Well thank you for coming tonight. I'm
going to give you a summary of my last
20 years or so of my research career in
studying dinosaur movement, especially
with the focus on size. So dinosaurs of
course are famous for being large and
that's what we'll largely talk about is big
dinosaurs and how they handled being big
in terms of movement. But it's great to
be here in Seattle, if you're a rock and
roll fan, you might well know that
Seattle has a long and proud history but
it also has some associations of
dinosaurs and rock and roll including
some of the bands. I really love like
Nirvana and Soundgarden, they worked dinosaur
imagery into their into their album
covers and posters and so forth.
I was an undergraduate student in
Wisconsin back in the early 90s working
at a music store when the grunge rock
movement came out and I was like, ah
Seattle, Seattle, that's where it's at but
I couldn't get out to Seattle, this is my
first time ever in Seattle so I'm really
really excited to be here! Finally I've
made it thanks to the Burke Museum. I've
made it to the home of my rock heroes
and I hope to present to you some, some
rocks that might be your heroes' rocks
that are dinosaurs. Anyway that's a
terrible joke.
Speaking of heroes when I was
growing up as as a kid and I see there
are some some kids in the audience, I was
really into into monsters in general. It
didn't matter if there were science
fiction monsters or dinosaurs to me
Godzilla was just as real as t-rex so, so
I was really excited about, about big
things in general, King Ghidorah over
there. The three-headed monster was one
of my favorites and still is and I think
 that fascination in giant
things, real and and and not real, just
continued and it explains why I now
study them as a scientist, including all
kinds of weird things interesting
like fanciful things that could never,
could never work and it's interesting to
think why they couldn't work and that
really, when I first learned as a kid
that a giant Godzilla just could
not work in terms of the physics of
movement it really bummed me out. I was
sad that Godzilla could not really
exist because it was too big to walk but
it also made a lot of sense to me so the
scientist in my mind began
working when I, when I realized that and
thought oh actually even though that
said that Godzilla could not work as a
real thing on land that teaches me
something that's valuable. So the work
I'll be talking about today is perched
upon the shoulders of many giants, I've
worked with a lot of people around the
world. I have to thank a lot of funders
there for supporting my research in the
in the UK and other parts of the EU and
the Royal Veterinary College I'm based
at. The structure motion lab which is out
here just north of London, we have a
lovely campus that occasionally gets a
very thin coating of snow that shuts
absolutely everything down for days and
days but we also get nice rainbows
landing in campus. And there's our team,
we've got a team of several dozen people
who study aspects of animal movement
applying physics and anatomy and in my
case evolution to the study of animal
movement. So that's where we're based and
a bit about what we do, but yeah today
I'm gonna really focus in on the problem
of size as applied to dinosaurs and if
you want to talk to me more about this
research after the talk I'm always on
social media on Twitter and I have a
blog and so forth, it's easy to find me
on the Internet,
I'm all over the place. But here's what
I'm going to talk to you about today. I
talk first about the project I began as
a PhD student 20 years ago, how fast
could a t-rex move. I'll give you an
answer to that question. I'll then talk
about sauropod dinosaurs, the really big
four-legged dinosaurs and how their body
shape affected the way they moved as
their size changed as well, and
then finally I'll get to a project I'm
working on now that I'm really excited
about which is about the earliest
dinosaurs, the humble beginnings of
dinosaurs
and what made them special, if anything,
and whether that might explain why
dinosaurs survived when many other
animals in the Triassic did not survive
past the Triassic into the Jurassic. So
that's a quick introduction, here's a
little bit about the evolutionary family
tree of dinosaurs in case you're not
familiar. We've got three main branches,
the ornithischians like Triceratops, the
sauropodamorphs or sauropods is one
group of them, and then the theropods. I'm
going to talk to you first about the
theropods which include t-rex of course,
then about the sauropodamorphs, that's
their, their cousins as currently
understood - although there's another idea
that moves this family tree around a bit
that's still controversial. I won't get
into that. Anyway and we've strayed into
those theropod dinosaurs so theropods
are great, they're all bipedal, they all
walk on two legs, they include birds so
we have a huge size range from
hummingbirds all the way up to things
like t-rex. One of the largest land
animals that's ever lived especially on
on two legs, up to eight tons or so.
So fascinating because in some ways they're
so conservative, they walked on two legs
They had a pretty similar body plan but also
because they're so different in terms of
size and some features like big tails,
big heads or flights or other features.
Now before I get into talking about
t-rex and the movement of theropod
dinosaurs, I want to kind of address a
problem, which is how do we reconstruct
dinosaur movement at all when all we
have at the beginning are bones. Well I'd
like to tell you right away that, that's
not true, we don't just have the bones of
dinosaurs. Of course we have footprints,
those are useful as well but even on the
bones, there's a lot of information we
can tell about the soft tissues, the
muscles, the tendons, the things that make
up us as well as dinosaurs and things
that actually generate movement, bones of
course, a skeleton alone cannot move.
