Ancient reptiles. Rebirth
Flowering plants have come to dominate most ecosystems over the course of
1) Paleozoic era
2) Mesozoic era
3) Proterozoic era
4) Cenozoic era
Explanation.
The first remains of angiosperms (flowering) plants were found in strata of the Jurassic and Early Cretaceous periods (135-65 million years ago) of the Mesozoic era. Traces of the widespread development and distribution of angiosperms were discovered during the Middle Cretaceous period (about 100 million years ago). In the Late Cretaceous, angiosperms proved to be the dominant form of plant life. As the end Cretaceous period(65 million years ago), temperatures rose and plants with richer foliage developed.
The Paleozoic era (Paleozoic) consists of the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian periods. The oldest representatives of the flora were psilophytes; in the early Devonian, other groups of terrestrial vascular plants arose from psilophytes: lycophytes, horsetails and ferns.
The Mesozoic era (Triassic, Jurassic, Cretaceous periods) is a time of undivided dominance of reptiles and gymnosperms. In the Cretaceous period, a rapid spread throughout to the globe angiosperms flowering plants. The ancestors of modern poplar, birch, laurel, oak, beech, willow, plane tree, magnolia, and grapes appeared. Terrestrial flora began to take modern look.
Proterozoic era - the second era from the beginning geological history Earth, huge in duration, the longest stage early life lasting ~2000 million years. During this era, bacteria and algae flourished.
Cenozoic era - newest era geological history of the Earth, covering the modern era. Terrestrial vegetation experienced renewal back in the middle of the Cretaceous period, when angiosperms (flowering) plants took a dominant place in its composition. To the beginning of K. e. not only the majority of currently existing families of angiosperms arose, but also many of their genera, which later, as climate changes, form typical communities characteristic of different climatic zones.
Answer: 2
Answer: 2
Source: Yandex: Unified State Exam training work in biology. Option 3.
Guest 22.10.2013 13:59
In your explanation it is written that the correct answer is 4 “when angiosperms (flowering) plants took a dominant place in its composition. No.
Natalia Evgenievna Bashtannik
The correct answer is 2. Mesozoic era (Triassic, Jurassic, Cretaceous periods) -In the Cretaceous period, angiosperm flowering plants began to rapidly spread throughout the globe. The terrestrial flora began to take on its modern appearance.
Guest 07.06.2014 17:15
During the Mesozoic era (more precisely, the Cretaceous period), angiosperms (flowering plants) appeared, but they took a dominant position in the CENIOZOIC era (Paleogene period).
Source: A.Yu.Iontseva "biology in diagrams and tables for applicants"
Guest 07.06.2014 20:35
Your explanation indicates that in the Mesozoic era, gymnosperms dominated, and not flowering plants (angiosperms)! In the Cretaceous period of the Mesozoic era, they just began to spread rapidly and a sharp decline in ferns and gymnosperms began! The answer is 4 definitely!
Natalia Evgenievna Bashtannik
Terrestrial vegetation experienced renewal back in the middle of the Cretaceous period, when angiosperms (flowering) plants took a dominant place in its composition.
Alexandra Tabratova 10.11.2014 16:23
Firstly, the explanation says 2 completely contradictory things:
“The Mesozoic era (Triassic, Jurassic, Cretaceous periods) is a time of undivided dominance of reptiles and gymnosperms” and “Cenozoic era... Terrestrial vegetation experienced renewal in the middle of the Cretaceous period, when angiosperms (flowering plants) took a dominant place in its composition plants"
Secondly, the SCHOOL textbook says:
“Changes in the flora of the Cretaceous period of the Mesozoic era are associated with the appearance of angiosperms (flowering) plants... In the flora of the Cenozoic, angiosperms took a dominant place” textbook by A.V. Teremova, R.A. Petrosova Biology, grade 11.
Natalia Evgenievna Bashtannik
Well, that means the authors of the question (FIPI) did not read the textbook by A.V. Teremova, R.A. Petrosova, Biology, grade 11.
Correct answer -2
But there is no contradiction in the explanation. The Cretaceous period belongs to the Mesozoic era.
Establish a correspondence between organisms that appeared or flourished in the process of evolution and the eras in which they appeared and flourished.
| A | B | IN | G | D | E |
Explanation.
Paleozoic era: the rise of mollusks. Mesozoic era: the emergence of the first birds; the rise of reptiles (dinosaurs). Cenozoic era: the rise of insects; the rise of mammals; distribution of birds.
Answer: 221333.
Note.
The flowering (and not the appearance or development) of insects occurs in the Cenozoic era, in parallel with the flowering of angiosperms.
Establish a correspondence between organisms that appeared or flourished in the process of evolution and the eras in which they appeared and flourished.
Write down the numbers in your answer, arranging them in the order corresponding to the letters:
| A | B | IN | G | D | E |
Explanation.
Archean era: emergence of bacteria and protozoa; the appearance of blue-green algae. Proterozoic era: appearance of red algae; flourishing of protozoa and coelenterates. Cenozoic era: the emergence and flourishing of primates; the appearance of man.
Answer: 311223.
Answer: 311223
Natalia Evgenievna Bashtannik
The first living organisms arose in the Archean era. They were heterotrophs and used organic compounds from the “primary broth” as food. (Biopalimers were discovered in sedimentary rocks dating back 3.5 billion years). The first inhabitants of our planet were anaerobic bacteria. The most important stage in the evolution of life on Earth is associated with the emergence of photosynthesis, which causes the separation organic world into plant and animal.
The first photosynthetic organisms were prokaryotic (prenuclear) cyanobacteria and blue-green algae. Eukaryotic green algae that then appeared released free oxygen into the atmosphere from the ocean, which contributed to the emergence of bacteria capable of living in an oxygen environment. At the same time, on the border of the Archean Proterozoic era, two more major evolutionary events occurred - the sexual process and multicellularity appeared.
Vladimir Parasochka 10.06.2018 20:09
Green algae appeared in the Proterozoic. "Biology 11th grade" A.V. Teremov, R.A. Petrosova
The picture shows Archeopteryx, an extinct animal that lived 150-147 million years ago.
Using a fragment of the “Geochronological Table”, determine in what era and what period did this organism live?
