Discover 1-2

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12

January/February 2018^ DISCOVER^23

FROM LEFT: SOUTHWEST RESEARCH INSTITUTE; MICHAEL BENSON/KINETIKON PICTURES; DEVIBORT VIA WIKIMEDIA COMMONS CC 3.0; ROBERT REISZ

Q

What did we know about Enceladus

before Cassini?

A

We knew nothing. We didn’t know anything
about the vents. We didn’t know anything about
the global ocean. We knew it was a small, icy moon
in the Saturn system. But the Saturn system is full of
small, icy moons.

Q

What would it be like flying along

with Cassini over Enceladus?

A

The action happens pretty fast because you’re
traveling at 7 or 8 kilometers per second.
And [Enceladus] is pretty small — it's like the
size of Arizona.
You’re getting pummeled by these little ice grains.
As you’re flying over, you’ll see these geological fea-
tures, these scars — little channels, basically — what
we call the “tiger stripes.” Within those tiger stripes
are the vents, straight from the global ocean. And
above the surface of the ocean, a splash comes up —
you can imagine a splash from a wave — that will in-
stantly freeze. That’s what creates these grains. These
have information about the salt content of the ocean
and some of the organics that are present there.

Q

How close did Cassini get?

A

We went really close. It was about 50 kilometers
— the closest flyby over the tiger stripes. We
could look at the chemical balance and determine
that the [hydrogen] we saw was sufficient to provide
food for microbes. The obvious message is let’s go
back and try to find life.

Q

At this point, would you be surprised

if we didn't find life on Enceladus?

A

I would be a bit surprised, yes. But I would be
happy to find the answer one way or the other
because I think both — whether you find it or not —
will lead to a better understanding of how life arose
on Earth and what it really means.

Protein in Dinosaur Rib

Is 195 Million Years Old

❯

RESEARCHERS IN TAIWAN used an

innovative technique to find the protein

collagen in a dinosaur rib that’s a whopping

195 million years old. Other researchers had

previously identified proteins in fossils less than

half as old, but those efforts required destroying

part of the fossil itself.

The new method,

described in Nature

Communications in

January, allows scientists

to read chemical

signatures present within

a specimen to identify

proteins and other organic

remains non-destructively.

“Most other material is

extracted by dissolving the bone,” says co-author

and paleontologist Robert Reisz of the University

of Toronto Mississauga. “But if you did that

with this specimen, you’d see nothing.”

The team looked instead at tiny blood

vessels, about half the diameter of a human

hair, within the rib of an Early Jurassic

Lufengosaurus specimen. There they found the

specific chemical signal of collagen, which is

crucial to connective tissue.

The specimen also contained hematite, likely

derived from the animal’s blood. The team

believes the hematite sealed the blood vessels,

protecting the collagen from contamination

and degradation.

Researchers hope the process of reading

the chemical signatures can be refined to

reveal details of dinosaur biology — such

as thermoregulation — that are difficult to

determine from conventional fossils.

“The point is that, if you look, you can

actually find remains of soft tissues in deep time,”

says Reisz. “It opens up our eyes.”  GEMMA TARLACH

Hematite (shown as dark spots)

sealed blood vessels in the fossil,

helping preserve the collagen.

Lufengosaurus