HOW IT WORKS DISCOVER THE DINOSAURS Ed2 2021

Trivia

Sauropods possessed a
number of traits that supported
such long necks

Dinosaurs such as Omeisaurus
needed long tails to

counterbalance their necks

feet (one meter) long. When it comes sauropoD secreTs Images: Getty Images
to extinct animals, the largest land-
living mammal of all time was the In their study, Taylor
rhino-like creature Paraceratherium, and his colleagues
which had a neck maybe 8.2 feet (2.5 found that the neck
meters) long. The flying reptiles known bones of sauropods
as pterosaurs could also have possessed a number of
surprisingly long necks, such as traits that supported such long necks.
Arambourgiania, whose neck may For instance, air often made up 60
have exceeded ten feet (three meters). percent of these animals’ neck bones,
with some as light as birds’ bones,
The necks of the Loch Ness making it easier to support long
Monster-like marine reptiles known as chains of them. The muscles, tendons
plesiosaurs could reach an impressive and ligaments were also positioned
23 feet (seven meters), probably around these vertebrae in a way that
because the aquatic environment helped maximize leverage, making
they lived in could better support neck movements more efficient.
their weight. But these necks were
still less than half the lengths of the In addition, the dinosaurs’ giant
longest-necked sauropods. torsos and four-legged stances
helped provide a stable platform for

Par acer ather ium

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their necks. In contrast, giraffes have having Pac Man/Cookie Monster Long necks would help with
relatively small torsos, while ostriches flip-top heads,” researcher Mathew reaching food, but they could
have two-legged stances. Wedel at the Western University of
Health Sciences in Pomona, have had other uses
Sauropods also had plenty of California, told us.
neck vertebrae, up to 19. In contrast, mammals to do. Just try it with a
nearly all mammals have no more “It’s natural to wonder if the lack length of garden hose,” Taylor said.
than seven, from mice to whales to of chewing didn’t, well, come
giraffes, limiting how long their back to bite them, in terms of As to why sauropods evolved such
necks can get. (The only exceptions digestive efficiency. But some long necks, there are currently three
among mammals are sloths and recent work on digestion in large theories. Some of the dinosaurs may
aquatic mammals known as sirenians, animals has shown that after have used their long necks to feed on
such as manatees.) about three days, animals have high leaves, like giraffes do. Others
gotten all the nutrition they can may have used their necks to graze
Moreover, while pterosaur from their food, regardless of on large swaths of vegetation by
Arambourgiania had a relatively giant particle size. sweeping the ground from side to
head with long, spear-like jaws that it side like geese do. This helped them
likely used to help capture prey, “And sauropods were so big that make the most out of every step,
sauropods had small, light heads that the food would have spent that long each of which would be a big deal for
were easy to support. These dinosaurs going through them anyway,” such heavy creatures.
did not chew their meals, lacking even explained Wedel. “They could stop
cheeks to store food in their mouths; chewing entirely, with no loss of Scientists have also suggested
they merely swallowed it, letting their digestive efficiency.” that long necks may have been
sexually attractive, therefore driving
guts break it down. wHaT’s a lonG neck the evolution of ever-longer necks;
“Sauropod heads GooD for? however, Taylor and his team have
are essentially all found no evidence this was the case.
Furthermore, sauropods and other
mouth. The jaw joint dinosaurs probably could breathe In the future, the researchers
is at the very back of like birds, drawing fresh air through plan to delve even deeper into the
the skull, and they didn’t their lungs continuously, instead of mysteries of sauropod necks. For
have cheeks, so they having to breathe out before instance, Apatosaurus had “really
came pretty close to breathing in to fill their lungs with sensationally strange neck
fresh air like mammals do. This may vertebrae,” Taylor said. The
Images: Getty Images, Alamy (skeleton) have helped sauropods get vital scientists suspect the necks of
oxygen down their long necks to Apatosaurus were used for “combat
their lungs. between males — fighting over
females, of course.”
“The problem of breathing
through a long tube is
something that’s very hard for

Apatosaur us

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Trivia

Sauropods had small, light
heads that were easy to support

Sauropods had more than
double the neck vertebrae of

most mammals

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CoulD Evolution
EvEr Bring BaCk
thE Dinosaurs?

