The Island of Huge Hamsters and Giant Owls

The Island of Huge Hamsters and Giant Owls

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Language: English

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Greek and Roman mythology is full of stories about exotic islands that were home to weird and fearsome monsters like one-eyed augur seductive sirens and man-eating Giants and I'm here to tell you back in the late miocene epoch there was in fact an island or maybe a group of islands in the Mediterranean Sea that was populated with fantastic giant beasts but these giants were actually pretty small some of them you might even consider cute there were enormous hamsters and big fat water birds that could neither fly nor swim and Hedgehog
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like animals that were as big as house cats these organisms were only Giants compared to their ancestors which had lived on the European mainland but once they became isolated on these Mediterranean island's some of these little critters attained massive body sizes that's because geographic isolation is a powerful force in evolution sometimes when a population of animals gets cut off from many of its normal predators or competitors it gives rise to new species of unusual sizes sometimes they turn out to be miniaturized versions of their
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ancestors other times Giants the tale of these Mediterranean island beasts of the Maya scene is no myth it's a lesson in the very strange but very real powers of natural selection [Music] in 1969 a group of dutch paleontologists were working in Gargano a region on the eastern coast of italy when they discovered deep fissures or cracks in the limestone quarries and road cuts there and these cracks turned out to be full of fossils for millions of years it seemed animals had been stumbling into
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these fissures like natural traps starting about 8 million years ago the result wasn't an amazingly rich fossil deposit a snapshot of life in this place in the late miocene epoch but a few things about the Gargano fossils turned out to be really odd for one thing scientists were confused about the fossils they didn't find elsewhere in Europe deposits from the late Maya scene tend to contain a lot of large mammals like extinct elephants cats and parasitic dolls a group of hoofed animals that include horses but at
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gargano none of those animals were anywhere to be found instead researchers uncovered an eclectic and bizarre bestiary including fossils of smaller animals that seemed overgrown there were extra-large owls alarmingly big hamsters and super-sized hedgehogs this strange assortment of animals came to be known as the macro sure fauna and for decades the gargano Peninsula along with a handful of nearby towns were the only places on the planet where these creatures were known then in the 1990s fossils of some of those same peculiar
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animals turned up at my scene sites near c-can't roni a town in central Italy so what exactly were these animals why were the Maya seen animals of gargano and c-can't roni so different from their counterparts in the rest of Europe for paleontologists the most likely explanation was that these areas must have been cut off geographically separated from the rest of Europe specifically they were probably Islands or maybe parts of the same island this would explain not only why these animals appear just at those sites it would also account for the strange
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body sizes of animals that were ordinarily quite small I've talked before about how in Island environments large body animals can often get smaller over time for example in the case of Colombian mammoths on the Channel Islands of California the absence of large predators combined with limited food led natural selection to favor smaller body sizes so after thousands of years some of the giant Colombian mammoths had developed into what scientists consider a new separate and smaller species the pygmy mammoths this phenomenon is known as insular dwarfism
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but it's only part of the story about how Island environments can tinker with animal's body plans the flipside is what happened to some of the animals on Gargano and c-can't roni insular gigantism both processes are part of what's known as Foster's rule identified by biologist Jay Bristol foster in 1964 essentially Foster's rule says that in isolated environments large animals frequently get smaller and tiny animals often become larger and this is what happened to many animals in the microtia fauna and it happened
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because their habitat allowed it to happen much like the modern Channel Islands the regions of Gargano and c-can't roni in the deep past were higher in elevation than the surrounding areas so as sea levels rose and fell over millions of years due to changes in climate these places became isolated from the rest of Europe and then reconnected many times and it may have been during one of these periods of low sea levels when some ancestors of the island Giants first made their way to gargano and c-can't roni researchers think that about 30 million years ago in the alig Essene
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epoch a global cooling trend lowered sea levels in the mediterranean and elsewhere forming a land bridge between the mainland and these two spots but then about 15 million years ago the climate warmed again and sea levels rose turning those high spots into islands and severing their connection to the mainland so maybe the ancestors of the microtia fauna simply walked across the land bridge before it became submerged but other scientists have proposed that most of them arrived much more recently just around 8 million years ago when the island or islands were properly isolated
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in that case it's thought that the animals might have rafted on piles of floating debris like logs branches and palm leaves much in the same way that the ancestors of South America's rodents are thought to have migrated from Africa either way once they reach their new island habitats many of these animals started to follow different evolutionary paths some stayed small and some may have shrunk but others responded to their new environments by getting downright huge just look at Dino gallery a shrew-like member of the hedgehog family that's
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found only in these microtia fossil deposits early species of this genus were about 30 to 45 centimetres long making them only slightly bigger than a modern European Hedgehog but over time bigger and badder Dino gallery started to evolve alongside them the largest species found only in the most recent deposits with some 60 centimetres long and even though it was a member of the Hedgehog family Dino gallery Rex had teeth that were more like those of cats and dogs using its long pointy incisors and crushing cheek teeth the largest of this
