PALEONTOLOGY. — From the Greek παλαιός “ancient,” ὁ “being,” and λόγος “discourse”: it is the science that studies fossils, namely the remains of animals (paleozoology) and plants (paleophytology or paleobotany) that lived in past ages of the earth.
Generally these remains consist of the hard parts of organisms (skeletal substance, woody tissue), their impressions, or petrified parts, while only exceptionally is the soft substance completely preserved, and very rarely entire bodies (especially in ice, amber, or asphalt).
OUTLINE:
I. General Notions
II. History
III. Paleozoology
IV. Paleophytology.I. General Notions
The aim of paleontology is the systematic study of fossils (“systematic paleontology”), whose determination can be made by comparison with living species or with already described extinct forms. Research is carried out both by macroscopic study of specimens generally freed from extraneous parts and by the use of instruments, above all the simple microscope, for special “thin sections” of transparent rock or “polished sections” of plants (under reflected light); the binocular microscope for isolated microfossils; and X-rays to reveal internal details of fossils themselves. Histological examination of some plants has permitted intimate knowledge of structure in fossil organisms even before it was known in living ones.Paleontology also studies the relationships among groups of fossils, since they fall within the major divisions of the systematics of animals and plants; sometimes completing the links between living species or other groups (genera, families, etc.) and contributing notably to phylogeny, morphology, and the distribution of living species.
The above, however important, is not the sole objective of the science of fossils; today it constitutes chiefly the most effective tool for the relative dating of geological time, for understanding past biological phenomena and climatic types.
Stratigraphic study (v. STRATIGRAPHY) indeed allows not only observation of how fossils were deposited in the strata that contain them (and thus to ascertain that their age is contemporaneous with that of the enclosing sediments, except as will be said later when dealing with “remanié” fossils), but also to establish, where the succession of strata is regular, that alongside organisms that have remained almost unchanged throughout geological time (“persistent forms”), there are others, fairly numerous, that have changed in the course of time; that is, they have been transformed or have evolved.
Moreover, some groups or species have disappeared at various ages in the history of the earth. Among these latter, some had a life cycle very limited in time, though sometimes widely distributed geographically, so that they may all occur in the same stratum.
Comparative stratigraphic study has also shown that some such short-lived faunas have preceded or immediately followed, at all points on the earth, other organisms having identical characters of temporal and spatial distribution. Thus it has been possible to construct a scale of terms (“stratigraphic scale”) made up of associations of species or of single species of characteristic fossils, also called “index fossils.”
In this way “stratigraphic paleontology” was born, based on the normal succession of strata; but at present it has advanced so far that it can be used alone, with certainty, to solve chronological problems even in terrains so disturbed by tectonics that they no longer preserve their original order of succession.
It must be noted at once, however, that only fossils deposited contemporaneously with the enclosing strata have stratigraphic value for that particular geological age; whereas if they are reworked, or as is said, “remanié,” they lose their contemporaneity with the enclosing strata, which will thus appear to be of greater age than they really are. Reworked or allochthonous fossils are recognized because they show traces of rolling or because they are still attached to fragments of pre-existing rock, usually of a different nature from the last enclosing rock. Thus, for example, a calcareous breccia containing rounded and eroded nummulite tests or their fragments together with mollusks of a definitely more recent age will have an age indicated by the latter fossils and not by the foraminifera.
Many fossils, though lacking stratigraphic value, can nevertheless serve to illuminate the environmental conditions of their deposition. In this case one speaks of “facies fossils”: continental (terrestrial and aquatic—fluvial and lacustrine); marine (benthic, fixed and mobile; pelagic—nektic and planktonic).
It may be concluded that paleontology and geology are intimately linked with each other, and that the study of one without regard to the other is practically devoid of results of real scientific value.