Could the evolutionary process
make Jurassic Park a reality?

By Jane Labous

D id you watch the 1993 movie Jurassic Park — could ever help
blockbuster Jurassic Park and recreate an extinct dinosaur.
wonder, “Could this happen for
real? Could the dinosaurs ever come “We do have mosquitos and biting
back?” The idea that these mighty flies from the time of the dinosaurs,
creatures could wander our Earth and they do preserve in amber,”
again some day is for most humans Maidment said. “But when amber
both fascinating and terrifying in preserves things, it tends to preserve
equal measure. the husk, not the soft tissues. So, you
don’t get blood preserved inside
Even real-life scientists are intrigued mosquitos in amber.”
as to whether the evolutionary
process could bring us back to the Researchers have found blood
time of the Tyrannosaurs. But Susie vessels and collagen in dinosaur
Maidment, a vertebrate paleontologist fossils, but these components don’t
at London’s Natural History Museum, have actual dinosaur DNA in them.
quickly dismissed the notion that a Unlike collagen or other robust
DNA-filled mosquito preserved in proteins, DNA is very fragile, and
amber for millions of years — as in sensitive to the effects of sunlight
and water. The oldest DNA in the

Jurassic Park and its sequels led to
people imagining the possibility of

dinosaurs living in our world

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Image: Shutterstock

fossil record is around 1 million years Ichthyosaurus were marine
old, and the dinosaurs died out about reptiles that lived during the late
66 million years ago.
Triassic/early Jurassic period
Maidment added: “Although we have
what appears to be blood from They say that dinosaurs went
mosquitos up to 50 million years old, extinct, but only the non-avian
we haven’t found DNA, and in order to dinosaurs went extinct
reconstruct something, we need DNA.”
Utahr aptor control,” he told us. This, in turn,
Jamal Nasir, a geneticist at the could create the right conditions for
University of Northampton in the evolution to take a path toward
United Kingdom, said he wouldn’t rule reinventing the ancient reptiles.
out the idea of dinosaurs evolving
back from the dead. In his opinion, However, while evolution might
evolution isn’t fixed or planned. In not be directional in any particular
other words, anything could happen. sense, something we do know is
“Evolution is largely stochastic
[randomly determined], and evolution that we don’t see the
doesn’t necessarily have to go in a same animal evolving
forward direction; it could have again, Maidment
multiple directions. I would argue that countered. “We can
going back to dinosaurs is more likely
to happen in reverse, because the see an animal that is
building blocks are already there.” closely related occupying a
similar ecological niche — for
Of course, Nasir pointed out, the example, ichthyosaurs were marine
right conditions would have to exist reptiles with long pointy snouts and
for dinosaurs to reappear. “Clearly, dolphin-like body shapes and tails,”
one could imagine viral pandemics she explained. “Today we see the
that might disrupt our genomes, our dolphin, and they probably occupy a
physiology and behavior beyond our similar ecological niche. But we
wouldn’t describe a dolphin as an
Unfortunately, being able to ichthyosaur because they don’t
extract dinosaur DNA from a possess the anatomical
preserved mosquito is unlikely characteristics that allow them to
be ichthyosaurs.”

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Trivia

Despite some visual similarities,
ichthyosaur and dolphins don’t

share anatomical features

Besides, dinosaurs never quite died birds evolving — and those will be new Things have changed drastically
out in the first place, Maidment said. species of dinosaur.” over 66 million years, and if one day a
Birds evolved from meat-eating dinosaur evolved back onto Earth, it
dinosaurs, and thus in strict biological Some scientists are even dabbling would be to a very different world.
definition, everything that evolved with the evolution process by trying to
from this common ancestor is a reverse engineer a chicken into a “An animal that died out naturally,
dinosaur, sharing the same dinosaur, dubbed the perhaps 150 million years ago, is not
anatomical characteristics, she said. “chickenosaurus.” However, this going to recognize anything in this
beast, if it ever comes to fruition, world if you bring it back,” Maidment
“Dinosaurs are still with us,” would not be a replica of a dinosaur, noted “What is it going to eat when
Maidment said. “They say dinosaurs but rather a modified chicken, Jack grass hadn’t [yet] evolved back then?
went extinct, but only the non-avian Horner, a research associate at the What is its function, where do we put
dinosaurs went extinct. Birds are Burke Museum at the University of it, does anyone own it?”
dinosaurs, and birds are still evolving, Washington, told us.
so we will certainly see new species of That said, it may be
best to let sleeping
dinosaurs lie, she said.