Scientists consider this animal to be a transitional form. Name the classes to which the depicted animal can be classified. What features external structure allow us to attribute it to these classes?
Geochronological table
Explanation.
In order to answer the questions, you need to use the corresponding columns of the Geochronological Table and make basic mathematical calculations.
Era: the period of residence of Archeopteryx is indicated: 150-147 million years ago. We carry out calculations using the second column, which indicates the beginning of the periods. The Mesozoic began 230 million years ago, and the Cenozoic began 67 million years ago. This means that Archeopteryx lived in the Mesozoic era.
Period: we take the beginning of the era 230 million years ago, subtract the duration of the Periods, - Triassic 230-35 = 195 million years ago;
minus Jurassic 195-58=137 million years ago. It turns out that Archeopteryx lived in the Jurassic period.
We determine the ancestor using column 4 (or use our knowledge).
Response elements:
1) Era – Mesozoic; Period – Jurassic;
2) an animal can be classified as a reptile based on the presence
jaws with teeth, long tail and developed fingers;
3) an animal can be classified as a bird based on the presence
feather cover and wings
1) Paleozoic
2) Cenozoic
3) Mesozoic
4) Proterozoic
Explanation.
Let us note that the question is somewhat vague. The plant world acquired its modern appearance over millions of years on the border of the Mesozoic and Cenozoic eras.
Distribution and Prevalence angiosperms began at the end of the Mesozoic era; to the beginning of the Paleogene, the first period of the Cenozoic era, vegetable world acquired a more familiar form to us, continuing to change and develop up to the present time.
Guest 21.04.2013 13:00
I believe that this assignment gives the wrong answer to the question of in what era the plant world acquired its modern appearance. In general, the prevailing opinion among experts is that the dominance of angiosperms began at the boundary of the Early and Late Cretaceous. There is even a special term - “Cenophyte”, which designates the time period of dominance of angiosperms starting from the beginning of the Late Cretaceous. Thus, the answer that the plant world acquired its modern appearance in the Cenozoic era is incorrect; the correct answer is the Mesozoic era.
Support
According to the dominance of groups of the animal world, the geological time scale is divided into three eras: Paleozoic - era ancient life, Mesozoic - era average life and Cenozoic - our era, modern life. The Mesozoic was the time when reptiles dominated the Earth, and the Cenozoic - mammals.
The same time scale, from the point of view of the development of the plant world, can be divided into paleophyte - the time of dominance of spores and the earliest gymnosperms, mesophyte - the time of gymnosperms, they are very numerous and diverse in this era, and cenophyte - the time of angiosperms or flowering plants.
The boundaries of eras do not coincide. The mesophyte begins in the middle of the Permian period and ends in the middle of the Cretaceous. Thus, the plant world gradually acquired the features of what is modern to us towards the end of the Mesozoic - beginning of the Cenozoic era. (In the same way that you can take Sunday night and Monday morning as the beginning of the week.)
However, evolution does not stop, and all living organisms on Earth change constantly from generation to generation. Therefore, although the birch genus has been known since the Upper Cretaceous, this does not mean that the chalk birch and the birch outside your window are the same thing. These are at least two different types. Many scientists believe that it is impossible to classify that Cretaceous plant as a modern genus “birch”.
The distribution of plants on Earth in those days was also very different from today. Those genera that we now encounter only in tropical and subtropical climate, like breadfruit or magnolia, were widespread in much higher latitudes in the Paleogene. Thus, on the territory of our country, along with oak, maple, alder, and birch, ginkgo, metasequoia, and magnolia grew. On Spitsbergen, where there are now only polar lichens and low-growing grasses, there was a noise broadleaf forests. In Europe at this time, coal was accumulating in the swamps of evergreen dense forests of swamp cypresses, laurel trees, beech trees, palm trees and tree ferns.
(By: V. A. Tsimbal, Plants. Parallel world)
Igor Bragin 30.04.2013 16:22
The Mesozoic is a period of time in the geological history of the Earth from 251 million to 65 million years ago, one of the three eras of the Phanerozoic. It was first isolated in 1841 by British geologist John Phillips.
The Mesozoic is an era of tectonic, climatic and evolutionary activity. The formation of the main contours of modern continents and mountain building on the periphery of the Pacific, Atlantic and Indian oceans is taking place; the division of land facilitated speciation and other important evolutionary events. The climate was warm throughout the entire time period, which also played a role important role in the evolution and formation of new animal species. By the end of the era, the bulk of the species diversity of life approached its modern state.
Support
Somewhat closer. Species diversity throughout its history has been approaching its current state. But do not forget that by the end of the Mesozoic era, at least 30-40% of the former animal world died out. In particular, all animals are larger than a crocodile. This is precisely the boundary between the Mesozoic and Cenozoic eras. Therefore, the species diversity of the Cenozoic is still closer to ours than the Mesozoic.
The era in which primates flourished and humans emerged
1) Paleozoic
2) Proterozoic
3) Mesozoic
4) Cenozoic
Explanation.
The era in which primates flourished and humans appeared is the Cenozoic.
The Cenozoic Era is the current era of the Earth's geological history. It began 66.0 million years ago and continues to this day.
Answer: 4.
Answer: 4
Using a fragment of a geochronological table, establish the era and period in which this organism died out, as well as its possible “ close relative"in modern flora (the answer is at the department level).
What structural features characterize the Noe medullosa plant as a higher seed plant?
Explanation.
Let's use the table, CALCULATE the period, focus on the indicated date of extinction - 270 million years ago. We find the closest date - 230 million years ago - Mesozoic, there are no seed ferns here anymore, which means they died out in the previous era - PALEOZOIC, by 230 +55 (Duration of the Permian period) = 285 million years ago
in the fourth column we will find the extinction of ferns - correct!; We determine by the first and third columns the era and period when seed ferns die out.
Seed ferns are the most primitive group among gymnosperms. Some scientists conclude that they occupy an intermediate position between true ferns and gymnosperms, while others consider these groups to have arisen and evolved in parallel.