II. HISTORY
The origins of paleontology, like those of many other sciences, can be traced to very remote times; but only in very recent times (the early 19th century) did it develop as an autonomous science, separating from geology.Classical antiquity possessed scant knowledge of fossils. Nevertheless, for many Greek natural philosophers and later for some medieval writers and thinkers (St. Albert the Great, G. Boccaccio, etc.), fossils undoubtedly represented remains of organisms that had lived in earlier ages. Others, however, considered fossils either the product of a hypothetical “vis plastica” or “formative force,” or even the “luxuriance of Nature.” In more recent times, definite opinions on the nature of fossils were held by Leonardo da Vinci, Bernard Palissy, Girolamo Fracastoro, and a few others.
Among the oldest natural history collections, which also included fossil remains, are those of London (17th century) and of various cities in France and Germany; that ordered to be made in the Vatican by Sixtus V and illustrated in the *Metallotheca Vaticana* of M. Mercati of 1574 (published in 1719); and a collection by Aldrovandi, etc. However, even in the centuries after the Middle Ages, especially in France and Italy, illustrious scholars attributed organic fossil remains to the Noachian Deluge (diluvian theory); perhaps because the fossils found in these countries, belonging predominantly to recent strata, were very similar to currently living species. In England, on the other hand, the presence of fossils very different from living species contributed to their being regarded as extinct forms. An important step in the progress of paleontology was the application of the microscope by R. Hooke in the 17th century to the study of microfossils, histological preparations of animals and of silicified woods, and ammonites, in which the suture lines were brought to light.
Yet it was only in the 18th century that the first papers appeared with a systematic descriptive aspect of fossils.
The credit for laying the scientific foundations of vertebrate paleontology belongs to Cuvier, as a result of his observations on the numerous fossil bones of animals, mostly extinct, found in the sedimentary layers of the Paris Basin, and through the application of comparative anatomy—which he himself founded—to the science of fossils. However, to explain the differences between the faunas that succeeded one another from layer to layer, Cuvier resorted to hypotheses involving almost universally catastrophic terrestrial disturbances, which would have caused the extinction of a great number of living beings in one epoch, after which others would have appeared through successive creations or mass immigration from other regions (theories of the revolutions of the globe and of successive creations). Cuvier thus acknowledged the differences between species in strata of different ages, but he defended the 'fixity of species.' Among his followers (A. Bronn, Agassiz, D'Archiac, etc.), A. D'Orbigny stood out for exaggerating his master's theories by admitting 27 successions of completely renewed faunas (about 18,000 species illustrated by him: Planes A, B, etc., of D'Orbigny), placing the oldest in the Silurian. Partly reviving the ideas of Buffon and others, Lamarck and G. S. Hilaire expounded the 'transformist' idea: the former believing that species tend to vary slowly through the transmission of acquired characteristics in relation to physiological causes (use and disuse of certain organs to adapt to varying conditions or habits); the latter attributing such variations to environmental factors through sudden changes. However, it seems that Lamarck had observed that his phyletic series were 'ordered' as if by a preordained plan from the Creator. These two French naturalists were the true founders of 'transformist' paleontology, which later evolved into evolutionary paleontology (v. EVOLUTION), subsequently developed by Darwin.
Given the importance of this theory, it is worth noting that there were also 'pre-Lamarckian' thinkers even in the Middle Ages and the modern era: St. Augustine, for whom things were not created as such but rather their causes were; and likewise the Jesuit Athanasius Kircher, who asserted a 'multiplication of species and not merely of individuals.' Other evolutionists included G. Bruno, Bacon, Descartes, Buffon, etc. Among the founders of invertebrate paleontology, besides D'Orbigny, Lamarck is remembered; of paleophytology, Adolphe Brongniart; and among the founders of stratigraphic paleontology, W. Smith, the Abbé Giraud-Soulavie, G. B. Brocchi, etc.
It is not possible to list the names of paleontologists from the late 19th century and the 20th century, given their great number.
