Orwell wrote:
If we saw it today, we might well call it a "fish" without taking note of the developments that have occurred in the fish lineage. But then, we would also probably call our pre-endosymbiotic ancestors bacteria, even though what we now call bacteria split off from our lineage (and, importantly, went a separate way with their own novel developments) before that point.
I think the problem here is the sort of implicit assumption that most of us have—namely, that humans are the most "evolved" species, and that if we "evolved" from monkeys, the extant monkeys today are the same as our ancestors, rather than simply another line that split off and went in a different direction after some point.
From Wikipedia (judge as you may):
Wikipedia wrote:
The term "fish" most precisely describes any non-tetrapod craniate (i.e. an animal with a skull and in most cases a backbone) that has gills throughout life and whose limbs, if any, are in the shape of fins.[2] Unlike groupings such as birds or mammals, fish are not a single clade but a paraphyletic collection of taxa, including hagfishes, lampreys, sharks and rays, ray-finned fishes, coelacanths, and lungfishes.[3][4] Indeed, lungfishes and coelacanths are closer relatives of tetrapods (such as mammals, birds, amphibianss...) than of other fishes such as ray-finned fishes or sharks, so the last common ancestor of all fishes is also an ancestor to tetrapods. As paraphyletic groups are no longer recognised in modern systematic biology, the use of the term "fish" as a biological group must be avoided.
http://en.wikipedia.org/wiki/Fish#Diversity_of_fish
If "lung-fish" are included as "fish" then there is no reason why tetrapods shouldn't be classified likewise. You get a paraphyletic group otherwise.
11 Dec 2010, 6:11 pm
