Disappearing dinos didn't clear the way for us
The mass extinction 65 million years ago had little effect on today's mammals.
The extinction of the dinosaurs had little impact on the evolution of today's mammals, say researchers. After building a family tree of nearly every living mammal, they show that the main groups arose millions of years before the dinosaurs went extinct, and did not become dominant until millions of years after they disappeared.
Read the story here.
Comments
There is no fossil evidence anywhere to suggest that one species turns into another species. There are subtle changes that occur within a species which is observable.(microevolution) The species remain the same species.
Posted by: John | March 29, 2007 03:33 AM
There are many transitional fossils. Transitions between fish and tetrapods,
Transitions between mesonychids and whales.Transitions from condylarths (a kind of land mammal) to fully aquatic modern manatees. In particular, Pezosiren portelli is clearly a sirenian, but its hind limbs and pelvis are unreduced, all are well documented.
Posted by: JONBOY | March 29, 2007 01:27 PM
something i always wanted to know: say there is a species living on a continent, then a small group of them colonise an isolated island and evolve into a new species, is the continental population still considered the original species (in which case it can not be a monophyletic group since it does not include the descendent island species) or must it too be assigned to a new species?
i assume the former is generally the case, but how do phylogenists/taxonomists etc square this with the concept that taxonomic groupings should ideally be monophyletic?
Posted by: marty k | March 29, 2007 03:59 PM
Is the full tree available anywhere for download, etc.?
[Editor's note: most of this tree is available in the supplementary information of the paper, which can be found at http://www.nature.com/nature/journal/v446/n7135/suppinfo/nature05634.html. You will need a password to access this.]
Posted by: R. Binder | March 29, 2007 07:44 PM
I don't know why this is such a startling find. My colleagues and I have known about this for at least the past 25 years. There are all sorts of anomalies in the traditional stories that students are told. Van Valen showed there was some evidence that late Cretaceous dinosaurs (Ceratopsians) survived for a period past the end of the Cretaceous, and over the past forty years there has been growing evidence of a sizable mid to late Mesozoic mammal radiation.
Posted by: Mark Norrie | March 30, 2007 01:36 AM
I am not surprised by this either. My own personal opinion is now that the molecular clock is very much miscallibrated, with the real divergence dates for lineages being off by a factor of 2.5 - 3.0 with respect to the commonly accepted ones. (For example, I would place the split of old world and new world monkeys at 90 Mya, when Africa and South America were last in contact.) So if I have a complaint here it is that the initial mammalian divergence is not placed further back than it is.
Posted by: Edward Schaefer | April 5, 2007 05:16 PM