From the Vault: The Paleoburrows

Enter the paleoburrows of South America, where evidence suggests construction not by human hands or tools but by giant claws – and for purposes we’re still trying to understand. (originally published 02/10/2022)

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Episode Transcript

Speaker 1 (00:05):
Hey, are you welcome to Stuff to Blow Your Mind?
My name is Robert Lamb and I'm Joe McCormick, and
it's Saturday. It's vault time. Uh. This episode originally aired
on February two, and it's on the phenomenon of Paleo Burrows.
Shall we go into the Tunnel's rob Let's venture in

(00:26):
Welcome to Stuff to Blow Your Mind production of My
Heart Radio. Hey, welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Joe McCormick, and
I think today we're doing tunnels, Is that right? Yeah,
we're going to venture into some strange tunnels in the earth. Um.

(00:50):
I don't know about you, Joe, but I love a
good creepy tunnel story. Um. You know, any caliber of
motion picture. If you have like a subway tunnel and
you have a monster sham going around down there, even
possibility of a monster shambling around down there, I'm generally
on board. Oh yeah, I mean it's one of the classics.
And you know your your your your fairy tale types.

(01:11):
One of the big ones is you've got to go
into the underworld, right, and what's what's closer in physical
reality to an underworld than cave or a tunnel. Caves
and tunnels, I mean, humans have have long been fascinated
by them. You know, we see a cave, we want
to get in there. We need to know what's going on,
We need to find out what kind of sacred uh
secrets are contained in there. And so, you know, I'm

(01:34):
also continually fascinated by tales of of you know, modern
tunnel systems, abandoned tunnel systems from from further back in history. UM.
I also love a good you know, tunnel of unknown
origin stories such as the Strange Tunnels and the Hyperion
novels or oh another a film in this case that
had some strange tunnels. There's the whole tunnel plotline in

(01:57):
Jordan Peel's two thousand nineteen film US. Yeah. Yeah, that one.
Let's not spoil anything about that. I'm not gonna spoil anything,
but it does open with a with a fun text
crawl uh quote. There are thousands of miles of tunnels
beneath the United States, abandoned subway systems, unused service roots,
and deserted mind shafts. Many have no known purpose at all.

(02:20):
So I instantly I was, you know, on board for that.
I love a good informational legend like that. And the
fun thing about that quote is that it's a It's
a fun one to ponder over because, on one hand,
it's sort of true. There are a lot of of
of abandoned tunnel systems in the United States, some with
some pretty engaging stories about them at times. You know,

(02:41):
old minds, abandoned subway projects, abandoned subway lines. I'm a
real I'm a real sucker for that sort of thing. Um. Also,
you know, ultimately, I think this is the filming question
is one that maybe doesn't you know, I supposed to
take it completely seriously and think, well, there's this entire
system of of tunnels and who knows what's going on

(03:01):
down there. But it also reminds me of what we're
talking about here today, uh, the story of mysterious tunnels
uh and caves caverns in South America. Now, what makes
today's example really interesting is normally you're going to think
about your your mysterious tunnels in two categories. One is

(03:22):
one is obviously you know, a cave of geological origin,
you know, uh, oh, you know here, here's a millions
of years old cave with with stalactites and stalagmites, clearly
a water formed cavity of some type. But then the
other bucket, of course is who made this tunnel? What
human doug this and for what purpose? But actually, uh,

(03:44):
those two categories leave out leave out another option, don't they? Yeah,
and it's not aliens. The fun thing about this is
you don't need aliens to get to the you know,
the wow moment, to the to the amazing content of
this particular topic, because we're still we still seem to
be dealing with a non human entity, a non human

(04:06):
will behind these um, these these tunnels or caves or
or burrows, Uh, is probably more appropriate to call them
these paleo burrows of South America. They're not the work
of of a pre Columbian society. Uh, they're older and
they're quite impressive. Well, but as we dive in here,
I want to mention that that one of my main

(04:27):
sources here is an excellent book that came out, I believe,
in seventeen by Anthony J. Martin, a paleontologist at Emory
University here here in Atlanta, titled The Evolution Underground Burrows, Bunkers,
and the Marvelous subterranean world beneath our feet. Um, I've
been meaning to cover this book in some form or

(04:49):
another for a while and I saw it on the
shelf again. I was like, all right, today's the day
I'm gonna I'm gonna bust this book out and see
what grabs my attention. So I haven't read this yet,
but my interest is p aeked because I like, you
love a tunnel burrow, a din under the earth. But
I was familiar with Anthony J. Martin's name, and I'm
not sure, but I think it was because he was

(05:12):
one of the authors of research from two thousand seven
that was famous for documenting the first fossil evidence of
a dinosaur, the Dug Tunnels. Did you read about this? Yeah,
this is covered in the in the in the book.
Uh yeah, there's something some wonderful illustrations, and even in
one case I believe a bit of folk art depicting

(05:32):
these creatures, which I loved. Uh So the brief rundown
on this The paper where they described this find came
out in two thousand seven and Proceedings of the Royal
Society b Biological Sciences. It was by David J. Verikio
Anthony J. Martin and Yoshihiro Katsura, and it was called
first trace and body fossil evidence of a burrowing Denning dinosaur.

