It came without warning, fast and furious — a bright light racing across the sky. When it hit, it hit so hard that it changed the face of Earth. Many scientists believe that some 65 million years ago a giant asteroid or comet about 6 miles (10 kilometers) across slammed off what is today the coast of Mexico. Along with all the tidal waves, fires, earthquakes and other assorted disasters it would have generated, the blast would have thrown up dense clouds of dust and rock that darkened the sky, eventually chilling the planet almost to its core and killing 70 percent of all living species.
The collision also marked the end of the Cretaceous Period. Beginning about 145 million years ago, this period represented the final chapter in the age of the dinosaurs. It was the time of gigantic sauropods plowing through forests, and pterosaurs and huge, feathered birds darkening the skies. Tyrannosaurs also bounded across the planet, as did triceratops and stegosauruses. However, as the supercontinent Pangea shredded, new coastlines emerged, temperatures spiked, then cooled, and ocean currents changed. As a result, new habitats for new animals appeared. Flowering plants took root, and forests of conifers emerged.
As this change began occurring, dinosaurs started sharing the world with more diverse species. In fact, many animals that aren't dinosaurs thrived during the Cretaceous Period. Some are still with us, although they've gone through millions of years of evolutionary changes. Others are long gone. Some may shock you. Others will make your skin crawl. Here are 10 of them.
Scratch, scratch, scratch! You'll find them in hats, on coats and sometimes, ugh, in your hair. Lice! They're itchy! They're disgusting! They're ugly! Yet, when the end came for the dinosaurs, the tiny louse survived.Perhaps it's because these itchy creatures were too small to die or because there were too many of them.
No matter. Originally, bird lice probably made their home on the downy feathers of avian-dinosaurs, the prehistoric monsters that evolved into modern birds. The parasites may have chowed down on dinosaurs such as the Shuvuuia, a genus of birdlike, meat-eating theropods that lived between 85 and 75 million years ago [source: Balter].
A few years ago, scientists discovered two lice fossilized in stone. One was 44 million years old; the other about 100 million years. After careful study, researchers concluded these lousy bloodsuckers not only survived the near destruction of Earth 65 million years ago, but also flourished afterward [sources: Choi, Switek].
The next time you hear the crinkling of a potato chip bag in the middle of the night and see an army of cockroaches scurry off the kitchen counter, consider this before you reach for the roach spray: Cockroaches have been around forever, or at least longer than dinosaurs. In fact, more than a decade ago, a geology student at Ohio State University found the largest-ever fossil of a complete cockroach. It was 3.5 inches (9 centimeters) long and 300 million years old. Scientists could see the veins in its wings, along with its legs and antennae [sources: CBC News, Ohio State University].
Cockroaches were around long before the Cretaceous Period began and survived long after it ended (as we're all too aware). During the Cretaceous Period, the insects feasted on dino poop, or so some scientists think. Researchers at the Slovak Academy of Sciences accidently made the discovery as they researched the diet of the ancient bugs. Using a sophisticated imaging method called synchrotron X-ray microtomography, researchers built a 3-D version of a fossilized cockroach that they found encased in amber. The bug was about 120 million years old, which puts it in the Lower Cretaceous Period. As they examined the roach's gut, they found bits of wood that they believe came from dinosaur excrement [source: Lewis].
At 16 inches (41 centimeters) long, it was perhaps the largest, not to mention, most obese frog to ever have hopped across a Cretaceous lily pad. When scientists found the remains of this fossilized frog in Madagascar, they were agog at its size. Known as the Beelzebufo ampinga, or "devil frog," it was 3.5 inches (8.9 centimeters) taller than the largest living frog ever found. It lived between 65 and 70 million years ago, right in the thick of the Cretaceous. The devil frog had an overly large mouth and stomach. It was so huge that it probably didn't do a lot of hunting on its own, but rather waited until its prey passed by. What did it eat? Smaller frogs, lizards and mice, and perhaps, just perhaps, baby dinosaurs [sources: Moskowitz, National Geographic].
Other amphibians also thrived during the Cretaceous. One was Koolasuchus, a half-ton giant with eyes on the top of its head. It was a tetrapod, or four-footed, vertebrate that liked to hang out in cooler regions but didn't fare well when Earth warmed [source: BBC].
What do you see when you first walk into a seafood restaurant? Lobsters — an aquarium full of lobsters. Pick one out and have yourself a grand meal. Just remember this: What's on your plate is an evolutionary marvel, a survivor who outlasted T. rex and all the others. Lobsters beat the Late Cretaceous mass extinction to become one of the tastiest dishes on today's menu.
