Hi, I am Dr. Adam Marsh.
I'm the lead Paleontologist at 
Petrified Forest National Park.
Welcome to Dinosaur Day!
Not a dinosaur, 
not a dinosaur, 
not a dinosaur, 
not a dinosaur.
That's a dinosaur!
Today we are celebrating 
the anniversary of 
Gertie the dinosaur, 
our own Chindesaurus- 
-bryansmalli 
from Petrified Forest 
National Park.
This is a virtual 
question and answer session.
Most dinosaur fossils 
have been discovered in 
North America, China, 
and Argentina.
But dinosaurs have been 
found in every continent 
all over the globe, 
including Antarctica.
Birds are one 
group of dinosaurs.
So all birds are more 
closely related to each other 
than they are to 
other kinds of dinosaurs.
The most closely related 
animal to the T. rex 
are its tyrannosaurid cousins;
Albertosaurus and 
Daspletosaurus.
So, Tyrannosaurus 
and a chick are more 
closely related to each other 
than they are to something 
like a Stegosaurus,
but they are not one anothers
closest relatives.
It's hard to constrain 
the age and life expectancy 
in fossil organisms,
especially if they don't have 
any living close relatives.
We do know that 
life expectancy and age 
 tends to vary 
even within a certain kind 
of animal group 
with body size, ecology,
and metabolism.
So with something like 
a hummingbird,
has a 3-5 year life expectancy,
whereas an ostrich might live 
for 45 years.
Now we can cut dinosaur 
limb bones in cross sections,
polish them up and 
look at them in a microscope.
And in some cases,
they lay down rings,
almost like a tree.
And we can look at annual 
growth rings,
and in that way we found 
that an animal like Sue,
the Tyrannosaurus rex,
is around 28 years old,
but something like a long necked 
Apatosaurus might live 
for more than 70 years.
What this person is referring 
to is a large phytosaur skull 
that we collected in 2016 
that's been in our fossil 
preparation lab,
essentially getting the rock
cleaned off of it since then.
There has been a lot of work 
 done since we posted on it 
on Instagram.
Right now, the back end 
of the jaw is being 
carefully taken apart, 
cleaned off and then 
and then put back together.
And eventually, we'll remove 
the lower jaw 
from the upper jaw 
so that we can make it 
more safe in the museum.
Saurischians are the group 
of dinosaurs to which 
meat-eating and 
long-neck dinosaurs belong.
These are the theropods 
and sauropodomorphs.
Now, we know that 
not all saurischians 
have been found with 
feathers in the fossil record.
In fact, only specific kinds of
saurischian theropod dinosaurs 
have been found with feathers.
No sauropodomorphs,
or long-neck dinosaurs,
have been found with feathers.
Now, people think that 
feathers might belong 
to a larger group,
like the saurischians,
because of 
the presence of what's called 
pycnofibers in pterosaurs,
which are the closely related 
flying reptiles. 
Pycnofibers are 
an almost filamentous,
feather-like structure that 
are probably developmentally,
very similar to feathers.
Now, is there an evolutionary 
reason for feathers?
Not necessarily.
There doesn't have to be 
a reason that we have 
the different physical traits 
that we have.
For example;
there is a difference between 
You hear about adaptation being
a physical characteristic 
that something has that 
may or may not make it 
better suited for 
its environment.
What happened with feathers is 
probably what's called 
exaptation, 
where feathers or feather-like 
structures existed for 
a purpose like 
thermoregulation,
and then were later 
exapted or used 
for a different purpose 
in this case flight.
The earliest, unambiguous 
dinosaurs are 
Eoraptor, Eodromaeus,
and Herrerasaurus.
These are from the 
istiglocial formation 
in Argentina, 
and they are about 230 million 
years old.
The oldest dinosaurs 
that we have from the park
are about 220 million 
years old.
Well, unfortunately,
we're not going to be 
bringing them back.
Even though DNA can survive 
in the fossil record 
for almost a million years,
DNA is meant to unravel 
and decay,
otherwise it could not unravel
and get replicated in cells
millions and millions of times
every minute.
As far as we know,
inactive sections of 
extant DNA doesn't code for
for specific traits of 
long extinct organisms.
For example, things that make 
long neck dinosaurs, 
long neck dinosaurs, 
may or may not be coded 
in inactive parts in a 
chicken's DNA.
Did you know that 
up to 8% of the human DNA
is actually viral in origin?
Well there are two kinds 
of dinosaurs that we find 
in the park.
One is called Chindesaurus
and the other is 
an animal like Coelophysis,
which is known from 
hundreds of individuals 
from Ghost Ranch, New Mexico.
They're equally abundant,
relative to each other,
but they're actually 
pretty rare compared to the 
other kinds of fossils 
we find in the park.
The oldest dinosaur that 
we found is something 
like Coelophysis,
and it's the upper part of the 
shin bone of that animal.
It's about 220 million 
years old. 
Petrified Forest didn't 
always look like this.
In fact, it's only looked 
the way it has for only the 
last maybe several 
thousand years.
Back 220 million years ago,
Petrified Forest would have 
looked a lot like Costa Rica,
and Coelophysis would have 
not had any problem running 
around in a coniferous forest 
and finding food and friends.
Well it's actually pretty hard 
to tell fossil species apart 
from eachother.
Unlike modern biologists,
who have colors and behaviors 
and specific features that we can use 
to tell species apart,
a lot of that doesnt fossilize.
We do know that more than 
500 species of dinosaurs 
have been named 
in the fossil record
but there's an estimate that 
2500 or more probably existed 
throughout the Mesozoic.
Birds, for example, 
living birds 
exceed 10,000 species,
which are all dinosaurs.
Feathers have not been found 
on any Triassic dinosaur.
The oldest feather belongs 
to something like Archaeopteryx
which is about 150 million 
years old.
That's almost 80 million years 
years after the animals that 
were alive in the Triassic 
were around.
We don't have any idea 
what dinosaurs sound like.
If you watched Jurassic Park,
they made dinosaur noises with 
modern animals.
They made the Tyrannosaurus 
noise with a slowed down 
baby elephant,
(elephant bellows)
and made the Velociraptor noises 
with mating turtles 
and angry geese.
(Goose honks)
Because birds are dinosaurs,
we suspect that at least some 
dinosaurs had the vocalization 
organ in birds called 
the syrinx. 
So, many dinosaurs probably 
sounded a lot more like birds
than they did things 
like lions.
The two types of dinosaurs 
we get at Petrified Forest 
are both meat eating 
theropod dinosaurs;
Coelophysis and Chindesaurus,
they're eating primarily meat,
and probably insects.
Now, most of the predators 
are not dinosaurs, but they're
 eating dinosaurs.
Some of them were 
ambush predators, lurking in
bogs, ponds, streams.
We understand that dinosaurs 
may or may not have relatively 
higher metabolic processes 
than the animals around them.
Perhaps they could have avoided
their predators by 
running away,
but it wasnt always successful.
Thanks for coming to our 
virtual question and answer 
session for Dinosaur Day.
We look forward to 
seeing you all in the park 
again soon.
Thanks to those who submitted 
questions and check back on 
our social media for more 
Dinosaur Day activities.