Response elements:
1) Era: Paleozoic
Period: Permian (Perm)
2) “Close relatives” of this plant in the modern flora: Gymnosperms
3) Characteristics of higher seed plants:
The body is divided into roots, stems, leaves and reproductive organs. Reproduction of seed ferns occurred using seeds. The sporophyte is the dominant generation; the gametophyte is extremely reduced. Sporophyte heterosporous, i.e. forms two types of spores: microspores and megaspores; microspore – pollen grain, megaspore – embryo sac. Water is not needed for sexual reproduction.
Note.
There is a point of view according to which seed ferns did not have a true seed, although they did have an ovule. In this regard, they, as well as modern cycads and ginkgos, were classified not as seed plants, but as so-called ovule plants.
Tree-like plants, the appearance and structure of the leaves resembled real ferns, but reproduced with the help of seeds. The development of the embryo most likely occurred after the seed fell to the ground. The large stems of seed ferns contained secondary xylem; pinnate leaves differed from true ferns only in the structure of the epidermis, stomata and petioles.
Section: Fundamentals of evolutionary teaching
Source: I WILL SOLVE the Unified State Exam
The picture shows a trilobite, an animal that became extinct about 270 million years ago.
Using a fragment of a geochronological table, establish the era and period in which the given organism became extinct, as well as the type to which the depicted organism belongs. Indicate the characteristics by which it belongs to the type you specified.
Explanation.
Let's use the table, CALCULATE the period, focus on the indicated date of extinction - 270 million years ago. We find the closest date - 230 million years ago - Mesozoic, there are no trilobites here anymore, which means they died out in the previous era - PALEOZOIC, by 230 +55 (Duration of the Permian period) = 285 million years ago
in the fourth column we find the extinction of trilobites - correct!; We determine by the first and third columns the era and period when trilobites become extinct.
Answer:
1) Era: Paleozoic
Period: Permian.
2) Trilobite belongs to Arthropods.
3) Trilobites belong to the phylum Arthropods - characteristics: segmented body and limbs.
Using a fragment of a geochronological table, establish the era and period in which these organisms appeared, as well as a possible ancestor of the plant division level.
Indicate by what characteristics psilophytes are classified as higher spore plants.
Geochronological table
| ERA, age in million years | Period | Vegetable world |
| Mesozoic, 240 | Chalk | Angiosperms appear and spread; Ferns and gymnosperms are declining |
| Yura | Modern gymnosperms dominate, ancient gymnosperms die out | |
| Triassic | Ancient gymnosperms dominate; modern gymnosperms appear; seed ferns are dying out | |
| Paleozoic, 570 | Permian | Ancient gymnosperms appear; a wide variety of seed and herbaceous ferns; tree horsetails, club mosses and ferns are dying out |
| Carbon | The flowering of tree ferns, club mosses and horsetails (forming “coal forests”); seed ferns appear; psilophytes disappear | |
| Devonian | Development and then extinction of psilophytes; the emergence of the main groups of spore plants - lycophytes, horsetails, ferns; the appearance of the first primitive gymnosperms; occurrence of fungi | |
| Silur | Algae dominance; the emergence of plants on land - the appearance of rhiniophytes (psilophytes) | |
| Ordovician | Algae bloom | |
| Cambrian | Divergent evolution of algae; emergence of multicellular forms | |
| Proterozoic, 2600 | Blue-green and green unicellular algae and bacteria are widespread; red algae appears |
Explanation.
Let's use the table and find psilophytes in the third column; We determine by the second and first columns the era and period when psilophytes lived
Answer:
1) Era: Paleozoic
Period: Silurian
2) The ancestors of psilophytes are multicellular green algae.
3) The characteristics of higher spore plants are:
Dividing the body into two parts - aboveground and underground
The presence of multicellular reproductive organs - sexual (gametangia) and asexual (sporangium)
Primitive conductive system, integumentary tissue
Note.
Psilophytes had a tree-like shape; individual thread-like processes served them to attach to the soil and absorb water and minerals. Along with the formation of a semblance of roots, stems and a primitive conducting system, psilophytes have developed integumentary tissue that protects them from drying out.
Higher plants are multicellular phototrophic organisms adapted to life in a terrestrial environment and characterized by the correct alternation of sexual and asexual generations and the presence of differentiated tissues and organs.
The main characteristics that distinguish higher plants from lower ones:
Adaptation to living in a terrestrial environment;
The presence of clearly differentiated tissues that perform specific specialized functions;
The presence of multicellular reproductive organs - sexual (gametangia) and asexual (sporangium). Male gametangia higher plants are called antheridia, female ones - archegonia. Gametangia of higher plants (unlike lower ones) are protected by membranes of sterile (sterile) cells and (in certain groups of plants) can be reduced, i.e. reduced and simplified;
Transformation of the zygote into a typical multicellular embryo, the cells of which are initially undifferentiated, but are genetically determined to specialize in a certain direction;
Correct alternation of two generations - haploid sexual (gametophyte), developing from a spore, and diploid asexual (sporophyte), developing from a zygote;
Domination in life cycle sporophyte (in all departments except Bryophytes);
Division of the sporophyte body (in most departments of higher plants) into specialized vegetative organs - root, stem and leaves.
Source: Unified State Exam - 2018, I will solve the Unified State Exam
Valeria Rudenko 15.06.2018 16:32
Hello. I don’t understand, how should we determine the ancestor of plants? Why do we take multicellular green algae?
Natalia Evgenievna Bashtannik
We use biological knowledge, and the drawing shows weak differentiation of the body
Vasily Rogozhin 09.03.2019 13:39
Of course, the ancestors of psilophytes, like all higher plants, are not ancient Green algae, but Characeae, which now form an independent department.
And in addition to the answer about the differences between higher plants and lower ones, it is worth noting that “the presence of clearly differentiated tissues” is not absolute today hallmark these groups of plants. Brown algae, for example, belonging to lower plants, have true tissues (tissue type of differentiation of the thallus). The presence of organs - yes, this is a sign only of higher plants, but both higher and lower plants can have real tissues.
In school courses, unfortunately, they will study information from 20-40 years ago for many years to come.
BUT! This is the “C” part, which means you can give an answer based on modern scientific data. If it comes to an appeal, in this case the points can be won back.
