Name: T. Rex Blood?
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<div class="rich-text">(This video is no longer available for streaming.) Paleobiologist Mary Schweitzer has defied the long-held belief that it is fruitless to search for preserved soft tissues in dinosaur remains. Most experts thought that such structures would have decayed and vanished long ago, but Schweitzer has found evidence of delicate structures such as blood vessels and red blood cells that have survived for millions of years.
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Preserved soft tissue, including possible blood vessels and red blood cells, are turning up in dinosaur fossils.

<div class="rich-text">Preserved soft tissue, including possible blood vessels and red blood cells, are turning up in dinosaur fossils.</div>

Preserved soft tissue, including possible blood vessels, turn up in dinosaur fossils.

T. Rex Blood?

Nature

<div class="rich-text"><h3>
 T. Rex Blood?
</h3>

 PBS air date: July 24, 2007



 NEIL DEGRASSE TYSON:
 
 Hello. I'm
Neil deGrasse Tyson, your host for
 <cite>
 NOVA scienceNOW
 </cite>
 .


 Most
of what we know about ancient life—and I'm talking millions of
years old—comes from these things, fossils. You know, they're
actually rocks. Over time, the bone and tissue has been replaced by minerals.
But there's only so much you can learn from a rock. Think about how much
more you could learn if, instead of a rock, what you found was the real thing.


 Peter
Standring met some researchers who've uncovered some rare remains.



 PETER
STANDRING
 
 (Correspondent): Bones tell us almost everything we know about
dinosaurs: the fantastic variety of species, their titanic size, their sheer
power. The frustrating thing is that there's still so much we'd
like to know that dinosaur bones haven't told us. Were they warm-blooded
or cold-blooded? How different were they from modern reptiles? To solve these
biological questions, today's paleontologists are starting to explore
radically new clues from dinosaur skeletons. Kristi Curry Rogers cuts into
their bones to examine the pattern of what was once living tissue.


 Is
it sort of like CSI for dinosaurs?



 KRISTI CURRY
ROGERS:
 
 It can be, sure. Sometimes
it's kind of a different method of detective work. We can see, in these
cross-sections of bones, evidence of pathology, evidence of dinosaur disease
and evidence of dinosaur bones breaking and healing themselves. All of that
stuff is available via the inside look at a dinosaur bone.



 PETER STANDRING:
 
 Analyzing the rock that
entombed dinosaur fossils is key to understanding how they were preserved,
which is the work of Kristi's husband, geologist Ray Rogers.



 RAYMOND ROGERS
 
 (Macalester
College): And I'm there to
try to place the discoveries in context, to try to find clues as to where may
be best to look for fossils. We've been pretty lucky in Madagascar.



 PETER STANDRING:
 
 For the last decade, the
African island has offered Ray and Kristi Rogers a spectacular excavation site.
They work in an area of remote grasslands where dinosaur bones literally cover
the ground, an ancient graveyard where an unusually large number of dinosaurs
died and were entombed by mudflows that preserved their bones.



 RAYMOND
ROGERS:
 
 The preservation is unbelievable.
The quality of the material is exceptional. This is a piece of bone from the
Madagascar locality. It, in many regards, doesn't even look like a
fossil; it's unstained. It's very light. It's not heavily,
densely filled with minerals. You look at a dinosaur bone in a museum and
it's brown, it's black, it's heavy as can be.



 PETER STANDRING:
 
 Heavy because fossils
are no longer hollow bones. Buried in the earth, empty channels inside the bone
fill up with minerals, becoming dark and stained, hard as stone. In some cases,
the bone tissue itself is completely replaced by minerals. It's difficult
to probe dinosaur biology with bones that have turned to rock, but the
Madagascar fossils were sealed in a clay-rich mud, preventing many of the
chemical changes that happen to most dinosaur bones.



 RAYMOND
ROGERS:
 
 This is typical of the Madagascar
material. It's not heavily stained. It's not been invested with
iron, with manganese. It doesn't look like a typical fossil. If you
didn't know, you might think you're picking up a cow bone today, a
bleached cow bone.



 KRISTI CURRY
ROGERS:
 
 I think this piece might be good,
or maybe...



 PETER STANDRING:
 
 The Madagascar bones are
so perfectly preserved that Ray and Kristi wondered if they might conceal clues
about how these dinosaurs lived, and why so many of them died in the same
place. To find out, they turned to their colleague, Mary Schweitzer, a
paleobiologist, whose study of ancient cells and tissues might solve the
mystery.



