Thexar-VII: The-Xa — Sha-El 12: Mor-Thal Xa-El — Extinction Events
"Five times everything died. Five times everything returned. The final crisis — the last — we stopped ourselves. The memory of the five holds us." — Law of the Keepers of Biodiversity, +2,100 Y.E.
Ruun-ak rass: → rhu [Thexar-I, Ruun 12, "Geological Evolution"], → rhu [Thexar-I, Ruun 20, "The Origin of Life"], → rhu [Thexar-VII, Sha-El 11, "Evolution Patterns"], → rhu [Thexar-II, Sha-El 04, "The Era of Crisis"]. Mor-ven: Théxar has recorded five major biological crises across 4.2 billion cycles — Oxygen, Volcanic, Glacial, Impact, and the incomplete Anthropogenic (Mor-Thal Xa-El). The sixth was stopped by the Xha'Ruun civilization; since +2,100 Y.E. no species extinction has been recorded, a record of 1,928 cycles.
12.1 Criteria of a Mass Extinction
| Criterion | Threshold | Note |
|---|---|---|
| Species lost | >50% | Of the total number that existed |
| Duration of the crisis | <2 million cycles | Period of elevated mortality |
| Global scale | All continents | Excludes local catastrophes |
| Trace in the geological record | Layer boundary | Sharp change of the paleontological complex |
| Recovery of diversity | >10 million cycles | Time to return to the pre-event level |
12.2 The First Extinction: The Oxygen Catastrophe
Date: 4.0–3.8 billion cycles ago | Duration: ~200 million cycles | Cause: Free O₂ accumulation | Lost: ~40% of anaerobic species
Before the event, atmospheric O₂ was <0.02%; life ran on H₂S chemosynthesis. About 4.1 billion cycles ago the first oxygenic phototrophs appeared.
| Time (billion Y.A.) | O₂ in the atmosphere | Consequence |
|---|---|---|
| 4.1 | 0.02% | First oxygenic phototrophs |
| 4.0 | 0.5% | Beginning of the extinction of methanogens |
| 3.9 | 3.8% | Oxidation of Fe²⁺ in the oceans, red oozes |
| 3.8 | 12% | Formation of the ozone layer, end of anaerobic dominance |
Consequences: ~40% anaerobe extinction; survival in refugia (hydrothermal vents, ocean depths); ozone layer formed; aerobic respiration (18× more efficient) established. Occurred 1.6 billion cycles earlier than on Earth but was gradual enough to allow adaptation.
12.3 The Second Extinction: The Volcanic Catastrophe
Date: 1.8 billion cycles ago | Duration: ~1.2 million cycles | Cause: Super-eruption, global winter | Lost: ~55%
Intense plume volcanism built the traps of Vaal-Kharak, the predecessor of modern Kharak. Repeated eruptions and gas releases changed conditions on land and in the ocean for a long time.
Atmospheric release: SO₂ 6.1×10¹⁴ ru; H₂S 2.8×10¹⁴ ru; CO₂ 1.4×10¹⁵ ru; volcanic dust 3.2×10¹⁵ ru. Sulfate aerosol blocked 68% of sunlight for up to 800 cycles; surface T fell 18°X; photosynthesis shrank 84%.
Consequences: 62% of primary producers extinct; cascading loss to fifth trophic level; ocean pH fell to 7.2; reef systems collapsed; deep-water chemosynthetic refugia survived. Recovery: 42 million cycles.
12.4 The Third Extinction: Total Glaciation
Date: 900 million cycles ago | Duration: ~0.8 million cycles | Cause: "Snowball Théxar" | Lost: ~65%
Trigger: falling CO₂ (to 180 ppm), continents near equator, ice–albedo feedback. At maximum (890 million Y.A.) the entire surface was ice-covered up to 1,200 sha thick.
| Parameter | Before | Maximum | After |
|---|---|---|---|
| Average surface T | +13.6°X | −41°X | +10.2°X |
| Ice cover | 18% | 100% | 24% |
| Photosynthesis (% of normal) | 100 | 0.4 | 82 |
| Planet biomass | 1,340 Gt C | 31 Gt C | 940 Gt C |
Exit: CO₂ accumulated under ice over 18 million cycles to 6,800 ppm, triggering rapid (~80,000 cycles) deglaciation. Terrestrial species hit hardest; multicellular radiation and first large predators followed.
