The question is very interesting and is not easy to answer, since depending on what is considered a plant or animal, one can refer to older organisms or more recent organisms. And both lineages emerged in various geological periods. But, in summary, I would say that both the ancestral and the recent ones appeared at the same time or almost at the same time.
When I talk about the ancestral ones, I am referring to some groups of protists (organisms whose cells contain a cell nucleus), such as the photosynthetic chromists, and to primitive algae (glaucophytes, rhodophytes and chlorophytes), which were plants (kingdom Plantae), and to other groups of primitive non-photosynthetic protists, such as amoebae, mucilaginous fungi and opisthocontes, which gave rise to fungi (kingdom Fungi). and animals (kingdom Animalia). All very ancient, from the Precambrian, that is, about 1,000-538 million years ago, or even earlier.
Over time, these lineages diverged, some conquering land and diversifying, while others became extinct. In the plant kingdom, after algae, bryophytes (liverworts, mosses and horns) and pteridophytes (lycopods, horsetails and ferns) appeared and diversified in the primary or Paleozoic era (which goes from 538 million years ago to 251 million years ago). The current coal deposits testify to the remains of the large forests of the Carboniferous period of this era, formed by pteridophytes and ancestors of gymnosperms (conifers and close relatives). Gymnosperms diversified in the Mesozoic (which lasted from 251 to 66 million years ago). Finally, angiosperms or flowering plants appeared at the end of the Mesozoic, in the Cretaceous (which is the third and final period of the Mesozoic, from 143 to 66 million years ago).
Animals also evolved during different geological periods, initially giving rise to various groups of invertebrates and, subsequently, to vertebrates. Early invertebrates ranged from sponges, jellyfish, corals, and anemones of the Precambrian, to molluscs, planarians, and nematode worms of the Cambrian (538 to 436 million years ago), and insects of the Devonian to Jurassic (360 to 160 million years ago). The oldest vertebrate fossils come from the Precambrian (Pikaia), while the oldest group of vertebrates consists of several lineages of Paleozoic marine fish, some of which conquered the land (lungfish). After them, the amphibians differentiated between the Devonian and the Carboniferous (370-315 million years ago) and various lineages of reptiles, such as the Sauropsids and their descendants, in the Permian (300-270 million years ago). The most recent group of vertebrates is made up of birds, originating from the Cretaceous period (120-105 million years ago), descending from a branch of dinosaurs, and Jurassic mammals, descending from a branch of ancestral reptiles.
This would be a very general answer to your question. But we can go deeper. If we trace the origin of life on Earth, the first living beings that appeared on it were bacteria, around 3,500 or 3,000 million years ago, we remember that the Earth was formed around 4,500 million years ago. Bacteria are apparently very simple unicellular organisms, which we call prokaryotes, which do not have a nucleus, and of which some strains have managed to survive to the present day. About 2,000 million years ago, eukaryotes appeared, complex cells with a nucleus, from which fungi, animals and plants arose.
According to the endosymbiotic theory, eukaryotes formed through the fusion of different bacteria with different functions, which gave rise to more complex cells with different organelles. If we therefore go to the origin, we could say that the ancestors of animals, fungi and plants were formed in that period which goes from 2,000 million years ago to approximately 530-540 million years ago, which constitutes the Proterozoic era. We know the origin of these ancestral eukaryotic lineages and their descendants because fossil sites have been found in various regions of the planet that have been dated.
The almost parallel evolutions of the different lineages of plants and animals during the various geological periods are also due to the dependence of some animals, such as herbivores, on the plants that nourish them, and to the creation of ecological food networks (carnivores, saprophytes, etc.) of each ecosystem based on their environmental adaptations. When an ecosystem disappears, due to environmental change, its inhabitants disappear. This is what happened to the frozen graminoid steppe of the Quaternary after the postglacial thaw, about 10,000 years ago, which led to the disappearance of the mammoths and other large herbivores that grazed it and, with them, the large carnivores that preyed on them. This ecosystem was replaced by humid temperate forests and associated fauna after the warming and rainfall of the boreal period.
As you can see, there is some uncertainty in estimates of the origins of some plant and animal lineages, which is normal, since the information we have comes mainly from the fossil record, which is not complete, and from certain dates based on DNA analysis, which are approximate. However, new paleontological, biological and genomic scientific advances allow us to increasingly refine the origins of living beings that we know or that have lived somewhere on our planet.
Pilar Catalán Rodríguez She is a professor of Botany at the University of Zaragoza, an expert in genomics and plant evolution.
Coordination and writing:Vittoria Toro.
Question sent via email fromJuan Carlos López Álvarez.
We answeris a weekly scientific consultation, sponsored by the programL’Oréal-UNESCO ‘For women in science’and forBristol Myers Squibbwhich answers readers’ questions about science and technology. They are scientists and technologists, partners ofAMIT(Association of Women Researchers and Technologists), those who answer these questions. Send your questions toarespondemos@gmail.comor via X #werespond.