III. Paleozoology
In the Algonkian of North America and the Baltic Shield, fossils of animals already exhibiting a high degree of evolution are known (echinoderms, gastropods, arthropods). Some remains, described as 'problematic,' appearing as imprints, such as *Palaeodictyum*, are by some referred to algae, by others to poriferans, medusae, etc. Among protozoans, the principal fossils belong to rhizopods: foraminifera and radiolarians, the former with calcareous shells, the latter with siliceous ones. Modern calcareous foraminifera, during their juvenile stage, have a chitinous shell, like their Cambrian ancestors.Among the foraminifera (once thought to be cephalopods even by Lamarck, first illustrated by Aldrovandi), which can reach up to 12–16 cm in diameter in their fossil state, numerous characteristic forms are found: among the imperforate: *Orbitolina*, of the Cretaceous; *Alveolina*, widespread in the ocean; among the perforate: *Globotruncana*, of the Cretaceous; fusulinids, of the Carboniferous; nummulites and *Assilina*, of the Paleogene; orthophragmines and lepidocyclines, of the Tertiary (the lepidocyclines underwent further development in the first half of the Miocene, when they were replaced by *Miogypsina*); *Amphistegina*, from the Miocene to the present. The limestones of the Maiella, Gargano, etc., are rich in nummulites. Today, microforaminifera are also given great importance, especially regarding the recent Tertiary and Quaternary, with studies conducted on a statistical basis.
Radiolarians, exclusively marine planktonic organisms, appeared in Precambrian times (in the radiolarian cherts of Brittany), with skeletons in the form of perforated spheres; however, few forms are of stratigraphic importance. Nassellarians and spumellarians predominate in the radiolarian oozes at depths of over 4,000 meters in the Indian and Pacific Oceans. Poriferans, also very ancient and little-evolved animals with skeletons composed of isolated and fused spicules, live in littoral zones as well as in the deep sea, down to over 4,000 meters. They are, among metazoans, the simplest; sessile and almost all marine. Poriferans had notable development in the Mesozoic (San Cassiano Triassic; Turonian of Normandy, etc.). The *Archaeocyatha*, characteristic fossils of the Lower and Middle Cambrian (Australia, Sardinia, Montagne Noire), are also attributed to poriferans.
Cnidarians, which correspond to the 'zoophytes' of ancient authors, include numerous forms important from a stratigraphic and lithogenetic perspective. The tetracorals, extinct by the end of the Paleozoic, were succeeded by scleractinians, which appeared in the Triassic and are still extant. Other important reef-builders include the tabulates of the Paleozoic; stromatoporoids; the ellipsactiniids, of the Jurassic-Cretaceous; the hydrozoans, of the Tertiary. Medusae, finally, have lesser importance, though sometimes displaying fine imprints, such as those in the Malm limestones of Solenhofen; in Italy, in the Cambrian shales of Sardinia and the Piacenzian marls of Farnesina (Rome).
The triblastic metazoans, generally sessile, include the types of bryozoans and brachiopods, both still extant. Among bryozoans, colonial forms with calcareous cells, marine (stenolaemates), which appeared as early as the Lower Silurian, have left fossil remains; they reached their first peak in the Permian (e.g., *Fenestella*), when tetracorals disappeared, and a second peak in the Cretaceous, when scleractinians declined. Today, cheilostomes abound, with important colonies currently found in the Red Sea and the Mediterranean; however, they were also widespread in the ancient Tertiary and Quaternary. Some authors include the *Chaetetes* among bryozoans, previously considered tabulates.
Of brachiopods, both valves generally remain in the fossil state. The brachidium is sometimes highlighted either by successive sections of the dorsal valve or by X-ray analysis. The first to appear were the inarticulate brachiopods (*Lingula*, in the Algonkian of North America); then the articulate brachiopods (from the Cambrian); both groups survive to this day. Brachiopods were highly developed in the Silurian (over 3,000 species), and after a slight regression in the Devonian, they renewed themselves in the Carboniferous (the curious *Richthofenia* of the Permian provides striking examples of convergence with Cretaceous rudists); there was another renewal in the Triassic, followed by a decline in the Tertiary, both in number of species and individuals.
