Humans evolved from monkeys

[Aractus]

What a mess.  We didn't evolve directly from creatures which would fit the modern description of monkeys to what we call humans without, along the way, evolving into creatures who fit the modern description of apes (but not of the specifically human kind).  He might just as well complain that we evolved from some more primitive creature with a rudimentary backbone.  Which we surely did .. along the way evolving into many distinctly different creatures which would meet the description of certain named categories.  I don't see any issue here.

Okay, well here's a different example then.

Take this creature:



It looks like a bird but it isn't, and it never became one through evolution either. It's a dinosaur, and it's name is Archaeopteryx. It lived 150 million years ago. Some people claim that it was transitional which is wrong because it didn't transition into a modern bird, it died out (though technically all theropoda dinosaurs were in a period of change from whatever they evolved from millions of years ago, but simply labelling it as being "transitional" is a gross oversimplification unless you recognising that ALL life is transitional which makes the term meaningless anyway). Birds evolved from other theropoda dinosaurs, and they evolved separately along different paths from different dinosaurs. Thus we have birds today that evolved from different dinosaurs, just as humans and other apes evolved from different "dinosaur" ancestors, but it just happens that we share a common ancestor with chimps sometime 7-14 million years ago. Birds would share common ancestors as well, of course, but not in the late Jurassic period. It's an example of convergent evolution - i.e. birds that are only distantly related to each other evolved similar features to each other (such as flight) independently of each other.

[God of Mr. Hanky]

[The Grand Nudger]

Just looked him up. Two PKDs..........three British Sci fi's......the guy is clearly good.  Not sure how he flew under my radar.  We should make a sci-fi appreciation thread.

[popeyespappy]

It looks like a bird but it isn't, and it never became one through evolution either. It's a dinosaur, and it's name is Archaeopteryx. It lived 15 million years ago. Some people claim that it was transitional which is wrong because it didn't transition into a modern bird, it died out (though technically all theropoda dinosaurs were in a period of change from whatever they evolved from millions of years ago, but simply labelling it as being "transitional" is a gross oversimplification unless you recognising that ALL life is transitional which makes the term meaningless anyway). Birds evolved from other theropoda dinosaurs, and they evolved separately along different paths from different dinosaurs. Thus we have birds today that evolved from different dinosaurs, just as humans and other apes evolved from different "dinosaur" ancestors, but it just happens that we share a common ancestor with apes sometime 7-14 million years ago. Birds would share common ancestors as well, of course, but not in the late Jurassic period. It's an example of convergent evolution - i.e. birds that are only distantly related to each other evolved similar features to each other (such as flight) independently of each other.

1. You left off a zero. Archaeopteryx lived about 150 million years ago not 15 million.
2. Humans don't have a dinosaur ancestor. Dinosaurs and humans share a reptile ancestor. Reptiles split into two branches about 260 million years ago. One was Sauropsids which evolved into dinosaurs, birds and modern reptiles. The other branch is Synapsida which evolved into modern mammals.

[Aractus]

Oops I fixed that.

I meant dinosaur in the non-literal sense when referring to humans (i.e. "really old/obsolete/extinct"): we didn't evolve from actual dinosaurs, but our distant ancestors are "dinosaurs".

Birds didn't evolve from dinosaurs either mind you, they evolved through a stage where they were theropoda dinosaurs. So while theropoda dinosaurs are their actual ancestors, they are not the "start" of their evolutionary trait but rather a point along their evolution from whatever it was before that.

[popeyespappy]

Let's talk about this for a minute.

i.e. birds that are only distantly related to each other evolved similar features to each other (such as flight) independently of each other.

Those that study such things believe the last common ancestor of all currently living species of birds lived 85 to 95 million years ago during the late Cretaceous period. That single species, whatever it was, had probably already developed most of features common to modern birds including flight. There were probably other related species living at the same time with similar features such as flight that evolved along divergent paths, but most of the features common to modern birds all date back to that single species that lived 85 to 95 million years ago.

[ignoramus]

Are they saying that no other animal developed flight independently since then?

[popeyespappy]

Are they saying that no other animal developed flight independently since then?

Is who saying? Flight, like eyes, has undoubtedly evolved on separate occasions throughout history. Insects, Pterosaurs and Theropodas evolved the ability to fly on divergent evolutionary paths. Different species of theropodas may have developed the ability to fly separately. I'm just doubting Aractus's hypothesis that non-common ancestors of vultures and hummingbirds developed flight on divergent paths. As far as since then I don't have a clue, but I'm not aware of any species that has developed the ability to fly from a non-flying recent ancestor since birds evolved from Theropodas.

[Aractus]

Let's talk about this for a minute.

i.e. birds that are only distantly related to each other evolved similar features to each other (such as flight) independently of each other.

Those that study such things believe the last common ancestor of all currently living species of birds lived 85 to 95 million years ago during the late Cretaceous period. That single species, whatever it was, had probably already developed most of features common to modern birds including flight. There were probably other related species living at the same time with similar features such as flight that evolved along divergent paths, but most of the features common to modern birds all date back to that single species that lived 85 to 95 million years ago.

Well not all birds developed flight, and that scenario doesn't take into account cross-breeding which allows genes from another species to be experimented with. It's virtually impossible to say with certainty that a common ancestor existed "here" instead of simply cross-breeding. Same thing with humans and chimps - we have a common ancestor at some point, we have to. But 7 million years ago did we really have a common ancestor? Or did our species of the time cross-breed and make it look as if there was a common ancestor?

Are they saying that no other animal developed flight independently since then?

Of course not, bats, flies, bees, spiders*, ants, and literally dozens of other creatures that can at least "glide" (*no modern spider can fly but there are species that can glide), all developed different ways of flying.

[popeyespappy]

All modern flightless birds such as ostrich, emu, cassowary, rhea, kiwi and penguins are believed to be the descendants of birds that could fly. Their ancestors could fly, but these species lost the ability to fly during their evolution. There were earlier species of flightless birds whose MRCA with modern birds probably lived in the early Cretaceous. Those lineages all died out millions of years ago leaving only birds descended from a more recent common ancestor. That ancestor is believed to have all the characteristics common to modern birds such as feathers, a toothless beak and the attachment point for shoulder muscles required for a strong upward wing movement.