(05:55):
So this fossil find came from a formation in southwest
mont Hannah's near the border with Idaho. I think it's
called the Black Leaf formation, and this formation dates back
to the mid Cretaceous period. The find consisted of both
the trace fossil of the borough itself as well as

(06:16):
skeletal fossils found inside. The skeletal fossils were of one
adult and two juveniles, which apparently all died and were
fossilized inside the burrow. The dinosaur was a member of
a previously undiscovered species of Ornithia, which the author's name
or Ricto dromius cubicularis. And that genus name, or Ricto dromius,

(06:40):
that means digging runners. That gives you a hint of
like the two main talents of the stat build of
this dinosaur. These would have been herbivorous dinosaurs that lived
roughly ninety something million years ago. And so one question
you might wonder is, well, how do we know that
the dinosaurs we found inside actually made the tunnel or
burrow instead of I don't know, finding a naturally occurring

(07:03):
hollow or tunnel made by some other mysterious creature. Well,
it seems likely that the dinosaurs themselves made it because
of the creatures anatomy and because of its relationship to
the burrow. So, in the words of the author's quote,
the features of the snout, shoulder, girdle, and pelvis are
consistent with digging habits. So it has multiple anatomical adaptations

(07:26):
you would expect to find in a creature that specializes
in digging. Like it's got a snout that is sort
of fused together in a way that would make it
kind of a good shovel for like kicking soil back
and forth, and its skeletal structure seems well put together
to kind of brace itself with the back limbs or
the pelvis as it uses its four limbs to dig

(07:46):
and and throw soil out behind it. Yeah, this is
something that's h that's touched on with various organisms in
this book. That no organism needs the tools for burrowing
or digging. But it's not just the you know, that's
something on matter of having claws or some sort of snout.
It also needs uh, like the body to back it up.

(08:06):
And so we can look at the bodies of many
of these organisms that are extinct now and we can
we can make very informed uh guess is about what
their body had evolved to do. Right. You need the
right kind of chassis to give you leverage with which
to dig, because you remember, your digging is not just
about what the hands are doing in the front. The

(08:27):
four limbs scraping away at things. You all, the bracing
is really important. You gotta hold your ground while you're scraping. Yes, yeah,
you can't just put a big scoop on the front
of your um, I don't know your prius and say
you're gonna go out and start moving earth around. But
another clue that that the dinosaurs inside this burrow dug

(08:47):
it were the fact that the burrow almost perfectly matches
the width and breadth of the torso of the adult.
So it seems like this is a burrow of the
right size to have been dug by the adult dinosaur.
And adult is found along with two juveniles inside the borrow,
and they were found with no bite marks or anything
on the bones, no signs of of carnivore bone assemblies

(09:10):
like you might sometimes find where you know, carnivore is
dumping all the bones from its recent meals. So it
looks like this was not just a tunnel dug by
a dinosaur, but one that an adult dinosaur lived inside
with its juveniles, and this would provide evidence of a
case of extended parental care in dinosaurs, something that I

(09:31):
think was uh less well evidenced and more controversial at
the time. And based on the size of the juveniles,
it appears that this parental care had gone on for
at least several months. Yeah, yeah, this is a This
is in stark contrast to some of the hypothesized ways
that say, giant sauropods would have dealt with their young.

(09:52):
I remember discussing that on the podcast, where like at
least one hypothesis was the like the eggs kind of
just fall out and they just rolled out the side
and then they do their thing. So yeah, yeah, yeah,
totally different parenting strategy. Anyway. The authors of this paper
note that vertebrates today create burrows, of course for a
number of reasons. Some actually use tunneling as a as

(10:13):
a food foraging strategy, trying to get underground food. Some
use it for escaping predators. That's a common one as
a type of shelter that protects you, and some use
it for avoiding the elements in harsh environments. But the
other half of the equation is that this animal, or rictodromus,
was also a cursor, which means a runner. Remember the

(10:34):
name means digging runner. And the authors of this paper
say that if we look at analogies today, running animals
that create burrows tend to do so for a pretty
specific reason, which is they create them as dens for
rearing their young. So, once you give birth to young,
the young and the juveniles are pretty vulnerable for a

(10:54):
while until they get bigger, big enough to run around
and defend themselves like an adult can, and so a
den provides a place to protect the young while they're
growing and still vulnerable. Now, Joe, you included a fabulous
bit of paleo art here from this uh this study.
This is actually in the book as well. Um. I
love a good bit of paleo art. But here we

(11:15):
see the parent, we see a cutaway of the burrow,
and we see the two young dinos at the bottom.
I like that the paleo artist in this case has
chosen to depict the adult Erictodromius as Sam the Eagle
from the Muppets as a very severe eyebrow and uh
and and a very well I think this is anatomically

