Mammal ancestors bided their time
in Life Science, Diversity of Organisms, and Biological Populations Change Over Time
Modern mammals waited for the right time to diversify: Photo of Hopi chipmunk by Mdf courtesy Wikipedia Commons.Results from a new study of mammalian diversity and origins show that most species of mammals alive today waited several millions of years after dinosaurs died out to diversify and take over the world left by their reptilian predecessors.
The conclusion comes from an international research team studying the evolutionary connections between some 4,500 species of mammals. In the process the researchers also developed a “supertree” of mammal relationships. Supertrees are created using numerous smaller studies to summarize the evolutionary history of a large group of organisms.
Some mammals did flourish in the bio vacuum created by the Mass Extinction Event (MEE) that took place at the end of the Cretaceous 65 million years ago - credited to a large asteroid colliding with the Earth - but most of those mammals later became extinct themselves. The ancestors of mammals alive today, including rodents, hoofed animals, primates and humans, existed some 20 million years before the dinosaurs’ demise, but appear to have waited in the shadows before diversifying and expanding.
"Our research has shown that for the first 10 or 15 million years after the dinosaurs were wiped out, present day mammals kept a very low profile, while these other types of mammals were running the show,” said professor Andy Purvis of Imperial College London’s Division of Biology, one of the study’s leaders.
“It looks like a later bout of 'global warming' may have kick-started today's diversity – not the death of the dinosaurs,” he added.
The diversification took place in the Eocene Period and seems to coincide with what is known as the Paleocene-Eocene thermal maximum, a time of peaking global temperatures during the Cenozoic era. But whether the high temperatures caused of biological expansion is not known.
The findings not only counter the widely held idea that ancestors of modern mammals evolved and spread quickly to fill the void left by the mass extinctions of dinosaurs, but also add invaluable insight into other aspects of mammalian evolution.
"Not only does this research show that the extinction of the dinosaurs did not cause the evolution of modern-day mammals, it also provides us with a wealth of other information,” said Dr. Kate Jones from the Zoological Society of London. “Vitally, scientists will be able to use the research to look into the future and identify species that will be at risk of extinction. The benefit to global conservation will be incalculable.”
The research appeared in the journal Nature.
STORY IN MINNEAPOLIS STAR TRIBUNE
MORE ON THE CRETACEOUS
MORE ON THE EOCENE PERIOD
MORE ON MASS EXTINCTIONS
MORE ON MAMMALS
MORE ON DINOSAURS
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It's kind of creepy that there actually might be life in space, with all the "War of the Worlds" stuff and all that.
Do you think that there will be another mass extinction? I hope not cuz the animals are all cute, and we would all die. that would be bad. Yes very bad. I like the animals and i want them to stay alive.
All animals are rather cute. Wait! It wouldn't be bad if insects like mosquitos and spiders died off because they're really creepy and ugly. But most animals and insects are very cute indeed.
Insects play a vital role in maintaining the environment. They eat all the dead stuff. Birds, frogs and other animals eat them. Insects pollinate flowers. Every animal has a role to play. (POST UPDATED when somebody pointed out the original was kind of crabby. Sorry!)
Replying to Sonya: I have never seen war of the worlds but it seems to be a creepy movie and it would be scary if there was life in space. And to Jessica: it wouldn't be bad for the earth if we died even though it would suck for us. Well, at least the planet would be healthy. 0_0
(My real name is Dylan Stoos but I go by Link for fun)
Anyway, if there was a mass extinction it wouldn't matter if all the cute animals were dead because we would be too busy being dead to care.
Why would you even think about being dead? Why don't you focus on being alive and about how much fun you are having! Besides the mass extinction won't happen for another 5 billion years when the sun burns out and the earth will die then but none of us living right now will ever see that so why should we care about it right now? I really don't want to know about cute bunnies dying so don't talk about it! It's so so so so so so so so so so so so SAD and CRUEL!!
Mass extinctions have taken place at various times throughout the history of life on Earth, and will probably continue to happen. They seem to be an important event in the process of evolution, as they allow new life forms to spring up where voids has been created by the extinction. Think of it this way: if the Cretaceous extinction hadn't taken place, we probably wouldn't be here. And because we're here, like any other life form, we're going to be vulnerable to a mass extinction.
Not so fast there! A new study, examining mammal fossils in museums worldwide, contradicts this statement in the article above:
"The ancestors of mammals alive today, including rodents, hoofed animals, primates and humans, existed some 20 million years before the dinosaurs’ demise...."
The new study claims that the ancestors of modern mammals did not evolve until after all the dinosaurs were gone.
A good example of the scientific method at work!
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