A skeleton needs muscles and tendons to
drive and support the movement of the
skeleton as a system of levers, so on the
bones we can see marks. I've got colored
dots on there, these are thigh bones,
femur bones
On the left, a crocodile. Here in
the middle is an early dinosaur, here's a
little bit later dinosaur, more closely
related to birds, and here's a turkey and
this blue dot is one muscle showing it
doesn't move its position very much
as we move along the family tree. There's
a red dot that's another muscle
attaching to the thigh bone on the side
and that muscle splits into two muscles
We can see scars on the bone that are
attachments for that muscle in an early
dinosaur, one of them the purple one here
stays put, whereas the other one moves
upward onto this big blade of bone that
we can see on many dinosaurs including
t-rex and that blade of bone fuses up
here at the top in birds into a big
crest that you can see in your
Thanksgiving turkey or chicken or
whatever. And so that muscle has come up
to the top of the thigh bone in living
birds and and some extinct dinosaurs as
well. So the take-home message is that
there is that the bones tell us about
muscles, where they attach and about how
the attachments of muscles have evolved
so we can reconstruct the musculature of
dinosaurs with some degree of confidence
and that allows us to get one step
closer understanding how they moved, if
we can add their muscles and stuff onto
them and we can begin piecing together,
what is all this wonderful diversity of
bones that we see. This is a family tree
of reptiles with the hip bones inside
view, so these are early reptiles, an
alligator here, some early dinosaurs
across the middle here up to t-rex,
there's its hip bones and a raptor
dinosaur Archaeopteryx, the first bird, a
much later bird, and then a turkey again,
showing all the different kinds of
pelvic bones. You can see how the pelvis
changes with a few, just a few examples
of the many species that would fill up
that family tree. To me an image like
this really raises the question, can
we make sense of what these differences
in hip bone structure mean for how these
animals would move? How does an early
reptile move versus something like an
early dinosaur versus a t-rex versus a
bird. Can we use the anatomy
and reconstruct how an animal would
actually work, how it would function and
how it would behave, how it would
actually move. How fast it could it
move or turn, could it jump, in order to
answer those higher-level questions
about behavior we need to start with the
anatomy. Which of course starts with the
bones, adds on more information about
muscles and tendons and so forth and
that's hard of course, there are many
challenges to do this. There are lots of
unknowns about the anatomy, physiology,
how the muscles would work, the behavior
itself is often or generally unknown in
many cases. We don't know how living
animals work, we don't know how we work, a
lot of our problems we can't fix because
we don't understand how we work. So I
went to Stanford and worked with
mechanical engineers to learn the
tools they use to try to fix problems
that we have with the way we walk, and I
learned those tools to then apply to
animals and try to figure out how
do animals work and and then I applied
those tools to dinosaurs as I'll show
you a little bit later. But all along the
way I've been working throughout my
career on living animals trying to
contribute new knowledge on how living
animals work. How do elephants move, how
do crocodiles move, ostriches. I've
contributed new information to that as
well as studying extinct animals to try
to help flesh out our general
understanding of how movement works. When
we do science we always have to balance
how many assumptions we make about
things, things we don't know and how
complicated are we making our science,
that's always a problem. Do we make very
simple models of animals, I'll show you
some examples of that, where
my research on t-rex really was
just a few simple equations, or do we
make really complicated models where
they're really really realistic, lots of
anatomy, lots and lots of assumptions
built into them we have to
juggle those kind of problems as
scientists. How do we
decide what level of complexity to put
into our research and of course
there's always potentially the problem
of, what if dinosaurs broke the rules,
what
if t-rex could breathe fire like
Godzilla, or what if sharks could shoot
out laser beams from
their bodies, fossil sharks as well of
course. If we have no evidence of that we
can't ever invoke those kind of
assumptions in science, we have the
mantra, the phrase, "extraordinary
claims require extraordinary evidence" We
can't say a t-rex had supercharged
muscles that were 10 times as powerful
as any other animal that's ever lived,
without evidence for that. So we can't
allow for dinosaurs to break the rules
without evidence of them breaking the
rules and that's very very important,
it's really a core part of science. And
gravity is one thing that didn't change,
one rule definitely that did not
change through the history of dinosaurs,
it was only t-rex, was only 66 million
years ago. That's nothing, I mean that's
like a few days ago in terms of the
history of the earth, gravity has has
not changed much at all, since
then, so we can assume the same level of
gravity as today in the time of
t-rex or even the earliest dinosaurs. The
solution to all these problems is to be
careful, to do science and that's what
I'll be showing you here today. It's easy
to look at an animation of a dinosaur
that looks kind of good, we worked with a
museum, about 10 almost, 15 years
ago to make this animation trying to
show. Here's what as scientists we
thought a t-rex moved like based on the
principles of how animals move, some real
science kind of but in the end we
realized in making this animation with
an animation expert, this was really just
making stuff up, there was almost no
really good science in this animation. It
was not really doing what we felt as
scientists was good
science, so it made us uncomfortable to
do this kind of animation even though it
was useful in showing to the public,
here's roughly what we think a t-rex
moved like.
we came up with a new approach inspired
by making that animation of t-rex
instead of just showing how t-rex
moved which is an easy way to approach
the problem, although for us it was
unconvincing, we started with showing how
t-rex didn't move so trying to start
with all the ways t-rex might have moved,
maybe, and get rid of the ones that just
wouldn't work. This approach just
applied the rules of how animals work to
try to say, well is that fairly upright
way of moving of a t-rex, is that
possible or impossible,
is that really straight legged
way of moving in a t-rex, is that
possible or impossible, or is that really
crouched way of moving possible or
impossible. We use an approach as I'll
show you to try to figure that out, get
rid of things that were impossible or
implausible so we started with a simple
leg posed in the middle of a step like
this, so it's just supporting a t-rex
supporting itself on one leg like it's
running, so supporting itself on one leg
at a time and it has a hip, an knee and an
ankle joint each of which can rotate
through 180 degrees so that's a large
amount of movement of each joint and
that gives us a big block of movement.