Our planet is completely different Images: Getty Images
to how it was when dinosaurs
roamed it

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Could dinosaurs
Have survived
THe asTeroid?

What were the odds of avoiding a mass extinction?

By Charles Q. Choi

T he age of dinosaurs met an more than 110 miles (180 kilometers)
unlikely end — because had the across near what is now the town of
cosmic impact that doomed it Chicxulub in Mexico’s Yucatán
hit just about anywhere else on the Peninsula. The meteor strike would
planet, the “terrible lizards” might still have released as much energy as 100
roam the Earth. trillion tons of TNT, over a billion
times more than the atom bombs
The impact of an asteroid about six that destroyed Hiroshima and
miles (ten kilometers) wide about 66 Nagasaki combined. The blast is
million years ago created a crater

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Trivia Image: Alamy

The mass extinction event occurred
around 66 million years ago, at the end

of the Cretaceous period

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More than three-quarters of all Volcanic eruptions
life was wiped out by the contributed to climate change
extinction event
and the mass extinction

thought to have ended the age of The probability of the mass
dinosaurs, killing off more than 75 extinction occurring was only 13 percent
percent of all land and sea animals.
surface to rapidly cool, leading to a The amount of hydrocarbons in
Prior work suggested the Chicxulub so-called “impact winter” that would rocks varies widely depending on
impact would have lofted huge have killed off plants, causing a global location. In a recent study, the
amounts of ash, soot and dust into collapse of terrestrial and marine Japanese researchers analyzed the
the atmosphere, choking off the food webs. places on Earth where an asteroid
amount of sunlight reaching Earth’s impact could have happened to
surface by as much as 80 percent. To explain why the Chicxulub cause the level of devastation seen
This would have caused Earth’s impact winter proved so with the Chicxulub event.
catastrophic, Japanese scientists
previously suggested the super-hot The scientists now
find the asteroid
debris from the meteor strike not that wiped out
only caused wildfires across the the dinosaurs
planet, but also ignited rocks happened to
loaded with hydrocarbon hit an unlucky
molecules like oil. They spot — had it
calculated that such
oily rocks would have
generated vast
amounts of soot.

Had the asteroid landed
elsewhere, life as we know it
would be completely different

Dimetr odon

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Trivia

Hot debris caused fires and
rocks loaded with hydrocarbon

to catch fire

landed in about 87 percent of have generated depending on the This would involve an asteroid
anywhere else on Earth, the mass amount of hydrocarbons in the impact sending 385 million tons (350
extinction might not have occurred. ground. They next estimated the million metric tonnes) of soot into
climate effects caused by these the stratosphere.
“The probability of the mass different impact scenarios.
extinction occurring was only 13 The scientists found that a mass
percent,” said study lead author The researchers calculated the extinction would have occurred from
Kunio Kaiho, a geochemist at Tohoku level of climate change needed to the impact only if it had hit 13 percent
University in Sendai, Japan. cause a mass extinction was a 14.4 of the surface of the Earth, including
to 18 degrees Fahrenheit (8 to 10 both land and oceans. “If the asteroid
The scientists ran computer degrees Celsius) drop in global had hit a low- to medium-level
models simulating the amount of average surface air temperatures. hydrocarbon area on Earth,
soot that asteroid impacts would occupying approximately 87 percent
of the Earth’s surface, mass
Those not killed by the crash or extinction could not have occurred,” Images: Getty Images
ensuing tidal waves would have Kaiho told us.

suffered under acid rain The scientists also analyzed the
level of climate change “caused by
large volcanic eruptions that may
have contributed to other mass
extinctions,” Kaiho said, to further
understand the processes behind
those mass extinctions.

Kaiho and his colleague Naga Oshima
at the Meteorological Research
Institute in Tsukuba, Japan, detailed
their findings online on 9 November
2017 in the journal Scientific Reports.

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Dinosaurs died out around 66 million years ago
but scientists estimate that their DNA could only

have survived one million years

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Is It PossIble to
Clone A DInosAur?

