40 | New Scientist | 1 August 2020
seems to have walked on four legs when
young, but graduated to two legs as it grew.
There may never be a simple answer
to the 200-million-year-old riddle of how
the dinosaurs took the Jurassic throne.
Our best guess is that they held a winning
hand of adaptations: efficient lungs, high
metabolism, fast growth and possibly
other assets that we don’t yet understand.
Together, they won the pot. But if the
environmental conditions they faced had
been just slightly different, the rules of the
game would have been changed, and the
age of the dinosaurs may never have come
to pass. As it worked out, however, those
footprints on the edge of the lake were the
start of an epic journey to greatness. ❚Steve Brusatte is a palaeontologist
at the University of Edinburgh.
His most recent book is The Rise
and Fall of the DinosaursTr ia s s i c wo r l d
In the days of the Triassic,
the world would have been
scarcely recognisable to us.
All land was joined together
into a supercontinent.
“Pangaea extended from
pole to pole and straddled
the equator, shaped like the
video-game icon Pac-Man,”
says Jessica Whiteside at the
University of Southampton,
UK. Surrounding this
was a vast ocean called
Panthalassa.
You might think that
animals would range freely
across Pangaea, as there
were no seas or major
geographic barriers breaking
up the land. But no. “Although
an ambitious animal could
walk across it in a single
lifetime, there were climate
zones that controlled whereorganisms lived,” says
Whiteside. Her research has
shown that the equatorial
region of Pangaea was
obscenely hot and muggy,
while its deserts would
routinely be hotter than 50°C.
Dinosaurs had trouble
colonising these extreme
regions and lived mostly
in mid-latitude areas.
Pseudosuchians, thesuccessful group of Triassic
lizards (see main story),
also lived in these latitudes,
but managed to spread
to the interior deserts too.
As animals go, they must
have been seriously
tough customers.a tad different from those of modern birds.
Cecilia Apaldetti at the National University
of San Juan in Argentina is contemplating
an idea that takes pneumaticity to a whole
new level. Over the past decade, her team
has unearthed a bounty of new dinosaurs
from the late Triassic rocks of the Marayes-El
Carrizal basin in Argentina. Among these
is a species she and her colleagues named
Ingentia prima. This may be the oldest known
dinosaur to get bigger than an elephant. And
its skeleton is riddled with holes, suggesting
the air sacs proliferated widely. Essentially,
this animal’s lungs ran through its whole
body. It is as weird as it sounds.
“These dinosaurs had an improved
breathing system that provided them with
numerous advantages,” says Apaldetti. With
air sacs spread throughout most of their
bodies, they were able to take in oxygen
super-efficiently and circulate air through
their innards, helping them keep cool. This, in
turn, would have supported a fast metabolism
and rapid growth. Their bones were also light.
All of these factors together would have set
dinosaurs up to get gigantic without running
into problems, like getting too heavy to
support themselves or overheating.
It is easy to imagine how any one of these
things might have helped dinosaurs ride out
a few hundred thousand years of global
warming, foul atmospheres and ecosystem
breakdown. Add them together, and they
may have been almost indestructible.
Where does that leave Bakker and Charig’s
hypothesis that dinosaurs were better
runners than the crocs? Hutchinson’s group
is revisiting this through an ongoing project.
“Past ideas about locomotion were based
almost solely on anatomy,” says Hutchinson.
But that doesn’t necessarily tell you how fast
an animal was. He and his team are instead
using laser scans of fossils to build digital
models of dinosaurs and pseudosuchians,
which they put through gymnastics routines
to test how the animals would have moved.
The work won’t be finished for another year or
two, but the team has already cast fresh light
on how dinosaurs got around. One species“ Essentially, this
animal’s lungs
ran through
its whole body.
It is as weird
as it sounds”
GARY
HI
NC
KS
/^ SCIENC
E^ PHOTO
LIBRA
RYAbout 220 million years
ago, Earth’s land mass
looked starkly different