Сбор, диагностика и обработка палеонтологических материалов при проведении учебных геологических практик. Учебное пособие на модульной основе

3. Methodology for the field study of fossil remains of organisms

When determining fossil organic remains, special attention should be paid to signs that have taxonomic significance, that is, signs characteristic of taxons of various ranks (for species, genus, etc.). Of course, for different organisms, the sets of taxonomic signs will be different, because it is clear that, for example, corals are arranged quite differently from mollusks, and arthropods differ sharply from bryozoans, etc. The characteristics of the main taxonomic features and explanations of the terminology used in the description can be found in special paleontological works, in regional atlases of fauna, etc.

At the first stage of determining the species belonging of a fossil of any group, it is compared with images in paleontological works. Having stopped at the figures of several species that are superficially similar to this sample, it is necessary to refer to the text of the description of these species. Careful acquaintance with the description of each species, and especially with the sections devoted to the characteristics of variability and comparison with similar forms, will allow us to conclude about the species of the object being determined.

The degree of reliability of the species definition largely depends on the breadth of use of paleontological works, which contain descriptions and images of representatives of the studied group of organisms. Often, when studying a group, a paleontologist does not limit himself to using literary sources, but also resorts to comparing his material with museum or reference collections and collections of previous researchers. The comparison with the originals, that is, copies previously described by other researchers is of particular value. In the paleontological description of each species, comparison with the holotype (Greek. holos – whole, complete; typos – sample) – a specimen allocated as a type of the species.

Naturally, it is difficult to have all the necessary literature in the field and it is impossible to use monographically processed collections. Therefore, field definitions of fossils are preliminary, and in-depth study of the material is carried out after returning from the expedition, in laboratory conditions.

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3. Methodology for the field study of fossil remains of organisms

The complete stratigraphic interval of the distribution of a taxon (species, genus, etc.) is called its biozone. For example, the biozone of the sea urchin species Micraster cortestudinarium goldf. corresponds to the upper Turonian-lower Conacian, and the Micraster biozone corresponds to the entire interval from the upper Turonian to the lower Maastricht.

For the fractional subdivision of sections, various groups of organisms are usually involved, and the distinguished biostratigraphic (based on paleontological criteria) units or zones are characterized by certain associations of fossils that form zonal complexes. The core of such a complex is formed by forms (most often species and subspecies), the distribution of which is limited to the boundaries of this zone.

Zones are designated by the names of 1–2 most characteristic types – indices. For example, the Lower Maastrichtian Ucanthoceras tridens zone got its name from the ammonite Acanthoceras tridens (Kner). When describing and designating precisely undefined organic remains, open nomenclature is used. It is called open because the names proposed in this nomenclature can be further refined and changed. They are not protected by the law of precedence, according to which the oldest name proposed for a given taxon is considered valid. The open nomenclature includes the following main designations:

1.If a systematic category is established only from the family and above, then the Latin word incertus (doubtful) is used: incerti ordinis – the order is unknown, incertae familiae the family is unknown. For example – Ammonitida incertae familiae – the remains reliably belong to the ammonitida order, but the family is unknown. If it is generally impossible to determine the systematic position of the remains, then the indications are used – incertae sedis (indefinite place). For example -sp. insertae sedis (spesies insertae sedis) species of unclear systematic position.

2.In cases where it is impossible to determine the genus or species, the word indeterminatus is used in an abbreviated form, – ta, – tum (indefinite, – th, th). For example, pachydiscidae

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3. Methodology for the field study of fossil remains of organisms

gen indet (the belonging of this specimen to the family has been established, but the genus – genus is unknown and preservation does not allow it to be determined). Pachydiscus sp indet (species indeter – minata – the affiliation of the remains to the genus has been established, but the species is unknown and the preservation of the remains is such that it cannot be recognized as a species).

3.If the generic name of the studied remains is determined, and its assignment to any species is in doubt, then sp (species) is put after the genus name; Pachydiscus sp. In the future, a more detailed study with the involvement of the necessary literature or collection can often make it possible to determine the species.

