When Giant Lemurs Ruled Madagascar

When Giant Lemurs Ruled Madagascar

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I am so excited to be the person that gets
to announce this… Eons enamel pins are available now! Get yours at DFTBA.com!! Just a few thousand years ago, the island
of Madagascar was inhabited by giants. Giant … lemurs. These remarkable primates lived only on Madagascar,
and they were part of an evolutionary event that continues to this day – a radiation that
saw primates adapt to fill the ecological niches that, in other places, were occupied
by totally different animals — like sloths, monkeys, and even woodpeckers. There were the so-called monkey lemurs, named
for their skeletal similarities to baboons. There were three species of koala lemurs,
which of course were not koalas, but they specialized in eating leaves and had grasping,
pincer-like feet that kept their large bodies in the trees. But maybe the weirdest of these extinct giants
were the sloth lemurs. This family included Archaeoindris, the biggest
lemur that ever lived, and most of its members seemed to have adaptations for hanging from
tree branches, like sloths do today. What all these strange creatures had in common
was their large body size: they likely ranged from the size of a large terrier to almost
as big as an adult male gorilla. But today, they’re all gone. Their largest living relative is the modestly
sized indri. So what happened here? How did such a diverse group of primates evolve
in the first place, and how did they help shape the unique environments of Madagascar? And how did they get winnowed down, leaving
only their smaller relatives behind? As far as that last question goes, the answer
might lie in the arrival of another, different type of primate on the island: us. Madagascar has been separated from all other
land masses since the Late Cretaceous Period, about 85 million years ago. And the fossils that date to the time after
its split from the Indian subcontinent include some very cool dinosaurs, like Majungasaurus,
and weird early mammals, like the cute little Vintana. But the fossil record of Madagascar stops
abruptly at the beginning of the Cenozoic Era, about 66 million years ago. There are almost no fossils on Madagascar
from that whole stretch of time, until about 26,000 years ago, which makes the early evolution
of the few mammal groups that got to the island kind of mysterious. But, based on genetic studies, we’re pretty
sure that the ancestors of modern lemurs made it there after it had already become an island. The most widely-accepted estimate says that
lemurs arrived on Madagascar between 50 million and 60 million years ago. So, how did those first lemurs get there? Experts think they probably … floated. That’s right! Some paleontologists have suggested the lemurs
rafted over on large mats of vegetation or maybe inside hollow trees that washed out
across the Mozambique Channel – a distance today of more than 400 kilometers. This kind of movement is called a “sweepstakes
dispersal” – a rare or chance event where an animal is able to cross a pretty extreme
barrier. And we’ve talked about this phenomenon before! Most scientists think rodents got from Africa
to South America by way of a similar ocean crossing. Those seafaring lemur ancestors were probably
very small, like modern mouse and dwarf lemurs, and they might’ve behaved like them, too
– sleeping the day away in small groups inside hollow trees. And it’s also been suggested that they could’ve
been able to enter a state of torpor or hibernation, again like modern mouse and dwarf lemurs do. This would’ve helped them survive a long-distance
trip and emerge ready to colonize Madagascar. At least, that’s how the most widely-accepted
explanation for how lemurs got to the island. But some experts think that lemurs might actually
have taken two trips. This is based on the study of two fossil species,
one from Kenya and one from Egypt, that date to well after the earliest lemurs were supposed
to have made it to Madagascar. And these two fossils bear some resemblance
to the aye-aye, the weirdest and earliest branch off the family tree of all living lemurs. So maybe aye-ayes took a separate trip to
Madagascar from all the other lemurs. We just don’t know enough yet to be sure. However lemurs got to the island, once they
landed there, they took over in what’s called an adaptive radiation. Over the last 50 to 60 million years, they
diversified into eight different families, five of which still have living members, and
they filled a huge variety of ecological niches. For example, take the aye-aye. Today, it’s the only species left in its
family, and it fills the same basic ecological role as … a woodpecker! It uses its extra-long, extra-creepy third
finger to tap on trees to find insect larvae. Then it chews a hole into the bark with its
rodent-like incisors, sticks that skinny finger into the hole and pull out grubs. But in the past there was a giant aye-aye. It weighed up to seven times more than the
modern aye-aye. And it lived in the dry forests of southwestern
Madagascar, where it likely used the same kind of foraging behavior, tapping tree trunks
in search of insects, much like a woodpecker. And while lemurs have managed to fill the
many vacant niches on the island, they also shaped its ecosystems. Living ruffed lemurs specialize in eating
fruit. So they play an important ecological role
as seed dispersers. They help plants move their seeds from place