Of worms, which have some stratigraphic importance in the Silurian and Devonian, few fossil specimens are known, consisting mainly of calcareous tube remains and annelid jaws. Perhaps to them can be attributed tubular imprints in the sands of Precambrian and early Paleozoic fossil beaches (*Arenicolites*).
Tropodi are animals of perfect bilateral symmetry, with a chitinous covering, aquatic and terrestrial. Of great importance is the class of trilobites, exclusive marine fossils of the Paleozoic, whose oldest representatives in Italy (Paradoxides, Olenopsis, etc.) are found in the Cambrian schists of Sardinia (Iglesiente, Sulcis), while they are very abundant in England, Bohemia, North America, etc. Among the crustaceans found in the Algonkian of Montan (Beltina Danai), the phyllopods are noted, with two small valves, such as Estheria, from the Triassic; the ostracods, such as Cypridina, from the Devonian; while some forms are from fresh and brackish water of the Quaternary. Among the malacostracans, the brachyuran decapods of the Venetian Eocene: Harpactocarcinus, Ranina, etc., from the Pliocene marls of Anzio and Monte Vaticano: Cancer, etc.
Aptychi are fossils of uncertain systematic position, once thought to be opercula of ammonites but now more generally attributed to crustaceans. They are flattened calcareous pieces, smooth or ornamented, common in the Middle and Upper Mesozoic of the Apennines (e.g., in the "Aptychus shales" of the Jurassic of the central Apennines).
Gigantostracans appear in the Silurian (e.g., Euryterus, in England) and have further development in the Devonian (Euryterus, Pterygotus, etc., of brackish facies). Among the arachnids, the oldest known air-breathing fossil is a scorpion: Palaeophorus nuncius, from the Gothlandian. Among the most interesting insects are orthopterans and neuropterans, such as dragonflies, with a wingspan of up to a meter, from the Carboniferous of France and Russia. In a group related to arthropods, that of the petrobranchs, some paleontologists currently include the graptolites, Paleozoic pelagic animals in floating colonies, of which the fossilized rhabdosomes of whitish, silicatic nature (gumbelite) are found in very fine, blackish, carbonaceous shales, especially from the Silurian and Devonian. The dendroids appear first, with thecae of three sizes (Cambrian-Carboniferous); later, the graptoloids, with thecae all equal to one another. Beautiful specimens of graptoloids are found in the Gothlandian sediments of southeastern Sardinia and the Carnic Alps. However, it is only among the mollusks that the most numerous and important forms of the fossil animal kingdom are found. They are equipped with a shell of one piece or two pieces (rarely more than two), internal or external; while only a few forms, and perhaps their ancestors, may have been naked. Among the mollusks of the Pliocene, 50% of the species are still living. Among the amphineurans is the genus Chiton, equipped with eight calcareous plates, which has lived from the Silurian to the present.
The oldest pulmonate gastropods are found in Carboniferous sediments, the first siphonostomes also in the Carboniferous (cerithids). In addition to the shell, variously shaped and ornamented (turriculate, flattened, helicoidally coiled, more rarely with a flat or conical spire [Patella], etc.), the "radula," a sort of lingual plate with teeth, and the operculum may also be preserved as fossils. In the Tertiary, gastropods take on their present characteristics, although Eocene species are almost all extinct. In an appendix to gastropods are mentioned the pteropods, which appeared in the Upper Cretaceous, with thin and transparent shells, and the genera Hyolithes, already recorded from the Algonkian of Colorado, and Conularia, Paleozoic. The scaphopods, with a shell in the form of a tube open at both ends, have lived from the Silurian to the present. Much more important are the bivalves, which appeared in the Upper Cambrian. Indeed, some genera still living today (Arca, Nucula, Leda, Avicula) date back to the early Paleozoic, while in the Devonian the first brackish and freshwater forms appear. With the Triassic, the fauna renews itself; reef forms reach their peak in the Cretaceous with the curious rudists; with the Tertiary, finally, we pass to the present forms, among which the pectinids are very widespread in the Neogene.