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genus probably behaved like a badger or racoon hunting much larger prey than its ancestors ever could and it did simply because it could back on the mainland the ancestors of Dino gallery needed to stay small in order to avoid all the large predators but in this island environment there were very few large terrestrial carnivores so without the selective pressure to remain small Dino gallerist was free to expand in size and take advantage of new niches its ancestors probably specialized in eating insects but this animal could
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have hunted other larger prey like vertebrates in the process it emerged as one of the area's biggest land dwelling hunters this was Foster's rule in action but a big old Hedgehog like things still had some competitors and natural enemies because these islands were also home to some unusually large birds of prey take the giant owl known as Taito gag antia which appeared on Gargano in the late miocene we don't know for sure which species it evolved from but we do know that there was nothing near its size on the mainland based on its fossil
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scientists think that Taito gargantia may have had a wingspan of two meters or more twice the size of a living bar now likewise the islands were also home to a bird of prey known as Gargano a ATIS which included two species the larger one probably rivaled today's Golden Eagle in size and it's only found in more recent deposits so this suggests that Gargano eiite is like the giant owl developed a bigger body size over time but here's a question on an island with few other predators why would these
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birds of prey get so large and it just mean that they needed to eat more food well some researchers think that on these islands of giants both predators and prey were engaged in a sort of evolutionary arms race research has shown that the modern barn owl can't swallow any rodents whose heads are larger than 17 millimeters but by being bigger these birds would have had an easier time hunting and gulping down the local rodents which were also getting quite hefty for example there's the burrowing rodent mccr Osia the gargano native that gave this whole group its
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name one species of macro sahat a skull that was twice the size of a modern rat's head suggesting the rest of the animal was pretty big too there was also a giant species of dormouse which are usually tiny and adorable but this one weighed about a kilogram which you know still sounds pretty cute to me and then there was gargano strange giant hamster hitomi's gargantuan it was three times heavier than today's common hamster and much bigger than any species that lived on the mainland at this time mind you not all of these Island animals expanded
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in size over time small and normal-sized birds and rodents coexisted with giant species but some rodents definitely got bigger either because they simply could or because it let them expand into new dietary niches and as they grew the birds of prey also evolved larger sizes in order to hunt and eat them this same phenomenon occurred among other kinds of birds to take the case of Gargan or nests first reported in 2013 Gargan or nests belonged to the same family of birds as ducks and geese but it weighed
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between 15 and 22 kilograms up to twice as much as a large Canada goose unlike modern geese and ducks its toes and lower leg bones were really short suggesting that it spent most of its time walking on land and not paddling in the water and judging by its bones in its wings it probably couldn't fly either so researchers think that Gargan or nests adapted to take advantage of its islands lack of big herbivorous mammals by growing bigger and staying on land it may have been able to broaden its niche and forage on a wider range of
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terrestrial plants while its size could have helped it fend off some of those birds of prey and size adaptations seem to have benefitted some larger mammals on the eye - what herbivore known exclusively from microtia deposits was the truly strange huh Pluto mirek a genus of hoofed mammal with sabor like fangs and five horns on their heads five and there were lots of different species of this so called prom deer that varied a lot in size by one estimate the smallest only weighed around five to six kilograms while the
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biggest may have tipped the scales at a hundred and thirteen kilograms and species of different sizes seem to have lived at the same time which kind of makes sense different sizes would make different food sources available to each species this would have not only kept the prong deer from competing with each other it could have also prevented them from over grazing their little island but there was a change on the horizon that none of the weird and beautiful microtia fauna could adapt their way out of about 5.3 million years ago a massive amount of Atlantic water passed through
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the Strait of Gibraltar which had once been lifted above sea level this flooded the Mediterranean rising water levels dramatically shrank the Little Giants Island habitat which is probably what drove them to extinction just a few million years later in the early Pleistocene some areas of central and southern Italy went through a period of tectonic uplift that reunited Gargano and scant roni with the rest of the mainland where they remain today so competition food availability predator-prey relationships and niche expansion any or all of these things can
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very gradually make either pygmies or Giants out of animals that are isolated on islands it's not mythology its natural history and we have they're fascinating fossil remains to remind us of the odd little giants that once roamed these ancient Mediterranean Islands thanks for watching we want to let you know about a new show from PBS Digital Studios soundfield is a new music education show that explores the music theory production history and culture behind our favorite songs and musical
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styles pop classical rap jazz electronic folk country and more sound field covers it all hosted by two supremely talented musicians Arthur LA Buckner and nari Sol every episode is one part video essay and one part musical performance so go subscribe to soundfield link in the description below thanks for joining me today in the newly named Constantine Hoffa studio and an extra big thanks to our current Yount ologists Jake Hart John IV John Davison II and Steve if you'd like to join them
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