50 Fun Facts About Dinosaur Extinction

Roughly how many years ago did the extinction that wiped out the non-avian dinosaurs occur?

It ended the Cretaceous and the Mesozoic and opened the Cenozoic era.

What proportion of plant and animal species on Earth are estimated to have died in the K-Pg extinction?

Marine fossils suggest 75% or more of species vanished.

By what earlier name was the K-Pg mass extinction commonly known?

'Tertiary' was dropped as a formal period name in favour of Paleogene.

Which metal, more common in asteroids than in Earth's crust, is unusually abundant in the K-Pg clay?

The Alvarez team found it at 20 to 160 times normal levels in the sections they first studied.

Which father-and-son team proposed in 1980 that an asteroid impact killed the dinosaurs?

Luis was a Nobel-winning physicist and Walter a geologist; chemists Frank Asaro and Helen Michel co-authored the study.

Which Dutch palaeontologist independently proposed the impact idea shortly after the Alvarez team?

The impact site was still unknown when the hypothesis was published.

How wide was the asteroid thought to have caused the extinction?

It struck around 66.043 million years ago and dug a transient cavity 100 km wide and 30 km deep.

On which peninsula does the Chicxulub crater lie?

The crater is about 180 km across, roughly the size the Alvarez team had calculated.

What is the approximate diameter of the Chicxulub crater?

It is oval, with a peak ring that was drilled in 2016.

The Chicxulub crater was first noticed in the late 1970s by geophysicists looking for what?

Antonio Camargo and Glen Penfield could not prove it was a crater and Penfield gave up until the 1990s.

What surface feature, visible in satellite images, traces a circle matching the buried crater rim?

The cenotes are thought to result from subsidence around the weakened crater wall.

What kind of object is the Chicxulub impactor now generally believed to have been?

Its composition best matches carbonaceous chondrites of the CV, CO and CR groups.

A 2021 study estimated the impactor arrived at what speed and angle?

Winds near the blast exceeded 1,000 km/h.

What did the 2016 drilling into Chicxulub's peak ring find surprisingly little of?

The sulfate rock had vaporised into aerosols, prolonging the climate damage; the ring held granite flung up from deep in the crust.

What is the main mechanism by which the Chicxulub strike is thought to have caused mass extinction?

Dust blocked sunlight for up to a year; soot and fine silicate dust deepened the cooling.

Tiny spherules found in the boundary clay formed from what?

Microtektites matching Chicxulub have even been found inside amber at the Tanis site.

Which volcanic province in India is the leading rival or contributing explanation for the extinction?

Gerta Keller has championed volcanism; a 2020 climate-modelling study favoured the asteroid.

Roughly how thick are the layered flood basalts of India's great volcanic province?

They cover about 500,000 square kilometres of west-central India with a volume of a million cubic kilometres.

Which palaeontologist is the leading critic of the impact hypothesis, favouring Deccan volcanism?

She argues for a more gradual extinction driven by eruptions.

Most tetrapods above what weight died in the extinction, cold-blooded species excepted?

Endothermic animals of any size needed far more food than ectotherms during the food-chain collapse.

Why are crocodilians thought to have survived while non-avian dinosaurs perished?

Their young are small, grow slowly and eat invertebrates and carrion for their first years.

Which group of dinosaurs survived the extinction and radiated into today's species?

Only a few ground and water fowl made it through, likely helped by the ability to dive, swim or shelter.

Which flying reptiles were wiped out entirely at the K-Pg boundary?

Two families, Azhdarchidae and Nyctosauridae, were still around in the Maastrichtian.

Which giant marine reptiles that preyed on shelled cephalopods went extinct in the K-Pg event?

Ichthyosaurs had already vanished tens of millions of years earlier; plesiosaurs also died out at the boundary.

Which coiled-shelled cephalopods became extinct at the boundary while their nautiloid cousins survived?

Nautiloids laid few large eggs; ammonites relied on masses of planktonic larvae, which the collapse destroyed.

Which reef-building clams became extinct at the K-Pg boundary?