Among the cephalopods, many are characteristic fossils of stages and even zones. Entire groups are extinct, e.g., the ammonoids and belemnites. Among the oldest cephalopods to be noted is the genus Wolborthiella (which is an orthoceratid) from the base of the Acadian. Of the tetrabranchiates, only the genus Nautilus survives today, while most other nautiloids became extinct in the late Paleozoic, and in the late Miocene Aturia, which began in the Cretaceous. The ammonoids represent one of the most interesting "closed series" of fossils, whose extremes are found in the Lower Silurian and Upper Cretaceous. In the Silurian primitive goniatites appear, while in the Carboniferous true ammonites are already known, but in the Triassic forms of all three types (goniatitic, ceratitic, ammonitic s.s.) coexisted, and the genus Pinacoceras showed the maximum complication of the suture line. Ammonites reached their peak in the Jurassic, while in the Cretaceous, before their total disappearance, uncoiled forms with ceratitic sutures (Neoceratites) appeared. Ammonites are of primary stratigraphic importance and are very abundant in some stratigraphic levels of the Mesozoic of the Apennines and the central and eastern Prealps, of the Paleozoic and Mesozoic of Sicily, etc.
The order of dibranchiates includes: decapods, with the belemnites, exclusive to the Mesozoic (which in the Triassic replaced the orthoceratids among the nautiloids), and which have left, for the most part, the "rostrum," a sort of conical, semi-massive calcareous piece like a javelin (fultinii of Jupiter, of the ancient Greeks); the sepiids, still living today, etc. Among the octopods, some imprints from the Cretaceous to the present. Of the type of echinoderms, whose skeleton in the fossil state is made of calcite with easy rhombohedral welding, all marine, the cystoids, with synthetic characters, lived from the Cambrian to the Carboniferous; the blastoids, probably derived from the former, from the Silurian to the Permian. The remaining class of pelmatozoans, that of the crinoids, is, however, much more important than the former, since from the Silurian it extends to the present, although now represented by only 12 genera. Crinoids are of great lithogenetic importance for Paleozoic, Triassic and Alpine Jurassic terrains (crinoid or "entrochite" limestones).
While asteroids, ophiuroids and holothuroids are of little importance, echinoids, on the other hand, have generally had a very rapid evolution: in the Silurian the regular paleoechinoids appeared, with Archaeocidaris, and in the Lias the irregular ones (holcotypids); in the Paleogene Italian terrains Echynolampas are frequent, and in the Neogene, Scutella and Clypeaster.
Vertebrates, although less numerous than invertebrates, also present considerable paleontological interest. The primitive jawless vertebrates, the cyclostomes, have curious affinities with exclusively Paleozoic forms. The main adaptive types of fishes are the fusiform type and the type compressed from top to bottom, which is realized by benthic species. The oldest fishes date back to the Ordovician. Selachians, ganoids and dipnoans have lived since the Devonian, when the ostracoderms or "armored fishes," of brackish facies, were in a senile phase, with morphological convergences with the gigantostracans. Elasmobranchs, ganoids and dipnoans had considerable development in the Carboniferous.
Only in the Triassic, following a renewal of the fauna culminating in forms with greater development of the bony part of the internal skeleton and a reduction of the dermal armor, did the teleosts appear. Of fishes, in addition to the imprints in fine sediments (marls, clays, diatomites: M. Bolca, M. Amiata, etc.), isolated parts, especially teeth, dermal plates, bones, vertebrae, otoliths (e.g., in the Miocene limestones of Sicily, Sardinia, etc.) are more frequently found as fossils.
