[♩INTRO]
Figuring out what ancient creatures ate
and therefore, what role they played in their
ecosystem, isn’t easy.
But thanks to a study published this month
in the journal iScience,
we have a pretty solid idea about at least
one ancient predator
one that ruled not the land, but the sea.
The specimen was found in 2010 in the Guizhou
Province
of southwestern China, dating back to the
Middle Triassic Period,
about two hundred forty million years ago.
It’s a five-meter-long ichthyosaur named
Guizhouichthyosaurus,
part of a group of fish-shaped reptiles that
dominated Triassic oceans.
And they may have been far more impressive
predators than we thought.
See, inside this ichthyosaur’s belly are
the remains
of another marine reptile named Xinpusaurus.
This was a thalattosaur, which was a predator
of smaller marine animals
like fish or shelled creatures.
Only about half of the smaller reptile is
preserved in the predator’s stomach,
but it would have been about four meters long.
Remember, our ichthyosaur was only a meter
longer than that.
So this was one big snack, and way more so
than we thought possible.
It’s really rare to find stomach contents
for ancient marine reptiles like these,
and what we do have doesn’t add up to much.
So paleontologists typically infer these animals’
diets
by their body size or tooth shape.
Big animals with sharp teeth are more likely
to have hunted large prey.
But ichthyosaurs like Guizhouichthyosaurus
had blunt teeth
that are thought to be best suited for grasping
soft prey like squids.
This new discovery is strong evidence that
these animals were megapredators
at least some of the time, they ate very large
prey.
We don’t know for sure whether this was
a case of hunting or scavenging,
but the authors of the study think this predator
probably caught its meal alive.
That’s because the fossilized stomach remains
contain the body and legs of the prey, but
without the head and tail.
Animal carcasses decomposing at sea tend to
lose their legs
before their head and tail detach,
so we wouldn’t necessarily expect to see
legs if the meal were scavenged.
What’s more, a disembodied fossilized tail
was found about twenty-three meters away from
this fossil!
The tail matches the size and shape of the
consumed thalattosaur,
and if it’s really part of the same animal,
then it must have been torn apart,
probably by the same bite-and-shake method
we see marine predators use today.
It paints a fearsome picture, but it’s also
a huge clue
that there may be more to prehistoric marine
reptile diets than we thought.
And while we’re on the subject of surprising
fossil finds,
another new study in the journal Current Biology
provides a rare glimpse at a dinosaur embryo!
No matter how big they eventually got, all
dinosaurs started out as hatchlings.
But for many dinosaurs, we don’t know very
much
about how they grew and developed.
This new study describes a single skull,
less than three centimeters long, found within
a fossil eggshell from Argentina.
Based on its anatomy, researchers identified
the skull as a sauropod,
one of those dinosaurs with the long necks
and pillar-like legs.
More specifically, this was a type of sauropod
called a titanosaur,
some of which were truly enormous -- meaning
this specimen could have grown
into one of the largest dinosaurs ever to
live.
Incredibly, this tiny skull is one of the
best-preserved titanosaur skulls ever found.
And it has a lot to tell us about the changes
that took place as sauropods grew.
Based on the developmental features of the
skull,
the researchers estimated that it was about
three quarters of the way to hatching.
And it had already developed enough adult
facial features
to be identified as a titanosaur.
But it also had some pretty striking differences
from adults.
For one thing, its eyes were more forward-facing
than in adult titanosaurs,
suggesting these babies were good at seeing
what was ahead of them,
but became more sensitive to what was off
to the sides later.
The embryonic skull also had an unusual projection
of bone sticking off its snout,
which appears to be a single small forward-pointing
horn.
Now, that sounds a lot like an egg tooth
the temporary tooth that some animal hatchlings
use to break out of their eggs.
But egg teeth are lost after hatching.
This little horn was built into the upper
jaw bone and would have stuck around
for a while before the babies lost it later
in life.
So even if this horn was used in place of,
or alongside, an egg tooth,
we don’t know what else the babies might
have used it for.
All this tells us that baby titanosaurs
probably had very different lives compared
to adults.
The researchers don’t know what species
this embryo belongs to,
and in fact, they don’t even know for sure
where it came from.
The specimen was illegally exported out of
Argentina
before eventually being brought to the scientists.
It’s now been repatriated to its home country,
but without any data on where it came from,
it’s hard to know more about its ancient
habitat or possible family members.
Fortunately, there are many more dinosaur
eggs known from Argentina.
With some luck, this little specimen might
end up being part of a series
that cracks open the mysteries of the earliest
days of the largest dinosaurs.
Thanks for watching this episode of SciShow
News,
and a titanosaur-sized thanks to our patrons
for helping to make it happen.
A grown titanosaur, not a baby one.
Biggest one you can imagine.
If you’re interested in joining our community
of supporters,
check out patreon.com/scishow.
[♩OUTRO]
