The earliest settlers in the New World were amazed by the passenger pigeon, a bird with flocks so huge that it would take days for them to travel overhead, blackening the sky as they passed. Any farmer who had the misfortune of hosting passenger pigeons for a meal would quickly find his entire crop decimated within the blink of an eye. Then, virtually overnight, the most abundant bird in North America suddenly disappeared from the planet.
The extinction of the passenger pigeon is an example of nature coming into direct conflict with man. Its population numbered an astounding 3 to 5 billion when the first Europeans arrived in America. However, there was not room enough in the New World for both species. Passenger pigeons were soon wiped out due to merciless hunting, deforestation and other factors related to humankind's ever-expanding range. The extinction was only becoming apparent at the start of the 20th century; by 1914, the last known bird was dead.
9 - Quagga
The quagga is a mammal closely related to modern horses and zebras. In fact, it looks like a cross between a horse and a zebra, with stripes only on its head and neck that disappear as they approach the brownish hindquarters of the animal. The quagga was native to desert areas of South Africa until it was hunted to extinction in the 1870s. The last captive animals died in Europe in the 1880s.
As an extinct species, the quagga has a couple claims to fame. For starters, it was the first animal to have its DNA analyzed, which led to the discovery that the quagga was not a distinct species but a subspecies of the plains zebra. Also, the quagga is the subject of an ambitious breeding effort by the aptly named Quagga Project, the result of which was a foal born in 2005. Based on appearances, the "re-created" quagga closely resembles the ancient quagga, but DNA evidence has yet to determine whether this animal is authentic.
8 - Archaeopteryx
Holding the No.8 spot in our countdown is an ancient creature named Archaeopteryx, whose discovery in the mid-1800s turned the world of paleontology upside down. It looked like some sort of feathered dinosaur, but it also had a number of bird characteristics. Was it a bird, a dinosaur or some other beast entirely? Clues would come in time, but only after decades of contentious debate and close examination.
In order to fully understand the natural history of Archaeopteryx, one needs first to take a look at some of its unusual characteristics. Its dinosaur features include a full set of teeth, a flat breastbone, a bone tail and claws on the end of its wing. On the other hand, its feathers and wings also made it quite birdlike. However, details of Archaeopteryx anatomy indicated that it was not ideally built for flight and probably spent as much time running, leaping, climbing and gliding as it did flying.
So what was this enigmatic animal? It is now widely believed that Archaeopteryx is the most primitive known bird, with several specimens dating back about 150 million years to the Jurassic Period. It is also an evolutionary link between modern birds and a group of dinosaurs that roamed the earth 150 million years ago. Thus, it is one of the most important fossil species ever found.
7 - Saber-Toothed Cat
Of all the cute, cuddly animals found in the fossil record, the saber-toothed cat (also called the saber-toothed tiger) is one of the last you would want to meet in a dark alley. With their daggerlike canine teeth and powerful bodies, this animal was one of the most ferocious predators of the Cenozoic Period. It lived in North America and Europe and went extinct about 10,000 years ago. There have been several thousand saber-toothed cat specimens found at the famous La Brea Tar Pits in Los Angeles, Calif. - so many that it was named the state fossil of California.
So, what were these big beasts like in the wild? Evidence suggests that the saber-toothed cat had a social structure much like modern lions, living together and cooperating in order to bring down prey. Interestingly, researchers also believe that a certain amount of nurturing went on in a saber-toothed cat pack. Many individual fossils show signs of extensive regeneration and healing after disease and injury, suggesting an environment in which individuals could be cared for by other members of the group. Despite their terrifying appearance, it seems these animals had a soft side.
6 - Plesiosaur
No collection of the top 10 extinct animals would be complete without the enigmatic plesiosaur, a large aquatic reptile that swam in the world's oceans during the Jurassic and Cretaceous periods. There are several different species of plesiosaur, but the most famous are the ones with a very long neck topped by a tiny head. Most of these animals were astonishingly large, sometimes reaching a whopping 65 feet in length.
Many people believe strongly in a connection between the plesiosaur and the Loch Ness Monster, a legendary creature that some say inhabits the waters of Loch Ness in Scotland. Indeed, some believe that the appearance of the Loch Ness Monster is evidence of a living plesiosaur. However, according to the fossil record, plesiosaurs disappeared at the end of the Cretaceous Period, about 65 million years ago. And contrary to popular belief, they were not dinosaurs, despite the fact that both groups lived and died off at the same time.
