Three characteristics dominate the legacy of Tyrannosaurus Rex: It was huge, vicious and had small arms. The story of how it lost those small arms is pretty simple, but why it kept the puny limbs is another tale. PBS Eons host Hank Green fills us in on the details.
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More than 600 million years ago, ice sheets covered our planet on both land and sea, with temperatures dipping to -130 degrees celsius. And there was no escaping the cold at the equator, where temperatures fell below zero!
Amazingly, this happened twice in the Cryogenian Period. So what happened? “The most popular theory is that our planet thermostat just failed,” says PBS Eons narrator Kallie Moore. “That thermostat is the carbon cycle, the flopping back and forth of carbon between the atmosphere and the Earth’s crust, and it starts with volcanoes.” Tune in to learn the details.
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When amateur archaeologist Charles Dawson came across some unusual human skull fragments in 1912 Piltdown, England, it was allegedly evidence of the earliest human ancestor ever found, a discovery that would forever change our understanding of human evolution. The find was hailed as a missing link, until it turned out to be fake. The venture came to be known in science circles as The Piltdown Man Hoax.
So yet another mishandling of fossil evidence dimmed the theory of the missing link. “There is no missing link in our lineage,” says PBS Eons host Kallie Moore. “That’s not how evolution works. Back then, the search for the missing link was just one more phase in our thinking of human evolution. The missing link was never missing. It turns out it had never existed at all.” She explains further in the following video.
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What are viruses and where did they come from? And most importantly, are they alive? Science has turned to recently discovered virus fossils, molecular trails that can help unvravel the mystery surrounding these genetic burglars. Learn more in this presentation by PBS Eons.
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Part of our fascination with dinosaurs is their size. Shaking the earth from the Jurassic to Cretaceous periods, some dinos reached the height of a five-story building. But how did they get so huge? And why did mammals get the short end of the stick? Host Hank Green has some answers in this edition of PBS Eons.
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The history of our climate is both complex and extreme. But if you look deeply into the geological record, you’ll find that the culprit is space. More specifically, Earth’s position in space, such as its orbit around the sun, and how far its axis is tilted and in what direction. Scientists have only recently determined that these factors change in cycles, which are counteracting and coinciding with each other, making our climate incredibly complex. PBS Eons host Kallie Moore elaborates.
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The vast majority of the electricity produced in human history have come from coal, which was produced from the remains of extinct organisms that have been exposed to millions of years of heat and pressure. But in the case of coal, these organisms consisted of some bizarre plants called lepidodendrales, or scale trees, which once covered Earth from Colorado to China. These powerful trees left a huge legacy, living and dying in large numbers, and forming carbon-rich peat that produced one of our most prolific energy sources. PBS Eons host Kallie Moore explains.
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The majority of prehistoric snake fossils reveal only a few bones. But 90 million years ago, an ancient species, known as najash, was discovered to have legs, some with two, others with four. “And because of this,” PBS Eons host Hank Green says, “the evolutionary history of snakes is among the most mysterious of all the vertebrates.
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Although we call our time the Age of Mammals, we should call it the Age of Insects, because there are way more of them than there are of us. But we like to think we’re in charge because we’re bigger. Fact is, insects and other arthropods weren’t always so small. About 315 million years ago, during the Carboniferous Period, they were not only abundant but enormous. PBS Eons host Kallie Moore tells us their story.
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Paleontologists know pretty much everything about the big cats that roam our planet, but the most illusive aspect of these magnificent creatures is their heritage. All of today’s big cat species evolved more than 11 million years ago, yet their evolutionary history remains a mystery. But scientists have recently discovered a major clue about their origins, one that could provide a whole new starting place for solving this puzzle. Get the lowdown in this edition of PBS Eons.
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