers mixed forests, and does not even approach the edge of the forest closer than 200-300 m.Black grouse (Lyrurus tetrix, Linnaeus, 1758) is found in both forest and forest-steppe, as well as in steppe biotopes, but prefers places with a predominance of birch (Betula sp.).One of the limiting factors for the species is the formation of crust in the winter period due to thaws and subsequent frosts.Molluscs -painter's mussel (Unio pictorum, Linnaeus, 1758) and thick shelled river mussel (Unio crassus, Philipsson, 1788) react to the hydrological regime and water purity; river crayfish (Astqacus sp.) -for water quality; sturgeon (Acipenseridae), pikeperch (Sander lucioperca, Linnaeus, 1758)oxyphilic species, common carp (Cyprinus carpio, Linnaeus, 1758), crucian carp (Carassius sp.), tench (Tinca tinca, Linnaeus, 1758) -are satisfied with a very small 12 Формозов А.Н.Снежный покров как фактор среды, его значение в жизни млекопитающих и птиц СССР.Москва: Издательство МГУ, 1990.287 с. 13 Ibidem. 14Nekrasova O., Tytar V., Pupins M. Local functional responses of the European pond turtle, Emys orbicularis, to bioclimatic habitat features: a comparison of populations from Latvia and Ukraine.Conference: II Congresso Nazionale Testuggini e Tartarughe (Italy, Albenga, 2019.04.11-13).Albenga,  2020.P. 150-158.amount of oxygen in the water15 , common nase (Chondrostoma nasus, Linnaeus, 1758), trout (the birthplace of Salmonidae) -loves rapids, clear, cool water with a fast current.The saiga (Saiga tatarica, Linnaeus, 1758) and the onager (Equus hemionus, Pallas, 1775) mark the steppe areas and indicate the aridization of the climate.
The best results and opportunities for reconstructions are provided by complex studies, which take into account the presence of remains of not only mammals, but also birds, reptiles (european pound turtle), fish and molluscs in the archaeological material, as well as the archaeological context.
In order to reconstruct the paleoclimatic and paleoecological conditions from a specific archaeological site, it is necessary, first, to determine the animal bones to species.Next -to analyze the species composition and ratio of species.For example, let's take the monument of the Scythian time Severinovka16 .A total of 2196 remains of animal origin have been studied.Of all this number of bones and species, only a few are of the greatest interest for reconstruction: wild boar, beaver, red deer, podust and mollusk.In addition, be sure to pay attention to such domestic species as horses, large and small cattle.Further, we can look at Table 1 and clarify what conditions are necessary for the existence of these species.
Thus, the wild boar primarily indicates the presence of a forest-steppe, with broad-leaved species, such as oak and hornbeam, and the maximum depth of snow cover in winter is not more than 40 cm.Red deer and beaver -for the presence of broad-leaved forests, possibly floodplain, with such species as willow, aspen, alder.For deer, the maximum depth of snow cover is also 40 cm.It should be remembered that in the past the climate has changed several times, and if now in this area the maximum depth does not exceed 13 cm on average, then in the past the situation could be completely different.The Discus rotundatus is a species that lives in dead wood or in old living trees, in broad-leaved forests (oak, hornbeam), sometimes in alder trees in beams among broad-leaved forests (but it is unlikely to be in floodplain forests).The common nase (Chondrostoma nasus) species prefers deep rivers with fast currents and rapids.In addition, in the course of the research, teeth of a domestic horse and a domestic cow with hypoplasia were found.This pathology of tooth enamel develops in animals (and humans) in case of lack of nutrition at an early age.Thus, after analyzing the data, we can say that the settlement was located in the forest-steppe zone, but next to it there was a large oak-hornbeam forest, with inclusions of willow, aspen and alder in the river and stream valleys.Open spaces are needed for livestock grazing.Perhaps, in this case, grazing took place in the floodplain of the river.And for large species, nutrition was insufficient (hypoplasia indicates this).Thus, after analyzing the data, we can say that the settlement was located in the forest-steppe zone, but next to it there was a large oak-hornbeam forest, with inclusions of willow, aspen and alder in the river and stream valleys.Open spaces are needed for livestock grazing.Perhaps, in this case, grazing took place in the floodplain of the river.And for large species, nutrition was insufficient (hypoplasia indicates this).The climate was quite warm, the snow cover in winter did not exceed 40 cm.The river had a fast current and rifts.Accordingly, the beaver could not build its dwelling and dam on the channel and could either dig holes in the steep banks of the river, or make a dam not on the main channel, but on the stream that flows into the river.
Based exclusively on animal remains, we reconstructed the paleoecological and paleoclimatic conditions for the early Neolithic sites of Starobilske-I (modern Luhansk region).Thanks to the developed method, exclusively due to the findings of bioindicator species it was possible to accurately determine the periods of warming and cooling in the studied periods at the archaeological sites and paleoecological conditions.
Starobilsk -Early Neolithic site (5900-5800 BC), located on the territory of Luhansk region, excavation materials of O.G. Shaposhnikov and Yu.Hurin for 1979-1980.Five species of mammals have been identified: tour, elk, wild boar, roe deer and beaver.In addition, the remains of a representative of the equine family (Equidae) were found, probably a onager.The bird bones cannot be determined to species, all the reptile bones belong to the terrapin species, and the mollusk shell fragment belongs to the Unio genus.