Support
Or you may not “win back.” The correct answers to the Unified State Exam are those reflected in the current school textbooks approved by the Ministry of Education. You can remember the story about a student who brought a textbook for appeal and then to court high school, confirming her answer to the Unified State Exam. Didn't count it.
Vasily Rogozhin 14.03.2019 15:13
An insignificant clarification for school, but significant for science, to the correct answer:
The ancestors of psilophytes, like all higher plants, are not green, but CHARAL algae, which belong to an independent department in the Archeplastid group, and differ significantly from representatives of the Green algae department.
The picture shows a belemnite, an extinct animal that lived 440-410 million years ago.
Using a fragment of a geochronological table, establish the era and period in which this organism lived, as well as the “close relatives” of this animal in the modern fauna (the answer is at the genus level). What features of the external structure allow us to draw such conclusions?
Geochronological table
Explanation.
In the Silurian period (440-410 million years ago), large animals first appeared in the seas; before that, their sizes did not exceed a few centimeters. The largest marine animals of the Silurian were cephalopods with an outer shell the size of a telegraph pole, its length sometimes reached 4-5 meters.
Belemnites are very similar to modern squids and, like them, were good swimmers. On their heads were large eyes and ten arms with suction cups - two long and eight shorter. Like some squid, belemnites had a shell inside their body - these shells are often found in Mesozoic deposits and are called " damn fingers" In shape and size they really look like pointed fingers. Most scientists believe that the shell was calcareous, like the shells of other mollusks, but some think that living belemnites had a soft, cartilaginous shell that petrified after death. Ammonites and belemnites became completely extinct at the end of the Mesozoic era.
Answer:
ERA: Paleozoic
Period: Silurian
Possible "relative": squid
Belemnites are very similar to modern squids and, like them, were good swimmers. On their heads were large eyes and ten arms with suction cups - two long and eight shorter. Like some squid, belemnites had a shell inside their body - these shells are often found in Mesozoic deposits and are called "devil's fingers".
Note.
How to calculate...
Source: Unified State Examination - 2018
The explanation for task 23 No. 22172 states that
"The most characteristic inhabitants of the Mesozoic seas were ammonites and belemnites." That is, for both ammonites and belemnites it is more correct to choose the Mesozoic period. But it turns out that in the task about belemnites it is correct to choose the Paleozoic Silurian, and in the task about ammonites - the Mesozoic Jurassic (or Triassic, or Cretaceous).
The geochronological table also lists the Jurassic period of the Mesozoic as the period of greatest flowering of cephalopods.
Natalia Evgenievna Bashtannik
And they appeared back in the Cambrian.
In this task you need to do calculations: (and not just use a table
Alexey Goreev 03.02.2018 18:56
But you have an error in the period, you should calculate more carefully))
Natalia Evgenievna Bashtannik
How to calculate...
We find the date closest to the condition in the second column (age). The closest to 440 million years is 570.
We decided on the era → Paleozoic.
Now let’s determine the period: 570 - 440 (410) million years ago = 130. Now we “go up” in the third column:
130-70 (Cambrian) - 60 (Ordovician) → we get Silurian
Nailya Mutalimova 28.06.2018 20:04
Please explain why Paleozoic
Natalia Evgenievna Bashtannik
We find the date closest to the condition in the second column (age). The closest to 440 million years is 570.
We decided on the era → Paleozoic.
The drawings show a skeleton and feather imprint and a reconstruction of an extinct animal that lived 150–147 million years ago.
Using a fragment of the “Geochronological Table”, determine in what era and what period did this organism live? Scientists consider this animal to be a transitional form. Name the classes to which the depicted animal can be classified. What features of the external structure allow it to be classified into these classes?
Geochronological table
Explanation.
Response elements:
1) Era - Mesozoic; Period - Jurassic;
2) an animal can be classified as a reptile based on the presence of a jaw with teeth, a long tail and developed fingers;
3) an animal can be classified as a bird based on the presence of feathers and wings.
Source: Demo version of the Unified State Exam 2018 in biology.
Darya Luchinkina 17.12.2017 16:24
Triassic period. After all, 186-51 = 135 million years ago the Triassic ended and the Jurassic began. That is, 136 million years ago the Triassic was still going on, and 137 million years ago it was going on, and 150-147 million years ago it was going on. But not Jurassic.
Natalia Evgenievna Bashtannik
You are subtracting from the wrong date... 186 is the duration, not the beginning of the period.
The figure shows imprints of a leaf, a seed and a reconstruction of an extinct plant that lived 350-285 million years ago.
Using a fragment of the “Geochronological Table”, determine in what era and what periods this organism lived.
This plant has the characteristics of two divisions, successively formed during evolution. Name these departments. What features of the external structure allow us to classify the depicted plant as belonging to these divisions? What is the name of a group of extinct plants that had such characteristics? Geochronological table
| Eras | Periods | |
| Name and duration, | Age (from the beginning of the era), | Name and duration, |
| Kainozoiskaya, 67 | 67 | Quaternary, 1.5 |
| Neogene, 23.5 | ||
| Paleogene, 42 | ||
| Mesozoic, 186 | 252 | Melovaya, 79 |
| Yursky, 56 | ||
| Triassovy, 51 | ||
| Paleozoic, 289 | 541 | Permsky, 47 |
| Kamenugolny, 60 | ||
| Devonsky, 60 | ||
| Siluriysky, 25 | ||
| Ordoviksky, 41 | ||
| Cambrian, 56 | ||
The Mesozoic era began about 200 million years ago. It is characterized by the flourishing of reptiles, the emergence of higher representatives of the organic world - angiosperms, dipterous and hymenopteran insects, bony fish, birds, and mammals.
At the beginning of the Mesozoic, during the Triassic period, land had its maximum distribution in the entire history of the Earth, the climate was warm. In the oceans and seas, new forms of sea lilies and urchins are developing magnificently, and six-rayed corals are forming powerful reefs. Brachiopods decrease in number and are replaced by bivalves. Trilobites and crustaceans disappeared, and long-tailed higher crayfish appeared. Particularly characteristic of the Mesozoic era are cephalopods - twisted ammonites and belemnites, the remains of which are often popularly known as "devil's fingers".
