New Scientist - USA (2022-04-16)

16 April 2022 | New Scientist | 27

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The columnist

Why Chanda Prescod-

Weinstein is focusing

on dark matter p28

Aperture

Incredible shots

of pufferfish, toxic

waste and more p30

Letters

Global catastrophes

also threaten to

destroy hope p32

Culture

A memoir about

finding love and the

science behind it p34

Culture columnist

Simon Ings on the

space-age animation

Apollo 10½ p36

T

HE study of dinosaurs
has made some amazing
strides in the past 20 years.
The discovery of numerous
fully feathered dinosaurs offers
incontrovertible evidence of
the evolution of birds from
their non-flying ancestors, for
instance. We also have fossils
that preserve ancient patterns
of these long-extinct animals.
Around 50 new dinosaur
species have been named every
year of the past two decades.
New studies have appeared on
dinosaur behaviour, ecology,
sex, physiology, brain structure,
hearing and many more features
besides. It is truly a treasure trove
of data, and new avenues of
research keep producing ever
more interesting and surprising
insights into these animals. And
yet, rather inevitably, the fossil
record is incredibly incomplete.
For all the progress that has
been made in two centuries of
studying dinosaurs, there are
still innumerable things that
we don’t know about them.
We may have some ideas about
the colours of a few dinosaurs,
but these are only a handful of
individuals that may not even
be that representative of their
species, let alone any others. We
have done detailed studies of how
Tyrannosaurus rex could stand,
walk, run and turn, but there is
nothing like this even for the other
30 species of tyrannosaurs, let
alone other groups. Those gaps
may at least be filled with new
MIfinds one day, but what about the
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things we might never know?

Think about some of the

strangest animals out there,

those that are most unlike their

near relatives or are hold-outs

of some long-lost group. Giant

tortoises, marine iguanas and

flightless cormorants on the

Galapagos Islands; kiwis, kakapo

and tuatara in New Zealand; the

(now sadly extinct) rails of Hawaii;

lemurs and extinct elephant

birds on Madagascar; and so on.

What they have in common is

where they live – islands, usually

ones that are both volcanic and

a long way from any other land

masses, and they are often tropical

too. These are places where

isolated populations can cling

on and take interesting turns,

as small groups evolve under

unusual conditions. They are

often free from some of the

constraints that come from

the presence of competitors and

predators, which can allow them

to flourish where elsewhere they

have perished, or to diversify and

produce new and unusual forms.

The thing is, though, such

environments are terrible for

forming fossils. Small bits of land

are likely to have limited numbers

of large rivers and lakes with lots

of silt to bury animals. Tropical

environments have very high

rates of decay, so dead bodies often

don’t last long enough to be buried.

Volcanic islands can easily sink

into the sea and be at the mercy of

tectonic activities, and such places

are generally very unlikely to be

exposed on the surface where

palaeontologists can pick at

them 100 million years later.

In short, however bizarre we

consider dinosaurs to be now,

they almost certainly produced

far more interesting and unusual

animals on all manner of islands

in the Mesozoic Era (around

252 million to 66 million years

ago), but it is incredibly unlikely

that we will ever find them.

Either the fossils never formed or

those islands have been destroyed

and are now inaccessible.

Our knowledge of the evolution

of animals on islands is enough

to give us confidence that strange

dinosaurs appeared in these

places, though similarly, our

understanding of the processes

of fossilisation tells us that we are

unlikely to access the fossils in

the future, however much we dig.

We have learned so much

about dinosaurs, and there

is still so much more to come.

But there are fascinating gaps

we might never fill, with only

tantalising hints about these

wondrous ancient creatures.  ❚

Mysterious beasts

Despite two centuries of incredible discoveries, there are some

things we will never know about dinosaurs, says David Hone

David Hone is the

author of The Future

of Dinosaurs (Hodder

& Stoughton)