4.In those cases where the genus is established, but belonging to some species is unreliable, but probable (due to incomplete preservation of the remains and limited material), the letters cf (couformis – similar, similar) are placed before the specific name. For example, Jnoceramus cf balticus Boehm.

5.5. If a certain form has some differences from the known species closest to it, but cannot be attributed to a new species due to the limited or lack of good preservation of the collected material, the sign aff (affinis) is used – (related, close), placed between generic and specific names. For example, Jnoceramus aff balticus Boehm.

6.If the conformity of the defined form to any known species seems doubtful and only its belonging to a group of related species is established, the designation ex gr (lat. ex grege – from the herd, from the group) is used. For example, Jnoceramus ex gr. Balticus Boehm.

3.5.Rules for the pronunciation of Latin names

The student of paleontology should clearly understand that all scientific names are written and pronounced in Latin transcription. For the names of large taxons, words of Greek or Latin origin are adopted. Sometimes geographical names or proper names are used (Bondarenko, 1986). The following is the Latin alphabet, indicating the pronunciation of the Latin letters:

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3. Methodology for the field study of fossil remains of organisms

Some peculiarities of pronunciation should also be noted. So, C, with before the sounds e, i, u, y, it is customary to pronounce it as c, in other cases ask: cephalopoda – tsephalopoda, cystis – tsystis (bubble), conularida – konularida, cranium – cranium (skull). E, e is pronounced like Russian a: pes – pes (leg, foot), much less often like e. G, g corresponds to Russian (Moscow) g in the word god, for example, gastropoda – gastropod, and H, h to Ukrainian (soft) g in the words of the Ganga, gora, for example, homo – homo (human), hexapoda – geksapoda (six-legged). L, l is pronounced softly, like Russian l’: Lagena – lyagena (bottle). Q, q corresponds to Russian k, is always combined with the letter u and is recognized as kv: aqua akva (water), quercus kvercus (oak). S, s sounds like Russian s: Spongia – spongia (sponge), and in the middle of a word between two vowels – like z: nasus – nazus (nose), rosa – roza. X, x denotes a double sound ks: maxilla – maksilya (jaw), hex – geks (six).

Y, y – upsilon, known as the letter Y, is used only in words of Greek origin and is pronounced like Russian i: ichtys – ichthys (fish), and Z, z – in words of Greek origin – like Russian z: zona – zona (belt), zoon – zoon (animal).

Combinations of vowels are pronounced as follows: ae as Russian e: phaeophyta – pheophyta (brown algae); oe – as Russian e: coelenterate – celentarata (intestinal); au – like au (with a short y): aulos – aulos (pipe); eu – as eu (with a short u) or ev: teuthis – teutis (squid), eurypterus – eurypterus.

The consonant combinations ch, th, rh, and ph are pronounced kh, t, r, and f, respectively. They are usually used in Latinized words of Greek origin.

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4.THE SYSTEM OF THE ORGANIC WORLD

4.1.Animal Kingdom. Regnum Zoa (Animalia) Protozoa sub-kingdom, or unicellular. Subregnum Protozoa

4.1.1.Sarcodes type. Phylum Sarcodina

Sarcodes type. Phylum Sarcodina. Foraminifera class. Classis Foraminifera.

Marine benthic and planktonic forms. Most of the 1000 modern species live in marine conditions. The total number of fossil species is 20,000.

The cell of the body has an external skeleton – a shell of various structures and shapes. The shell is equipped with holes – foramens, its size is from 0.02 to 100 mm. Movement, food collection and partial digestion is carried out with the help of long and thin pseudopods (pseudopodia), intertwined with each other in the form of a trapping network. The speed of movement is from several mm to 1 cm per day. The food is microorganisms and organic detritus captured by pseudopods during movement. According to the method of feeding, they are filterers.

The shell is formed by the products of protoplasm excretion – organic substances and mineral salts. Sometimes the composition of the shell includes material borrowed from the environment (grains of sand, fragments of shells). In this case, the shell is called agglutinated, and the substance secreted by the protoplasm is a cement that holds together disparate foreign particles. Lime secretion shells consist of an organic (chitinous) base impregnated with carbonic lime.