to place by eating their fruits and dropping the seeds in new places as they move through
the forest. And ruffed lemurs can swallow seeds that are
more than 30 millimeters around — bigger than an American quarter! But there are trees on Madagascar that produce
fruits with even bigger seeds. And in the past, there was a giant relative
of the ruffed lemurs called Pachylemur that might’ve helped disperse those seeds. We know it was a fruit-specialist, like its
living relatives, because of the pattern of wear on its teeth. And at about three or four times the size
of living ruffed lemurs, it could’ve easily taken on those really big seeds. But there were also less-friendly interactions
taking place between Madagascar’s plants and animals that have left their mark on the
island’s plant life to this day. In southern and southwestern Madagascar, there’s
an incredibly unique ecoregion called the spiny forest. The vast majority of the plants there are
only found on the island, and they’re adapted to hot temperatures and short rainy seasons. They’re also, as the name suggests, totally
covered in sharp, thick thorns. Which is strange, because their relatives
on the African mainland don’t have thorns. So researchers have hypothesized that the
thorns of these tree species are an adaptation for defending its leaves from climbing, leaf-eating
animals that aren’t found on the mainland – namely, lemurs. To test this hypothesis, researchers have
compared carbon and nitrogen isotope levels from the bones of extinct lemurs to the levels
seen in the plants of the spiny forest. This method is based on the idea that you
are what you eat – the elements found in the food you eat are incorporated into your tissues. And they found that those isotope levels matched! So it looks like one of the extinct monkey
lemurs and one of the extinct sloth lemurs probably ate a lot of the plants of the spiny
forest! But since most living lemurs generally don’t
eat those plants anymore, it seems that those thorns have become an evolutionary anachronism
– a trait that coevolved with species that no longer exist. So, what happened to all the giant primates? After thriving on Madagascar for millions
of years, what put an end to their reign? Well, in the Late Pleistocene Epoch, the climate
was changing rapidly and becoming more variable. From around 9000 to 5000 years ago, the island’s
climate swung back and forth between being much wetter than Madagascar is today and also
much drier, with droughts sometimes lasting up to 300 years. Between 4000 and 2500 years ago, the climate
continued to become drier, changing vegetation and ecosystems throughout Madagascar. And then, maybe around 2300 years ago, a new
primate arrived on the island that would change everything: humans. There’s some controversy about when exactly
that happened, because the early archaeological record of the island is incomplete. But the giant lemurs were still alive when
people showed up. And it seems like we might have hunted them. There are cut-marked bones of two species
of extinct giant lemur from two sites in southwestern Madagascar that seem to be around 2000 years
old. But those bones were collected in the early
1900s, and we don’t have a very good record of their context, so some researchers have
argued against this as evidence of butchery. However! Some incisors of a giant aye-aye with holes
drilled through them were also found in the early 1900s, and were rediscovered in a museum
collection in the 1980s. They can’t be radiometrically dated, but
there’s no question that humans modified these teeth. We just don’t know when. What we do know is that many of the giant
lemurs went extinct around 1000 years ago, along with other megafauna on the island,
like pygmy hippos and elephant birds. So it seems the lemurs were able to coexist
with the early human inhabitants of Madagascar, at least for a while. This is also when we start to see an increase
in charcoal in the sediment record of the island. That charcoal suggests a greater human impact
on the landscape, as people started fires to clear land and promote the growth of grass
for cattle to feed on. The last known remains of a giant lemur – one
of the sloth lemurs – date back just 500ish years ago While we can’t definitively say that human
hunting was responsible for their extinction, it’s clear that the extinction was selective:
all the large-bodied lemurs are gone. It might also be because they were more easily
hunted than their smaller relatives. It might be because larger animals need more
space, so they’re more vulnerable to habitat loss and fragmentation. Or it might be because they tend to reproduce
more slowly than smaller species. It was probably some combination of all of
these. Researchers are still working on figuring
out exactly what happened. They’re finding new remains, including some
from underwater caves. They’re rediscovering old material in museums. And they’re examining DNA from both ancient
and living lemurs to try to piece together the end of the story. And while the giants are gone, the ecosystems
that they shaped — and the lemurs that we still find today — are reminders of that
time when giants ruled Madagascar. Big high fives to this month’s Eontologists:
Patrick Seifert, Jake Hart, Jon Davison Ng, and Steve! To become an Eonite, go pledge your support
patreon.com/eons! And thanks for joining me in the Konstantin
Haase Studio. If you like what we do here, then subscribe
at youtube.com/eons.