In fact, the ancestors of today's lobsters keep popping up in the fossilized record. In 2009, scientists announced they had found a new species of Late Cretaceous lobster in Iran. They called the critter Paraclytia valashtensis. It's special because it was the first time scientists found this particular species outside of Europe. Scientists discovered the well-preserved fossil in a limestone bed on the southeastern bank of Valasht Lake in northern Iran [source: McCobb and Hairapetian].
The Cretaceous Period brimmed with decapoda (10-footed) crustaceans, which include lobsters, crayfish and shrimp. In British Columbia, Canada, for example, scientists have found fossilized evidence of 22 species of decapoda crustaceans. Less than half became extinct by the end of the Cretaceous, with most species thriving in North America and Central America. They were able to scuttle up the evolutionary ladder, and their ancestors survive today [sources: Schweitzer et al.].
Pass the butter, please.
Whether they were mosasaurs or long-necked plesiosaurs, the seas of the Late Cretaceous Period teemed with gigantic marine reptiles. For example, plesiosaurs could grow up to 60 feet, or18 meters, long. Many of these enormous creatures did not survive the great extinction, but one marine reptile did — the sea turtle.
The first sea turtles appeared more than 245 million years ago. Most scientists believe they were land creatures that evolved to become sea dwellers during the Cretaceous. They were much larger than today's sea turtles with longer necks. One of the largest ancient sea turtles was the now extinct Atlantochelys mortoni. It lived about 75 million years ago in North America. It was 10 feet (3 meters) long and resembled a modern loggerhead [sources: Sci-News, Amos, SCISTP].
Lizards, Lots of Them
Although "dinosaur" means "terrible lizard," it's just a description. Dinosaurs aren't related to the reptiles, despite what Hollywood screenwriters might tell you. Each is a distinct group. However, various lizard species did live alongside the great dinosaurs. And like the dinosaurs, many died out during the mass extinction at the end of the Cretaceous.
At first scientists thought most lizard species survived the asteroid strike. They didn't. The problem, it seemed, was how paleontologists classified the lizard fossils they found. In fact, as many as 85 percent of all snake and lizard species disappeared once the space rock hit [source: Prostak].
One broad category of lizards that was wiped out was Polyglyphanodontia, which included nearly 40 percent of all lizard species living in North America. Scientists ultimately determined that the larger the lizard, the less likely it was to survive. It took about 10 million years after the Cretaceous Period for lizards to make a comeback [sources: Prostak, CBC News].
Although crabs first appeared during the Jurassic Period, many species emerged in the Cretaceous, including an oversized behemoth that had a curved tooth on a movable finger on the right claw. Known as Megaxantho zogue, the crab's large right claw was able to break shells, while the smaller left claw allowed the crab to funnel its prey into the "crusher" claw.
M. zogue did not survive the great extinction, but its features lived on in other species of crabs during the Cenozoic Era, which came right after the Cretaceous, and those species evolved into modern crabs [source: Ramanujan].
Interestingly, some Cretaceous crabs had both male and female characteristics. There weren't many of these so-called intersex crabs, but a few lived in what is now present-day South Dakota, where shallow seas provided a home for strange marine creatures. A subset of the Dakoticancer crabs, as scientists call them, were not strictly male, nor were they strictly female. Scientists speculate the crabs' habitat was contaminated, which caused the birth defects. Others say a prehistoric barnacle latched on to young crabs and wreaked havoc with their male hormones. This created a crab shaped like an adult female but that was, in reality, male [source: Pappas].
Toothless Pterosaurs (and More)
Pterosaurs were the denizens of the sky during the last age of the dinosaurs. They were the first animals, besides insects, to learn how to fly by flapping their wings. They were related to the dinosaurs, but not dinosaurs themselves. These giant reptiles died out during the mass extinction. During the Upper Cretaceous, the azhdarchidan species ruled the skies with wings up to 40 feet (12 meters) long. These toothless pterosaurs lived all over the world near rivers and lakes [sources Maynard].
Many of the 100-plus species of pterosaurs lived during the Cretaceous. Some were pterodactyloids, such as ornithocheiroids, which had a wingspan of about 20 feet (6 meters). Some were smaller,such as Jeholopterus, which lived during the Early Cretaceous in what is today Inner Mongolia. Jeholopterus' wingspan stretched only 35 inches (90 centimeters) [source: Pterosaur.net].
