Birds and Dinosaurs

[Mojo]

That's kinda my point. Being feathery was one of the defining features of being a bird not a dinosaur. The question of my OP turns on whether there is much left that still distinguishes birds from dinosaurs at the taxonomic Class level.

Robert Bakker devoted a chapter of his book The dinosaur Heresies (1986) to arguing that dinosaurs should be considered as a class which includes birds. I'm not sure how much general acceptance this idea has gained in the meantime.

 

[Badly Shaved Monkey]

Hence the phrase 'as rare as hen's teeth'.

It's all right, I'll shut the door behind me.

On second thoughts, within Class Mammalia, there is the Order Edentata, as for tails, apes don't have them but they are still mammals.

I guess what it boils down to is the question of what distinguishes taxons at the Class level.

 

[Mojo]

On second thoughts, within Class Mammalia, there is the Order Edentata, as for tails, apes don't have them but they are still mammals.

I guess what it boils down to is the question of what distinguishes taxons at the Class level.

Doesn't it come down to whether members of the group have a shared ancestor, as well as shared characteristics? That's what Bakker was using as his argument for considering dinosaurs (and birds) to be a class, if I recall correctly.

 

[Badly Shaved Monkey]

Doesn't it come down to whether members of the group have a shared ancestor, as well as shared characteristics? That's what Bakker was using as his argument for considering dinosaurs (and birds) to be a class, if I recall correctly.

I think what I'm groping towards is the realisation that the taxon divisions- phylum, class, order etc are almost arbitrary, but I'd like to find out what are the conventions that define these levels in general terms, but you must be right, cladistics reveals actual relations without the artificial boundaries of a human-imposed tiered structure of taxonomic levels.

So, saying "I'm a mammal" ends up being a only rough shorthand, but we lack any usable nomenclature that can summarise your cladistic location in one or two words. Is that right?

 

[fishbob]

I think what I'm groping towards is the realisation that the taxon divisions- phylum, class, order etc are almost arbitrary, but I'd like to find out what are the conventions that define these levels in general terms, but you must be right, cladistics reveals actual relations without the artificial boundaries of a human-imposed tiered structure of taxonomic levels.

Taxon divisions- phylum, class, order etc ARE arbitrary. Career long paleontological fueds have resulted from disagreements on this topic. The basis for classification often boils down to individual interpretations of whether differences or similarities are more important.

 

[Mojo]

Taxon divisions- phylum, class, order etc ARE arbitrary. Career long paleontological fueds have resulted from disagreements on this topic.

According to Bakker, when he and Peter Galton published a paper suggesting that dinosaurs are a natural group, "all hell broke loose."

 

[Badly Shaved Monkey]

Taxon divisions- phylum, class, order etc ARE arbitrary. Career long paleontological fueds have resulted from disagreements on this topic. The basis for classification often boils down to individual interpretations of whether differences or similarities are more important.

So, at the Class level, what is the rough degree of difference that is required between 'adjacent' taxons? Is it even possible to answer that in a simple way?