Secretion flint shells are the most rare. They arise when the chitin base is impregnated with earth silicon.

The shells of foraminifera living in warm seas are richer in lime than cold-water forms. In the case of desalination of the reservoir, the skeletons are depleted of lime. Agglutinated forms are representatives of the benthos of cold waters and great depths.

Among the fossils, calcareous shells are found in organogenic carbonate rocks, while agglutinated shells are found in clayey and coarsely-fragmented ones.

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4. The system of the organic world

According to the number of chambers, foraminifera are divided into single-chamber, two-chamber and multi-chamber. Planispiral shells differ in the shape of the cross section and the degree of their overlap. If the last whorl overlaps the penultimate shell is called involute. When whorls only touch and everything is visible from the outside, then the shell is evolute.

Externally, involute shells look like coin-shaped, lenticular, spherical, fusiform. In all cases, the ratio of the shell diameter to its width is taken into account. As additional forms of the skeleton, ribs and spines are present on the outer surface of the shells of foraminifera.

In the geological past, foraminifera were repeatedly rockforming (carbonate rocks of the Middle Carboniferous of the Russian Platform,

Western Urals). The rock-forming role of nummulitids (order Nummulitida K – N), globigerinids (order Globigerinida Paleogene – present) is most fully manifested. For stratigraphy, the Fusulinida (D – P) and Nummulitida (K – present) orders are the most informative.

Radiolarian class. Classis Radiolaria.

These are unicellular animals with sizes from 100–200 to 700 microns. These are solitary animals, although colonial forms are found as an exception.

Most radiolarians, including all fossil forms, have a siliceous skeleton. It consists of individual silicon needles. Straight, curved, smooth or prickly, simple or branched, they form an elaborate, openwork skeleton.

The skeleton serves as a support, performs a protective function. Its most important role is to ensure a floating, planktonic lifestyle.

The oldest radiolarians are known from the Cambrian sediments of southern France. Cretaceous and Cenozoic radiolarians have a wide, planetary distribution.

They are found both in sedimentary and sedimentaryvolcanic rocks, being rock-forming (radiolarites, siliceous clays, jaspers).

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4. The system of the organic world

4.1.2. Sponges type. Phylum Spongiata

The sponge type combines marine and limnetic attached multicellular organisms, the skeleton of which consists of simple or differently interconnected needles – spicules. According to the method of feeding, sponges are filterers, and their body is permeated with channels that form a water-irrigation system. Along with water, nutrients enter the body cavity. The walls of the cavities are lined with flagellated cells – choanocytes, and the movement of the flagella creates a flow of water in the system.

The channels of the water-irrigation system open with pores outside and inside, which is the reason for the other name of the type – Pore bearers, or Porifera.

Sponges class. Classis Spongia.

The body shape is varied. Their sizes change sharply from 1 mm to 1.5 m in height and from 3 cm to 1–2 m in diameter. The color of modern sponges, due to the presence of various pigments, varies from dull gray to emerald, blue and black.

According to the degree of complexity of the water-vascular (irrigation) system, three types are distinguished: ascon, sycon and leucon. Leucon – the most complex and characteristic of most sponges.

The sponge skeleton is the support for the gelatinous, soft body – the mesoglea. Its composition is mineral, organic and mixed. The mineral skeleton is calcareous or siliceous, and the shape of the spicules is varied. The main and most common type is a triaxial spicule, formed by a single crystal of calcite in calcareous sponges, or amorphous silicic acid in siliceous ones. The organic skeleton consists of spongin, a protein compound similar to ligament collagen. It has the form of threads, fibers, films.

The fusion of spicules leads to the formation of skeletal lattices. In some cases, spongin can envelop mineral spicules from the outside, forming a mixed, siliceous skeleton. Flint sponges are one of the oldest multicellular, their findings have been known since the Cambrian.

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4. The system of the organic world

In modern reservoirs, sponges live at depths from 0 to 5000 m or more. Deep-sea forms have a flint skeleton. Only siliceous sponges live in fresh waters.

The unconnected skeleton, characteristic of most sponges, disintegrates after the death of soft tissues, and accumulates to form a silica-enriched rock. Calcareous sponges with an unrelated skeleton are not preserved in a fossil state.