5 - Hallucigenia
No. 5 on our countdown dates back more than 500 million years to a time known as the Cambrian Period when most of the major groups of animals first appeared. The Cambrian Period was also a time of evolutionary experimentation in which countless bizarre body plans were tried out and then left behind in the primordial soup. One particularly odd set of fossils come from an area of the Canadian Rockies known as the Burgess Shale, including a strange little arthropod named Hallucigenia.
Hallucigenia gets its name from its body plan, which appears to have been designed by someone under the influence of psychedelic drugs. It has an elongated body with a row of tentacles on one side and a string of stiltlike spines on the other. At first, researchers had no idea which way to orient the animal — on its tentacles or on its spines — but chose the spines since the tentacles appeared to have mouthparts on the end of them. However, recent evidence suggests that Hallucigenia's tentacles were actually paired appendages used for walking and that the spines were most likely for protection from predators. Based on this discovery, Hallucigenia was finally turned right side up.
4 - The Dodo
Contrary to popular belief, the dodo was not a stupid or lazy bird. After all, it lived in a predator-free environment where food was plentiful on the ground. Why bother flying when you can simply stroll about at a leisurely pace? But what was by all accounts the sweet life for the dodo came to an abrupt end in the1600s, when European explorers landed on Mauritius, the island in the Indian Ocean where the dodo made its home. After their arrival, it would be only a few short years before the animal was hunted to extinction, primarily because it was a much-needed source of meat for weary sailors. In addition, the pigs, dogs and rats that inevitably accompanied sailing ships made short work of dodo eggs, which were all too accessible from their nests on the ground. The dodo never stood a chance.
3 - Woolly Mammoth
If there is one animal most associated with the Ice Age, it has to be the woolly mammoth, that giant shaggy beast with long ivory tusks curling up from its massive trunk-like nose. The woolly mammoth was one of several species of mammoth, the earliest of which were probably small and amphibious creatures living in North Africa until about three million years ago. Their descendants eventually dispersed throughout Eurasia and the woolly mammoth, one of the smaller mammoth species, migrated to North America across the Bering Land Bridge sometime during late Pleistocene. Alas, this enigmatic creature did not survive long in the New World. The last of the woolly mammoths died out at the end of the last ice age, about ten thousand years ago.
2 - Flores Man
When researchers stumbled onto remains of what appeared to be a group of mini-humans in an Indonesian cave in 2003, they could hardly conceive of the significance of their find. There were several individuals, each of which had tiny heads and were about 3 feet tall. Did these creatures represent a new species of hominid, some sort of advanced ape or were they merely humans with a medical condition that would account for their diminutive size? The debate rages on, but recent evidence suggests that they may represent a distinct line in human evolution.
Nicknamed "Hobbits," these tiny primates were eventually named "Flores man" for the Indonesian island on which they were found. The last of them appear to have died out about 12,000 years ago. Incredibly, this means that Flores man overlapped with modern man for centuries, living in caves and using tools much like primitive humans. Did Flores man encounter modern man and, if so, what was their interaction like? We may never know the truth, but we now have a great mystery to ponder
1 - Tyrannosaurus Rex
Topping our countdown at No. 1, Tyrannosaurus Rex is an animal whose fossil remains are known to school children and adults from all parts of the world as the most fearsome predator that ever walked the planet. Standing about 40 feet in length, with a massive head and jaws that could have eaten an adult man in a single bite, one look at the remains of this brutish beast sends chills down the spine of anyone considering time travel to the Cretaceous Period.
So, if Tyrannosaurus Rex and the other dinosaurs were so ferocious, why did they die out? This is one of paleontology's great mysteries, but evidence from the fossil record suggests that there may have been a catastrophic event such as a meteor impact or volcanic eruption that killed off dinosaurs and most other living things on the planet at the time.
One thing is certain about dinosaurs in general and Tyrannosaurus Rex in particular: no other group of extinct animals has captivated humans quite so much. Perhaps it's not so much the animals themselves that command our attention but the idea that such a catastrophe could cause humans to suffer a similar fate. Then, millions of years later, a future life form might be sitting around a table wondering what wiped out such a seemingly well-established creature as Homo sapiens.