Paleontologist Peter D. Ward and astronomer Donald Brownlee of the University of Washington, recently published their insights into the future of the planet. The excerpted sections from their new book "The Life and Death of Planet Earth", poetically portrays a very fragile future - one profoundly grounded by what we now know so far about the distant past.
||Donald Brownlee, co-author of "Rare Earth," "The Life and Death of Planet Earth", and Professor of Astronomy of the University of Washington in Seattle.
||Peter Ward, co-author of "Rare Earth," "The Life and Death of Planet Earth", and Professor of Geological Sciences at the University of Washington in Seattle
In a dramatic conflict between brains and brawn, a clash between the apex predator of the Paleozoic era--the gorgon--and some of the earliest ancestors that foreshadowed later triumphant mammals--the cynodonts--highlights the fate of species that come and go as the Earth itself evolves.
Excerpted from The Life and Death of Planet Earth: How the New Science of Astrobiology Charts the Ultimate Fate of Our World
In the last days of the Paleozoic era, some 250 million years before the emergence of Homo sapiens, a small cynodont trotted across a patched landscape in the vast interior of the southern continent we today call Gondwanaland.
|The jigsaw of continents that combined in the supercontinent, Gondwanaland. Continental drift and plate tectonics spread the land masses across the globe.
It rapidly skirted the corpses of dying glossopterid trees and low gingku shrubs to get to the nearest water hole. Rotting skeletons of newly dead anaimals lay about this bleak oasis, hardly scavenged, simply dissolving into bacteria-rich slime under the immensely powerful Sun.
The temperature was normal for this early morning time of day, over 40 degrees C (104 degrees F) and the cynodont could not bear to spend much time out of its burrow. A quick drink, and then back to the safety and coolness of its deep underground lair, where its mate suckled a new litter.
The cynodont was a small predator only a foot and a half in length, and looked something like a future evolutionary descendant that it would someday spawn: a small dog. But although roughly doglike in size and shape, the cynodont would never have been mistaken for the cute doggie in the window were it resurrected in the time of man: it was a dog without hair, a dog with scaly lizardlike skin, cruel downward-pointing fangs, yellow-slitted lizard eyes, and a brain barely larger than that of a pigeon.
It was bent on survival in a world gone hellish. It was not a mammal--yet--but it would be the seed from which all mammals would spring. It was also soon to belong to one of the lucky few on Earth: its species would survive the most hideous mass extinction ever, a period of mass death that killed off nearly 90 percent of all organisms on the planet.
The cynodont spent the nighttime hours seeking insects and the daylight hours deep underground, sleeping. But finding food and water was becoming increasingly difficult, even here near the South Pole, where the temperatures were still--barely--cool enough to allow animal life. Farther north, nearer the equator, the Earth was already sterilized of all animal life save for insects and spiders. There was not much life to be found anywhere on the planet, and each year it dwindled.
The cynodont approached the water hole warily. It barely cast a shadow even though the day was cloudless, for the sky was hazed with volcanic dust and immense volumes of carbon dioxide and methane, causing the planet beneath to broil like the interior of a greenhouse on a hot summer day.
|The piglike, herbivore, or lystrosaurus
As usual a few of the piglike lystrosaurus were grazing stolidly around the shrinking pond, skirting the large mud cracks to feed upon a few still-living reeds and the tubers taht gave rise to them. The cynodont was the most intelligent creature ever to have evolved on Earth until that time, intelligent enough to be wary of whatever might hide in the piles of large boulders adjoining the water hole.
It began to lap up the hot, fetid water, and then froze as a flash of movement caught its eye. Past the cringing cynodont the menacing shape of a gorgon lunged, ten feet of coiled muscular fury.
Here was the largest predator that the vertebrates had yet produced, the nightmarish top carnivore of the late Paleozoic world. The gorgon bowled into the now-squealing lystrosaurus, slashing into one terrified animal with its giant saber teeth, its jaws disemboweling the herbivore.
But the rush of the gorgon had carried both it and its prey into the center of the pond, a region where black oozing tar was barely concealed by a thin layer of fresher water. All four legs of the gorgon became mired in the black ooze, and slowly its predicament became apparent.
The huge reptilean head raised skyward and roared in fury, but it could not break free. The cynodont would hear the roaring for several days from the safety of its burrow, and then no more.
The gorgon's skeleton eventually sank into the ooze and was covered in sediment. The bones held together in the sticky mud even as the flesh rotted away, and as years passed into decades, then into millenia, then into intervals of time counted in the hundreds of millions, its lithified remains became deeply buried under thousands of feet of sedimentary rock.
Far above its resting place the first dinosaurs evolved, small and timid, and then increasing in size and number until they ruled the Earth.
|The clash of the smartest creature on Earth in the Paleozoic era, the cynodont (right), and the apex predator of its time (left), the largest vertebrate top carnivore: the gorgon. Both were reptiles, but the cynodont's descendents went on through much climatic change to deliver an erect, biped.
The huge supercontinent of Gondwanaland split asunder, its pieces wandering in various directions across the Earth's surface. The gorgon's resting place became Africa, and more time passed.
Mountains rose and fell, and the dinosaur's long summer came to a shocking end in a single day in the forma of an impacting asteroid. Tiny mammalian survivors--all descendents of the cynodonts--inherited the Earth; they multiplied, diversified, and one branch of them left a life in trees to become erect, ground-delling bipeds with giant brains. These were creatures with curiousity, and they dug up the bones of the long dead simply to satisfy their curiousity.
Accordingly, 250 million years after its death in a small drying pond on an aging planet, the long slumbering bones of the gorgon were disturbed for the first time. A hammering of blows rained down on the quiet crypt, and the Sun shone once again on the gorgon.
Reprinted with permission. Copyright Peter D. Ward and Donald Brownlee. The coauthors also published the acclaimed and bestselling Rare Earth. Don Brownlee is a professor of astronomy at the University of Washington and has been involved in many space experiments; currently he is leading NASA's Stardust mission to collect samples of a comet and return them to Earth. Peter Ward is a professor of geological science and zoology at the University of Washington and the author of nine other books, including Future Evolution, In Search of Nautilus, The Call of Distant Mammoths, and The End of Evolution, which was a finalist for the Los Angeles Times Book Prize.
Related Web Pages
Rare Earth Debate Series
Interactive Presentation: The Life and Death of Planet Earth
Tree of Life
The Tree of Life Web Project First Complete Gorgon Fossil Found (ABC-AU)