What facts may indicate the connection between extinct and modern plants and animals?

According to the synthetic theory of evolution, the evolutionary process occurring in nature is divided into two stages: microevolution and macroevolution.
Macroevolution includes processes leading to the appearance of systematic units larger than a species. Studying macroevolution, modern science has accumulated a number of scientific facts proving the evolution of the organic world. Evidence of evolution can be considered any scientific fact that proves at least one of the following points.
The unity of the origin of life (the presence of common signs in all living organisms).
Family relations between modern and extinct organisms or between organisms in a large systematic group (the presence of common features in modern and extinct organisms or in all organisms in a systematic group).
The action of the driving forces of evolution (facts confirming the effect of natural selection).
Evidence of evolution, obtained and accumulated in the framework of a particular science, makes up one group of evidence and is called by the name of this science.
Paleontology is the science of the fossil remains of extinct organisms. The founder of evolutionary paleontology is considered the Russian scientist V.O. Kovalevsky. Evidence for evolution includes fossil transitional forms and phylogenetic series of modern species.
Fossil transitional forms are extinct organisms that combine the characteristics of older and evolutionarily younger groups. They allow you to identify family ties that prove the historical development of life. Such forms are established both among animals and among plants. The transitional form from brushed fish to ancient amphibians – stegocephalus – is ichthyostega. The evolutionary relationship between reptiles and birds allows you to establish a primitive bird (Archeopteryx). The connecting link between reptiles and mammals is the beast animal from the group of terapsids. Among plants, the transition form from algae to higher spores is psilophytes (the first land plants). The origin of gymnosperms from fern-like ones is proved by seed ferns, and angiosperms from gymnosperms – by cypresses.
Phylogenetic (from the Greek. Phylon – genus, tribe, genesis – origin) series are sequences of fossil forms that reflect the historical development of modern species (phylogenesis). Currently, such series are known not only for vertebrates, but also for some groups of invertebrate animals. Russian paleontologist V. O. Kovalevsky restored the phylogenetic series of a modern horse

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