Molecular paleontologist Mary Schweitzer explains whether
there is a chance of cloning the prehistoric creatures

By Laura Geggel

A pologies to people keen to DNA has been discovered in
revive extinct dinosaurs, but dinosaur bone, but identifying it
researchers have never
recovered the DNA needed for cloning. seems unlikely
But, intriguingly, they have found
fragments of mystery DNA in dinosaur We couldn’t recover it, [and] we
bone, experts have told us. couldn’t characterize it. Whoever it
belongs to is a mystery
It’s unknown whether this DNA is
dinosaurian, or whether it belongs to Schweitzer explained. “It is too prone required to clone an extinct dinosaur. Images: Getty Images, Alamy (fossil)
other life-forms, such as microbes; to contamination and really difficult Here is the science that it would take
non-dinosaurian animals, such as to interpret.” to create an actual Jurassic Park-
earthworms; or even paleontologists style dinosaur, according to
who have worked with these fossils. Instead, Schweitzer analyzes molecular experts.
dinosaur fossils for soft tissue, such
“I’ve found DNA in dinosaur bone,” as the blood vessels that she and her How long CAn DnA survIve?
said Mary Schweitzer, a molecular colleagues found in an 80-million-
paleontologist at North Carolina State year-old duck-billed dinosaur. But Scientists need DNA to clone
University. “But we did not sequence it she has still pondered the steps dinosaurs, but an organism’s DNA
— we couldn’t recover it, [and] we
couldn’t characterize it. Whoever it
belongs to is a mystery.”

It’s no surprise that dinosaur
remains contain DNA, she said. Bone
is partly made up of a mineral called
hydroxyapatite, which has a strong
affinity for certain biomolecules,
including DNA. In fact, researchers
often use hydroxyapatite to purify and
concentrate DNA in the lab,
Schweitzer said.

“That’s one of the reasons that I
don’t work with DNA myself,”

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starts decaying the moment after that million or six million years, Schweitzer Over 66 million years, DNA
organism dies. said. That’s woefully short of 65 breaks down due to enzymes
million years ago, when the asteroid
That’s because enzymes (from soil slammed into Earth and killed the and other elements
microbes, body cells and gut cells) non-avian dinosaurs.
degrade DNA. So does UV radiation. what conditions, DNA can survive,
What’s more, oxygen and water can However, more experiments are Schweitzer said.
chemically alter DNA, causing the needed to determine how long, and in
strands to break, said Beth Shapiro, Moreover, don’t expect a Jurassic
an associate professor in the Despite what films tell you, Park twist to work. In the 1993
Department of Ecology and dinosaur DNA cannot be blockbuster, scientists find dinosaur
Evolutionary Biology at the University preserved in amber DNA in an ancient mosquito caught in
of California, Santa Cruz. amber. But amber, it turns out, does
not preserve DNA well. Researchers
“All of these things will break down tried to extract DNA from two stingless
the DNA into smaller and more bees preserved in copal, a precursor of
degraded pieces, until eventually, amber, in a 2013 study published in
there is nothing left,” Shapiro the journal PLOS ONE.
explained to us.
The researchers couldn’t find any
The oldest recovered and “convincing evidence for the
authenticated DNA from bone belongs preservation of ancient DNA” in either
to a 700,000-year-old horse from the of the two copal samples they
frozen Klondike gold fields in Yukon, studied, and they concluded in the
Canada, said Shapiro, who co-wrote a study that “DNA is not preserved in
2013 study on it in the journal Nature. this type of material”.

Still, it’s unclear just how long DNA They added: “Our results raise
can survive. Scientists have proposed further doubts about claims of DNA
that DNA can survive as long as a extraction from fossil insects in
million years, but definitely not amber, many millions of years older
more than five than copal.”

DInosAur DnA?

If researchers choose to study the
DNA lurking in dinosaur bone, it will be
difficult to say whether it was
dinosaurian in nature, the experts said.

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We are unsure of just how long
DNA can survive, as more
experiments are needed

“The DNA fragments that were Don’t Images: Getty Images, Alamy (Corythosaurus, egg)
recovered from that horse bone were expect a
short (on average 40-ish letters long) Jurassic Park
and showed characteristic signs of twist to work
post-mortem damage,” Shapiro
explained. “But they could be mapped Cor ythosaur us
to the genome of a modern horse,
and so we know that they were of
horse origin.”

