Dinosaurs were the dominant life form on Earth for at least 160 million years. From the gigantic Tyrannosaurus rex to the speedy Velociraptor, dinosaurs were a pinnacle manifestation of dinevolution. And then, in what seems like a geological instant, they were gone. The loss of dinosaurs represents one of natural history’s most intriguing mysteries — and a mystery we still attempt to explain. But, when did dinosaurs become extinct? What were the causes of their extinction, while some other species survived? And, how long ago did this event occur?

In this blog, we look at the timing, reasons, and implications of dinosaur extinction — addressing some of the most searched questions from this mass extinction event.

When Did Dinosaurs Go Extinct?

Dinosaurs went extinct approximately 66 million years ago, the answer is quite consistent across geological evidence.

And just for fun: How many seconds ago did dinosaurs go extinct?
Approximately 2.08 x 10^15 seconds ago — that’s 2 quadrillion seconds!

What Period Did Dinosaurs Go Extinct?

Dinosaurs went extinct at the end of the Cretaceous Period, which is the last period of the Mesozoic Era. The periods of the Mesozoic are:

1. Triassic Period (252–201 million years ago)
2. Jurassic Period (201–145 million years ago)
3. Cretaceous Period (145–66 million years ago)

So what year did dinosaurs go extinct? While not a “year” in the human sense, scientists believe they went extinct approximately 66 million years ago, which is the Mesozoic Era, ending precisely at the Cretaceous–Paleogene (K–Pg) boundary

How Did Dinosaurs Go Extinct?

The most-referenced idea to explain dinosaurs’ extinction is the asteroid impact. According to this hypothesis, a huge asteroid—about 10 kilometers in size—hit the Earth near the Yucatán Peninsula in Mexico, forming the Chicxulub crater.

The impact generated:

• Global wildfires
• Earthquakes and tsunamis
• A nuclear winter, whereby dust and soot blocked out sunlight, dramatically reducing global air temperatures
• Disruption of photosynthesis and productivity, leading to explosions in food web collapses,

This annihilating progression of events made survival impossible. In total, mass extinction was inescapable for almost all species, especially large terrestrial dinosaurs.

Some other contributory ideas are:

• Volcanism, especially as seen in the Deccan Traps in India
• Changes in sea level
• Climate shifts and longer-term ecosystem stress

While it is likely that the asteroid impact dealt the decisive blow to the biosphere, some of these other considerations may have already compromised biosphere integrity.

Why Did Dinosaurs Go Extinct but Not Other Animals?

This is one of the most fascinating questions: why did dinosaurs become extinct, but not mammals, birds, or reptiles like crocodiles? Here are a few reasons:

1. Body size and metabolic requirement: Many dinosaurs were large and had massive food resource requirements. After the asteroid impact, food was not abundant in the environments where dinosaurs lived which meant it would be difficult for animals to survive [Note: especially hard for herbivores].
2. Egg-related reproduction: Dinosaurs reproduced by laying eggs which they likely laid in open and exposed environments so their nests may have been subject to significant destruction or interruption during the climatic upheaval.
3. Sensitivity to the environment: They may have been more sensitive to environmental changes and simply not adapted to recover quickly given their [cold and hot] bloodedness while mammals and other tetrapods may have better survived the climate change.
4. Mammals had advantages: Mammals tended to be small, burrowing, and omnivorous. These traits indicated a better chance of survival during immediately after the cataclysmic event.

So did dinosaurs survive? Not all dinosaurs became extinct. Birds evolved from theropods and, therefore, birds are really theropods which means that they are technically a form of dinosaur and the only lineage to survive this extinctions event.

What survived the dinosaur extinction?

While many species went extinct, some survived, including:

• Birds (avian dinosaurs)
• Mammals (especially small, burrowing mammals)
• Crocodilians
• Turtles and amphibians
• Insects
• Aquatic species including fish and some mollusks

These survivors adapted to the new conditions, then evolved to the diverse ecosystems we observe today.

Are all dinosaurs extinct?

No. Birds are modern dinosaurs. When you see a pigeon or a hawk, it is a member of the last remaining lineage of dinosaurs. Non-avian dinosaurs are extinct, but their avian cousins are alive and well.

What if dinosaurs did not go extinct?

This is a popular question; both speculative science and fiction have attempted to answer it.

If dinosaurs did not go extinct:

• Mammals may not have reached dominance.
• Humans may never have evolved.
• The biosphere of Earth is dramatically different, perhaps dominated by intelligent species of dinosaurs (as seen in speculative fiction).

However, without that mass extinction event, it is likely we would never have seen the evolutionary trajectory that eventually lead to mammals and then to people.

What Caused the Extinction of the Dinosaurs According to the Bible?

This is a common question and one often asked relative to the idea of reconciling one’s faith with the unearthed discoveries of science. The Bible makes no reference to extinction of dinosaurs, nor dinosaurs at all.

Although some interpretations may be that dinosaurs lived before Adam and Eve or dinosaurs cohabited with early humans and became extinct during the Great Flood in the story of Noah’s Ark. There is no scientific evidence to substantiate any of these interpretations.

When Did The Last Dinosaur Become Extinct?

The last non-avian dinosaurs became extinct about 66 million years ago, during the K-Pg extinction event. Many studies about fossils reveal a distinct and abrupt change in the density of dinosaur fossils after this line in the geological strata.

How Long After The Dinosaurs Became Extinct Did Humans Appear?

Humans (modern Homo sapiens) evolved about 300,000 years ago — leaving an interval of 65.7 million years between the extinction of non-avian dinosaurs and the emergence of modern humans.

Conclusion

The extinction of dinosaurs was one of the most significant events in the Earth’s history. While catastrophic, the extinction of dinosaurs made room for new life, including humans. Now that the when, why, and how of dinosaur extinction has been explored in ample detail, the research is ongoing as fossils and geological evidence are continuously changing and being discovered.

From a planet dominated by giants, to one dominated by small mammals, to one which includes intelligent life, the extinction of dinosaurs reminds us of the unpredictable devastation of nature, and its ability to regenerate overall.

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