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The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years). [3] It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or ...
Classical antiquity – Broad term for a long period of cultural history centered on the Mediterranean Sea, comprising the interlocking civilizations of ancient Greece and ancient Rome, collectively known as the Greco-Roman world. It is the period in which Greek and Roman society flourished and wielded great influence throughout Europe, North ...
The plant shows a high degree of development in relation to the age of its fossil remains. Fossils of this plant have been recorded in Australia, [ 39 ] [ 40 ] Canada, [ 41 ] and China. [ 42 ] Eohostimella heathana is an early, probably terrestrial, "plant" known from compression fossils [ 43 ] of Early Silurian (Llandovery) age. [ 44 ]
The eponymous Silurians on Doctor Who are a race of reptilian humanoids from Earth's past, making their first appearance in the show in 1970. Frank and Schmidt cite Inherit the Stars, a 1977 novel by J. P. Hogan as containing a similar hypothesis, but also say they were surprised by how rarely the concept was explored in science fiction. [2]
The first known footprints on land date to 530 Ma. [74] 520 Ma Earliest graptolites. [75] 511 Ma Earliest crustaceans. [76] 505 Ma Fossilization of the Burgess Shale: 500 Ma Jellyfish have existed since at least this time. 485 Ma First vertebrates with true bones (jawless fishes). 450 Ma First complete conodonts and echinoids appear. 440 Ma
c. 298.9 ± 0.15 Ma – End of Carboniferous and beginning of Permian Period. By this time, all continents have fused into the supercontinent of Pangaea. Seed plants and conifers diversify along with temnospondyls and pelycosaurs. c. 296 Ma – Oldest known octopus fossil. c. 295 Ma – Dimetrodon evolves. c. 295 Ma – First beetles appear. [28]
This second, follow-on event is known as the oxygen catastrophe, which some geologists believe triggered the Huronian glaciation. [ 2 ] [ 3 ] Since the time period from 2,420 Ma to 2,250 Ma is well-defined by the lower edge of iron-deposition layers, an alternative period named the Oxygenian , based on stratigraphy instead of chronometry, was ...
The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale.It spans the time between 251.9 Ma and 246.7 Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a unit in chronostratigraphy.