180 degrees of movement of each joint
times three different joints, gives us
six million ways we could pose that limb
of a t-rex, but of course not all of
those are possible. Some of those six
million ways we could pose a t-rex's
leg at one instant in time must be
impossible so what can we get rid of
there. Well we applied a bunch of rules
of animal movement that we understood
fairly well including, well of course, a
t-rex, its joints can only move in
certain ways and we got rid of most of
that red space here now colored in
yellowish, most of that was gotten rid of
by ways that the limb just could not be
posed in at all without
disconnecting the joints and also t-rex
couldn't go through the ground, it was
solid, it wasn't a ghost or something, so
positions in which the leg went through
the ground. We got rid of those that
helped and so forth
until finally get down to the point
where we know t-rex could walk, that's a
pretty safe assumption, it could at least
walked so it could support itself
with one body weight on one leg at a
time so I could do this and it could at
least walk slowly, so our model
accounted for that by getting rid of
postures in which the required size of
muscles and other things would be too
large in order for a t-rex to actually
support one body weight on a leg at a
time, so that little bit of yellow space
that kind of a crouched posture has
gotten rid of and then also we asked,
well are there any postures left over in
which a t-rex could run and support at
least one and a half times its body
weight on a leg at a time, that's a very
slow run that's kind of a jogging sort
of force one and a half times body
weight on on one leg at a time is
pretty slow, and yes we found some
positions we could pose a t-rex's leg
that were feasible and some that were
not feasible that we got rid of and
that's what is left over here, 3,000
poses of the beginning, six million are
left over as possible slow running poses
for a t-rex, so our analysis using basic
math and physics and anatomy allowed us
to figure out that, yeah maybe a t-rex
could run slowly with certain
assumptions, we can't get rid of that
possibility but we could get rid of fast
running, we couldn't find any solution
that will allow a t-rex to run really
really quickly, like forty five miles to an
hour but these kind of postures that are
just slightly bent legged but not very
straight legged, not very bent legged,
these are all possible postures ways we
could pose a t-rex's leg we couldn't
choose between any of those four or any
of the of the other 3019 poses in
between them. So that's pretty good that
we got that far with that kind of a
simple analysis and overall what we
found from looking at a variety of
models of t-rex, and we also took a
chicken and made it the size
of a t-rex in a computer model so there
is a chicken at about two kilograms of
body mass down here, we scaled it all the
way up to t-rex size and found that a
giant chicken at six tons, a chicken
would need to have almost a hundred percent of its
body weight as leg muscle in order to be
able to move, of
course that wouldn't work, chickens need
to have skeletons, they need brains and
lungs and digestive systems. KFC might
really love to have a 6-ton chicken but
it's just not possible to have such an
organism. But a t-rex, it is of course
possible, it's better off, how much muscle
a t-rex would need depending on what
kind of assumptions you make. It
would need about ten to twenty percent
of it per leg of its body weight to be
muscle that supports the body against
gravity and the most muscle any animal
has ever had is an ostrich, right here at
that point, right there has about 15% of
its body weight per leg as muscle that
works against gravity to support the
ostrich. Humans have nine or ten percent
per leg of their of their body weight as
as muscle that helps support us so
ostriches are more muscular than we are
and they're the most muscular animal
that's ever lived as far as we know, more
muscular than an elephant or a
rhinoceros, or a giraffe, a horse,
anything. T-rex, we have no signs that
t-rex was more muscular relatively
speaking than an ostrich, ostriches are
pretty much adapted to be all, you know,
we're almost pure muscle in many way.
T-rexs aren't so much in terms of leg
muscles, they've got a big head with a
lot of jaw muscle that does not help
them support body weight. They've got a
lot of other features that don't make
them as well adapted as an ostrich's for
supporting their body weight. So the
take-home message from this very messy
graph is that t-rex was so big, that it
couldn't move very very quickly like an
ostrich can. T-rex could run at best
maybe fifteen, twenty-five miles an hour
which is around the speed of what humans
can run so that's not bad and it's about
as fast as a probably a duck bill or a
triceratops could move at best but it's
not as fast as a racehorse or a cheetah
or something like that, so that's what we
found out, that was pretty satisfying but
since then we've applied some more
sophisticated computer models to our research trying to figure out can we
get any better estimates of how a t-rex
could move and we found that better
models continue to support what we found
so we do better anatomical models of the
leverage of muscles around the joints of
t-rex.
We do better models of the mass and the
center of mass is the
point at which the weight of an animal, can be abstracted to be concentrated
So your center of mass is right around
your belly button,
more or less center of mass is very
important, you need to keep your center
of mass over your feet or else you'll
fall down. So center of mass determines
your posture, if your center of mass is
too far forwards, you can't get your legs
under your center of mass and therefore
you either fall down or you walk on four
legs which t-rex couldn't do. So that's
very important to know where its center
of mass was and we were able to to get
pretty good estimates of that along with
other things. So we also looked at how
t-rex grew, there are some nice
skeletons of young tyrannosaurs like a
specimen called Jane. That's about ten
years old and we were able to estimate
using some computer modeling how big
t-rex, young t-rex at about ten years old
was. It was about 600 kilograms, give or
take a bit so that's pretty big, that's a
size of a large horse at just ten years
of age. Are there any 10 year olds in the
audience? Do you weigh as much as a horse?