Long before the cataclysmic space-rock crash marked the end for the dinosaurs, mammals had already begun to spread out across the ever-changing planet. One mammal that roamed with the dinosaurs during the Cretaceous was a fuzzy guy called Vintana sertichi, a groundhog-like critter that lived in Madagascar.
No one knew the creature existed until scientists found a nearly complete skull in 2010. As scientists began to study V. sertichi, they determined that it was larger than most mammals that lived with the dinosaurs, weighing in at 20 pounds (9 kilograms). One scientist even called it "Punxsutawney Phil on steroids."
V. sertichi belonged to a group of mammals known as Gondwanatherians, which developed on the land mass known as Gondwana. That great swath of land eventually broke apart into Africa, Antarctica, South America, Madagascar, India, Arabia and Australia. Scientists speculate that V. sertichi developed in isolation, causing it to have strange but interesting features, such as a tilted brain case and a tremendous sense of smell [sources: Drake; Encyclopedia Britannica].
About as big as a chipmunk, Rugosodon eurasiaticus was an extremely versatile rodent-type mammal that lived through the Cretaceous and died out around 35 million years ago. The oldest R. eurasiaticus fossil ever discovered dates back 160 million years ago to the Jurassic Period.
When scientists first reported the discovery of the fossil in 2013, they had determined that R. eurasiaticus paved the way for other mammals that chowed down on plants and lived in trees. These so-called multituberculates flourished during the Cretaceous. They could jump, dig tunnels and climb trees. These rodent-like mammals first appeared during the Jurassic Period but managed to survive for more than million years. Some were as small as a mouse, others the size of beavers [sources: Science, Yandell, AAAS].
Geckos are so cool, they take lizardhood to a whole new level. HowStuffWorks gets to know these little guys.
Author's Note: 10 Cretaceous Animals That Weren't Dinosaurs
It was the so-called Chicxulub asteroid that ended the reign of the dinosaur, or so many scientists believe. However, some say the mass extinction could have occurred 300,000 years before or some 180,000 years after the Cretaceous Period. New evidence suggests that another asteroid might have struck India, causing the extinction. Other scientists say it could have been a series of volcanic eruptions.
More Great Links
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- Amos, Jonathan. “Monster turtle fossils re-united.” BBC. March 24, 2014. (March 1, 2015) http://www.bbc.com/news/science-environment-26717415
- Balter. Michael. “Did Feathered Dinos Spread Lice?” Science. April 6, 2011. (Feb. 27, 2015) http://news.sciencemag.org/paleontology/2011/04/did-feathered-dinos-spread-lice
- BBC. “Koolasuchus.” (March 1, 2015) http://www.bbc.co.uk/nature/life/Koolasuchus
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- Encyclopedia Britannica. “Gondwana.” (March 2, 2015) http://www.britannica.com/EBchecked/topic/238402/Gondwana
- Lewis. Tanya. “Cockroaches Munched on Dinosaur Poop.” Dec. 6, 2013. (March 1, 2015) http://www.livescience.com/41735-cockroaches-ate-dinosaur-poop.html
- Lucy Martha Evelyn and Vachik Hairapetian. “A new lobster Paraclytia valashtensis (Crustacea, Decapoda, Nephropidae) from the Late Cretaceous of the central Alborz Range, Iran.” Paläontologische Zeitschrift. September 2009. (March 1, 2015) http://link.springer.com/article/10.1007%2Fs12542-009-0033-5
- Maynard, James. “Toothless pterosaurs (no, not Night Fury) once ruled Late Cretaceous skies.” Tech Times. (March 2, 2015) http://www.techtimes.com/articles/13470/20140820/toothless-pterosaurs-no-not-night-fury-once-ruled-late-cretaceous-skies.htm
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- Pappas, Stephanie. “Crazy Cretaceous Find: Intersex Crabs.” LiveScience. Nov. 13, 2013. (Feb. 26, 2015) http://www.livescience.com/41156-cretaceous-intersex-crabs.html
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- Schweitzer, C.E.; Feldmann, R.M.; Fam, J.; Hessin, W.A.; Hetrick, S.W.; Nyborg, T.G;. Ross R.L.M. “Cretaceous and Eocene Decapod Crustaceans from Southern Vancouver Island, British Columbia, Canada.” NRC Research Press. 2003. (March 1, 2015) http://www.nrcresearchpress.com/doi/book/10.1139/9780660190921#.VPSDu_nF-Sq
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