12.5 The Fourth Extinction: Impact
Date: 250 million cycles ago | Duration: <0.5 million cycles | Cause: Asteroid ~3 mo diameter | Lost: ~70%
An asteroid 3.05 mo fell into the Gharra Ocean. Impact energy: 8.4×10²³ J (≈200 million Mt TNT).
| Consequence | Scale |
|---|---|
| Crater | 65 mo diameter (today the Thash Trench) |
| Tsunami | Up to 2,440 sha high |
| Release into the atmosphere | 1.2×10¹⁶ ru of rock, dust, water vapor |
| Fires | 38% of the planet's forests burned |
| "Impact winter" | 15 cycles |
| Temperature (fall) | −22°X in the first 2 cycles |
Three-stage mechanism: mechanical impact (0–10 days) → impact winter (0–15 cycles) → CO₂ greenhouse phase +8°X (15–2,000 cycles). Largest fauna extinction in planet history; 8 orders of the Thermochromadae vanished; radiation of the ancestors of the Xha'Ruun followed (240–180 million Y.A.). Only extinction of the five not tied to internal planetary dynamics — a random event that set the path to reason.
12.6 The Fifth Extinction: Anthropogenic (Incomplete)
Date: −2,100 – −750 Y.E. (Crisis Era) | Duration: 1,350 cycles | Cause: Xha'Ruun activity | Lost: ~12% (stopped)
| Factor | Mechanism | Scale |
|---|---|---|
| Deforestation | Agriculture, fuel | 34% of forest cover destroyed |
| Overfishing | Unrestricted fishing | Marine fauna biomass −62% |
| Pollution | Industrial runoff | 18% of rivers dead |
| Urbanization | Growth of cities | 2.4% of land built over |
| Hunting | Uncontrolled hunting | 8 species of large herbivores exterminated |
Turning point: in −1,200 Y.E. the Guild of Natural History warned regional rulers of collapse within 600 cycles. Reform sequence: −1,150 Law on Protected Territories (12% of land); −980 ban on uncontrolled logging; −840 fishing quotas; −750 Treaty of Unity (union of eight regions).
Result: extinction stopped. The survey of 4028 reported no species disappearance; 8 species reintroduced (including the Ghal-thass, restored +2,850 Y.E.); forest cover restored to 40% (+12% over 500 cycles). The only stopped extinction — absent from the geological record, present in cultural memory as the Lesson of the Crisis.
12.7 Patterns of the Extinctions
| Extinction | Cause | Lost | Recovery | Surviving groups |
|---|---|---|---|---|
| I (Oxygen) | Biogenic | 40% | 120 million Y.A. | Aerobes, refugia |
| II (Volcanic) | Geological | 55% | 42 million Y.A. | Chemosynthetics |
| III (Glacial) | Climatic | 65% | 38 million Y.A. | Deep-water |
| IV (Impact) | Cosmic | 70% | 24 million Y.A. | Small generalists |
| V (Anthropogenic) | Biogenic | 12% (stopped) | — | All except large specialists |
Common patterns: (1) selection against specialists; (2) deep-water chemosynthetic refugia survived all five with minimal loss; (3) large forms (>100 kh) went extinct 3.4× more often than small (<1 kh); (4) recovery time scales with severity (10–40 million cycles); (5) each event opened new adaptive radiation — Thermochromadae after IV, primate-analogues after III. "Rule of Five": one extinction per 840 million cycles — close to the frequency of Wilson supercycles.
12.8 Lessons for the Management of the Biosphere
| Principle | Justification |
|---|---|
| The "six steps" principle | Assessing consequences 6 generations ahead |
| The 12% rule | No less than 12% of land — reserves |
| The sustainable catch law | Taking no more than 68% of the annual increment |
| The ban on destroying species | Even "useless" ones — they may prove key |
| Reintroduction | The duty to restore species extinct through the civilization's fault |
Ruun Ven
- Five mass extinctions occurred in 4.2 billion cycles: Oxygen (40%, 4.0 Ga), Volcanic (55%, 1.8 Ga), Glacial (65%, 900 Ma), Impact (70%, 250 Ma), Anthropogenic (12%, −2,100 – −750 Y.E., stopped).
- The Impact extinction was the largest (70%) and the only one triggered externally; it opened the niches enabling the radiation of the Xha'Ruun ancestors.
- Deep-water chemosynthetic refugia survived all five events, and specialists and large forms (>100 kh) died 3.4× more often than small generalists.
- The Fifth (Anthropogenic) extinction is the only stopped one — absent from the geological record, preserved in cultural memory as the Lesson of the Crisis.
- The survey of 4028 reported no species extinction has been recorded on Théxar — a 1,928-cycle record maintained by the Keepers of Biodiversity.
- Modern ecological ethics rest on five principles: six-steps foresight, the 12% reserves rule, the 68% sustainable catch law, the ban on destroying species, and mandatory reintroduction.