(11:38):
accurate the beak like mouth. Yes. Well, anyway, sorry if
that was a digression from the paleo burrows, but I
just wanted to say, Yeah, so you're looking at this
book by Anthony J. Martin, and Martin has a history
with with the Diggers. Yeah. And Martin knows his his
tunnels and his his burrows here, and so he he
discusses the paleo burrows in the Evolution Underground, uh, pointing

(12:00):
out that geologists in Argentina and Brazil noted these burrows
back in the nineteen twenties and nineteen thirties. Uh. Some
had partially or wholly filled with sediment, but others remain
quite open. Uh. They were cutting a variety of soft um, igneous,
metamorphic and set and sedimentary bedrock. So we're talking about

(12:22):
we're talking about rock here. That's one of the the
important and I think really impressive things about about this. Uh.
Some of some were visible in outcrops, others as cylindrical chambers.
There are some actually some wonderful photographs you can find
online and attached to various um articles about these papers

(12:42):
about these Uh, they're quite impressive. They look just like
a tunnel cut through a rock. You can, uh, you
know that you they look like that. They look like
real tunnels. We're not just talking about just an indention
in the side of a hill. Yeah. Some of them
look like somebody brought in the boring machine, like a large,
like several meter wide, basically circular, cylindrical tunnel. Others are smaller,

(13:07):
more compact, or more kind of a half moon shape.
But I just wanted to flag it. This was interesting
because so Martin notes that the people had previously observed
these things in the twenties and thirties in Argentina and Brazil. Now,
I had been reading about the paleo burrows in some
articles that came out in seventeen, and those articles were

(13:29):
were essentially saying that that nobody had ever reported these
things until just recently, that they just sort of come
on the radar. But it seems like Martin has turned
up some other previous reports of of these things. Yeah, yeah,
that that's what seems to be the case. But the
important thing is that they weren't exactly sure what they
were looking at here now, and that over the decades

(13:50):
to follow, hundreds of these caves were uncovered, with a
lot of concentration in the area of what is now
Rio Grande do So in southern Brazil. Um others, other
of paleo burrows of this nature are simply undiscovered. Uh.
I've seen a total number express somewhere around like fifteen hundred,

(14:10):
and again they're likely others as well that haven't been
discovered or will never be discovered, you know. Yeah, the
reporting I was reading said that most of these are
clustered in kind of a kind of strange geographical bands,
like right in this area in southern Brazil, but not
further south than like Uruguay. But then if you go

(14:30):
even further south, there are some more down further into Argentina. Yeah.
So the archaeologists came back and they were studying them
with renewed interest in the seventies and eighties, and they
hypothesized that these were surely the work of human beings
Martin Wrights quote. Considering their proportions and geological setting. This
was a perfectly reasonable hypothesis, as they superficially resembled human

(14:54):
made tunnels and chambers in Cappadocia and elsewhere. Now Capa
Dosia Is is noted here as u is a place
that in what is modern day Turkey where you have
these hit wonderful historic cave houses that can still be
seen today. Um, Joe, you might be interested to also
note that they filmed parts of your The Hunter from

(15:16):
the Future here. Yes, there there are quite clear signs
of the movie has scenes of of the of its
muscly superstar reb Brown scuttling around over these beautiful rock formations.
I think he fights a dinosaur in what is clearly
Cappadocia than now. While some of these paleo burrows, again

(15:41):
in South America, who were too small to have served
as anything other than hiding places for children, um, he
writes that others were large enough to have potentially been
human dwellings. The largest word as wide as thirteen feet
or four meters. Um, they were six point six feet
tall or you know, or two meters, and they were
more than three hundred and thirty feet long or about

(16:04):
a hundred meters in length. So again, well, you know,
in many of these cases, we're not just talking about uh,
some sort of a narrow burrow, but but something that
that that a that a family or a small group
could have lived in. Quote. Moreover, some tunnels connected with
one another or join larger sub spherical chambers to make
more complicated networks. Once put together, some of these spaces

(16:28):
feasibly could have served as underground homes for families or
small communities. A few even contain petroglyphs showing that pre
Columbian people entered at least some of them. And as
we've we've touched on already, and there's a there's a
long history of humans using naturally occurring caves, if not
for shelter, then for for other purposes, be it like, um,
you know, a burial or some sort of sacred purpose,

(16:51):
or in some cases, you know, we're not sure exactly
what that purpose might have been. Uh. And then we
have excellent examples of places like Cappadocia, which we just mentioned,
which demonstrate that if local geologic conditions are conducive to excavation,
then homes can be manufactured in the substance of the earth.
There are also various traditions of pit houses partially buried

(17:13):
or excavated homes. Again, it just kind of depends on
the culture what's available there in the given environment. But
in looking at these paleo burrows, researchers begin to notice
things that made it less likely that humans built these
particular tunnels at all. So, first of all, while artifacts
and petroglyphs did factor into some of these sites, we

