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This is Episode 2 of the 4-part “Charm”. TRUE big bird. You can listen to Episode 1 here.
Flora Lichtmann: If you’ve never heard of the elephant bird, what do you need to know?
James Hansford: First of all, it’s the size. Huge.
[Music]
Lichtmann: I’m Flora Lichtmann from Scientific American. science fast, and this is episode 2 of my tribute to the real big birds of the earth. In the last episode we talked about the biggest birds that fly in the sky. Today we will focus on the heaviest bird to set a scale foot on the planet, the elephant bird.
Hansford: they are outstanding.
Lichtmann: This is elephant bird expert and paleontologist James Hansford…
Hansford: An absolute giant of the bird world.
Lichtmann: Madagascar was inhabited by bird elephants. They appear to have been predominantly herbivorous. None flew. There were many different types, from the size of an ostrich to the size of a smart car.
Hansford: The largest elephant bird I have weighed is about 1,900 pounds.
Lichtmann: Gee, it’s really hard to even imagine that.
hansford: yes. How do you image it? Now, when I measured the circumference of my femur, it was 30 centimeters in circumference and over a foot. That’s tremendous.
Lichtmann: oh my god. The circumference of the femur is over one foot.
hansford: yes.
Lichtmann: Shut up.
hansford: [Laughs]
[Music]
Lichtmann: These giant creatures appeared 30 million years ago and have been around for a long time.
hansford: They lived up to 1000 years ago, but we know far less about them. tyrannosaurus rex.
Alicia Greeley: All these questions exist because there are very large gaps in the fossil record.
Lichtmann: Paleogeneticist Alicia Greeley. She collaborated with James and his other colleagues to answer some basic questions about elephant birds. Something like this: how did they evolve? Who made that group?
Greeley: There has been much debate throughout history about how many species there are.
Lichtmann: Scientists have debated the elephant bird genealogy since the discovery of elephant birds in the 1800s. Of particular interest are the most elephantlike members of the elephant bird flock.
[Music]
Like the one James was talking about with giant foot bones. For a long time, the largest specimens have been classified as jumbo members of the species known as genus. Aepyornis the strongest. But they’re quite huge, hundreds of pounds heavier than the others. A. Maximus Specimens, and even their bones, look a little different.
Greeley: And a few years ago there were suggestions that these largest bones were so large that they must have belonged to another species.
Lichtmann: Alicia wanted to investigate this. And as a paleogeneticist, she thought her ancient DNA might help. The challenge was that DNA degrades rapidly in tropical environments.
Greeley: Indeed, water damage, erosion, and UV light combine to degrade DNA.
hansford: The ability to obtain genetic material is very difficult in Madagascar. I liken it to getting blood from a stone.
Lichtmann: But Alicia had an idea. She wondered if she could use her eggs to solve the mystery of this big bird.
Greeley: Egg shells preserve DNA very well. And sometimes it’s the only source of DNA from animals that live in very hot tropical climates. And having previously recovered DNA from the eggshells of other extinct birds, we wondered if we could do the same for elephant birds from Madagascar.
Lichtmann: And there are a lot of egg shells. This elephant bird egg was huge.
Greeley: It was about 150 times the size of a chicken egg. And it’s bigger than any dinosaur egg.
Lichtmann: It weighs more than a bowling ball in your hand and has a shell as thick as a dinner plate.
Greeley: Yeah, they were about 10 kilos…so about 22 pounds…
Lichtmann: And unlike elephant bird bones, eggs are easy to find. Alicia, she says, would walk on eggshells when she went to the beach where she worked in the southwestern part of the country.
Greeley: They are really scattered everywhere. One described it as paved with eggshells.
Lichtmann: However, is it too easy to collect the eggs, it is not so easy to extract the DNA from the eggs. DNA may have been scrambled into beach-fried eggs. So the team searched for shells buried in dig sites and dunes. Alicia then took each shell, cleaned it and ground it into powder. From the egg powder, she surprisingly extracted a piece of DNA from a bird that had died 1,000 years ago.
Greeley: In fact, it’s daunting even for me.
Lichtmann: She then used that DNA to try to figure out if these very large elephant birds were a unique species.
Greeley: DNA evidence from eggshells suggests that the area was not inhabited by two different species. Basically, all egg shells are genetically identical. So if we had expected the largest elephant bird to be a different species, we would have seen some genetic differences in the egg shells, but we haven’t seen that.
Lichtmann: So how is the XXL bone explained? One possibility is Big Mama.
[Music]
Greeley: A very large elephant bird is considered a female, and a slightly smaller elephant bird is considered a male.
Lichtmann: Male miniers are not uncommon in birds because ladybirds have to lay eggs, but it literally takes a lot of effort to do so.
Hansford: Birds build egg shells from the material inside their hollow bones. I said that the circumference of these femurs is 30 centimeters, or 1 foot. One reason for this is that females have stored substances in them to make eggs.
Lichtmann: But that wasn’t the only “ah” that popped out of the cracked egg. Egg shells also tell us about how these giant and unusual birds evolved.
Elephant birds were known to be ratites. Ratites are an ancient group of mostly large, flightless birds that include Australian emus and cassowaries, African ostriches, and South American rhea.
Greeley: Basically any large flightless bird. However, it is actually the closest relative of the chicken-sized kiwi bird. That’s a little surprising.
Lichtmann: And for a long time, scientists had a simple explanation for how these birds landed all over the world.
Greeley: They were mostly flightless and because of their size, it was thought that they had a common flightless ancestor on a supercontinent called Gondwana. And as Gondwana split, some populations became trapped on those different continents, then continued to diverge from one another over time, becoming more distinct.
Lichtmann: These different lineages—ostriches, rheas, and elephant birds—broadly split when Gondwana split. That was the idea.
[Music]
But DNA data overturned this hypothesis
DNA evidence indicates that many ratite lineages diverged long after Gondwana broke up. So how did these large flightless birds land around the world?
Greeley: Therefore, the common ancestor must have been very small and flew to each continent independently.
Lichtmann: The data suggest that the ancestors of these mostly large terrestrial birds were small and flying.
Greeley: The fact that they are mostly flightless and large seems kind of coincidental. Flightless animals appear to have evolved independently among ratites at least six times, which is quite surprising.
Lichtmann: This is surprising because it means that each of these large flightless birds (which also includes groups of elephant birds) seems to have followed its own winding path to flightlessness and enormity. . Alicia says it’s a reminder that in evolutionary history, the simplest or most obvious explanations are not always correct.
Greeley: So the elephant bird is helping change the way we think about the evolution of all birds.
Lichtmann: In the next episode of this four-part fascination…
Anusuya Chinsamy Sister: Not quite like the birds we commonly think of sitting on bird feeders, you know, definitely not that kind of bird…
Lichtmann: We’ll meet another evolutionary curveball of birds: the roaring, chariot-like goose with the wings of the Chickadee.
science fast Produced by Jeff DelViscio, Tulika Bose and Kelso Harper. Our theme music was composed by Dominic Smith.
don’t forget to subscribe science fast Get podcasts anywhere. For more scientific news, visit ScientificAmerican.com.
for science fast–I’m Flora Lichtmann.
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