Well that might tell you something
because at 17 years of age, a t-rex
weighed about six tons as big as an
elephant. Is there a 17 year old in the
audience anywhere that weighs as much as
an elephant? Probably not if
you do some math, it's very
difficult to estimate exactly how fast a
t-rex grew but during its teenage years
it's very clear a t-rex grew really
quickly.
Maybe as fast as five kilograms a
day or about 11 pounds a day, which if
you think about that, that's really fast,
that is a lot of cheeseburgers or in the
case of t-rex, a lot of duck-billed
dinosaurs and Triceratops. So just
thinking about a six hundred to a
thousand kilogram animal that could
probably run pretty quickly. It wasn't
very big and thus was fairly athletic.
Young tyrannosaurs were really scary
animals, they were hungry, they needed to
eat a lot too to grow quickly, and they
were probably reasonably athletic indeed
as t-rex grew its legs got relatively
smaller, and its muscles also got
relatively smaller, so young t-rex are
pretty leggy, they have nice long legs,
pretty big muscles attached to them
whereas an adult t-rex is relatively
less muscular than a ten year old
t-rex was. So that really reinforces
the idea that the most athletic
t-rex were the teenagers,
much like in humans and there's one
muscle in particular attached to the
tail and you can see this, if you ever
look at a t-rex skeleton or any dinosaur
for that matter matter there's a big
muscle. It's also present in crocodiles
and various other reptiles. It runs
from the tail down to the thigh bone,
it's called the Caudofemoralis and
that muscle weight is as much as three to
six percent of body weight of a t-rex
per leg, so that's a couple hundred
kilograms or so of muscle in each leg of
a t-rex. Just one muscle there that help
support the leg of a t-rex or the hip, in
particular against gravity so that's a
huge muscle, it's one of the biggest limb
muscles ever in relative terms in in any
in any animal living or extinct and
that's very impressive, but it was
necessary just to support a t-rex. It
wasn't big enough to generate really
rapid locomotion in a big t-rex but it
certainly helped young t-rex move
pretty quickly and I would not want to
engage in a footrace with
with a ten-year-old t-rex. It
would be pretty scary but that's not
going to happen. So far I've
mostly focused on extinct dinosaurs but
of course there are dinosaurs amongst us,
today we can study ostriches, and this is
a computer model of an ostrich that I've
worked with. We do a lot of work, really
try to use computer models of living
things to test how well the the models
actually work by comparing the results
of a computer model to actual
experimental measurements, to see how
well they compare and we found that
generally they compare pretty well. So
we're able to predict how an ostrich can
move using a computer model and we are
able to measure the same kind of ostrich
and see that it matches the
computer model pretty well and that
gives us confidence that what we're
doing with Dinosaurs, which we can't
directly test, we can't ever get a t-rex
into our lab and put it on a treadmill
like we can with an ostrich but we can do the computer models of
dinosaurs, extinct ones, but we can do a
lot more with ostriches and other living
animals and that's one reason why we
bother. So we've done a lot of those kind
of tests to add information. Moving on a
bit, onto the sauropod dinosaurs away
from the theropods. We, a bunch of
colleagues and I asked well, how did body
shape influence the way sauropod
dinosaurs moved? There were a lot of
changes in the shape of sauropods as
they evolved, they started off with
pretty short necks and pretty short for
legs and long hind legs, and then of
course during their
evolutionary history. They diversified
into all kinds of forms, some of whom had
very long necks and tails and long front
legs, some of whom didn't but we know
that the earliest sauropodamorphs, the
earliest cousins of the true big
sauropods in the Triassic were small and
they probably walked on two legs mainly.
But once you get to the Jurassic it's
very clear
that the the sauropods were big and
quadrupedal, and once you get to the
Cretaceous there's a group of sauropods
called the titanosaurs which really
really huge, the largest land animals
ever, much larger than an elephant
and they had some changes in their limb
posture, some of them even had this
weird, kind of wide gauge posture, when
they spread their legs out to
accommodate a really bulky gut so it's
been observed that there are a lot of
changes in body shape that might have
influenced the way sauropods moved
throughout their history, and we wanted
to estimate how body shape changed the
way sauropods moved using computer
modeling, and we focused on the center of
mass of sauropods which I've already
introduced, talking about t-rex. Center of
mass determines how an animal moves if
your center of mass is too far forwards,
you have to shift into moving on four
legs, you can't walk on two legs if your
center of mass is closer to your front
legs or your head. So we tried to
estimate where the center of mass was
using digitized skeletons. Here's our
approach that we used much like we did
with t-rex, used various digital
technologies to make 3d skeletons of all
sorts of sauropods and sauropodamorphs
added
lungs to them and wind pipes and
so forth were able to change the sizes
of those, what if they had bigger lungs,
smaller lungs, even if they were missing
bones in the neck, we were able to
estimate how long the neck would be
based on what was missing and do some
careful analysis of that and even
account for, well what if the sauropod
was bigger at the back end than the
skeleton suggests or bigger at the front
end. We're able to do a variety of models
to give us some kind of error bars for
our estimates of how big our
sauropods were and where their center of
mass was and this is the take-home
message of that analysis through the
evolutionary history of dinosaurs from
early cousins of dinosaurs here, early in
the history, this is 250 million years
ago so back in the very very early
triassic, the center of mass is pretty
close to the hips, that's what this
number is moving up this way, is closer to the head moving back this way,
is closer to the hips so the center of
mass starts off close to the hips,
moves even closer to the hips as we get
close to dinosaurs, that's where we have
a shift on to two legs from four legs. At
that point in the evolution of dinosaurs
and then it goes the other way as we get
into sauropods or sauropodamorphs
in the Jurassic, the center of mass
starts shifting further forwards toward