In contrast, the dinosaurs’ living
relatives are birds. But birds evolved
out of the theropod line — a group of
bipedal, largely carnivorous
dinosaurs such as Tyrannosaurus rex
and Velociraptor. All of the other
dinosaur groups — including the
hadrosaurs (the duck-billed
dinosaurs), the ceratopsians (such as
Triceratops), the stegosaurs and the

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There are so many problems said. “The carbon dioxide content
researchers would have to in the atmosphere was different;
the oxygen content was different;
overcome to clone a dinosaur the temperatures were different —
how is it going to function [in the
ankylosaurs — do not have any living “There’s more to developing a modern environment]?”
relatives to compare DNA with. vertebrate organism than just what its
DNA says,” she said. “A lot of the Moreover, the creature’s digestive
In addition, any surviving dinosaur timing is dictated by enzymes might not work on modern
DNA will be highly fragmented and genes and proteins that animals and plants, and it wouldn’t
badly damaged. the mother produces have Mesozoic microbes, which it likely
during development. would need to digest and absorb
“Here is a key problem with dinosaur How is it going to get nutrients, Schweitzer said.
DNA,” Shapiro said. “I would then have the developmental
to ask, ‘Is this dinosaur DNA, or signals that it needs?” “[Dinosaurs] were designed to break
microbial DNA that got into the down dinosaur proteins,” she
dinosaur bone while it was buried?’” Again, let’s say that, explained. “Or [ancient] plants, if you
somehow, the host want to bring a plant eater back, which
ClonIng ADventures mother was able to give I’d highly recommend.”
birth to this creature. The
For the sake of argument, let’s say that resulting offspring would It would be cruel to bring back just
researchers found fully sequenced be a half-bird, half- one dinosaur for our own amusement,
dinosaur DNA. This means that dinosaur creation, she said. And it takes at least 5,000
researchers would have an entire Schweitzer said. But animals to create a sustainable
genome, including the so-called junk could this animal population with genetic diversity,
DNA and the viral DNA that’s actually survive in Schweitzer said.
incorporated itself into the dinosaur’s today’s climate?
genetic code. This viral DNA could be a They’d
problem, especially if it could infect “Its genes and have to find a
modern plants and animals, proteins survived in a host organism
Schweitzer said. very different world,” she to help clone
the beast
Next, they’d have to find a host
Images: Getty Images, Alamy (egg) organism to help clone the beast. That
would likely be a bird. But a mother
bird is a far cry from a mother
dinosaur, Schweitzer said.

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“How are you going to clone 5,000 T. Dinosaur fossils may have
rex?” she asked. “And, if you could, collected other DNA after they
where are you going to put them?”
entered the soil
There are so many problems
researchers would have to overcome
to clone a dinosaur, Schweitzer said.
“Getting the DNA, which we have not
done — that would be the easy part,”
she said.

Still, she plans to continue her studies
on dinosaur bone. And though cloning
might be a pie-in-the-sky idea, she still
thinks about it from time to time.

“To be honest, I’d really like to see a
T. rex,” Schweitzer said. “It would be
very cool.”

Dinosaurs may not be able to
survive by eating today’s meat

and vegetation

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Would it have been
possible for us to live side by
side with these huge beasts?

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Trivia

Could Humans
and dinos Have
Coexisted?

What would the world be like if
dinosaurs still lived among us?

By Laura Geggel

W hat if the dinosaur-killing The Megazostrodon lived over Artist rendition on the evolution Images: Alamy, Getty Images (evolution chart)
asteroid never slammed 200 million years ago and was of life from billions of years
into Earth and the paleo- ago to today
beasts weren’t vanquished from our one of the first mammals
planet 66 million years ago? Would it Megaz ostr odon
have been possible for us to live side 119
by side with these huge beasts?

“It’s completely impossible,” said
Thomas Williamson, curator of
paleontology at the New Mexico
Museum of Natural History and
Science, referring to dinosaurs ever
being alive alongside humans —
something that could never happen if
the dinosaurs were to survive.