100 comments

  1. When the first lemurs rafted unto Madagascar during what I presume was the Eocene, was it as close to the African mainland as it is today, or was it even closer? I ask because the last video on how the capybara evolved from the first rodents showed that South America was much closer to Africa during that time period, and there were islands interspersed between the two continents that would have made it much easier for African species to hop from place to place before they came to South America. Was there a similar dynamic going on between Madagascar and Africa?

  2. It's a little surprising that primates are closer relatives of rodents than either are to other mammals… until you look at lemurs.

  3. Isn't 60-50 MYA Madagascar was very close to Africa? So why you are hypothesizing today's distance of 400 KM (actually around 250 KM from Africa), with the lower sea levels at that time it could be much less don't you think?

  4. Today Madagascar sees huge soil erosion and floods due to clearing of forests. So much deforestation that it's disheartening. Commercial Farming didn't help either.

  5. Lame People: don't clone animals!
    Eon: shows off obscure and awesome extinct species
    Awesome People:…let us not be rash.

  6. 9:39 ….or they might've tasted better.

    (this comment brought to you by P.E.T.A No, not that PETA!! No, I'm talking about PETA People for the Eating of Tasty Animals!! )

  7. How about a video that delves into the science and moral implications of bringing back extinct species, like the giant lemur. At least that one disappeared in recent times, so might fit in again.

  8. Learn something new every day. When Ms. Moore said that Madagascar separated from the Indian subcontinent, I was like, "Say what?" But it's true. Madagascar was never touching the east coast of Africa at what is now Mozambique. Part of Antarctica was nestled there.

  9. OMG it's like these scientists haven't even seen Disney's Dinosaur. They have no idea what they are talking about! Discredited!

  10. Large fauna went extinct since the last ice age, occam's razor should always mean the first question is when did humans arrive!

  11. can u guys make a series where in each (largest chalicothores/giant sloths ever)episode its like a mini-documentary and is a few hours long and talks about a certain period of time like the Triassic or something and all the animals that lived at that time like dinosaurs, giant reptiles and so many more and about the food chain what it was like for the plants how earth was, etc. and than u could go to another period like when the bone-crushing dogs lived or giant bears or mammoths or sabertooths or the largest gorillas/apes ever or titanoboa or the giant turtle or whatever and than do an episode there cuz that would be awesome and then u could do one on an extinction event and it all these episodes would be like hours long hopefully lol or do one of these on a single animal/species like a titanoboa or desmostylia but this one could only be 45 mins long or something

  12. hey Eons team, long time fan here! Id love to support you by buying merch but an enamel pin that just says "eons" isnt wow-ing me…. what about a shirt featuring some creatures from your videos? you always show great works of art and maybe some artists would like to work with you for shirts as well? thank you and stay great!

  13. Always exciting to see another great video of yours.

    I'd love one on the evolution of social insects.

    Or the evolution of butterflies or flowering plants.

    Actually, anything will satisfy me.

  14. You guys have quickly become one of my favorite channels. Thanks for the consistently amazing content! Can I throw a request in for a future video? The split between monotremes, placentals, and marsupials; and which factors in early mammalian evolution played a role in selecting for (and shaping) each.

  15. The evolution of spiny forests has made me think.
    The New World arid areas have similar appearing vegetation adaptation to that of arid Madagascar – plants with whopping great spines and spikes.
    The giant sloths of the Americas and the giant lemurs seem to have similar lifestyles.
    I'm wondering if the cacti of the Americas evolved big spines for the same reason; to dissuade big lumbering herbivores from eating them? Sadly as both these lines of giant mammals are now extinct, we'll probably never know.

  16. 9k-5k years ago, massive fluctuations in global warming, answer, must have been humans and charcoal that hadn't happened yet.

  17. Crazy to think that these guys were giants at one point considering I just saw a pet ring tailed lemur at the vets office with a diaper and a harness on. It was sad :/

  18. Here in South America.

    Snakes, frogs, rodents, birds, they all like to travel in a green floating carpet down the river.

    It is the "Camalote", a floating plant that tend to form big islands by entangling their roots.

    Eichhornia crassipes
    With the flooding they can reach as far as Buenos Aires, (too cold in winter to survive) and their passengers can't get a ticket back.

  19. Island gigantism and island dwarfism. These are the trends of animals when they got into isolated habitats from the mainlands.

  20. I would love to learn about why the nautilus survived but the ammonite didn’t, and more about their family tree

  21. Humans to Animals throughout the ages: That's a nice habitat you got there…….be a shame if someone…… destroyed it.

  22. Would be cool to see a video about something that went extinct that wasn't caused by the big 3 (humans, climate, great dying)

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