the head and fore limbs and then once we
get to the Cretaceous, the titanosaurs do
something weird because their body shape
changes a lot but generally their center
of mass moves forwards a little bit at
least and we were able to show that
these three changes in the evolutionary
history of dinosaurs especially sauropodamorphs
relate to changes in body shape,
that in particular in sauropods as their
necks got longer, that moved their center
of mass forwards, they're also their
forelimbs getting longer, moved their center
mass forwards a little bit - and that
was correlated with getting bigger, so
sauropods as they got bigger, their necks
got longer their forelimbs also got a
little bit longer and that was related
to them, becoming quadrupedal, moving on
four legs instead of two legs around
this point in their evolutionary history
so in the early Jurassic or late
Triassic roughly. It's pretty
early in the history of sauropods, they
became gigantic and four-legged because
of their long neck, you know to a large
degree, so that's pretty satisfying. We're
able to show kind of three phases in the
evolutionary history of dinosaurs and
sauropods that really show how body
shape influenced the locomotion of
dinosaurs in in the early history of
dinosaurs, they became better at being
bipedal, then they became worse at being
bipedal and shifted to being quadrupedal
and then they became really weird
titanosaurs that moved in very
strange ways different from other
sauropods because of their very strange
body shape
 
So for the last bit of my talk I'm going
to change gears a bit, I've been talking
about giant dinosaurs like the sauropods
and t-rex but now I want to talk about
research I'm doing. Right now of course,
all good things must come to an end
dinosaurs except birds got wiped out at
the end of the Cretaceous, but let's
rewind and think about how dinosaurs got
starts. Dinosaurs got started because of
the mass extinction in to a large degree.
At the end of the Permian period, about
250 million years ago, there was a major
catastrophe that almost wiped out life
on Earth as we know it, much like there
was a catastrophe at the end of the
Cretaceous but much much much worse at
the end of the Permian, and that's what
kind of cleared the slate and allowed
dinosaurs to take over on land. So
dinosaurs appear shortly after that
major extinction at the end of the
Permian and they appear alongside a lot
of really weird animals that look kind
of like big armored land crocodiles and
dinosaurs in the
late mid, mid to late triassic are pretty
small, many of them kind of house cat
size,
not like some of the the big land
crocodiles that got to be up to 20 foot
long and armored with big teeth. None of
the earliest dinosaurs were like that
really, so early dinosaurs had it pretty
rough, they were really lightly
built animals in a very dangerous world
with a lot of a lot of nasty characters both plant eating and meat-eating
so it's a really weird ecosystem in the
Triassic. I really like the Triassic
period because it's so different from
the Cretaceous, the Cretaceous to me is
kind of familiar, it's sort of like yeah
kind of like today but with
dinosaurs instead of
wildebeest and lions. But the Triassic is
nothing like that, it's a very arid
period of Earth's history with these
land crocodiles and little tiny
dinosaurs and lots of other weird things.
Just really weird, life on land in
general so I wanted to understand the
dawn of the dinosaurs and and got some
funding from Europe to
do a project called Dawn of the Dinos, we
have a website, Dawn of the Dinos.com that has
some nice artwork like this illustrating,
what that time period looked like and
some of the characters that were around
at that time. These are wonderful
reconstructions by artist John Conway of
some of these critters, like one of those
big land crocodiles there and we wanted
to address the question that's
been lingering for over 40 years, what
was, if anything, special about early
dinosaurs? It's been proposed that early
dinosaurs had what's called locomotor
superiority, there was something about
them in terms of their movement that
made them better than those land
crocodiles and other things that went
extinct at the end of the Triassic
except for the lineage that led
to true crocodiles. So were dinosaurs
superior in some way, could they run
faster, turn more quickly, jump better, do
something more athletic than those big
clunky armored crocodiles could do,
that's never really been tested it's
just been either dismissed entirely,
"they're dinosaurs, just got lucky ,there was
nothing special about them" or it's been
accepted "oh yeah
dinosaurs were great, that's why of
course, that's why they
succeeded" But we wanted to test that
idea using physics again, so using the
same kind of computer modeling and
Anatomy based approaches I've already
shown you, we're just getting started
with that project. Here's an introduction
to some of the cool archosaurs, that
group that includes dinosaurs and the
crocodile lineage, so the big land
crocodiles and the plant-eating land
crocodile type things, there's a living
crocodile and their relationships with
various other things including what
looks like what an early archosaur
would look like, something like that, like
a small crocodileish thing. There are
some of the early dinosaurs that were
not much around that size or even
smaller and then we get into true
dinosaurs like that feathered or
filamentous, the sauropodamorphs have already talked about and the
theropods including birds, so those are
the two main lineages we're focusing on
the crocodile lineage,
the bird lineage,  we're
comparing them and different members
of those groups to see what's different
about them if anything in terms of how
they can move and we're going to figure
that out using the computer modeling
approach, and here we've already started
looking at one of them. This is an early
sauropodamorph called Mussaurus
patagonicus -- as the name implies it's
from Patagonia and what's really cool
about it is, we have a whole growth
series of Mussaurus, so we have a little
tiny baby hatchling Mussaurus, that's
why it's called Mussaurus, "the mouse
reptile", it looks kind of mouse like and
that's one of the first skeletons that
was found, it was one of these little
hatchlings but also there's a 20 foot
long adult animal. That's what it looked
like
whether it was two-legged or four-legged is uncertain, that's one of the
questions we wanted to address and we
asked with Mussaurus, did it the way it
moved actually change as it grew,
some dinosaurs just like us we start off
on four legs and then move to two legs.
