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these species would have died within a year or two. Plummeting global temperat-
ures also would have contributed further to this massive die-off of photosynthes-
izers, as the dust cloud would have acted like the ultimate sunscreen, preventing
infrared radiation (heat) from making it to the earth's surface.
Far fewer photosynthesizers meant less food was being produced at the base
ofnearlyallecosystems, whichmeantanimalsthatatethesephotosynthesizers died
too. After that, animals that ate the animals that ate photosynthesizers died. (Al-
though I also imagine scavengers very briefly having enjoyed an end-of-the-world
party, greedily chowing down on a sudden bounty of dead animals.) Think of the
food web holding together an entire ecosystem having one thread after another
ripped apart. We witness such trophic cascades today in ecosystems that undergo a
precipitous shock such as a major forest fire, volcanic eruption, or tsunami.
Yet the end-Cretaceous was far worse because it was global in scale, affecting
the food supply for animals in the seas and on the continents alike. Also, animals
living at the end of the Cretaceous with the misfortune of having large body sizes
had greater caloric needs, meaning bigger was not better for them in this situation.
So large animals likely died the soonest after the impact, and yes, I am talking
about dinosaurs, including much beloved ones such as
Triceratops
,
Tyrannosaur-
us
,
Hadrosaurus
, and
Ankylosaurus
, to name a few. All non-avian dinosaurs had
no way to survive such terrible conditions, even the ones living in polar environ-
ments. Thus they went extinct, while some of their somehow luckily adapted des-
cendants—birds—survived and thrived, giving dinosaurs a second chance in a rad-
ically transformed world. Among land-dwelling vertebrates, mammals, crocodili-
ans,turtles,lizards,andamphibiansalsogotticketstorideontheCenozoicExpress;
their lineages evolved and had their own more modest extinctions since.
Now throw a post-Cretaceous monkey wrench into this scenario in the form of
burrowing dinosaurs. Burrowing was a strategy that at least a few small non-avian
dinosaurscouldhaveusedtosurviveanend-Cretaceous “meteorite winter.”Justre-
call a few of the advantages of a burrowing lifestyle, and suddenly an apocalypse
