[Rockhounds] What does the fossil record tell us about when truebirds appeared?

[Axel Emmermann]

> One of the most contentious issues among scientists who study the
> evolution of birds is identifying precisely when the modern birds
> (Neornithes) first appeared.

I always find these issues somewhat artificial in nature.
When I look at a pelican I cannot help to see a dactylosaurus (however they
bare more resemblance to our modern bats)... 
A giraffe is as strange to me as a diplodocus. Stranger, in fact, because it
lacks the tail for balance.
I think that most classifications are based on the shaky ground that
evolution is a discrete, non-continuous process.  The idea is a bit of an
inherited notion from back when people thought that the earth was 8.000
years old in my opinion. 
When a species is successful there are many individuals of it and chances of
finding a fossil record increases. Intermediate species, thrown into the
world by the pressure of a changing environment may be less numerous and
therefore we may lack knowledge of their existence.
I would not be very surprised if the greater part of dinosaurs were
warm-blooded or in other ways closer to mammals. 

Also: some geological periods or events favour conservation of fossils while
others give rise to decay. Isn't it likely that entire families of dinosaurs
just never dwelled in an environment that was "fossil-friendly".

Cheers

Axel

> -----Oorspronkelijk bericht-----
> Van: rockhounds-bounces at lists.drizzle.com
[mailto:rockhounds-bounces at lists.drizzle.com]
> Namens Kreigh Tomaszewski
> Verzonden: vrijdag 26 december 2008 3:42
> Aan: Rockhounds at drizzle.com: A mailing list for rock and gem collectors
> Onderwerp: [Rockhounds] What does the fossil record tell us about when
truebirds
> appeared?
> 
> One of the most contentious issues among scientists who study the
> evolution of birds is identifying precisely when the modern birds
> (Neornithes) first appeared. This is due to conflicts between the
> fossil record and molecular dating methodologies.
> 
> But there is another way to address this discrepancy. Because the
> evolution of parrots and cockatoos reflects the evolution of the birds
> (Aves) themselves, studying the psittaciformes offers compelling
> insights into this mystery.
> 
> Further, because psittaciformes generally are not migratory and because
> they tend to occupy discrete ranges, their ancient patterns of
> diversification are easier to discern than for many other taxonomic
> orders of birds that have dispersed widely.
> 
> http://scienceblogs.com/grrlscientist/2008/12/
> the_evolution_and_origin_of_pa.php
> 
> 
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