Some dinosaurs did that too, they start
off on all fours and then move to two
legs as they grew up, other dinosaurs
start off on two legs and they move down
to four legs as they grew up, so what did
Mussaurus do, it seemed to change its
body size and shape a lot that adult
Mussaurus is about the size of a rhinoceros,
about 1,500 kilograms, 20 foot long, it's
a pretty big animal, not much much bigger
than that mouse-sized little hatchling
so it changed a lot in terms of its size,
and its body shape changed as well, so we
wanted to figure out how its movement
changed as it grew up so there's where
Mussaurus is from, it's from the very
very tip of Argentina down here in South
America. Here's another little hatchling
right there, beautiful little skeleton,
it's actually much smaller than that
picture. Here's a juvenile you can barely
see some of the leg bones there, but
that's the hip and the foot is down
there, the head would be this way, that's
a couple year old individual from
several skeletons that we have from
Santa Cruz province down here in this
region of southern Argentina. So we
worked with my colleague Alejandro Otro
and Diego Pol to build computer models of the
hatchling, the juvenile and the adult
Mussaurus to see what they were built
like, and whether that could tell us how
they might have moved, and we also
started by looking at the arms of
the adult Mussaurus. This is an
important take-home lesson about
dinosaurs, most dinosaurs kept their
palms facing inwards like this, so if you
ever see a two-legged dinosaur walking
around like this with its palms facing
down, the t-rex is often shown this way.
You point to the person that's showing
that and say, you got it wrong, that's
you're showing your t-rex wrong.
Dinosaurs mostly have their palms like
this, they could not do this kind of
thing like we can do, most dinosaurs - a
few could do this, so they couldn't do
what's called pronation and supination.
This kind of motion that mammals are
really good at, where we're unusual,
especially humans, at being able to do
this kind of a movement but most
dinosaurs could not. They had their arms
just fixed like this, could not rotate
their hands much at all, so could
Mussaurus, was it able to plant its hands
flat on the ground like this and
therefore pronate its hands, or was it
fixed into this kind of a posture? We
built a computer model to test that and
that's what this animation goes through,
it showed us very clearly there's no way
we could pose the joints of that limb,
even taking into account missing
cartilage and other tissues, there's no
way we could get that hand to be planted
flat on the ground. It could only keep
its palm inwards so that really
supported the idea that adult
Mussaurus was bipedal, it could not plant its
hands flat on the ground to be a
quadruped so it had to 
keep its hands facing inwards
like that and furthermore... I'm gonna skip
that, that's not important
that's too much text, so we digitally
prepared Mussaurus fossils. This is
some work we're finishing up right now,
that's what the actual fossils look like
on the left there, after CT scanning
we're able to extract all the beautiful
bones from that, from that rock and
here's our computer models - the hatchling,
the juvenile, and the adult. That's
relative sizes, really about how big they
are, so that's a 20 foot long
adult. It's almost actual size, there on
the screen, pretty close, there's a little
juvenile and hatchling, so that's
what they look like, we're still adding
the skulls on to them. You can see
they're obviously missing from some of
them but we've accounted for them with
some simple geometry and what we did was apply some simple computer modeling
to add flesh onto the skeletons, like I
did earlier for t-rex and the sauropods
with my colleagues. There are two
approaches, one's called convex hull,
laying the others called spline based
modeling if you're really into computer
modeling, you might care about that.
Otherwise don't worry about it, it's just
two different methods, we wanted to see
if they matter, which approach we use, so
we apply both methods. Convex
hulling is basically shrink-wrapping a
3D shape onto the skeleton, spline-based
method is adding more realistic
anatomy that reflects the the missing
flesh, not shrink wrapping it to the
skeleton so there's our hatchling on the
left, in the middle is our juvenile, on
the right is our adult Mussaurus,
that's what the the models look like so
far, and here's the growth, roughly of
those three models so this is the mass
of the animal hatchling is tiny, it's
only a few grams, the juvenile at about
one year of age is already eight
kilograms, almost 7.8 there
about, and then the adults like I said
is about 1,500 kilograms. Using that
method and the two methods agree pretty well
in terms of estimating mass, so again
we're using the other method, we get
pretty similar results - about eight
kilograms for the juvenile, a little more
than 1,500 for the adult, but yeah with a
certain margin of error that's pretty
close, pretty close agreement,
and so in 10 years, Mussaurus got to be
over 1,500 kilograms, pretty impressive
that it was able to grow that big, that
quickly, though what about its locomotion?
Did it change from a quadraped to a
biped, a biped to a quadruped, what
can center of mass tell us, well showing
us, very very clearly regardless of what
method we used that the hatchling Mussaurus had a center of mass really really
close to the the front legs.
