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The first fossil records of vascular plants, that is, land plants with vascular tissues, appeared in the Silurian period. The earliest known representatives of this group (mostly from the northern hemisphere) are placed in the genus Cooksonia. They had very simple branching patterns, with the branches terminated by flattened sporangia.
Fossils of plants from the early Devonian show that a simple form of wood first appeared at least 400 million years ago, at a time when all land plants were small and herbaceous. [87] Because wood evolved long before shrubs and trees, it is likely that its original purpose was for water transport, and that it was only used for mechanical ...
Basilosaurus, one of the first of the giant whales, appeared in the fossil record. 38 Ma Earliest bears. 37 Ma First nimravid ("false saber-toothed cats") carnivores — these species are unrelated to modern-type felines. First alligators and ruminants. 35 Ma Grasses diversify from among the monocot angiosperms; grasslands begin to expand.
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
Earth forms 3.4 billion years ago First photosynthetic bacteria appear 2.7 billion years ago Cyanobacteria become the first oxygen producers 2.4 – 2.3 billion years ago Earliest evidence (from rocks) that oxygen was in the atmosphere 1.2 billion years ago Red and brown algae become structurally more complex than bacteria 0.75 billion years ago
For much of the Paleozoic Era (542–251 Ma), the fungi appear to have been aquatic and consisted of organisms similar to the extant Chytrids in having flagellum-bearing spores. [14] Phylogenetic analyses suggest that the flagellum was lost early in the evolutionary history of the fungi, and consequently, the majority of fungal species lack a ...
To zero in on exactly when LUCA appeared on Earth, scientists had to work backward. First, the team compared genes in living species and counted the mutations that have occurred since sharing a ...
Earth is the only place in the universe known to harbor life, where it exists in myriad environments. [8] [9] The origin of life on Earth was at least 3.5 billion years ago, possibly as early as 3.8-4.1 billion years ago. [2] [3] [4] Since its emergence, life has persisted in several geological environments.