On land there is also vigorous replacement lower forms life highest. The magnificent flowering of Mesozoic gymnosperms begins, covering the earth with new forests. These forests and all terrestrial vegetation consisted mainly of ancient conifers and their relatives - gingkovaceae and bennettites.
Triassic terrestrial vertebrates, more than Permian ones, are characterized by the following contrasting development, apparently associated with sharply continental climate this period. Some have an affinity for water conditions, while others have an affinity for land conditions. Many reptiles adapt to life in the sea. Bipedal archosaurs, the ancestors of the Jurassic and Cretaceous dinosaurs, became widespread in swamps and lowland forests. The movement of archosaurs and dinosaurs on two limbs was the result of their adaptation to life among tall vegetation. They moved quickly on their hind limbs and could navigate well among tall trees.
In the Triassic, the first mammals probably arose, which, however, did not play a noticeable role in the organic world during almost the entire Mesozoic era.
Despite the fact that mammals have characteristics common to amphibians and absent from reptiles, in particular, an abundance of skin glands, their origin from Permian and Triassic theriodonts is beyond doubt. Theriodonts gradually develop features characteristic exclusively of mammals. Their skeleton is not much different from the skeleton of ancient mammals and in a number of ways physiological characteristics they were probably also close to them. A well-developed secondary bony palate and complex teeth made it possible for theriodonts to breathe continuously and at the same time chew food well. They, just like mammals, already stood high on their feet and were very active animals.
We can point to the following main milestones in the progressive development of mammals: the transformation of the horny covering into hair, which protects the body from heat loss; transformation of the skull associated with nutrition and development of the complex ear; development of respiratory and circulatory organs; progressive development of the brain, especially the cerebral cortex; viviparity and feeding of young with milk. The complex of these characteristics determined the development of warm-bloodedness. Throughout the Mesozoic era, mammals existed in the form of small forms, from which we know remains usually in the form of skulls, jaws, and teeth.
In the Jurassic and Cretaceous periods, the seas were vast and, for example, Europe was then an archipelago of islands. The climate was even and mild. In the seas, protozoa were widespread: foraminifera, sponges, six-rayed corals, sea lilies and urchins, bivalves, decapods, crabs, but ammonites, belemnites and various fish are especially numerous. Shark fishes were close to modern ones, and bony fishes had a structure intermediate between sturgeons and true bony fishes, which developed in the Cretaceous period.
On land, in conditions of average humidity and fairly high temperatures Gymnosperms were widespread. The herbaceous cover consisted of small ferns, mosses, horsetails, and mosses.
Reptiles have reached enormous numbers and diversity. They populate all land, seas, and rise into the air. River crocodiles, turtles, and lizards appeared on land, but dinosaurs were its complete masters.
IN Jurassic period dinosaurs are already represented by the most gigantic land animals - brontosaurs, diplodocus, etc. with a very long tail and neck, a small head and a huge body. These giants, reaching 30 m in length, lived in the coastal zones of large bodies of water and ate soft plant foods. Other dinosaurs had a bird-like four-rayed pelvis. These include armored lizards - stegosaurs, quadrupeds with a small head. Their backs were lined with a long row of vertical bony plates. Predatory carnosaurs also appeared, walking on their hind limbs.
The seas were inhabited by beautifully swimming dolphin-like fish lizards - ichthyosaurs. They had a spindle-shaped body, flippers, and well-developed dorsal and caudal fins. Short with a barrel-shaped body and long neck Plesiosaurs swam with flippers in shallower sea zones than ichthyosaurs. These aquatic viviparous reptiles were predators and often reached a length of 15 m.
Flying reptiles - pterosaurs - were of two types. Rhamphorhynchus with long narrow wings and long tail- rudder, had a gliding flight, broad-winged and short-tailed pterodactyls - fluttering. The wing of pterosaurs was formed by a fold of skin extending from the sides of the body and supported by the long fourth finger of the forelimb.
Birds appeared in the Jurassic period. Birds have a lot common features with reptiles and, despite a number of significant new acquisitions and a variety of forms, they represent a group of reptiles that, like pterosaurs, have adapted to flight. Based on paleontological data, there is no doubt that birds descended from climbing pseudosuchians - small lizard-like predatory reptiles of the Triassic period that lived in trees, where they were well protected from enemies and ate insects, berries, etc.
This relationship is especially clearly shown by the Jurassic first birds - Archeopteryx. These long-tailed animals, the size of a pigeon, had feathers on their body, tail and three-toed front paws, and the toes were free and armed with claws. Despite the presence of feathers, hind limbs and a bird-type pelvis, their structure still contains many features characteristic of their ancestors - a weak sternum, the presence of abdominal ribs and a long tail (18-20 vertebrae), the presence of teeth, etc. But these are mainly tree climbers birds could already make a gliding jump, which was a transitional step to flight.
The Cretaceous period, lasting about 70 million years, is transitional to the era of new life - the Cenozoic. At the end of the Cretaceous period, the seas and land approached the outlines of modern ones. Grandiose mountain ranges rose along the ocean coasts. Wet and warm climate becomes cooler, continental, the difference between climatic zones and landscape areas.
The organic world of the Cretaceous seas is similar in general appearance to the Jurassic: ammonites, belemnites and especially bony fish are still abundant. Towards the end of the Cretaceous period sea lizards, as well as ammonites and belemnites die out.
On land, first of all, the vegetation cover changes. Already in the Early Cretaceous, angiosperms, or flowering plants, appeared, and of the gymnosperms, only a few new conifers continued to play a significant role in the vegetation cover of the Earth.
The world of terrestrial vertebrates changes dramatically during the Cretaceous period. True, various dinosaurs continue to live until the end, reaching the climax in their development. Slender, long-necked and small-headed bipedal runners are Struthiomimus, similar to ostriches; the greatest predators ever living are tyrannosaurs, two-legged giants weighing several tons and reaching 9 m in height with a body length of 14 m. Ornithischian duck-billed dinosaurs are numerous - with an elongated duck-like skull, with numerous teeth, they move on two legs, leaning on massive tail. Mammals lived in warm wet forests. They were the size of a mouse and a rat, which helped them lead a hidden lifestyle and protected them from huge lizards. Pterodactyls and toothless giant pteronodonts, reaching 8 m in wingspan, soared in the air along with the appearing toothy birds. So, throughout the history of the organic world, we always observe the extinction of some organisms and the prosperity of other organisms.