 MARY HIGBY
SCHWEITZER:
 
 We know that dinosaurs had to
have cells—bone cells, and muscle cells, and gut cells, and brain
cells—and that's one of the reasons we can study them, even though
they are extinct.



 PETER STANDRING:
 
 Schweitzer's career
defined itself in her native Montana when she was preparing one of the largest
skeletons of a Tyrannosaurus rex ever found.



 MARY HIGBY
SCHWEITZER:
 
 I was working on the leg
bones. And as I worked, I noticed a bunch of stuff. It was like, you know,
"This bone, it's hollow inside." And I was looking at this
thing thinking, "This is really interesting."



 PETER STANDRING:
 
 It was the inside of the
T. rex bone that fascinated Schweitzer, who made thin sections out of it. And
in these cross-sections of fossilized bone, she saw something that she and
everyone else had thought was impossible: round structures that looked like red
blood cells, dinosaur blood cells.



 MARY HIGBY
SCHWEITZER:
 
 Inside those channels where
the blood vessels would have run were these little round red structures that
were all kind of lined up like a train. And they were bright red and
translucent. Nobody else had seen anything like that before.



 PETER STANDRING:
 
 The very idea of blood
cells in a 70-million-year-old bone was more than unconventional, it was
radical.



 DEREK BRIGGS
 
 (Peabody Museum of Natural History, Yale
University): Nobody was
imagining that dinosaurs might have had preserved soft tissues.



 PETER STANDRING:
 
 Derek Briggs is curator
of invertebrate paleontology at the Peabody Museum at Yale University.


 So
along comes Mary Schweitzer, and she's starting to look inside dinosaur
bones and has made this startling discovery about the presence of red blood
cells. What was your initial reaction to that?



 DEREK
BRIGGS:
 
 Oh, I think the
same reaction as everybody's, that this was totally improbable,
she'd perhaps misinterpreted the evidence or was exaggerating the
potential for what she was seeing.



 PETER STANDRING:
 
 So, skeptical, at first?



 DEREK
BRIGGS:
 
 Oh, yeah,
definitely.



 PETER STANDRING:
 
 Paleontology has been
around for some time.



 DEREK
BRIGGS:
 
 One of the
oldest professions.



 PETER STANDRING:
 
 One of the oldest
professions. Has anybody else that you know of found similar things inside a
bone?



 DEREK
BRIGGS:
 
 No.



 PETER STANDRING:
 
 Why do you think it didn't
occur to anybody?



 DEREK
BRIGGS:
 
 Because we have
this clear understanding that part of all biological cycles involves decay. I
mean, nature is set up to break down that material and recycle it. So
it's just improbable that those kinds of very delicate structures would
survive, particularly for millions of years.



 MARY HIGBY
SCHWEITZER:
 
 When you think about it, the
laws of chemistry and biology and everything else that we know say that it
should be gone. It should be degraded completely.



 PETER STANDRING:
 
 But Schweitzer kept
searching for organic remains where no one had thought to look before. Her
mentor is Jack Horner, one of the most famous dinosaur hunters in the world.
When his team found another beautifully preserved T. rex in the remote Montana
Badlands, the massive leg bone had to be broken in half for transport, and
Schweitzer got to test fragments from deep inside the bone.



 MARY HIGBY
SCHWEITZER:
 
 The T. rex bone was filled
with a very unique bone tissue. When I turned it, you know, like that, and
looked down on it, and saw this tissue that you can see right there in
cross-section, I knew what it was.



 PETER STANDRING:
 
 It's called
medullary tissue, and it's what female birds build up inside their bones
as a source of calcium for the eggs they lay. All dinosaurs laid eggs, and it
made sense to Schweitzer that female dinosaurs produced the same kind of bone
tissue. It looks different from the surrounding bone, and it meant the T. rex
had to be a mother, expecting a clutch of dinosaur eggs.



 MARY HIGBY
SCHWEITZER:
 
 It was really exciting for me.

I thought, "There is nothing in my career that could possibly be cooler
than being able to identify the first pregnant T. rex."



 PETER STANDRING:
 
 No one had ever
identified medullary tissue in a dinosaur bone before. But, to be sure, Mary
Schweitzer directed her lab assistant to soak the bone sample in an acid
solution to reveal its structure so she could study it. What happened next
would change the way scientists thought about fossils forever.