Inoceramids, giant relatives of scallops, also died out, though their decline had begun earlier.

What percentage of colonial coral species, dwellers of warm shallow water, went extinct?

Solitary deep-water corals, not dependent on photosynthetic algae, fared far better.

Which kinds of animals survived best on land, feeding on insects, worms and snails?

Neither strictly herbivorous nor strictly carnivorous mammals seem to have survived.

What size were the mammals that survived the extinction, generally?

Within about 700,000 years some mammals had reached 50 kilos, a hundredfold increase.

Which mammal group suffered the heaviest losses at the K-Pg event?

They largely disappeared from North America; eutherians recovered quickest.

What share of Cretaceous turtle species passed through the K-Pg boundary?

All six turtle families alive at the end of the Cretaceous still have living species.

What percentage of modern frog diversity traces to three lineages that evolved after the K-Pg extinction?

Amphibians as a whole show little sign of extinction at the boundary.

Which plants led the recovery, showing up as a 'spike' in the geological record?

The same fern recolonisation pattern was seen after the 1980 Mount St. Helens eruption.

Which fossil site in North Dakota appears to record the very hours after the impact?

Robert DePalma excavated it in near-total secrecy from 2012; the fossils seem buried by an impact-triggered flood.

Sturgeon-like fish bones at Tanis suggest the impact happened in which Northern Hemisphere season?

Isotope records and bone growth in acipenseriform fishes pointed to springtime.

What kind of impact-related deposits are found around the Gulf of Mexico and Caribbean?

Metre-thick debris beds occur as far away as northern New Mexico.

Which two-scientist effect makes it hard to tell if dinosaurs died out suddenly or gradually?

Most species probably died out well after their last known fossil.

Which Montana rock unit holds the key dinosaur-bearing strata up to the K-Pg boundary?

Its late Maastrichtian rocks hold the biggest members of clades like Tyrannosaurus and Triceratops, suggesting food was still plentiful.

What is the name of the last age of the Cretaceous, in which the final dinosaurs lived?

Non-avian dinosaurs are found in Maastrichtian rocks on every continent but nowhere in the Cenozoic.

Which era began with the K-Pg extinction and continues today?

Mammals diversified in the Paleogene into forms such as horses, whales, bats and primates.

Which insects became dominant and diverse with larger colonies in the Eocene, after the extinction?

Butterflies and mound-building termites also rose in importance.

Approximately what fraction of teleost (bony fish) families survived the boundary?

Skates and rays, by contrast, lost nearly all identifiable species.

Which mammal-era fish groups appeared in the Paleocene and Eocene, filling niches left empty?

Teleosts diversified explosively after a brief 'Patterson's Gap' in diversity.

Only one lizard-like reptile group survives from the once-widespread rhynchocephalians - which animal?

Kawasphenodon peligrensis in Patagonia is the one rhynchocephalian known to cross the boundary outside New Zealand.

Research in October 2019 proposed that the impact rapidly did what to the oceans?

Ocean life in the water column suffered far more than bottom-dwellers feeding on detritus.

The Chicxulub crater takes its name from what?

Chicxulub Pueblo sits at the centre of the ring of cenotes that traces the buried crater's rim.

Which researcher supplied Glen Penfield in 1990 with samples showing Chicxulub was an impact site?

Evidence for an impact origin includes shocked quartz, a gravity anomaly and tektites scattered around the region.

A 2007 Nature paper linked the impactor to which asteroid family, a theory since disproven?

A 2009 spectral study showed 298 Baptistina is an S-type body, unlike the carbonaceous chondrite composition of the impactor.

Roughly how much energy did the Chicxulub impact release, in TNT terms?

Estimates range from about 10^23 to 10^25 joules, enough to drive winds above 1,000 km/h near the blast centre.

Which 24 km crater in Ukraine dates to roughly the same time as the K-Pg boundary?

Some researchers have suggested multiple impacts; the North Sea's Silverpit and the disputed 600 km Shiva structure are also cited.