Amphibians are organisms adapted to terrestrial life in the adult stage, with an aquatic larval stage resembling the fish from which they derive (crossopterygians). The skeleton is generally well ossified, but while the skin is naked in present-day forms (lissamphibians), it was covered by a solid dermal armor in a large number of fossil forms (labyrinthodonts), including the stegocephalians, which first appeared in the Upper Carboniferous and were very widespread in the Permian, e.g., *Archaeosaurus*, *Branchiosaurus*, etc. From the stegocephalians originated the Triassic labyrinthodonts (e.g., *Mastodonsaurus*), which were the most gigantic amphibians. Among fossil forms, the Miocene salamander *Andrias scheuchzeri* is noteworthy, having been mistakenly considered the skeleton of a child drowned in the Noachian Deluge.
Reptiles also derive from crossopterygians or stegocephalian amphibians, and the oldest known forms (*Saururus*) date back to the end of the Carboniferous in Pennsylvania. In the Permian, reptiles were mostly terrestrial, rarely aquatic (e.g., *Mesosaurus*); among terrestrial carnivores, the theriodonts displayed convergent features toward the mammalian type, such as heterodonty, and may have given rise to them. In the Triassic, there are also tracks of unknown reptiles, called *Cheirotherium*, due to the shape of the footprint resembling that of a human hand. During this period, reptiles underwent great diversification in general morphology, adaptation to various types of food and environment (ichthyosaurs, sauropterygians, rhynchocephalians, dinosaurs, crocodilians, theromorphs, testudinates, pterosaurs, etc.), reaching their peak with gigantic and bizarre forms that disappeared in the Cretaceous (e.g., pterosaurs, dinosaurs such as *Tyrannosaurus rex*, the most gigantic, also a fine example of bipedalism), ichthyosaurs (notably ichthyornithiform), when lizards and snakes first appeared.
The oldest known birds to date are *Archaeornis* and *Archaeopteryx* from the Upper Jurassic of Solenhofen (Bavaria); the latter, the size of a large pigeon, had jaws and alveolate conical teeth, a bony tail, thus reptilian traits, and is derived from reptilian pterosaurs, according to some, or from arboreal reptiles with forms adapted first to gliding flight.
Other toothed birds are found in the Cretaceous of Kansas (United States): *Ichthyornis* and *Hesperornis*.
By the end of the Cretaceous, birds with reptilian traits disappeared, and the fauna became similar to that of today. The last giant birds are found in the pigeon of Santa Cruz, in South America; in the Quaternary, with the *Aepyornis* of Madagascar and the *Dinornis* of New Zealand, with eggs of enormous size holding up to 10 liters. Fossil eggs and feather impressions are also found in Quaternary travertines of central Italy (e.g., Acque Albule near Tivoli); in the peperino tuffs of the Lazio volcano (Rome; vulture feather impressions).
The oldest known mammals are represented, in the Upper Triassic of southern Africa and Europe, by teeth of multituberculates, which seem to descend from theromorph reptiles: they had a very long first evolutionary phase throughout the Mesozoic, with small-sized forms of primitive placentals (insectivores). It was only at the beginning of the Tertiary that mammals assumed importance. In this geological era, they had two evolutionary phases: first, with rapid evolution followed by sudden extinctions of archaic mammals, e.g., creodonts (carnivores), condylarths (primitive ungulates with slender limbs adapted for running and synthetic traits, e.g., *Phenacodus*), amblypods (ungulates with massive limbs; Europe and America); followed by another phase that gave rise to precursors of modern forms. Leporids are of North American origin. Likewise, *Equus*, which appeared in the Eocene (*Eohippus*, the size of a dog) and became extinct there by the end of the Tertiary; it then spread to Asia and from there to Europe and Africa, where it attained its present form.
Terrestrial mammals—proboscideans (mastodons, deinotheres), rhinoceroses, ruminants with horns, catarrhine monkeys of Asian-African origin—invaded Europe in the Miocene. They underwent intense evolution in the Pliocene: many genera of carnivores, equids, rhinocerotids, camelids, bovids, cervids, proboscideans, cetaceans, etc. At that time, close relationships existed between India and Europe, and between Africa and India, while direct ties between Europe and North America diminished. However, a migratory flow was established from Africa to North America via Asia, and another between the two Americas, already interrupted in the Eocene.