In the Carboniferous period, stegocephals became widespread. The humid, warm and even climate of that time favored these amphibians, who still had insufficiently perfect pulmonary respiration.
However, at the end of the Carboniferous period large uplifts occurred earth's crust, and at the same time dry conditions established over a significant area of land, in some places hot climate. At the same time, growth rings on the trunks of fossil trees of that time indicate cold winters. Vast deserts began to form. The coal forests with their swamps and lakes gradually declined. The lush swamp flora was replaced by coniferous and cycad vegetation.
The new environmental conditions were unfavorable for stegocephals. Some of them, oppressed by the arid climate, gradually died out, others, maintaining connections with drying up reservoirs, gave rise to modern amphibians, others, completely departed from aquatic environment, gave rise to a new branch of vertebrate-reptiles.
Reptiles acquired primarily two extremely important differences from stegocephalians. Firstly, a dense horny cover that protects their body from excessive loss of moisture. Secondly, the ability to reproduce on land by laying eggs that have received a dense shell and a larger supply of nutritious yolk, as well as a special system of embryonic membranes formed during the development of the embryo. In addition, all organ systems, in particular the brain, have received more or less significant progressive changes. All this raised reptiles to a higher level of organization compared to amphibians.
Being significantly more adapted to dry climate conditions and truly terrestrial existence, reptiles had already largely replaced stegocephalians by the beginning of the Mesozoic. Meeting no competitors, they settled everywhere, adapting to the most different conditions terrestrial environment. Some returned to life in the water for the second time. Throughout the Mesozoic, reptiles occupied a dominant position on the globe, reaching, especially in Triassic period, extreme abundance and variety of forms. The Mesozoic era was even called the age of reptiles.
The oldest reptiles, already known from the upper Carboniferous deposits, were cotylosaurs (Cotylosanria). They had a massive body and thick five-toed legs. Some of them were small, others reached several meters in length. The skull of cotylosaurs was covered with a solid shell of integumentary bones with openings only for the nostrils, eyes and parietal organ. Both in the structure of the skull and in a number of other characteristics, these ancient reptiles are extremely close to the stegocephalians, which undoubtedly were their direct ancestors. At the same time, cotylosaurs had many of the characteristics of true reptiles. In particular, they had one condyle for articulating the skull with the spine. Cotylosaurs received significant development in the Permian period. Among them, Seymouria (Samurai), which reached no more than half a meter in length, is considered the most primitive of all known reptiles. Cotylosaurs became extinct in the Triassic.
Cotylosaurs gave rise to all other reptiles. In the evolution of later groups, there was a significant lightening of the skeleton while maintaining its strength. In particular, this was largely the case in the skull, the bony armor of which underwent partial reduction due to the formation of the temporal foramina. The reduction of the cranial armor, as already mentioned in the previous chapter, occurred in different ways. In reptiles of one group, called synapsids (Synapsida), a single lateral temporal opening was formed. In reptiles of another group (Diapsida), two temporal openings were simultaneously formed - the upper and lateral and, respectively, the upper and lower temporal arches.
Seymouria.
We will begin our brief overview of Mesozoic reptiles with those that had only one temporal arch.
A very ancient group of reptiles consists of turtles (Testudines), apparently descended directly from cotylosaurs. The first turtles are already known from Permian deposits. These were lizard-like reptiles with short and wide ribs that formed a kind of dorsal shield under the skin. Their abdominal shield was not yet developed, and their jaws were armed with teeth. Quite typical turtles are already known from the Triassic. During the Jurassic and Cretaceous times, numerous cryptonecked and side-necked turtles lived, which have survived without significant changes to the present day. The oldest turtles were exclusively terrestrial animals, and only much later did some of them adapt to an aquatic lifestyle.
An extremely unique group of Mesozoic reptiles were ichthyosaurs (Ichthyosauria), adapted exclusively to an aquatic lifestyle. They had a spindle-shaped body, a highly elongated snout, a tail with a large bilobed fin and limbs in the form of short flippers. The skin of ichthyosaurs has lost its horny cover. There was a cutaneous fin on the back. The vertebrae were biconcave, and the pelvic bones were underdeveloped. In appearance, ichthyosaurs were similar to dolphins. Their body length ranged from 1 to 13 meters. Ichthyosaurs appeared in the Triassic and went extinct at the end of the Cretaceous. They inhabited the seas, where they ate mainly fish and shellfish. Ichthyosaurs were viviparous. The origin of this group of reptiles still remains unclear.
Another group of reptiles that also adapted to life in the sea were plesiosaurs (Plesiosauria). Unlike ichthyosaurs, whose organ of movement was a powerful tail, plesiosaurs swam with the help of limbs transformed into huge flippers. The tail, on the contrary, was poorly developed. More ancient plesiosaurs had a lizard-like build, while later ones had a short barrel-shaped body, a very long neck and a small head. Their skin was bare, their teeth sat in separate cells. Among them were small forms half a meter in length and thirteen-meter giants. Plesiosaurs lived at the same time as ichthyosaurs. Unlike the latter, they apparently stayed in the coastal zone of the sea, and, like seals, could go ashore.
A large group of reptiles, which probably separated from the ancient cotylosaurs already in the Upper Carboniferous, consisted of Theriodontia. Representatives of this group combined primitive organizational features with a number of characteristics that later became characteristic of mammals. Thus, they had biconcave vertebrae and teeth, sitting in separate cells and differentiated into incisors, canines and molars. Thanks to the reduction of the middle part of the triple occipital protuberance, they acquired a double occipital promontory. Many had a secondary bony palate. And not only these, but also a number of other features of the wild-toothed animals leave no doubt that they were the ancestors of mammals. The ability to move on high legs, which developed in later forms, gave their appearance a surprising resemblance to animals.