(17:34):
did not find anywhere near the amount of human bones
and human artifacts that we'd expect to find at a
place where humans lived. Humans visited, but they did not
seem to live here. And this is something that you know,
you think of any of any of the episodes we've
record or anything you read about about ancient sites of
human habitation, you have, you know, you have these layers

(17:56):
you can go through. You can you can essentially sort
through the garbage of human civilizations and learn what they
were up to and how long they were there. And
in these cases, it does not seem like there is
there are enough artifacts, enough remains or even enough you know,
um petroglyphs uh to indicate that they were here. And
that's another thing. Petroglyph rarity in these tunnels indicated. According

(18:19):
to Martin quote folks were not inspired enough to hang
out in these places and make art. Another fact, and
this gets into the artifact issue as well, is indigenous
people's in south eastern South America did not have access
to the right materials for rock carving tools, and no
evidence of of said tools were found. So, again getting

(18:40):
back into the that the lack of artifacts to support
the the idea that humans made these uh these burrows
uh and or lived here. So during the nighties, researchers
began to turn their attention away from human beings. Uh.
They looked at the scale of these caves and tunnels.
The small child size tunnels that we mentioned, they decided

(19:01):
were likely the result of of a smaller burrowing prehistoric
animals such as giant armadillo. But the grand caves and tunnels,
the ones in which human families or communities could have
potentially lived. A new hypothesis emerged for these architects, and
it's it's not human beings. It's not flowing water or

(19:22):
you know, natural geologic processes. It is the giant ground sloth.
The big boys, the big boys. Yeah, so um, I
know we've talked about sloths, uh, extant sloth species on
the show before, and I guess giant ground sloths have
come up but at least a time or two. But
I don't think we've really discussed like what they were

(19:42):
and why they're so cool, because today we have in
the world, I believe, six extant species of our boreal sloths.
You know, they live in the trees, and these are
certainly weird and wonderful animals. Um. I'll be the first
to admit that they can be a bit of a
bore if you encounter them in the zoo. You know,
they're typically just um, you know, bunched in the corner
of a of an exhibit, you know, just chilling or

(20:05):
staying warm. Uh. But I find that they often look
like a like a wig hanging on a hook. Yeah,
and uh, I mean I'm not commenting on their their
happiness or lack of happiness there, but they're not as interests.
They're not magical to behold. But in the wild, uh,
they come off like these just strange elemental spirit beings.

(20:27):
I had the privilege to glimpse one in the wild
ones and it was just magical. It's got like this
kind of thing that like slowly emerges out of the
canopy and the distance and you glimpse it for a
short amount of time and then it's gone. They're also
magical in a different way if you get up close
enough to see their face, because they often appear to
be smiling. Yes, they have very the their faces are

(20:51):
in this wonderful place that where they you know that
we lean into anthropomorphizing them veryther easily. They look kind
of like they're smiling. They look a little a little dirty,
which is you know which, which is cute too? Cuteness
um and yeah, and don't even get it started on
baby sloths absolutely adorable. So we have today three toad

(21:12):
slots and two toad slots. This refers to the four
limbs only, and these represent two distantly related families that
experience convergent evolution to our boreal life. Okay, so the
sloth lineage is not one that that always existed in
the trees. The species we have today are the ones
that happened to move into the trees at some point

(21:34):
in in in deep history. That's right. Yeah, Because plenty
of these other slots or or slothes if you, if
you were rather believe it's the British pronounciation, um, many
of them were ground slots, and in some cases we're
talking giant ground slots, and these can be quite impressive.
I've enjoyed looking at at bones, you know, fossil exhibits

(21:57):
of these over time. There's also a wonderful, full scale,
muddy and shaggy recreation of of of a ground slot
at Atlanta's own firm Bank Museum of Natural History. I
don't know if you've been over to see this, Joe,
but it's in the walk Through Time in Georgia exhibit. Yeah.
I have been through that before, though I don't remember
exactly what this one looks like. I wonder if there's

(22:18):
a picture of it online. Hold on, Oh yeah, okay,
here it is. I remember this now. Okay, this sloth
needs a bath. First of all, it is filthy. It
looks really gross. Yeah, it's it's it's it's impressive. I
imagine it's been I don't know how long it's been there,
but it has to have been impressing school children for
for quite a while at this point. And I hope

(22:40):
that if at some point they they they change anything
in that exhibit, they keep the sloth. Uh. This would
have been a keep it dirty, Keep it dirty, keep it,
keep it, keep it on display. Uh, this would have
I believe this would have been an airmatherium, which was
a giant ground slow that would have lived four point

(23:01):
nine million years ago to around eleven thousand years ago.
And it was It was a pretty big big guy,
rivaling but not surpassing the megatherium in size. Now, megatherium,
this is the this is the biggest of the known
ground sloths of prehistoric times. Uh. Megatherium is Latin for

(23:22):
the great beast. Oh, I've never put that together before.
The theory um theoryum being beast. But that would be like,
as in the word thee amorphic, taking the form of
a beast. Yeah. So these guys reached heights of twenty
ft or six meters and they probably weighed roughly four tons. Uh,
you know, dealing with the adults here obviously. Um. It

