Dinosaur extinction cleared way for 'little timid mammals' to become Earth's big guys
WASHINGTON — New research pinpoints how the torch passed from one dominant creature on Earth to another, from the brutish dinosaur to the crafty mammal.
Two studies published on Thursday in the journal Science better explain the Earth-shaking consequences of a catastrophic cosmic collision 66 million years ago when a comet or asteroid smashed into the Gulf of Mexico.
The crash seemed to end the reign of the dinosaurs. And it gave way to the age of mammals that probably started with a cute squirrel-like critter and eventually led to us, the researchers report.
“I think it's fair to say, without the dinosaurs having gone extinct, we would not be here,” said Paul Renne, director of the Berkeley Geochronology Center, who led the research on the dinosaurs and cosmic crash. The dinosaurs' disappearance “essentially releases the little timid mammals to become the big guys.”
Renne demonstrated how the timing of the cosmic crash exquisitely matches the disappearance of the slow-footed dinosaurs of Jurassic Park fame. His findings provide more evidence for the theory that an extraterrestrial crash was most responsible for the extinction of dinosaurs.
Scientists have long thought that there were 200,000 years between the big crash and the end of the dinosaurs, but Renne's more detailed examination of fossils and soil at Hell Creek in northeast Montana puts the two events within 32,000 years of each other. That strengthens the case for the space crash as the “straw that broke the camel's back” and killed off the dinosaurs, said Renne.
He said other environmental factors, such as a changing climate from volcanic eruptions, also had made life harder for the dinosaurs, but that the big final dagger was the giant collision that caused a now-filled crater more than 100 miles wide at Chicxulub, on the coast of the Yucatan peninsula.
“The asteroid really rang the bell of the planet,” said Smithsonian Natural History Museum Director Kirk Johnson, who wasn't part of either study, but praised them both. Together they showed how that one event “had a profound impact on the nature of organisms that live on this planet.”
Dinosaurs are a distinct grouping of species, some of which evolved into birds. Scientists don't know how long it took for the large non-avian kinds like Tyrannosaurus Rex to die off.
The second study details the family tree of the most predominant type of mammal, those that give birth after a long gestation period. The researchers propose that the first such mammal was a shrewish critter slightly bigger than a mouse with a nasty set of teeth. And it popped into the world a little more than 65 million years ago — just after that cosmic crash.
When an asteroid or comet hits Earth and kills off the dinosaurs, it's both a tragedy and an opportunity, said Maureen O'Leary of Stony Brook University and lead author of the mammal study: “In some sense, we are a product of that opportunity.”
Show commenting policy
TribLive commenting policy
You are solely responsible for your comments and by using TribLive.com you agree to our Terms of Service.
We moderate comments. Our goal is to provide substantive commentary for a general readership. By screening submissions, we provide a space where readers can share intelligent and informed commentary that enhances the quality of our news and information.
While most comments will be posted if they are on-topic and not abusive, moderating decisions are subjective. We will make them as carefully and consistently as we can. Because of the volume of reader comments, we cannot review individual moderation decisions with readers.
We value thoughtful comments representing a range of views that make their point quickly and politely. We make an effort to protect discussions from repeated comments either by the same reader or different readers.
We follow the same standards for taste as the daily newspaper. A few things we won't tolerate: personal attacks, obscenity, vulgarity, profanity (including expletives and letters followed by dashes), commercial promotion, impersonations, incoherence, proselytizing and SHOUTING. Don't include URLs to Web sites.
We do not edit comments. They are either approved or deleted. We reserve the right to edit a comment that is quoted or excerpted in an article. In this case, we may fix spelling and punctuation.
We welcome strong opinions and criticism of our work, but we don't want comments to become bogged down with discussions of our policies and we will moderate accordingly.
We appreciate it when readers and people quoted in articles or blog posts point out errors of fact or emphasis and will investigate all assertions. But these suggestions should be sent via e-mail. To avoid distracting other readers, we won't publish comments that suggest a correction. Instead, corrections will be made in a blog post or in an article.
- Search for missing U. of Va. student shifted
- Wallenda’s next challenge: Chicago
- White House committed to ethanol, Agriculture Secretary Vilsack says
- Astronauts to hitch U.S. ride to space station
- Astronauts to hitch U.S. ride to space station
- Door left ajar to boots on ground to combat the Islamic State of Iraq and Syria
- 3,000 U.S. troops to join fight against Ebola with $763M plan
- Entire Calif. town lost to wildfire as dozen other blazes rage
- HealthCare.gov website’s security flaws put users’ personal info at risk
- ATF told to pay ex-agent $173K
- Ohio bus driver dies removing girl from harm’s way