Based on the species composition and the presence of 5 model species (some of them were selected during the work of previous years), we can reconstruct the paleoecological conditions around the ancient site.Thus, the presence of roe deer and beaver indicates the presence of broad-leaved (including floodplain) forests, elkconiferous forests (probably pine), roe deer and tur to a greater extent forest-steppe species that prefer meadows and edges, the presence of horse bones (kulana?) indicates significant open spaces.The depth of the maximum snow cover in winter is important in the life of animals and is often the main limiting factor in the dispersal of species.So, roe deer is not found where the depth in winter is more than 30 cm, for wild boar the critical depth is 40 cm.
Thus, in the early Neolithic around the Starobilsk-I site there was a forest-steppe with significant areas of the steppe, with a predominance of broad-leaved species (probably with interspersed oaks and pines) and a snow cover depth of 30 to 40 cm in winter.These paleoreconstructions are fully confirmed by the studies of soil experts and paleobotanists who worked at the same site 17 .
In addition, the method made it possible to reconstruct for the Northern Black Sea region not only the end of the Roman climatic optimum 200 years later than previously thought, but also the beginning -in the 5 th century BC, 200 years earlier than the generally accepted dating (fig.1).At the same time, most of the finds of lions (Panthera leo, Linnaeus, 1758) from this territory date back to the 5 th -2 nd centuries BC.Since the beginning of the 20 th century, enough data has already accumulated to confirm that lions (not only cavemen) were in the fauna of Ukraine.And just the transition of the climate from a colder one, with woody vegetation, through the forest-steppe stage to the steppes, is most suitable for the distribution of this species in the Black Sea region.This is in good agreement with our dating data.
Among others, the unique site of Ratniv-II (Volyn region) was investigated.Zooarchaeological materials from 18 objects of different times have been identified, due to which two historical periods, which are almost continuous in terms of the availability of materials, have been identified (from 5400 BC to 1100 BC and the 8 th -12 th centuries AD).Paleoclimatic conditions on the site of modern Ratnov were reconstructed and a comparison was made with own reconstructions in the Poltava region (fig.2).
1. Object 17, Linear Pottery culture (LBK).According to the results of the analysis of the osteological collection, it can be assumed that the settlement was located in a forest-steppe landscape, most likely with mixed forests (the main species are oak, linden, elm, pine).During the studied period, the climate was warm, the average winter temperature did not fall below +2.3°С, which corresponds to the Holocene climatic optimum (early Atlantic period AT1).
2. Tshinetsko-Komariv culture.The settlement was located in a forest-steppe landscape, most likely with mixed forests (the main species are oak, linden, elm, pine).In the studied period, the climate was warmer than today, but colder and drier than the previous Atlantic period.
3. Mezhanovitska culture/Stzhizhov culture and the Middle Ages (8 th -9 th century AD and the beginning of the 11 th century AD).Thanks to the presence of indicator species in the material, paleoclimatic and paleoecological conditions for the studied objects were reconstructed.Thus, the period of existence of objects 21 and 36 fell on the subboreal -at the end of cooling and the beginning of warming.Settlements were located in the forest-steppe, but with a predominance of coniferous forests and heather plants in the undergrowth.But the average winter temperature did not fall below +2.3°С.
The period of existence of object 24 refers to the sub-Atlantic period, in particular to the end of the climatic pessimism of the early Middle Ages.The settlement was located in the forest-steppe zone, the forests were mainly mixed: represented by broad-leaved (oak-hornbeam) and coniferous (pine and spruce) species.The maximum depth of the snow cover in winter ranged from 30 to 40 cm.
The functioning of object 32 also belongs to the sub-Atlantic period, in particular to the Middle Ages climatic optimum, which is indicated by the presence of roe deer bones in the material.The settlement was located in the forest-steppe zone, but the area of forests increased, broad-leaved forests with species with soft wood (aspen, alder, willow, poplar) prevailed, especially in river floodplains.The maximum depth of the snow cover in winter did not exceed 25.0 cm.The average monthly temperature was ≥+10°C for 150-160 days a year, and the annual amount of precipitation was 450-650 mm.
The results were compared with the data of paleobotanists and climatologists from the territories of these monuments in the studied period.To a large extent, the reconstructions coincided, which gives us the opportunity to recommend the abovementioned species as indicators of paleoclimatic and paleoecological changes.

CONCLUSIONS
To date, work on the identification of other indicator species continues, we have carried out reconstructions of the paleoclimate on the basis of osteological materials found in the excavations, and for a number of monuments we have compared the results with the data of paleobotanists and soil scientists from the same areas.The similarity of the obtained results is significant, which allows us to propose a method of reconstruction of paleoclimatic and paleoecological conditions based on the findings of the indicator species selected by us as effective.The most effective is a comprehensive study of osteological materials, taking into account the presence of the above-mentioned species in the material.In terms of time spent, the identification of zooarchaeological materials is a simpler and faster method than paleobotanical research, and the results are largely comparable.In addition, the same species can be used to model predictions of habitat changes due to climate change in the future.