(23:42):
was simply put the sloth as mega fauna fear and
feeling that filling that niche in the in the ecosystem,
A giant eating machine that didn't have to worry too
much about predators, ate a lot to maintain their enormous
bodies and then also slept a lot to digest it.
This particular, a guy would have been as big as
an elephant, and it exceeded at the time only in size,

(24:05):
uh you know, concerning mammals by some terrestrial mammals, by
some mammoths during its day. So this was a huge animal.
And while there are some I think these are mainly controversial.
There's a controversial hypothesis that it might have been partially carnivorous, uh,
you know, perhaps feasting on scavenged dead animals, such as
I believe the glyptodonts, but it's wildly thought. I believe

(24:28):
that they were merely selective herbivores, though there are some
ground slots that I think there there's more robust evidence
that they may have been sporadically omnivorous, such as the
Mila don Darwini. There was I believe a two thousand
twenty one study looking at the copper lights of it,
the fossil pooh of this particular slot, and they determined that, yeah,

(24:51):
it was probably scavenging some meat here and there to
to make things to make ends meet. Though as we've
discussed on the show several times, they're actually u quite
a there's quite robust documentation that many animals we think
of as pretty much strictly herbivorous, will in some strange
occasions eat meat. Right. Nature is just pretty opportunistic. I mean,

(25:12):
it's gonna take what it gets. Yeah, So you know
that this is just a starter on just how weird
and strange these uh, these these sloths truly were. I mean,
they're they're huge. There's the there's this idea that some
of them are also eating a little meat here and there.
But then when you start realizing that, Okay, looking at

(25:33):
these paleo burrows, we're talking about giant ground sloths. They
were not just digging in mud and dirt. They were
burrowing through rock. Uh, We're just in a whole different
dimension of wonder here. In my opinion, Martin writes that
as paleontologists in Argentina and Brazil started looking closer at
the at the the paleo burrows, they begin to find

(25:54):
clear signs that they were made. They seem to have
been made by giant sloths. They were so for of
all they saw there were groove marks in the walls
that matched the size and claw account of ground slots,
usually two toad and then also the dimensions of the
tunnels pointed towards the slots. These were not smooth and
cylindrical tunnels, but quote a series of semi elliptical chambers

(26:17):
with flat floors but ceilings that's that were possibly buffed
out into concave shapes by the sloths backs and the
resulting complexes of tunnels and rooms. Again this this feeling
that you're going into a multi chambered subterranean habitat. These
were likely the result of many generations of ground slots
returning to a given sight year after year, So not

(26:41):
just one creating this, but you know, coming back to
the same location and uh and essentially adding onto it. Right,
And from what I was reading these paleo burrows, they
vary greatly in like size and complexity, right, So some
are just sort of a straight cylinder that that goes
aways in and and then terminates. But there are these

(27:01):
other ones like you're talking about that have these uh
more elaborate branching tunnels and sometimes open up into what
appeared to be kind of rooms inside. Yeah, yeah, and
these you know, I guess we could if you know,
it's it's difficult to compare these types of constructions to
human constructions, but you know, it's kind of like thinking about, well,
think about a newspaper shop. Sometimes it's a freestanding place

(27:25):
out here on on a street with nothing around it.
Other times, well it's it's got this thing next to
it and this other thing, and it gets depends on
just how much uh sloth activity was going on in
that given spot, like how how prime this location was
for the burrows, and how many generations of of of
animals were coming back to this place and digging these

(27:45):
spaces out and redigging, thank thank, thank Okay. So another
interesting point of comparison based on the articles I was
reading versus Martin's take on this, is that the stuff
I was reading made it seem like it was less
well agreed on what what exactly had made these tunnels

(28:09):
and why, and that the ground slots and extinct species
of armadillos where the main contenders. But it sounds like
Martin is is way more on the sloths side. Yes, yeah,
And and he writes when you when you look at
giant ground sloth anatomy as well, especially um uh skellow
doth the ethereum and gloss ethereum, you find that their

(28:30):
claw hands have these closely spaced thick fingers that make
for quote natural shovels when applied against soft rock. Uh.
They also had, you know, coming back to our example earlier,
they had the muscle to back it all up. They
had the four limbs and the shoulders. He compares it
to the muscles necessary for a galloping power, like a
galloping horse, except that in this case it's applied to digging.

(28:53):
So instead of running, this is this is power that's
clearly meant to dig. Also, their center of gravity was
more towards the ear of the body, which he indicates
would be would be more in line with a creature
that's burrowing. Now, these two species that he ends up
writing about, they're not they're not quite as big as
the megathereum. But Martin he compares them to automobile. So

(29:14):
he says that the skelet ethereum was the size of
a Smart fort Woe electric car. These are these kind
of mini car. I didn't really know what these were called,
but you see them how driving around. Oh yeah, okay,
I didn't know what these were called either, but yeah,
they're they're like the little little cars the I don't
know which you could like compact electric cars, you might

(29:34):
see it, you imagine driving around some European city or something,
right right, Uh, And then he says that gloss ethereum
was more of the size of an average midsize car.
That you know, we do some some car ads for
this show occasionally, and I think we need to start
asking the advertisers to indicate what species of it of

(29:55):
extinct ground sloth was the size of this vehicle, so
that you know, listeners will be a little bit more
informed about their potential auto purchases. Now what Martin doesn't
really discuss megathereum in his book. It's but it seems
like megatherium may have burrowed as well. I found some
articles that we're talking about the megathereum and and burrowing possibilities.

