Carbon Sequestration

100 million years ago, atmospheric carbon was 2,000 ppmv (versus 417.68 today), the global temperatures were 5-10°C higher than today, and sea levels were 50-100m higher.
https://eos.org/science-updates/an-unbroken-record-of-climate-during-the-age-of-dinosaurs
https://www.futurity.org/cretaceous-dinosaurs-temperature-climate-2598172-2/

There was also abundant plant and animal life.  Plants like CO², herbivores like plants. Carnivores like herbivores.

Whether the abundance of plants caused it, or the Chicxulub meteor, at some point the CO² fell, the dinosaurs and plants died, the Earth cooled, ice sheets covered the poles, and all this organic matter got buried and under pressure turned into coal and petroleum.

Which we burn today, releasing the stored energy and carbon dioxide.

And raising the planet's temperature again.

It's a cycle, 100 million years long.  How many more times can it continue?  Possibly until the death of the sun, 4.5 billion years or 45 cycles from now.

How many cycles happened before the Cretaceous?  The Earth was formed 4.5 billion years ago, so potentially, 45?

Except:
The oldest known fossils are Dickinsonia (558 mya), sponges (890 mya) and Cyanobacteria (3.5 bya).  That far back there wouldn't have been any buried carbon, nor any lifeforms advanced enough to avail themselves of it anyway.

The oldest land animals were about 360 mya, or 2 cycles before the Cretaceous.
https://www.worldatlas.com/articles/the-first-ever-animals-to-walk-on-land.html
https://www.science.org/content/article/ancient-global-warming-spikes-suggest-dinosaurs-died-double-disaster

Were there global temperature variations of this magnitude before the Cretaceous?

• Precambrian era, 4.6 bya to 542 mya.  Insignificant life. 40 cycles.
  
  
• Paleozoic era, 542 mya to 250 mya.  Mostly sea critters and primitive land animals.  95% were extincted in the Permian Extinction when plate tectonics created Pangaea and raised ocean temperatures by 10°. Two cycles.
  https://earth.stanford.edu/news/what-caused-earths-biggest-mass-extinction#gs.5z88l6
  
  
• Mesozoic era, 250 mya to 65 mya.  Rise of land animals, "Age of the Dinosaurs,"  creation of carbon deposits. Two cycles.
  
  
• Cenozoic era, 65 mya to today.  "The Age of Mammals," leading to use of the stored energy and carbon from the Mesozoic. 2/3 of one cycle. Wiping out 200 million years of carbon deposits in just 200 years.
  

So, did the dinosaurs die out because they built nuclear power plants and despoiled their environment?