Hi everyone, my name is Daniel Field and
I'm a lecturer
in Vertebrate Palaeontology here in the
Department of Earth Sciences at
Cambridge
and I'm going to tell you a little bit
about studying at the interface of
biology
and earth sciences in our Department. So
first of all - what is palaeontology? Well,
very simply, palaeontology is the study of
past life
on our planet. And some palaeontologists
study the fossil record of invertebrate
animals - like those trilobites on the
upper left.
I'm a vertebrate palaeontologist, which
means that I study the fossil record
of animals with backbones like dinosaurs
and birds.
Other palaeontologists are
palaeoanthropologists who study the
fossil record of humans and their
relatives,
palaeobotanists study the fossil record
of plants at a macro and a micro scale.
So you can study the fossil record of
any group of organisms as a
palaeontologist -
but the one thing that unites all of us
together is an interest in studying how
life on this planet has changed through
time,
and an interest in using the fossil
record to study the evolutionary history
of our groups of interest. So the group
that I spend most of my time
studying happens to be birds - so I'm
interested in their early evolutionary
history
and how they evolved into all the
interesting forms
that they exhibit today. And most of the
data that I tend to work with
look something like this - the birds don't
have feathers on them anymore. Typically
I'm just looking at their fossilized
bony remains.
And this is the skull of a new fossil
bird that we've been studying that we're
very excited about -
we call it the Wonderchicken and it
happens to be the oldest modern bird
fossil
found so far - and its skull is so well
preserved
that it's allowed us to infer with some
degree of accuracy
what this bird probably would have
looked like when it was alive
66 million years ago. So one thing I'm
very interested in doing
in palaeontology is using the fossil
record
of birds and their dinosaurian relatives
to study the evolution of
key avian features, and one of the
features of birds that we're interested
in studying is the origin of their
characteristic
toothless beak. So to do that we
start with the family tree
of birds and their dinosaurian relatives,
if we
take a look at the family tree over on
the top left we have
scary carnivorous theropod dinosaurs
like velociraptor,
below that we've got Archaeopteryx
one of the
earliest feathered flying dinosaurs that
we know of
and then, if we skip down to the bottom
of our family tree, right down at the
bottom
we have modern birds themselves - so
obviously between Archaeopteryx, which
lived 150 million years ago,
and modern birds we have a lot of
evolutionary time.
And fortunately that intervening portion
of the family tree
is represented by lots of really cool
fossils of early bird-like forms,
but there's a bit of an issue with that
portion of the family tree
and that is the fact that most of those
fossils have
fairly poorly preserved skulls - and it's
very difficult to extract much
information
about the evolution of the modern
toothless bird beak
from these fragmentary and broken skulls.
So fortunately as a palaeontologist we
have a really fun way
of filling these gaps in our knowledge -
and that is doing field work, and trying
to find new fossils
that answer the evolutionary questions
that we're interested in.
So a few years ago we set off to find a
really beautifully preserved bird skull
out in the Jurassic of Colorado, but
unfortunately
we failed - we didn't find anything but, as
luck would have it, our colleagues
working one state to the East
in Kansas in the USA discovered this
skeleton
of an animal called Ichthyornis, which is
about 86 million
years old. We were really excited
about this because,
as you can see on the family tree,
Ichthyornis is right down there at the
bottom -
it's one of the closest relatives that
we know of from the age of dinosaurs
of modern birds and so we were really
hoping that there would be a nice skull
associated with this specimen.
So we took that precious fossil and
brought it to a CT-scanning facility,
in order to X-ray that fossil specimen
with very high energy X-rays so we could peer
inside the rock
and see what was there. And, when we did
that, we were amazed
to find that inside that block we had an
extremely well preserved skull
of this early fossil bird-like animal
and, as you can tell, very simply
that skull is much better preserved than
most of those other close relatives of
modern birds from the age of dinosaurs.
So the skull can actually tell us a lot
about the origin of the modern bird
skull
and its toothless beak. In fact, if you
sort of 'zoom in',
at the tip of the upper jaw you'll see
something very interesting which is a
little bit of a toothless portion of the
upper jaw -
and that happens to be the earliest
manifestation of a toothless beak
homologous with that of modern birds
that we know of in the fossil record.
So, you can take our CT-scans and
turn them upside down to see the
underside
and indeed that portion of the beak is
toothless - and what's remarkable is that
this toothless portion of the beak sits
right at the very end
of long jaws full of sharp pointy
dinosaur teeth, so this tells us that the
origin of the characteristic modern bird
beak
evolved while birds still had sharp
pointy dinosaur teeth
which teaches us something we
really didn't know much about before,
in terms of how and when the modern burn
beak
evolved. So a lot of the work that we do
involves this kind of detective work -
we'll start with dinosaurs that
are much more distantly related to
modern birds,
we'll try to figure out what kind of
questions we want to ask based on modern
bird biology
and anatomy, and we'll try to fill in
those gaps in our knowledge
with new discoveries of bird-like
animals that can tell us how, when
and why modern birds in the
characteristic forms that we see
today
came to be. So, I hope you found that
interesting you can find out more about
our research group
at the website shown there - and I
really hope to see all of you
in the Department of Earth Sciences come
Michaelmas Term to learn more
about the subject of Earth sciences
as part of the Natural Sciences Tripos.
