What I’m going to discuss today involves looking at ecology
at the broadest of scales and actually [also] in the smallest
of scales in the fossil record.
Just to begin, I’m Conrad Labandeira.
I’m in the Department of Paleobiology. I am the curator of fossil arthropods
and I joined the museum in 1992.
The Eocene Messel Deposit is an amazing place.
It’s a 48 million year old deposit that was deposited
in central-west Germany
and it consists of one of the most exceptionally preserved deposits
in all of the [entire] fossil record.
And just to give you an idea of what this entails,
we have up here on the board, we have [images of Messel]
beetles with pollen in their guts, and you’ll see throughout this talk at least
the beginning part of it, that there’s a lot [preserved in this deposit] that’s
involved in constructing trophic relationships among organisms.
We have an example of cannibalism in the center left, and then we have
all of these organisms from bacteria, to plants to insects to fungi, to
various groups of vertebrates and all of their intricate relationships
suchas gut contents, in the case of the woodpecker we have seeds in
its gut. We have an amazing example of dentition in the lower left, and in
that organism we have seeds and fish fragments [in its gut].
Many of these vertebrate [groups] are extinct, but in the case of the
insects, they’re still around.
A lot of these groups no longer occur at the higher lineages.
We have, in the case of the hedgehog at the upper left, cuticle
of a beetle, other kinds of insect contents, bacteria [in its intestinal tract.]
other kinds of insect contents, bacteria [in its intestinal tract.]
For another kind of hedgehog-like organism at the left, [there are consumed]
fish rays and scales [left in the gut.] And then we have kind of a primitive
insectivore at the left with reptile bones, vertebral fragments and
other kinds of interesting things in the guts.
And we can have an example of carnivory at the upper right.
And there are all kinds of intricate insect-plant relationships such
as seed predation, leaf mines and oviposition.
And even in the case of bats, moth scales in their guts as well. So there’s
a lot of trophic information.
One of these interesting associations involves the bees
and at the left, we have an extinct tribe of apine bees closely
related to honeybees [of] today
and also related to stingless bees and
bumblebees and other kinds of related bees. And if you
note, there are little ellipses on the bodies of these things [fossils]
and those little dots on those ellipses represent pollen.
And then in the lower left, we have a leg and that is a pollen basket that
also has pollen in it. Those little orange dots [are beautifully ornamented pollen grains],
which some of which are illustrated on the right.
What we did is that we looked at the bodies of these insects
and we found out that
the head, the thorax, and the abdomen in the yellow, blue
and green [in this slide] contain a broad spectrum of pollen that
represents the ambient forest.
So these bees were foraging on flowers and collecting the
material as they foraged
and offered a pollination service to the flower.
But the legs, in orange, contain a completely different suite of pollen
and their pollen was restricted just to a few families of plants
such as the mallows and the spurges and that pollen—contained--
represented flowers that are very stereotyped
and contain a very particular type of floral design.
And that was the source of pollen was basically going back to the nest
to basically provide for food for the larvae.
[Consequently,] here we have a dual collection strategy, generalist on one
hand, and specialists on the other hand for two different types of functions.
This demonstrates that at least midway in the [one-hundred million-year]
history of bees that began in and probably sometime in the early
to late Cretaceous boundary. We already have evidence for this use,
this dual pollen collection strategy, specialist on one
hand and then generalist on the other.
I realize it's only a week after Halloween but in the upper left we have
modern day zombies,
that’s the [cult movie] Night of the Living Dead.
I’m sure all of you familiar with that.
But it turns out that in the fossil record we also have examples of zombies
except they’re ants.
And how do we know?
Well we had this very interesting leaf, at the top [of the screen], with very
distinctive death-grip marks
that actually correspond to Damage Type 212
in my compendium [Guide to Insect Damage Types]
and this was created by an ant, [such as] the ones in the lower left are
modern and if you notice issuing out of their head is a stroma—[this feature]
is a fungal fructification [fruiting structure] and this ghoulish contraption
actually represents how a fungus hypha can actually enter the [ant]
head capsule and actually immobilize the ant
to do its own bidding and so the [zombified]
ant actually crawls underneath the leaf and dies as the [parasitoid]
fungus reproduces.
So here we have an example of a really interesting interaction
at three trophic levels
and it was also reported on [an episode of] The Simpsons. [Messel zombie ants]
[ laughter ]
didn’t make it to [the journal] Science,
but nonetheless the Messel has a lot of really interesting associations
that are no longer around today such as these three.
So here’s the food web.
700 species, 6,444 links and a connectance of 0.13.
It’s very diverse. It's very highly resolved
and if we plot [48 million-year-old Messel] with modern food webs, there
are two variables: numbers of species and the fractions of links that are
predicted. That's where [Messel] occurs.
Because [Messel] it’s way out in the outlier; [but] if we degrade [Messel]
to 100 species, it occurs there [in the range of modern food webs].
And then we have the Weddell Sea web which is kind of strange
because there aren’t that many primary producers [in that food web].
So what this says is that that modern webs are highly unresolved and
that sometimes we have to go to the fossil record to really get a really
good web so that it can be compared to modern webs. And in the
case of the Messel we have one of the best [food] webs ever known.
Thank you.
[ applause ]
Question for Conrad. What is the quality of the neurological tissue in some
of these Messel fossils? It’s an incredible preservation but recently
there’s been news about arthropod preservation back into the Cambrian
of neurological tissue, so I’m just curious about that in your specimens.
Yeah, thanks for that question Kay.
It is quite remarkable. We do get tissue preservation in some of these
Messel especially in the vertebrate and insect material.
It doesn’t quite approach that of amber
but you can see for example z-rings on some of the muscles
and you can see individual fibers and they seem to be mineralized but you
can see the three dimensional structure of the muscles of especially
insect white muscles probably the best example.
But in case of plant tissues you can make out things like parenchyma, and
other epidermal layers with individual cell walls although the protoplasts
seem not be preserved.
So it is quite spectacular and it’s probably about
one of the best examples in the compression fossil record
that you see of this kind of preservation.