A brief tour of the last 4 billion years (dinosaurs not included) | Lauren Sallan


Paleontology, a science geared towards small children, focused on digging up dinosaurs while sporting a “Jurassic Park” costume. Skulls are popped out of the ground and put on display for public gawking. The relevance of this, beyond clickbait,
coloring books and monster movies is unknown. No … Wait. That’s not paleontology at all. Paleontology is nothing less
than the study of past life. All past life. From ancestors to alien forms. It involves fundamental questions
like “Who are we?” And “How did we get here?” — using the broadest possible
definition of “we”: life itself. Dinosaurs, a category of birds, are just a small percentage of that. (Laughter) Yet they get the most media attention. [The incredible diversity of ancient life,
Dinosaurs, Paleontology] It’s a very accurate meme;
I didn’t even make this one. This is just the truth. Anyway, most of us paleontologists
consider dinosaurs to be a gateway drug. There is so much cooler stuff
in the fossil record, and we know so much about it. Let’s go on a brief, dinosaur-free tour of the last four billion years. (Laughter) First up, genetic material. Viruses, basically,
started producing proteins and wrecking their environment. The Earth was infected with life. Some of these new bacteria
learned how to eat sunshine, producing oxygen, pulling in carbon from the air and destroying the iron food
of other microbes by turning it into rust. This went on for billions of years. Some bacteria consumed other bacteria, gaining their power
to turn oxygen into energy, becoming the precursors
of animals and plants. But as a result,
there were climate shocks, from hot to cold and back again, which ended up turning the Earth
into a snowball covered with glaciers. The technical term for this time period
is “Snowball Earth.” (Laughter) Seven hundred, eight hundred
million years ago. Anyway, microbes banded together, creating multicellular life. Six hundred million years ago, geometric colonies appeared,
sucking microbes from the water. These were soon replaced
by the ancestors of modern animals. The Cambrian explosion. Lobster relatives ate other animals, capturing them using their grasping arms. Armored wriggling clam worms
crawled across the seafloor and into it, creating new ecosystems. Our tadpole-like ancestors
flitted along ancient coastlines, while their eel-like relatives
with gnashing throat teeth swam above the ice-cream cone corals
of the first reefs, dodging school-bus-sized krakens and hungry sea scorpions. Plant fungus came onto land. But then the glaciers returned,
killing pretty much everything. But mass extinctions open opportunities. Jawless fishes invaded the ocean, sporting points, prongs,
and finally, fins. Spiders, scorpions, snails
and worms came onto land. Somewhere around China,
a fish developed jaws, and its descendants drove jawless fishes, sea scorpions and branching plankton to extinction. Some of these fishes, which had arm bones in their fins, sprouted fingers, seven or eight per flipper. On land, plants became trees, growing massive or spreading their spores
only once before dying. But then the glaciers came back again, and it was mass extinction number two. It was the age of weird fishes
and plated sea lilies. Sharks with wings. Sharks with buzz saw jaws. Sharks with fins covered in tiny teeth. Sharks with crushing tooth plates. Bony fishes that looked like
modern angelfish and eels for the first time. Wetlands developed, sporting ten-foot-long millipedes
and giant dragon flies. These spread across the supercontinent
of Pangaea and died, creating coal, leading to a 100-million-year Ice Age. Finally, vertebrates made it onto land
on a permanent basis, leading to alligator-like amphibians and saber-toothed protomammals. But then, volcanoes erupted
all over Siberia, everything almost died and it was mass extinction number three. (Laughter) The day life nearly died. A single, lonely tusked mammal
survived and thrived, but it was soon replaced
by galloping crocodiles. In the ocean, marine reptiles, giant rafts made of the living
relatives of sea urchins and armored squids, ammonoids,
of every kind and form. But then, Pangaea started to split apart, forming a sea of lava that would one day become
the Atlantic Ocean, spewing toxic gas into the atmosphere and mass extinction number four. (Laughter) Yeah, there’s actually
a lot more than these five, these are the big ones. (Laughter) So, finally, there were
whale-sized fishes, and modern fishes mobbed corals, made gigantic by using
their captured algae to eat sunshine. Crabs, stingrays and other fishes
with crushing teeth appeared, smashing shells and leading to an arms race
between predators and prey. There was an explosion
of marine biodiversity. Mammals climbed trees, flew and did a lot of other things
that are seemingly sort of modern. They were feeding on the first flowers
pollinated by the first bees. There were ecological revolutions
on land and at sea, leading to the modern world. Except that an asteroid hit Mexico, and then that triggered volcanoes
on the other side of the world in India, and everything almost died again. (Laughter) But — there’s always a but,
because we’re still here — mammals arose from the ashes, became small under extreme heat
and then ever larger. There were palm trees
and snakes in the Arctic. Predatory deer dogs frolicked
along ancient rivers, while their relatives
returned to the ocean to become the first otter-like whales. Not hyenas and other sort of carnivores were chased off by giant
long-necked rhinos. Everything at this point
seems kind of familiar but not really. In Antarctica, an ice age started, forming the first permanent polar ice cap
in two hundred million years. This dried out the rest of the world, but it allowed the rise of grasses,
of rodents, of cats. Somewhere in Africa, an ape started walking
across the new savannah. Oh, and there were giant
saber-toothed salmon, I just have to mention that. (Laughter) So, we know all of this happened and so much more. How? Why? Paleontology is a thriving science at the intersection of multiple
other fields and technologies. There is no bigger data
than the fossil record, and we mine every bit of it. We use CAT scans, we use isotopes, we use genomes, we use robots, we use mathematical simulations and all kinds of analytics. We maximize all of it
so that we can understand the past and how evolution works. It also lets us make
predictions for the future. What will happen after the next
mass extinction? What weird things will show up? Will mammals get smaller again? Will there even be mammals? In sum, we have learned a lot about dinosaurs. But there’s so much left to learn from the other 99.9 percent of things
that have ever lived. And that’s paleontology. Thank you. (Applause and cheers)

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