Any science about the Earth and life on it may have the prefix "paleo". Paleoecology and paleogeography restore the appearance of the planet in antiquity, paleoclimatology - the features of its climate. Paleozoology studies the fauna of bygone eras. Looking into the past, it is easy to see how unstable the planet's surface is, how changeable its biosphere. A million years ago, under present-day Krasnodar, one could meet mammoths, our extinct neighbors. In the Jurassic period, swift and predatory ichthyosaurs swam on the Middle Volga. On the seabed in the Leningrad Region, long-eyed trilobites crawled leisurely - only half a billion years ago.
Dvinskaya Bay, Arkhangelsk Region
555 million years ago, Ediacaran (Vendian).
At that time, the land was merged into the supercontinent Pannotia. It was washed by ancient oceans, in which the first multicellular animals began to appear just then. The current Arkhangelsk Territory was located almost at the South Pole, under the water of a shallow and icy coastal sea. Cold water held more oxygen, and life flourished here: the flat bottom was covered with bacterial films and carpets of algae, which were devoured by the soft-bodied representatives of the Ediacaran biota.
One of the most numerous "Arkhangelsk citizens" of that time were kimberellas (Kimberella quadrata) - they are found in abundance, for example, in the vicinity of Zimnegorsky lighthouse. These flat oval animals up to 15 cm long developed teeth and scraped off nutrient films of bacteria at a depth of 10 m. Flexible, not yet mineralized shells made them look like molluscs, although real mollusks appeared only ten million years later, during the Cambrian explosion, when the oceans filled the ancestors of modern types of animals, including arthropods, echinoderms and chordates.
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Ferzikovsky district, Kaluga region
350 million years ago, Carboniferous period.
In the Early Carboniferous, continental plates began to converge into the supercontinent Pangea, and the warm shallow waters of the Paleotethis Ocean covered all of today's Central Russia. Numerous islets, shallows and swampy lowlands are overgrown with dense forests, which will later form the Moscow Region brown coal basin. The main representatives of the Kaluga fauna of that time - brachiopods and cephalopods, which in that era were experiencing their golden age, are also found under the village of Brontsy. Modern cephalopods can reach impressive sizes, but even then in the Kaluga region there were real giants, up to Rayonnoceras more than 5 m long. Their huge conical shells were divided into internal compartments connected by a thin channel, like in modern nautilus. By filling the chambers with liquid one by one or emptying them,the mollusk could regulate its buoyancy, rise closer to the surface or sink to the bottom, where it was possible to grab gape fish or other prey.
Volkhovsky district, Leningrad region
450 million years ago, Ordovician period.
After the Cambrian explosion, the level of the World Ocean rose strongly, and most of the modern continents formed in Gondwana near the South Pole. However, the north of Europe was part of another, half-water-covered Baltic continent that moved northward across the equator. The Leningrad region at that time was inhabited by a variety of benthic animals, such as trilobites. During their lifetime, they shed several times, shedding their shell, and today thousands of them are found on the limestone cliffs of the Volkhov River.
Among dozens of trilobite species on the Volkhov banks, Kovalevsky's azathuses (Asaphus kowalewskii) are found. Like many of their relatives, they were distinguished by incredibly complex faceted eyes, in which the role of a proteinaceous lens was played by mineral lenses made of calcite. The eyes of the azafuses sat on elongated stalks, like those of crayfish or crabs: they may have buried themselves in the silt at the bottom of the Leningrad region, exposing them outside.
Ochersky District, Perm Territory
255 million years ago, the Permian period.
At the close of its existence, Pangea has absorbed all the continents. The low Ural Mountains rose into giant peaks no worse than the modern Himalayas. To the west of this ridge stretched a vast lowland with numerous sea bays, rivers and lakes. Here, in the ravines near today's Permian village of Yezhovo, they find the remains of the rich fauna of that time - fish, mollusks and even large animal-toothed dinosaurs.
The famous Yezhov biarmosuchs (Biarmosuchus tener) reached a length of 1.5−2 m. These agile, dexterous predators were armed with saber-like canines, had excellent eyesight and could hunt much less agile herbivorous neighbors - their bones are often found mixed with each other. Note that the animal-toothed dinosaurs cannot be called completely extinct: after millions of years they will give rise to mammals. Perhaps, including the fact that they inhabit the Perm Territory today.
Ulyanovsk district, Ulyanovsk region
150 million years ago, Jurassic.
Pangea split into the southern and northern continents - Gondwana and Laurasia - and continued to split. A gigantic sea strait passed through today's Middle Volga region, where cold northern waters penetrated, then southern ones from the Tethys tropical ocean. Ravines on the banks of the Volga in the Ulyanovsk and Samara regions are the classic locations of ancient animals of that time. They have been studied since the end of the 19th century, when fragments of a skeleton belonging to an inhabitant of Jurassic Russia, the ichthyosaur Ichthyosaurus volgensis, were found here.
While dinosaurs dominated the land, the reptile-related ichthyosaurs remained the kings of the seas, hunting fish and cephalopods that swarmed the Jurassic ocean. One of them - an ophthalmosaurus undorensis - was found near the Ulyanovsk village of Undory and described in the 1990s. It reached a length of several meters and had the largest eyes among all animals (up to 35 cm in diameter), protected by strong bony plates. Most likely, they retained their shape better under high pressure, allowing the ichthyosaur to see and hunt at depths.
Roman Fishman