The systematics is based on the composition of the skeleton, the shape of the spicules and the type of skeletal lattice. The importance of sponges for determining the age is small, in contrast to the rock-forming role and paleogeographic reconstructions of the settings of past geological epochs.

4.1.3. Hemichordates type. Phylum Hemichordata

Graptolites class. Classic Graptolithina.

Extinct colonial organisms with a scleroprotein skeleton. By chemical composition, these are protein polymers. The skeleton is solid, in rare cases it is formed by skeletal fibers that create a mesh frame. Colonies are diverse in shape: reticulated, nonreticulated, tree-like.

Graptolites were marine organisms. They attached themselves to the bottom (benthos) or lived in the water column (plankton). Some colonies were attached to floating objects (pseudoplankton).

The finds are confined to clay shales, less often to sandstones and limestones. Massive accumulations of rocks are called graptolitic shales.

The taxonomic rank and position in the system of the animal world is debatable: an independent class of the type cnidaria, hydroid polyps, or bryozoans.

4.1.4. Arthropods type. Phylum Arthropoda.

Animals descended from annelids. Modern forms inhabit water, land and air. This is the most numerous species – 3 million individuals. They make up half of the total number of

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4. The system of the organic world

species of the animal kingdom. The senses are well developed, including complex eyes.

The skeleton can be impregnated with calcium phosphate or calcium carbonate.

When dividing into subtypes, special attention is paid to the structure of the head department, the specifics of the respiratory organs.

Reliable finds from the Vendian Period. Geologically, trilobites are the most important.

Trilobites class. Classis Trilobita.

Extinct organisms existed only in the Paleozoic. Imprints and remains of shells are preserved in from thema fossil state. They lived in an aquatic environment, inhabiting the bottom of Paleozoic seas. According to the method of feeding, – herbivores, scavengers, mud-eaters. They are important for the stratigraphy of Cambrian and Ordovician sediments, less important for Silurian and Devonian. The division into subclasses in trilobites is carried out according to the number of trunk segments – small-jointed and multi-jointed.

Project specification for the material

Guided by the methods of primary processing of paleontological material, using the methodology of conducting field paleontological studies, determine the groups of rocks from which representatives of the above types can be distinguished. Make a reference collection of them, having previously determined the species and generic affiliation. Compare different sections containing the same organisms.

Questions for self-control

1.Why are the Foraminifera and Radiolarianы classes the most important from the numerous protozoa in paleontological terms?

2.To what order do the largest foraminifera shells (up to 60 cm in diameter) belong?

3.Which rocks consist of foraminifera?

4.What is the skeleton of representatives of the Radiolarians

class?

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4.The system of the organic world

5.What rocks form radiolarians?

6.Which organisms are the best indicators in the search for oil deposits?

7.What is the reason for the ability of radiolarians to move vertically in the water column?

8.What are sponge spicules?

9.What is the composition of the sponge skeleton?

10.The lifetime of sponges?

11.What determines the rock-forming role of sponges?

4.1.5. Mollusca type. (Mollusks) General characteristics of fossil organisms. Phylum Mollusca

It is the second largest type of animal kingdom, with more than 15,000 modern and fossil species. Fossil mollusks are extremely important for biostratigraphy and are a good indicator of habitat.

Mollusk shells are external, less often internal, sometimes absent (naked slugs). More often the shell is single, less often it consists of two shucks, and the most primitive forms have only a few plates overlapping each other (Class Loricata or loricates).

The soft body consists of a trunk enclosed in a pallium, a head, legs and tentacles. It closes completely or almost completely the animal’s body.

Marine mollusks inhabited all latitudes and depths. There are nectonic, planktonic and benthic forms.

According to the method of feeding, herbivores, carnivores, scavenger are distinguished. Some actively collect food, others filter water.

Mollusks have been known since the Cambrian. According to the structure of the shell and soft body, they are divided into ten classes, among which cephalopods have a special geological significance.

Characteristics of the Cephalopods class Classic Cephalopoda.

This is one of the most important groups of invertebrates. These include stenohaline marine organisms with a highly

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