(30:16):
But this kind of blew me away. There's at least
one hypothesis out there that megatherium might have have been hairless,
like like a naked mole rat, like a towering naked
mole rat. Uh yeah, And I included uh, a bit
of paleo art here um indicating what this might have

(30:38):
looked like. I found it completely strange and wonderful. Oh yeah,
because you shared this with me and well, he looks
like the engineers from the Alien franchise. Yeah, you managed
to even find a pose from one of the engineers
where it's it's it looks like they're they're doing the
same pose here. Yeah. I wish I could have done
it though. What would have been perfect is if it

(30:58):
was the engineer but he had the mask on, like
when they find the body in the original Alien. Oh goodness, Yeah,
because the this naked giant sloth head, it's fleshy head
with it's it would have, you know, probably had a
pretty like fleshy lip situation for uh, for all of
the delicate consumption of of tree bits. Uh. Yeah, it

(31:20):
would have it looked it looks a lot like that
mass that they wear in those in those movies. Okay,
so wait a minute, did you did you credit this
hypothesis yet? No, I haven't yet because the comment Okay,
this is a hypothesis by a paleontologist from Uruguay, Richard A. Farina.
He wrote a paper in two thousand and two titled

(31:42):
Megathereum the Hairless Appearances of the Great Quaternary Sloths, arguing
that this is in part because modern large this may
be the case he's arguing in part because modern large
mammals such as elephants and rhinos are mostly hairless to
prevent overheating and hot climates. Okay, so, as far as
I'm aware, this is not the dominant view of of

(32:04):
of these ancient ground slots, but this is one idea.
This is funny because I came across yet another paper
where one of the two authors is the same guy,
Richard Farina. Uh. This one was from nine in Proceedings
of the Royal Society B by Farina and somebody named R. E. Blanco,
And this one is called Megatherium the Stabber. That's the

(32:26):
title of the paper. And this one hypothesizes. Now you
may have already sort of touched on this when when
talking about the the different ideas about the diets of
these slots. But here Farina and Blanco are looking at
characteristics of the remains of of the giant ground sloth
of of Megathereum and saying maybe it wasn't so herbivorous.

(32:48):
They write, uh, quote, Megatherium american um had morphological features
that are better explained by its having had carnivorous habits
rather than by solely herbivorous ones. Specifically, the question of
its four arms having been designed for optimizing speed rather
than strength of extension is addressed. So they argue that

(33:09):
the anatomy of the four arms is such that this
is an animal that would have been using vicious attacks
with its claws rather than just sort of uh slow
slow extending actions of like tearing branches out of trees
or something. And then they also say that the high
mechanical advantage of the megatherium's biceps would have made it
possible for the animal to have lifted and carried heavy weights.

(33:32):
And they're like, well, what if this means it was
like turning animals over to get at the soft underbelly.
I'm not sure if anybody agrees with this today, this
seems this seems possibly out there. But I like the
idea that Verena has has made a career, at least
partially on on proposing alternate interpretations of the megatherium. Yeah,

(33:55):
I think I I did look at part of this paper.
The idea I think is that glyptodonts it would have
been like turning the glip to dot over and then
using the claws and the forearms to like dig into
the belly and start eating the flesh thing, flip it
and then stab with the claws. Yeah, and I'm not
sure entirely if we're talking about a a living glipto

(34:15):
dot or a dead one. If we're ultimately talking is
he arguing like the this was the Mighty Hunter or
that basically it's eating a lot of plants, but if
it finds a dead glipto dot, yeah, it's going to
flip it over and dig in a little bit. They're
saying predatory behavior. So again, again I want to be
very clear, I've not found any indication that this is
a widely accepted interpretation of of megatherium remains. But interesting,

(34:40):
you know, yeah, that's funny. Alright, So coming back to
paleot burrows, um, one of the big remaining questions, and
ultimately I guess one of the big remaining mysteries is Okay,
so if we if we're gonna go with the hypothesis
that these were dug out by giant ground slots, why
did they burrow in the ground, why did they seem
to come act to the same places, uh, you know,

(35:02):
year after year, generation after generation and maintain these spaces.
So Martin gets into this because the whole book is about,
you know, deals with questions of why animals do this,
Why is the burrow advantageous, Why is it helped you know,
why in some cases did it enable certain creatures to
survive cataclysms on the earth? Well, well, Martin points out that, Okay,
if we're looking at the small opaleo burrows, we're looking