In the Permian and Triassic periods, mammals reached great diversity. Among them were both predatory and herbivorous forms. Some animal-toothed animals were the size of a rat, others reached large sizes. Among them, Inostracevia, a predator with powerful fangs from Permian deposits on the Northern Dvina, reached three meters in length. Cynognathus from the Triassic deposits of southern Africa was up to two meters in length.
In other groups of Mesozoic reptiles, as a result of partial reduction of the cranial armor, two temporal arches were formed.
The most primitive reptiles among diapsids are considered to be the first lizards (Rhynchocephalia), known since the Triassic. It's great that it's the only one; the modern representative of this group, the New Zealand tuateria, differs relatively little from its ancient ancestors.
Probably, pseudosuchia (Pseudosuchia) evolved from a common ancestor with the proto-lizards, which in turn gave rise to crocodiles, pterosaurs, dinosaurs and birds. These were small lizard-like reptiles with teeth sitting in deep cells, with a fixed square bone, but lacking a secondary bony palate. Pseudosuchians lived in the Triassic period, inhabiting mainly Europe.
Even in the Triassic, ancient crocodiles close to them separated from the pseudosuchians, but real crocodiles (Crocodilia) appeared only at the beginning of the Jurassic. The secondary bony palate of these reptiles has undergone a long evolution. In early forms it was composed of processes of the jaw and palatine bones; in later forms, processes of the pterygoid bones also took part in its formation. At the same time, there was a gradual movement of the internal nasal openings deeper into the oral cavity. Modern crocodiles differ little from their Upper Cretaceous relatives.
Ichthyosaur.
Cynognathus.
An extremely unique group of flying reptiles, which also branched off from pseudosuchians, was represented by pterosaurs (Pterosauria), known from Jurassic and Cretaceous deposits. They had wings formed by a fold of skin stretched between the sides of the body and an extremely elongated fourth finger of the forelimbs. Some pterosaurs - rhamphorhynchus - had narrow, long wings and a very long tail with a rhombic plate at the end. Other pterodactyls had wider wings and a completely reduced tail. The first ones flew in a gliding, gliding flight, with the tail serving as a rudder. The second ones flew in a heavy rowing flight. In connection with adaptation to flight, pterosaurs acquired a number of features common to birds, but these features were not homologous and developed independently in both groups. The wide sternum of pterosaurs had a keel for attaching large pectoral muscles. The bones had air cavities. The jaws of later forms, elongated into a beak, were devoid of teeth. The size of pterosaurs varied greatly, from a few centimeters to 8 meters in wingspan.
The third extremely large and diverse group of reptiles that branched off from the pseudosuchians were the dinosaurs (Dinosauria), which lived from the Triassic to the end of the Cretaceous period. The most ancient representatives of this group moved on their hind legs, which received preferential development. The spinal cord of dinosaurs had a powerful thickening in the sacral area, sometimes exceeding in volume twenty times the volume of the brain, which was generally very small in size. Very early on, dinosaurs split into two branches, which later developed in parallel. Due to the difference in the structure of the pelvic girdle, these branches are called lizard-hazed and ornithischian.
The earliest lizards (Saurischia), known from Triassic deposits, were small running and jumping predators on their hind legs. Their skeleton was very light, since the bones had air cavities. The sharp teeth were compressed at the sides and jagged along the edges. They probably used their shortened forelimbs only for grasping prey. The powerful hind legs had a long metatarsus. The first finger of these limbs was opposed to the others, and the fifth was underdeveloped. Later carnivorous lizards had significantly large sizes, and the later ones were huge bipedal reptiles up to 10 meters in length.
In the Jurassic period, giant herbivorous lizards appeared, and for the second time returned to walking on four legs, which received a more uniform development. They had a small head, a relatively short body and a very long neck and tail. The frequently replaced teeth located in the front of the jaws were adapted for plant food. These were not only the most gigantic of all known reptiles, but also generally the largest terrestrial vertebrates that ever existed on earth. Among them, Brontosaurus reached 18 meters, and Diplodocus up to 24 meters in length.
Ornithischia, widespread from the Upper Triassic to the end of the Cretaceous, were represented by an equally abundant variety of forms. The oldest of them also moved only on their hind legs, while the later ones moved on four. These were exclusively herbivorous reptiles. Walking on its hind legs, the iguanodon reached at least 5 meters in height and was devoid of skin armor. Most other forms, on the contrary, were distinguished by a well-developed armor, often equipped with various outgrowths, spikes, horns, etc. Stegosaurus had a double crest on its back made of huge triangular bone plates. The rhinoceros-like Triceratops reached 13 meters in length and had a horn at the end of its snout and a pair of horns above its eyes.
Dinosaurs, displaying a wide variety of adaptations and living in a wide variety of natural conditions, were distributed throughout the globe. Having reached their greatest development in the Cretaceous, at the end of this period they became completely extinct.
Pterosaurs.
Adjacent to the diapsids is a group of scaly reptiles (Squamata), which, however, occupy a unique position. The oldest representative of this group, Araeoscelis, known from Permian deposits, was a small lizard-like reptile of a slender build, with long legs. His quadrate bone was movably articulated with the skull. The gradual increase in mobility of the articulation of the quadrate and pterygoid bones was characteristic feature in the evolution of squamate reptiles. The fossil remains of this group are extremely scanty, but it is undoubtedly of very ancient, although still unclear, origin. Some people compare Araeoscelis himself with the most ancient proto-lizards. True squamates appeared in the Triassic. The original forms were lizards, from which snakes separated in the Cretaceous. In the Triassic and Cretaceous, squamates gave rise to a number of lateral branches adapted to the aquatic environment. Among them, mosasaurs (Mosasauria) were huge marine reptiles with a serpentine body and limbs transformed into fins. Some mosasaurs reached 15 meters in length.
If the enormous Mesozoic era deservedly received the name of the age of reptiles, then no less deservedly the end of this era is called the era of great extinction. The vast majority of reptiles became extinct in a relatively short period of time at the end of the Cretaceous period, and only a small number of groups of this class, which dominated the land for a long time, passed into the Kenozoic era. Causes of extinction Mesozoic reptiles are still not entirely clear. The following assumption is considered the most probable. In the long process of struggle for existence, reptiles have achieved narrow specialization in adapting to certain environmental conditions. At the end of the Mesozoic, due to significant changes in the landscape and climate, they found themselves in different conditions, in which their narrow adaptability lost its expediency. At the same time, birds and mammals emerged as new competitors on land. The new conditions of the struggle for existence that emerged in this way led to the extinction of reptiles and the beginning of the flourishing of more highly organized vertebrates.