As for South America, it should be noted that in the Pliocene there survived strange autochthonous forms of marsupials and placentals that had undergone characteristic evolution in situ since the Eocene, manifesting as convergences. Among marine mammals, important are the Neogene odontocetes, e.g., *Squalodon*.
Some important vertebrate deposits include: the Eocene gypsum deposits of Montmartre (Paris), famous for their wealth of forms and Cuvier’s discoveries; Eocene deposits of Wyoming, Utah, Colorado, New Mexico; Oligocene deposits of Dakota, Nebraska, eastern Colorado; Eocene mammal deposits in the sands of Orléans, the island of Samos, and the Pontic of Pikermi (Athens); vertebrates from various Miocene and possibly Pliocene levels near Sahabi (south of Benghazi), including: fish (elasmobranchs and teleosts), freshwater reptiles (crocodiles, *Trionyx*) and terrestrial ones (emyds), numerous mammals (cetaceans, suids, hippopotamids, rhinocerotids, antelopids, felids, proboscideans, etc.). The fauna of Sahabi resembles that of Egypt (140 km southwest of Alexandria) and the famous Sivalik deposit, with numerous species of carnivores, ungulates, proboscideans, and primates from the Miocene and Pliocene.
There are numerous fossil vertebrate deposits in Italy, including: the famous "Pesciara" of Bolca (Vicenza), with over 150 species of Eocene elasmobranchs and teleosts of tropical Indo-Pacific climate; those with reptiles (e.g., *Crocodilus vicetinus*, turtles) and mammals in the Paleogene lignites of Veneto, similar coeval fauna near Cadibona (Western Alps); the lignite series of Gavitelli (Messina), with Pontian mammals; the lignites of Montenbamboli (Tuscany), with fish, reptiles, and mammals; those of Casino near Siena, etc.; Quaternary deposits, sometimes in cave and marine karst deposits (e.g., Puntali, S. Teodoro in Sicily), Tyrrhenian coast (Circeo, etc.); Pleistocene deposits with mammoths and Mousterian flints in the alluvium of Musone near Asolo (Treviso); alluvium of Arena Po (Pavia), with: *Megaceros*, *Alces*, *Cervus*, bison, *Bos*, etc.; alluvium of the Arno, Tiber, and Aniene in the Roman Campagna, with: *Elephas antiquus*, hippopotamus, *Rhinoceros mercki*, red deer, *Megaceros*, *Bison priscus*, *Bos primigenius*, etc.; Pignataro Interamna (Cassino), with *Elephas antiquus*; Roccasecca (Liri Valley), where, among other finds, a notably large canine of *Hippopotamus major* was discovered; Lake Venosa (Lucania); deposits in diatomites, e.g., fish in M. Amiata; mammals, including elephants and bovids, in the Viterbo area; deposits in volcanic tuffs of the Roman Campagna and in the travertines of the same region, containing, among other things, bird eggs and feather impressions.
In western Europe, Aurignacian and Magdalenian prehistoric art has preserved many drawings and sculptures depicting animals now extinct or migrated to other regions, such as the mammoth, woolly rhinoceros, reindeer, bison, bears, etc.
IV. PALEOPHYTOLOGY
The first descriptions of fossil plants in England and Germany date back to the 17th century, but the founder of paleophytology is considered Adolphe Brongniart, who in 1822–28 made the first classification of fossil plants. Other fundamental works include those by Blumenbach, von Schleothaim, Unger, Schimper, etc. Silicified woods had already attracted the attention of St Albert the Great in the 13th century.