Center of mass was up here, well in
front of the hips,
no way that a hatchling Mussaurus
could have gotten its hind legs under its
center of mass and walked around on two
legs at all, it had to have supported
itself in some way on its front legs,
but the juvenile in both cases here seems to have been pretty close to being able to
be bipedal, and the adults certainly so,
the center of mass of the adult was
really close to the hips, and very well
adapted to being bipedal, so that
reflects that Mussaurus must have had a
shift during its development from
walking around on four legs probably
pretty clumsily, to moving on two legs,
probably pretty early in its life, maybe
even by when it's 1 year old it was able to to
walk or run around on two legs, instead
of four. So that's pretty neat that we
were able to show that with this
approach. And since then we're also
working with living animals to
understand how living archosaurs,
members of the dinosaur bird and
crocodile radiation, how they actually
move, so we've been working with Nile
crocodiles and running them on
treadmills. That's a lot of fun, they can
be very stubborn and a little bit bitey
but we like them and we also worked
with some little - whoops didn't show that -
We also work with some little South
American birds called tinamous which
are very primitive birds, they look a lot
like what we think the ancestor of
all modern living birds look like,
they're very chicken like, but they're
different from a chicken. They are
actually cousins of ostriches and emus
and rios,
that's a tinamou right there, the elegant
crusted tinamou, there are lovely birds
fairly nervous but very athletic, they love
to run, they don't like to fly and that's
one reason we chose them, so we've been
working with those animals to see how
they move, and here's some example
footage, here's a crocodile. You may not
know it, but crocodiles can bound and
gallop, they can use a whole range of
gates that mammals can use, that's one
thing that makes crocodiles different
from other reptiles, no lizard can do
what you're seeing in this
crocodile on a treadmill,
lizards cannot bound or gallop like that,
so watch that crocodile, it's moving
its front legs together like this and
it's moving, but it's
moving its hind legs together like that
it's using a squirrel like gate bounding,
is what we call it technically, it's very
similar to a gallop, and that's what
crocodiles do when they want to go
really quickly. but they can only do it
at small size - once crocodiles get big
they lose that ability, once they pass
about two metres or so in length they
become much less athletic and slow down,
and lose their bounding ability.
So we're excited to be able to get our
crocodiles able to bound and gallop on a
treadmill, and we also used a new
technology that's really powerful to
peer inside of crocodiles as they move
and see how their joints actually move.
So this is an x-ray video of a Nile
crocodile walking through
the video with some markers attached to
the surface of it, so we can track it
more accurately. Let me play that one
more time because there's a lot going on
there, so we can see inside of it, there's
like, the light space is some of the
nasal cavity, you can even see it
breathing if you watch very closely,
the lung, the air pipe would be in here,
there's the lung, that's the front leg on
the ground, there's the hind leg, the heel,
the ankle right there, and the knee,
there's the tail, all the vertebrae of
the tail, and you can even see the
microchip the vet implanted into it.
There's the microchip, a lot of beautiful
detail in in that x-ray video of that
crocodile walking through our
experimental setup.
So this is called x-ray reconstruction
of moving morphology, it's changed our
whole field now instead of looking at
animals from the outside, like in that
last video, and guessing how the
skeleton is moving. We're actually now
able to measure how the skeleton is
moving with a very very high level of
accuracy, which helps our computer models
and other methods be more accurate, and
allows us to do better science, basically
it's totally transforming how we study
human movement, animal movement,
everything, and it's actually at various
hospitals, they're using it now as well
to look at our knees and shoulders
and other parts of our body to study
what goes wrong with our joints and
their motions, so we're using this to
study animal movement. So to wrap up
that's just a teaser of that Dawn of the
Dinosaurs project, it's going on for
the next three and a half years, we'll be
showing a lot more on our website,
dawn of the dines.com but I've gone through
three projects with you here today, going
from the dawn of the dinosaurs to the
dusk of the dinosaurs with titanosaurs
and t-rex, the earth-shaking giants
and the not so earth-shaking early
dinosaur. The giants live in extreme,
where gravity really really dominates
the way we they live, big dinosaurs
everything about their body, and a t-rex
and in a sauropod, really to me as a
scientist,
screams the influence of gravity much
more. So even in that, than in a human
we're pretty big and gravity influences
us a lot, but the way gravity
influences us is nothing like it
is compared to how it influences a
sauropod, an elephant, a t-rex
a rhinoceros, other big things, gravity - as
you get bigger it influences the way you
work, in drastically different ways as
you get bigger and bigger and bigger.
I'm sure adults in the audience can
sympathize with that too, compared to how
we were when we were younger and lighter,
but big animals needn't be simply
walkers. So I've shown you some examples
with t-rex where there's potential for
diversity to evolve, so t-rex need
only to have walked, maybe t-rex could
have run slowly, it couldn't have run
quickly, I think most of my colleagues
have probably convinced a few holdouts.
They're still always going to be some
holdouts that disagree with me, but I
think there's a general consensus
nowadays that t-rex could not run very
very quickly, might have been able to run
slowly or walk quickly, we're not
totally sure because there's a lot of
uncertainty there in those computer
models, different sauropods move
differently because they had a different
center of mass, different body shape and so
forth, titanosaurs move differently from
early sauropods, things like Diplodocus
or Mussaurus, sauropodomorphs
themselves showed a shift during their
growth from quadrupedal to bipedal like
Mussaurus. I showed that toward the end
of my talk and why did early dinosaurs
get dominance across the Triassic -
Jurassic, around 200 million years ago,
well we still don't know, I don't
know, I have no real horse in that race, I
just like to have an answer to that
long-standing question and you can watch
that website and find out how we're
doing with that research or follow me on
Twitter or ask some questions if you
have any questions at this point. Thank
you very much!