(35:24):
at the work presumed to be created by giant armadillos.
He thinks they likely burrowed for the same reason that
modern armadillos do. It's just it's safer underground. It allows
them to hide somewhere that major predators cannot go. And um.
And so you know, these ancient armadillos, even though there
they were bigger than what we have today, they would
still have to avoid things like sabertooth cats and short

(35:47):
faced bears. But when we look at the great ground
slots here, digging tunnels so big that they wouldn't have
been able to keep these predators out, you know, we
have a slightly different situation. Uh, And we're also dealing
with creatures that were they were you know, large enough
in some cases that they probably didn't really have to
worry about these predators, not while they were healthy at

(36:10):
any rate, and you know, not when in uh, you know,
certainly when you get into you know, young being around,
that's just a different situation. But you know, they're not
as threatened by these predators, and they also are not
creating spaces that would adequately protect them anyway. Yeah, so,
I mean these are kind of the perks of being megafauna,
with only climate change and human hunting seeming to be

(36:33):
big enough threats to to end their reigns. According to Martin,
the most popular current hypothesis here is that the primary
reason that ground the giant ground sloths um dug these
tunnels was ultimately to cope with a climate that was
drier than today's. So the idea here is the cave
would have maintained more human conditions as well as an

(36:55):
average temperature, thus helping the animal out no matter what
the side temperature, as if it's colder or hotter than
what would be comfortable for the organism. Now that is
interesting and it also makes me think about how I
think it's certainly the case that when animals get bigger,
they have more heat dissipation problems to worry about, right right, right,

(37:20):
So so that, Yeah, this hypothesis seems to revolve, you know,
roughly around that like how does this this, this, uh, this,
this large ground sloth maintain appropriate body temperatures? And um,
I can only guess how this might mash or not
mesh with Farina's hairless ground sloth hypothesis, Like does a

(37:40):
hairless ground sloth would it need to climb into a burrow?
Even more, I don't know. This is not something that
I think experts have weight in on that I have seen.
As a side note, I will say that I did
notice that looks like giant ground sloths do feature into
some video games. I wonder if anyone has been inspired
by Phonina's hypotheses and decided to make them aggressive and

(38:05):
maybe they come up and like they if you're in
a vehicle, they turn your vehicle over and like dig
you out through the bottom of the vehicle. Ground slots
the naked stabber. Yeah. Now, as as I mentioned earlier,
the ground slauce we're talking about, they did overlap with
human beings for for at least a short time, and
it seems like human beings probably had played a major

(38:27):
role in their extinction. Um, you know, there there there
have been sites where we find evidence of of butchery
taking place with the with these giant ground sloths. So
ultimately human beings survived, some arboreal sloth survived, but the
age of the giant ground sloth um came to any end. Okay,
So this is not super related to what we're talking about.

(38:48):
But did you happen to read that thing about the
giant ground slots and the paper arguing that that like
twenty two of them that were found dead, all in
the same place, died in a in a poop related
mass casualty incident. No I did not. Uh. So the
paper was published in paleo Geography, Paleoclimatology and Paleoecology in

(39:08):
in by Lindsay at all uh and it was documenting
a large death assemblage from the from the late place
to scene in a place called tonke Loma in the
southwest of of Ecuador. And so it was this place
that had the remains of at least twenty two different

(39:30):
giant ground sloths, the Ramotherium laurel ardi. And they they
found all of these animals together in a in a
deposition pattern that indicated that they basically all died right
around the same time gathered around this marshy little pool
of water that looked like a place that had repeatedly

(39:53):
been been filled with water and then and then dried
up and allowed plants to grow, and then filled with
water again. So maybe one of these sort of intermittent
watering holes, places that that sometimes have water and sometimes don't.
And based on a number of cues around this area,
the authors decided that they thought the most likely interpretation

(40:14):
of what happened here is that a bunch of giant
ground slots were hanging out in and around this water,
using it to cool their bodies and as a as
a watering hole, to drink from and to eat the
plants that were growing around, and that by fouling this
water source that was ever shrinking with their fecal matter,

(40:34):
they essentially poop poison to themselves and and many of
them ended up dying. You know, I don't have Is
there a paleo art to go with this one show?
It's not very inspiring for the children's books, is it.
But but they end up writing and and their their
modern analogies for this. The fountains like like shrinking watering

(40:55):
holes in in the present day savannah environments. They write, quote,
we suggest that this death event could have resulted from
drought ind or disease stemming from the contamination of the wallow,
paralleling situations observed among hippopotamus populations in watering holes on
the present day African savannah. So sometimes this apparently happens,
like a watering hole in a in a dry area

(41:17):
is filled with hippos and they just keep pooping into
it and drinking it, and obviously that's that's not good
for them. Well, we can see how, you know, we
can see like changing climates potentially impacting these situations as well. Yeah, yeah,
so um Martin and his But again, the whole book
is full of full is full of wonderful explorations of
of burrowing creatures, um, you know, and not all of

