Paleontology · deep time, fossil evidence and changing interpretations
A broad, sourced atlas of paleontology, geological time and scientific inference, from Earth's early setting to modern imaging, geochemistry and ancient DNA.
Coverage and limits
Includes all 178 distinct units with numerical boundaries in the current ICS chart dataset: four eons, ten eras, 22 periods, two subperiods, 38 epochs, 101 other ages, and the Precambrian super-eon grouping. The RDF assigns Pridoli both epoch and age rank; it is represented once as the epoch, with the dual assignment documented, rather than counted twice. This includes named and currently unnamed chart subdivisions. Hierarchical ranks overlap by design; they are not conflicting dates. The data reflect the June 2026 calibration changes.
The biological strand surveys microbial evidence, eukaryotes, algae, fungi, Ediacaran organisms, Cambrian animals, marine invertebrates, land plants, fish, tetrapod origins, synapsids, dinosaurs, pterosaurs, marine reptiles, birds, mammals and hominins. It contains individual specimens, named taxa, important deposits and transitions. It is representative, not a catalogue of every paleontological specimen or every described species. Such a catalogue requires collection databases and continuing taxonomic curation. Use the Paleobiology Database, Royal Ontario Museum fossil gallery and linked specimen collections for deeper occurrence-level research.
Scientific interpretation has its own chronology: Steno, Cuvier, Smith, Lyell, Anning, Darwin and later researchers; radiometric dating, extinction hypotheses, anatomical reconstruction, pigment evidence, genomes and revised calibrations. These dates represent changes in knowledge, not the times when the fossil organisms lived. Historical entries are selected milestones, not a claim that European scientific publication marks humanity's first recognition of fossils. Local knowledge, collecting, preparation and the histories of credit remain relevant.
Dates and uncertainty
Deep-time ages are approximate scientific estimates. Ma = millions of years and Ga = billions of years. For one consistent plotting convention, age A years is placed at astronomical Gregorian year 2000 − A, January 1 UTC. This is an approximate reference-year-2000 conversion, not a claim that a fossil formed on a Gregorian day. Standard radiocarbon BP uses 1950 and is a different convention; rounded Ma here are not uncalibrated radiocarbon dates. Modern year-only discoveries use January 1 only as a year anchor. No historical year zero is displayed in BCE/CE notation. Adaptive labels show mya/bya at deep-time scales.
A representative contextual anchor is deliberately labelled. For broad taxon ranges, a midpoint places the entry within its cited record; it does not claim a species originated or went extinct there. First fossil appearances usually constrain a minimum lineage age. Modern specimen labels, research dates, geological ages and uncertain affinities are kept distinct. Do not read a numerical coordinate as greater scientific precision than the source supports. Fossil papers and older museum summaries can use older boundary calibrations; formal unit bands follow ICS, while individual fossil age summaries retain their stated estimates.
Duration policy
No duration ends at today, the research cutoff, or a fabricated modern endpoint. Only the 173 completed units in the ICS data receive duration bands. Their geological endpoints can have numerical uncertainty while remaining definite closed boundaries. The five ongoing units—Phanerozoic, Cenozoic, Quaternary, Holocene and Meghalayan—have start moments only. Living groups such as Homo sapiens, corals, brachiopods and crinoids are not given artificial extinction dates. Fossil occurrence ranges and individual lifespan estimates have not been converted indiscriminately into durations.
How to explore
Use Separate by tags to distinguish fossil record, discovery and interpretation, and geological time scale. Within geology, use geological eon, geological era, geological period, geological epoch or geological age. Biological and method tags provide additional views, including plants, fungi, arthropods, mammals, hominins, mass extinctions, molecular paleontology and contested interpretations. Expand moments for sources, methodological cards and image qualifications.
Useful windows: 4,600–500 mya for early Earth and early life; 550–250 mya for Cambrian through Paleozoic ecosystems; 250–66 mya for Mesozoic evolution; 66–0.01 mya for Cenozoic life; and 1650–2027 CE for discoveries and deductions. Geological bands nest and can be dense: separate by rank and zoom before reading age-level details. Directional arrows connect evidence to its later study; other arcs are thematic comparisons. Neither kind silently asserts direct evolutionary ancestry.
Evidence prioritizes original research, institutional collections, geological surveys, museum specialists, scholarly histories and primary historical texts. Recent selected research extends through 29 October 2026, checked on 4 November 2026. This does not claim a comprehensive survey of every paper published by that date.
Data and image credits
Geological ranks, hierarchy, colors and numerical ages are derived from the International Commission on Stratigraphy chart and its official RDF dataset. Cite: Cohen, Harper, Gibbard & Car (2025), The ICS international chronostratigraphic chart this decade, Episodes 48:105–115, doi:10.18814/epiiugs/2025/025001, with 2026/06 updates. Chart reuse: CC BY 4.0. Record data retrieval separately from claims of scientific certainty; subsequent ICS changes may revise numerical calibrations.
Cover and backdrop: a photographed Jurassic Dactylioceras commune ammonite, one illustrative fossil rather than a proxy for all life. Each selected image has an individual public-domain, CC0 or Creative Commons reuse record. Photographs of mounts, casts and reconstructions are distinguished from original material; later images are not portrayed as discovery photographs. Backgrounds illustrate selected organisms within a closed interval and do not claim that a pictured species spans the whole interval. Duria Antiquior is historical 1830 paleoart. No modifications beyond thumbnail scaling.
347 moments · 4566998001-01-01T00:00:00Z BCE – 2026-10-29T00:00:00Z CE · by @athan · @athan
Siderian period begins
geological time scale
geological period
siderian
completed geological interval
The Siderian is a geological period within the Paleoproterozoic era, Proterozoic eon and Precambrian super-eon in the international framework used to organize Earth’s history. The numerical ages recorded here place its beginning at approximately 2500 million years ago and its end at approximately 2300 million years ago, an interval of about 200 million years. The name describes a globally correlatable time division, rather than one locality or the lifespan of a particular species. Within this classification, it precedes the Rhyacian period. The Siderian supplies a named interval for comparing the ages of rocks, fossils and environmental records that can be correlated with it. The International Commission on Stratigraphy maintains the chart and the boundary information used here. The dataset marks its base as having a ratified Global Standard Stratigraphic Age, a numerical reference used to define a geological boundary. This differs from defining the boundary through a selected physical section. Numerical boundary estimates from ICS; physical stratigraphic definitions and age estimates are different. This moment marks the beginning of the unit. Dating a specimen or deposit to this unit requires geological evidence; the unit’s boundary alone does not establish the origin or extinction of every organism represented within it. **Evidence:** - [International Commission on Stratigraphy: current international chronostratigraphic chart (2026/06)](https://stratigraphy.org/chart/) - [ICS official chart RDF data: rank, hierarchy, numerical boundary ages and uncertainty](https://raw.githubusercontent.com/i-c-stratigraphy/chart/main/chart.ttl)
Date precision
Numerical boundary estimates from ICS; physical stratigraphic definitions and age estimates are different.
Coordinate convention
Deep-time ages are approximate scientific estimates. Ma = millions of years and Ga = billions of years. For one consistent plotting convention, age A years is placed at astronomical Gregorian year 2000 − A, January 1 UTC. This is an approximate reference-year-2000 conversion, not a claim that a fossil formed on a Gregorian day. Standard radiocarbon BP uses 1950 and is a different convention; rounded Ma here are not uncalibrated radiocarbon dates. Modern year-only discoveries use January 1 only as a year anchor. No historical year zero is displayed in BCE/CE notation. Adaptive labels show mya/bya at deep-time scales.
timescale.info