Yeah so I'm going to start with one
question which is for John,
which movie do you think actually best depicts motions and dinosaurs
To be honest I still really love how
Jurassic Park depicted movements in
dinosaurs for a large part, especially I
really like their t-rex, and a neat story
there with the way their t-rex moved is,
if you go back and watch Jurassic Park,
when the the t-rex is chasing the Jeep,
watch how that t-rex moves - it always has
one foot on the ground, in fact mostly it
has two feet on the ground, never goes
airborne and in fact I talked to the
animators who made Jurassic Park and
they tried to animate t-rex going 4050
miles an hour ,as some paleontologists
argued it did and it looked ridiculous,
they thought they said it looked like
the roadrunner going off a cliff, the
legs were going so fast they slowed it
down, so it just goes boom boom boom boom,
it was only going 15 to 20 miles an hour
so that's pretty bit close to what I
estimated t-rex could do, and so that's
an interesting case where art and
science have come to more or less the
same answer, they just felt like yeah
that didn't look right the audience
wouldn't believe it, for it to move
quickly and and the science reinforces
that ,okay so other end of the spectrum
how fast do you think Velociraptor could
run, yeah, smaller dinosaurs could move
more quickly, especially medium-sized, so
as you look at any land animal, in
general the speed of the animal as the
animal gets bigger through evolution
starts off pretty slow, so small animals
are not very fast, a mouse can be outrun
by a house cat for example, and then
speed goes up as animals get bigger and,
then the optimal size for being fast is
around thirty to fifty kilograms, so like
cheetah, greyhound, racing hare or
something like that is the best size to
be for being fast, and ostrich is pretty
close but then as you get bigger speed,
goes down,
so big things even horses are slower
than smaller things, rhinoceros is,
giraffes, hippopotamuses, elephants are
all slow because they're large so a
Velociraptor would be moderately fast, we
don't know exactly how fast but probably
pretty good, I wouldn't want to
race it! I don't know if you've ever had
this question before, but could a t-rex
hop? Yeah I get that question a lot,
it's a good one, we have no tracks
of any extinct dinosaur hopping, that's
one thing and we have lots of tracks
of them walking and running but hopping
is actually really really hard, it's the
worst way to move if you want to go
quickly
unless you're small, so kangaroos can hop
because they're not too big, but big
kangaroos like a red kangaroo at about a
hundred counter kilograms at top speed,
is very very close to to rupturing its
muscles and tendons, the kangaroos are
close to the biggest a hopping animal can
possibly be, and still hopping is
really hard to do, it's about twice as
hard as running at the same speed, so you
can try it try hopping and try running
and see what you can do more quickly.
You'll be able to run more quickly than
hop, hopping is terrible for a big animal
to do and if a t-rex tried to hop, it
would break its legs so I can guarantee
you. So a couple times you mentioned in
the talk, of the age of these dinosaurs
and the question here is, how do you tell
the age of a dinosaur years older than 20 years old? I didn't explain that and that
was very naughty of me. We can, the best
way is, you can take sections of bones
and Chris's lab does a lot of this,
take a section of the bone just like you
take a section of a tree and count the
rings in the tree or the bone, there are
growth rings there that allow you to
estimate how old a dinosaur was, if it's
a well-preserved bone you can count that,
so come to Dino days tomorrow and you
can see some slides that show that kind
of stuff and talk to people that
actually study that because I don't do
that myself. I work with colleagues that
do it and know how
to determine the age of a dinosaur,
that's really the only precise way to
figure it out. So moving away from the
carnivorous dinosaurs,
Pachycephalosaurus was bipedal, can
you say anything about its locomotion? It
was bipedal, yeah,
again moderate size to moderate to
medium largest size dinosaur, so it was
moderate speed more or less, I haven't
studied it so I can't give more detail
to that but I doubt it would give us any
big surprises in terms of its movement
it would be pretty much as we'd
expect. Zoey has a question here, she
wrote her name, how long do you think
t-rex could maintain a running pace?
That's a really hard question, endurance,
we just don't know from fossil remains
there's no easy remain, no easy method to
calculate fatigue or endurance of an
animal from the skeleton or
computer model, the science just is not
that far along, no one's figured out a
way to answer that question, so Zoey if
you are or if you become a scientist
maybe you can figure that out because
I'm at a loss, we just don't know. Okay to
a little bit more lighthearted questions,
and then we'll finish up.
First of all classic question, what is
your favorite dinosaur? Well I have to
say Trex is one of them but
because I've worked on t-rex and it's
cool I admit, but I also, the only
dinosaur ever discovered was a little
tiny bird-like dinosaur called an
alvarezsaurid from the Hell Creek
Formation of Montana, it was in a museum
drawer at Berkeley and I discovered a
little bit of its hip bone and in the
hip bones were so distinct, I knew
exactly what it was and they're really
cool animals, they're only about this big
with stubby little arms and
long tail and there were feathered
really cool things that people think,
maybe dug in ant hills because they had
these big stubby arms and little tiny
heads with very sharp needle-like teeth.
I still don't know what they did there,
they're mysterious animals but they're
they're really really cool and the fact
that I I found a piece of one that I
didn't get to name but at least it's
some sort of new animal from Montana,
that makes it one of my favorite
dinosaur. Oliver age 7 asks the
question, what's your favorite rock band
with dinosaurs? Oh there aren't that many
and there's t-rex, there's
dinosaur jr., there's - what else is there -
anyone else, dinosaur rock bands
there's probably some death metal bands
with dinosaur names that I'm not
thinking of. Is there an Allosaurus? I
can't think of any,
I mean t-rex is alright, and Dinosaur Jr
is a cool grunge band, they're not from
Seattle they're from Amherst. So that's,
that's not great but I like them alright!
Let's thank Jon one more time!