(41:39):
which are vertebrates. H for sure, I recommend picking that
up if you're at all interested in this topic. But
he writes that scientists would have once thought that creatures
as large as these, uh these ground floss would have
would not have burrowed, that the borrowed burrowing creatures do
not grow this big. But he points out that in fact,
the largest burrowing animals today are bears, especially, says if

(42:01):
you count snow as a substrate for burrowing, which he does,
you know, I think we've all seen uh. He points
out that, you know, we've all seen documentaries at this
point showing polar bears doing the burling in the snow,
creating a burrow. Uh. Mother Polo polar bear anyway for
her young and uh and yeah, if you if you
count snow as a substrate for burrowing, then that's that's burrowing,

(42:22):
and that's a pretty impressive. Interesting. So this comes in
a way back to the dinosaur paper we talked about earlier,
because this would primarily be a dinning behavior for the
protection of young while they're while they're still vulnerable. Yeah,
now I do have to mention as well, quite amusingly
and of course very much touching on my interest. He

(42:44):
also compares the giant ground sloth to the grab lloids
from the movie Trimmers. This was pretty fun when I
was looking through the index and this. When I first
got the book, I was like, oh, he talks about
trimmers at some point. This seems like our our kind
of scientists, because was the giant ground sloths also had
multiple snake tongues that would go out and get well, no,

(43:05):
but but he points out, like he seems to be
a fan of tremmors. But he points out that, Okay,
you have these fabulous worm like creatures that are digging
these tunnels, burrowing through the ground in this corner of Nevada. Um.
He says, well, well, there would probably be some remnant
of that. There would be some uh, there's some evidence
so the ancient grab boids in this area, um where

(43:26):
the burrowing would have taken place. Right, So even if
the animal decomposed, it would leave the trace fossils of
its burrows, right. And I don't know, thinking back on
the grab Boids, it looked like there were some hard
parts that might fossilize. Oh yeah, maybe that's beaks or something. Yeah,
the beak. Yeah, I don't know. Awaiting his his full

(43:48):
paper break doing a breakdown of the grab Boids. Now,
wait a minute. Didn't we learn in some of the
Deep Trimmor sequels that they have multiple life cycle stages
and that some of them are like flying and junk
like running around. There's a version of legs. Yeah. Um,
I I don't know that I ever really watched any
of the sequels, but I have a lot of love

(44:10):
for that first Trimor's film. That was just that's a
pretty perfect monster movie, pretty great. So Kevin Bacon is
not in the sequels. The sequels end up focusing back
at some point, or he was because they did a
TV series. They did a lot of I think, you know,
I didn't know that Sci Fi Channel kind of sequels there,
but then they did a TV show at some point,

(44:31):
and um, I feel I feel like Kevin Bacon finally
came back. The sequels I'm familiar with don't have Bacon.
They focus more on that guy who's Reba's husband, and
the first one, the like the gun the gun prepper guy. Yeah,
that played by Michael Gross. Yeah that's right. Yeah, he's
the he's the like heavily armed Dale Gribble guy in

(44:53):
the first movie. Yeah. Yeah, he was in a bunch
of him and he was fun in that. I don't
know why, but we we often go around quoting Reba
McIntire from the first Trimmer's movie. She she's just got
a lot of a lot of punchy delivery. You know,
he didn't get pantrition anyone with the elphant gun. Yeah,
Reba's great in that yeah. Oh, and I am correct.
There was a two thousand eighteen TV movie called Trimmers

(45:17):
and it had the return of Kevin Bacon and Fred Wards.
So there you go. I have not seen it, can't
vouch for it. I apologize I was wrong. All right,
Well we're gonna go. Yeah, I'm sorry. I just I
just googled it and I found that, uh sorry, on
Reba's website, she has a page dedicated to Trimmer's. Oh

(45:39):
that's great, so you can go to reba dot com
slash trimmers. Let's let's also not forget that Victor Wong.
Isn't that and it's also pretty fabulous? Oh yeah, yeah,
that's right. All right, we're gonna go ahead and close
it out here, but we'd love to hear from anyone
out there who has thoughts on these if you had,
you know, if you have any thoughts on giant ground
sloths or modern arboreal sloths. Um, everything is is up

(46:03):
for grabs. Here. Are there interesting tunnels that you're aware of,
be they you know, naturally occurring caves and so forth,
or modern or ancient human constructions that we're trying to
figure out. We'd love to hear about all of that.
In the meantime, if you would like to listen to
more episodes of Stuff to Blow Your Mind, you'll find
us in the Stuff to Blow Your Mind podcast feed

(46:24):
Core episodes on Tuesdays and Thursdays, listener Mail on Monday,
Artifact on Wednesday, and on Friday, we do Weird How Cinema.
That's our time to satisfide most serious matters and just
talk about a strange film. Big thanks as always to
our excellent audio producer Seth Nicholas Johnson. If you would
like to get in touch with us with feedback on
this episode or any other, to suggest topic for the future,

(46:45):
or just to say hello, you can email us at
contact at stuff to Blow your Mind dot com. Stuff
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(47:06):
your favorite shows.