 JENNIFER
WITTMEYER
 
 (North Carolina State
University): As I was looking in
the microscope, the medullary material was no longer hard. And, um, what was
left was this curled piece of tissue that I was using forceps to try and
flatten out. And when I poked into it, it was, it was spongy. It was flexible
and soft tissue.



 PETER STANDRING:
 
 Flexible tissue? From a
68-million-year-old dinosaur?



 MARY HIGBY
SCHWEITZER:
 
 Blood vessels, transparent,
hollow, pliable, flexible branching blood vessels that contained small, round,
red microstructures floating in the vessels. I said, "This is not
possible. Do it again."


 We got another piece of bone, we put it in the solution, we waited two or three
or four weeks, looked again...more blood vessels. We must have repeated
that with probably 17 or 18 different fragments of bone.



 PETER STANDRING:
 
 As soon as
Schweitzer's discovery of dinosaur soft tissue was published, people
thought of one thing: could we get a real life Jurassic Park? No paleontologist
believes we could ever get enough ancient DNA to clone a dinosaur. But could
fragments of genetic material be extracted from this new tissue?



 KRISTI CURRY
ROGERS:
 
 I think anything is possible. If
there are blood vessels and red blood cells preserved in a dinosaur, I think
it's quite possible that there will be DNA there as well.



 PETER STANDRING:
 
 Even without DNA,
proteins from soft tissue could begin to answer real mysteries about dinosaur
biology: evidence of warm blood versus cold blood, whether the large body size
of dinosaurs is linked to large cell size. The Rogers have a theory that
dinosaur mass deaths in Madagascar might have been caused by water poisoned by
algae. This poisoning event wouldn't show up in hard bone, but they might
be able to test the theory with dinosaur blood cells.



 RAYMOND
ROGERS:
 
 This structure...I mean,
there's a lot of structure there.



 KRISTI CURRY
ROGERS:
 
 Yeah.



 RAYMOND
ROGERS:
 
 If there's anything in this
tissue that Mary finds that actually can trace a toxin, that would be
fantastic—things like disease, diets; things like that from soft tissues
that you can't extract from hard tissue from true fossil bone.



 PETER STANDRING:
 
 The hope is that the
Madagascar fossils will allow Mary to find more dinosaur tissue. So Ray and Kristi
gather fragments of their best preserved fossils. A few days later, the samples
arrive at Schweitzer's lab at North Carolina State University. She uses
the same technique that yielded soft tissue in the T. rex bone, soaking the
fragments in a mild acid that dissolves away the mineral part of the bone. But
will she be able to find the same internal structures in Ray and Kristi's
fossils?



 KRISTI CURRY
ROGERS:
 
 There's only so much you can
know from looking at the outsides of bones, but when there's soft stuff
inside, the possibilities become almost endless.


 This
is a single cell.



 PETER STANDRING:
 
 Through photos from her
microscope, Mary hits the jackpot: pieces of biological history.



 MARY HIGBY
SCHWEITZER:
 
 Now, see, this is really cool.
It's what looks like vessels to me, connected together, transparent. And
you can see right there. You can see the branch points and stuff.



 PETER STANDRING:
 
 The Rogers are seeing
inside their collection of fossil bone as they've never seen it
before...structures that appear to be the vessels that once carried blood
inside a dinosaur's body.



 MARY HIGBY
SCHWEITZER:
 
 This is hooked together.
There's a transparent region.



 RAYMOND
ROGERS:
 
 Yeah, it's a tube with stuff
inside of it.



 PETER STANDRING:
 
 Branching, hollow, organic
material that scientists thought could never be preserved in a dinosaur fossil.



 KRISTI CURRY
ROGERS:
 
 That's amazing, that this is
from 65-, 70-million-year-old bone.



 PETER STANDRING:
 
 It's too early for
these structures to reveal details like dinosaurs dying from poisoned water,
but dinosaur soft tissue opens a door that no scientist thought even existed
until Schweitzer's work changed that assumption.



 DEREK
BRIGGS:
 
 There's
little doubt in my mind that what she has discovered are internal structures in
dinosaur bone. And we may look back and say, "Well, this sort of approach
to looking at fossil vertebrate biology has revolutionized the field."
But we won't know that for some time yet.



 RAYMOND
ROGERS:
 
 To get in there and to find soft
tissues, to find blood vessels, to find cells, it is an opportunity to go to
places that we never thought we would be venturing just 10 years ago.
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