Reptiles or reptiles– lat. Reptilia, the first class of terrestrial vertebrates that have inhabited our planet for many years. Primary or ancient reptiles (reptiles) arose from ancient amphibians, and this was due to climate change. In the ancient era, the climate on the planet gradually became drier and colder, as a result, water bodies began to dry up, large wetlands turned into huge dried out “craters”, etc. Changes in climatic conditions began to occur due to colossal mountain-building processes.
At this time, most of the ancient amphibians became extinct due to the presence of thin and bare skin, poorly developed internal organs, etc. In the rest of the animals, the skin gradually began to horny and harden, the structure of the lungs became more improved, as a result, the ability to better absorb oxygen appeared, the brain of the animals changed, and also the appearance of new way reproduction - laying hard-shelled eggs. This is how the primary or ancient reptiles arose.
The primary reptiles that appeared in the ancient era began to develop quite quickly, as a result of which the ancient amphibians were relegated to the background. In the Middle or Mesozoic era, this development reached its maximum peak, and it was then that vertebrate animals of enormous size began to appear, called ancient reptiles. They filled the entire territory of the planet and gained a dominant position on land, in water and in the air.
The most common species among ancient reptiles or reptiles are:
Squad of crocodiles- predatory vertebrates, only 22 species of crocodiles are now registered.
Dinosaurs, brontosaurs, ichthyanosaurs, pterosaurs - these and many other of their relatives are known modern people thanks to archaeological excavations. IN different time In different regions, individual fragments of the skeletons of ancient reptiles were found, from which scientists scrupulously reconstructed the appearance and lifestyle of archaic animals. Today, the remains of reptiles can be admired in many museums around the world.
General characteristics of ancient reptiles
Archaic reptiles are the second stage in the ontogenesis of the animal world after amphibians. Ancient reptiles are pioneers among vertebrates that are adapted to life on land.
A common feature of ancient reptiles is the skin of the body, covered dense layer horny formations. Such “protection” made it possible for animals not to be afraid of the scorching rays of the sun and to freely settle over the entire surface of the Earth.
The apogee of the development of ancient reptiles occurs in the Mesozoic era. Archaic dinosaurs are the largest vertebrates living on our planet. Over time, they adapted to fly and swim underwater. In a word, animals reigned supreme in all earthly elements.
The history of ancient reptiles
The cause of the emergence of archaic lizards was a change in climatic conditions. Due to the cooling and drying out of many reservoirs, amphibians were forced to move out of their usual aquatic habitat onto land. As a result of evolution, ancient reptiles appeared as a more advanced link of lower vertebrates.
Climate change has caused major mountain-building processes. Ancient amphibians had thin skin without protective covering, underdeveloped internal organs, imperfect lungs. The creatures reproduced primarily by spawning. This method of procreation could not be carried out on land due to the fragility of the future offspring. The lizards laid eggs that had a hard shell and could withstand changing climatic conditions.
The ability to adapt to any habitat led to the emergence of various species of ancient reptiles. The most famous of them:
- terrestrial animals (dinosaurs, theriodont lizards, tyrannosaurs, brontosaurs);
- swimming fish lizards (ichthyosaurs and plesiosaurs);
- flying (pterosaurs).
Types of ancient lizards
Depending on their habitat and method of feeding, archaic reptiles are divided into the following types:
- Flying dinosaurs - pterodactyls, rhamphorhynchus, etc. The largest gliding lizard was the pteranodon, whose wingspan reached 16 meters. The rather fragile body deftly moved through the air even in weak winds thanks to a natural rudder - a bone ridge on the back of the head.
- Aquatic reptiles - ichthyosaur, mesosaur, plesiosaur. The food of lizard fish included cephalopods, fish and other sea creatures. The body length of aquatic reptiles ranged from 2 to 12 meters.
- Herbivorous chordates.
- Carnivorous dinosaurs.
- Animal-toothed lizards are reptiles whose teeth were not the same, but were divided into fangs, incisors, and molars. The most famous theriodonts are pterosaurs, dinosaurs, etc.
Herbivores
Many ancient reptiles were herbivores - sauropods. Climatic conditions contributed to the development of plants suitable for food by lizards.
The lizards that ate grass included:
- Brontosaurus.
- Diplodocus.
- Iguanodon.
- Stegosaurus
- Apatosaurus and others.
The teeth of the found remains of reptiles were not developed enough to eat carnal food. The structure of the skeleton indicates the adaptation of archaic animals to pluck leaves located on the crown of tall trees: almost all herbivorous dinosaurs had a long neck and a rather small head. The body of “vegetarians,” on the contrary, was huge and sometimes reached 24 meters in length (for example, a brachiosaurus). Herbivores moved exclusively on four strong legs, and for reliability they also relied on a powerful tail.
Lizard predators
The most ancient predator reptiles, unlike their herbivorous relatives, were relatively small sizes. Most major representative archaic carnivores - tyrannosaurus, whose body reached 10 meters in length. Predators had strong, large teeth and a rather terrifying appearance. Reptile carnivores include:
- Tyrannosaurus
- Ornithosuchus.
- Euparkeria.
- Ichthyosaur.
Reasons for the extinction of ancient reptiles
Having adapted to the conditions of the Mesozoic, dinosaurs inhabited almost all habitats. Over time, the climate on Earth began to become harsher. The gradual cooling did not contribute to the comfort of heat-loving animals. As a result, the Mesozoic era became a period of prosperity and disappearance of archaic dinosaurs.
Another reason for the extinction of ancient reptiles is considered to be the spread large quantity plants that are not suitable for dinosaur food. The poisonous grass killed many species of lizards, most of which were herbivores.
The natural struggle for survival did not contribute to the further development of ancient vertebrates. The place of reptiles began to be taken by stronger animals - mammals and birds, warm-blooded and with higher brain development.