Though there were mammals during
the dinosaur’s reign of the Mesozoic
era, these animals were small, no
larger than the size of a house cat. It
wasn’t until the non-avian dinosaurs
went extinct that mammals grew in
size and specialty, eventually giving
rise to the human lineage about 60
million years later.

“Dinosaurs had been around for
over 150 million years when the
asteroid hit, and were doing quite well
up until that fateful day,” said Steve
Brusatte, a paleontologist at the
University of Edinburgh. If the
asteroid hadn’t hit Earth, “I have no

Mammals didn’t grow to the size doubt that they would have kept of species, spread around the world
of German Shepherds until after evolving and thriving.” and grew to gargantuan sizes.

the dinosaurs went extinct If dinosaurs hadn’t perished, “Mammals stayed in the shadows,”
“mammals would have never gotten and none of them seemed to
their chance to evolve in that brave dominate their environment, Brusatte
new world, free of their dinosaur explained. Instead, early mammals
overlords,” Brusatte told us. “Without mostly ate insects, maybe seeds and
mammals getting their chance, then the occasional tiny dinosaur,
there would have been no primates, according to fossil evidence.
and then no humans.”
When the six-mile (ten-kilometer)
Mammals originated about 220 wide asteroid collided with Earth,
million years ago, about the same time mammals and dinosaurs alike
as the dinosaurs during the late suffered great losses. All of the
Triassic. But dinosaurs got the upper dinosaurs — except birds — bit the
hand — they diversified into thousands dust, and about 75 percent of all

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Citipati

Avian creatures were the only
dinosaurs to survive after the
asteroid crashed into Earth

Mammals originated
about 220 million years ago

Despite what you see in films and TV, mammals died, said Gregory Wilson, and eating lots of different foods —
humans didn’t walk the Earth until long an adjunct curator of vertebrate traits that helped them endure the
paleontology at the Burke Museum of chaos after the asteroid hit.”
after the dinosaurs had died out Natural History and Culture in Seattle.
Once the non-avian dinosaurs were
But there were some survivors. gone, the mammals took over their
“A few plucky mammals made it ecological niches. Within a few
through the devastation of the hundred thousand years, mammals
extinction,” Brusatte said. “These rapidly evolved (geologically
mammals seemed to be ones that were speaking) into new species,
particularly small and had generalist diversified their diets and achieved
diets, so they could survive by hiding new sizes. About 500,000 years after
the dinosaur’s demise, some
mammals had reached the size of Images: Getty Images
German Shepherds, Williamson said.

These spirited survivors are the
reasons why there are more than
5,000 species of mammals today,
Brusatte added.

“It’s pretty obvious to me that none
of this could have happened if the
dinosaurs didn’t die out,” he said. “The
mammals that lived with the dinosaurs
had about 150 million years to make it
happen, but they could never do it. But
then, boom, right when the dinosaurs
died, the mammals began to
explosively diversify.”

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Could dinosaurs
swim?

While they spent most of their time on land, there
were things that motivated dinosaurs to enter water

By Charles Q. Choi

Yang chuanosaur us

They might not
have been graceful,
but they could swim
nevertheless

Some dinosaurs were
amphibious but the majority
spent most of their time on land

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Spinosaur us

w hether a team of even to swim across a river or a bay
dinosaurs could win an to a barrier island, and all the other
Olympic relay race is up reasons that an animal would decide
for debate. But they wouldn’t be to swim,” Gillette said.
afraid to jump in the water.
Like all reptiles,
All dinosaurs could swim, said dinosaurs breathed air
Dave Gillette, curator of paleontology and had to take regular
at the Museum of Northern Arizona breaths, whether they
in Flagstaff. were in or out of the water.

“They might not have been graceful, “Dinosaurs were
but they could swim nevertheless. surely just as adept at
Think of elephants or horses – they swimming, and just as
swim quite well even though their talented at taking in
bodies do not look like the bodies of sufficient air to continue breathing,”
swimmers at all.” Gillette said. “This all means that they
had to be buoyant, too, so they could
why swim? stay close to the surface of the water,
rather than sinking and drowning.”
Dinosaurs were motivated to swim by
the same instincts that send a beaver Although most dinosaurs spent a
or a duck to take a dip. majority of their time roaming the
land, some dinosaurs, such as
“They might swim to find food in Spinosaurus and Baryonyx, were likely
water, to hide from predators, to cool amphibious. Both of these species
off, to go from one bank or another, or

Baryonyx, like many other Images: Getty Images, Alamy (Baryonyx in water)
dinosaurs, are believed to have

entered water to hunt prey

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Other than skeletons of swimmers,
scientists have also discovered tracks
of wading dinosaurs.