In the oldest geological formations, also because they are generally metamorphosed, there are no certain traces of determinable fossil plants. Indirect evidence of the presence of lower plants in Precambrian sediments is, however, provided by graphite deposits; coal (“shungite”) on the shores of Lake Onega; iron ores, due—as is the iron of swamps—to the action of bacteria, which were probably among the first organisms to appear. In the Algonkian, “problematic” forms are present in North America, in the “Belt series,” perhaps Cyanophyceae algae (*Cryptomonadaceae*), *Neolandia*, etc.; *Corycium enigmaticum* in Finland.
Among the Thallophytes, marine algae that can be certainly identified date back to the Cambrian and Silurian, contained in calcareous rocks; they were very developed in the Triassic with *Gyroporella* and *Diplopora*, while the Lithothamnia were especially abundant in the Tertiary. Calcareous algae have been able to contribute, in the same way as certain animal organisms, to the formation of the oolitic and pisolitic structure of calcareous masses, iron rocks, etc. (e.g., the codiacean algae forming the nuclei of oolites in the Dogger limestones of Sardinia). Among the siliceous algae, diatoms, with a shell of amorphous silica and decorations sometimes visible only under the electron microscope, fall into three main forms: boat-shaped or naviculoid; round or ellipsoidal; with polygonal outline. Diatoms date back to the Cretaceous and perhaps to an earlier age and have formed the diatomaceous earth of which the highly prized “fossil flour” of S. Fiora [in Amiata], originating in tiny Pleistocene lakes, is composed.
The first vascular cryptogams (plants with roots, stems and leaves) appear in the Silurian; for the Coal Measures, the cycadophytes are noteworthy, ancestors of ferns and comparable to the present-day tree ferns of tropical forests (gen. *Sphenopteris*, *Pecopteris*, *Neuropteris*, etc.); the calamariaceae, *Calamites*; among the Lepidophytes, *Lepidodendron*, *Sigillaria*, and the root-like rhizomes called *Stigmaria*. Horsetails and ferns were still developed in the Triassic. The latter and the conifers were also present in the Jurassic. Among the phanerogamous gymnosperms, the following are noted: *Cordaites*, 30–40 metres tall, and *Noeggerathia* among the cycads of the Carboniferous; among the conifers: the genera *Voltzia* and *Ullmannia* of the Permian. Angiosperms appear in the Jurassic (Dogger of Yorkshire and Sardinia), when the pteridosperms tended to disappear. They developed in the Cretaceous: *Salix*, *Populus*, *Ficus*, *Quercus*, *Eucalyptus*, etc. Monocotyledons also appear in this period. In the Tertiary, palms are important, of which numerous trunks are found silicified (Sardinia, Cyrenaica [Sahabi], Egypt, North America, etc.).
With regard to the fossil plant kingdom, the following observations can also be made: in the Carboniferous two botanical provinces are distinguished: boreal and austral. In the latter, i.e., corresponding to the Gondwana Land (Australia, India, southern Africa, Borneo), the flora is made up of *Glossopteris* and *Gangamopteris*; the phanerogams of the Carboniferous are all in the environments of tropical coasts, comparable to present-day swamps, such as the swamps of Virginia, the Gulf of Mexico, etc., or to the marine areas with mangroves of the Red Sea and the Indian Ocean; the plants of the Permian show notable affinities with those of the Triassic. In the Quaternary there are well-defined paleobotanical provinces; in the Pleistocene, paleobotanical associations show fundamental characters parallel to the faunas of the same period. Among the “cold” forms occupying glacial areas, there is the “Dryas” flora (*Dryas octopetala* L.) of tundra or high-mountain facies, followed by *Pinus montana*, *Betula nana*, *Salix polaris*, etc.; while in the interglacial phases there are warm forms, e.g., *Ficus carica*, *Buxus sempervirens*, *Vitis vinifera*, etc., which spread northward. A renewed evolutionary phase of plants occurred after the last glaciation, with forms that still live today.
The reconstruction of the climatic periods of the Quaternary is based on the qualitative and quantitative study of pollen contained in layers, peat bogs, etc. Pollen grains have such special forms that they sometimes allow the specific determination of individual plants.