Bar yonyx Mosasaurs like the Mosasaurus TraCks of swimmers
lived in shallow waters and
would lay eggs on land “Some trackways indicate that
dinosaurs ‘poled’ their way around in
There were a number of reptiles shallow water, like a boatman uses a
living in the seas during the pole to push a boat,” explained Gillette.
Mesozoic period “Or, like the way humans push off and
glide, then sink a little and then push
were as large as T. rex and had off again, and glide…”
an anatomy similar to that of
crocodiles. They also had huge For example, in 2007
skeletal spines on their backbone paleontologists from the University of
that looked like a sail, but Gillette said Nantes in France came across
those spines were covered with S-shaped prints on the bottom of
muscle and tendons and skin, and what was once a lake in the Cameros
could not have functioned as an actual Basin in Spain. The unusual tracks
wind-catching sail. suggest the animal’s body was
supported by water when it scratched
the lakebed.

In 2005 in Wyoming, Debra
Mickelson from the University of
Colorado at Boulder discovered
dinosaur tracks in what was an
ancient sea floor. The footprints
were left behind 165 million years ago
by a dinosaur believed to be about the
size of an ostrich.

“The swimming dinosaur had four
limbs and it walked on its hind legs,
which each had three toes,” Mickelson
said. “The tracks show how it became
more buoyant as it waded into deeper
water, the full footprints gradually
become half-footprints and then only
claw marks.”

Dinosaurs weren’t the only
creatures showing off their swim
strokes during the Mesozoic period.
Many reptiles living during the same
time as dinosaurs were restricted to
living in the sea.

“Plesiosaurs, mosasaurs and sea
turtles are all non-dinosaurian reptiles
that lived in the sea in the Mesozoic
and perhaps only came to land to lay
eggs,” Gillette said.

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Spinosaurus were more adept at Dinosaurs weren’t the Images: Getty Images
swimming through water than only creatures showing off
other dinosaurs their swimming strokes

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What If...

a Giant asteroid
Had not Wiped
out tHe dinosaurs?

How would creatures have evolved if Pur gator ius
dinosaurs still walked the Earth?

By Adam Hadhazy

o ther factors were involved in Most mammals during the time
dinosaurs’ extinction, but the of the dinosaurs were no bigger
resounding death knell was
the impact of a six-mile-wide asteroid than rodents
in present-day Mexico’s Yucatán
Peninsula 65 million years ago,
creating what is known as the
110-mile-wide, six-mile-deep
Chicxulub crater. The event
unleashed mega-tsunamis, planet-
wide wildfires and kicked up enough
dust and debris to block the sun and

126

Trivia

Intelligent “dinosauroids” might there be enough food for mammals to
have evolved in humanity’s place seize the day and eventually give rise
to us (knocking out the predators that
cause a period of global cooling, geosciences at would eat mammals helped, too).
which killed off many plants. Ohio University. Researchers have speculated that
Mammals did intelligent “dinosauroids” might have
HoW Would life look? co-evolve evolved in humanity’s place, based on
alongside the relatively large brain size of late-
Still dinosauric in all likelihood, dinosaurs, but they emerging trodontid species, which
assuming no other catastrophic, occupied fringe were bird-like predators.
extinction-level events transpired. After ecological niches and
all, dinos had a good long run of grew no larger than Of course, some of those dinosaurs
dominance on land for 160 million years rodents in most cases. that have survived into modern day
prior, and if that continued, primates Only with dinosaur — becoming birds — are quite smart,
like us would not be around, according plant-devourers gone would but not smart enough to have ended
to Damian Nance, a professor of up on the other side of the insult
“bird-brained.”

The mass extinction event killed Interpretation of what a Images: Getty Images, Alamy (big pterosaur),
around 75 percent of all life on dinosauroid may have looked like Wiki/FunkMonk CC BY 2.0 (Dinosauroid)

the planet if dinosaurs had never died out

127

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