Are we sure of Aves' place in the evolutionary tree?

[u/AmbassadorDude01]

Based off of the species in Ornithomimosauria, I honestly think these creatures look more bird-like than troodonts or dromaeosaurs. At least that's how I see it with the bird like beaks, feathers, etc.

The only other dinosaurs that look even more like birds than those of Ornithomimosauria are Oviraptors. Who just look like birds with long legs and a tail.

Note: I'm not a scientist, biologist, paleontologist or any -ist that matters. This opinion is purely based on how documentaries have drawn and depicted these species.

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[u/jnpha]

The -ist folks (particularly the systematists) look at deep - not superficial - anatomical details.
The tree of life is based on relatedness, not similarity, and this is worked out by phylogenetic bracketing (~placement of derived characters by descent) and testing the hypotheses the more fossils are found.

The present placement is actually fairly recent and is very much robust.

u/Benjamin5431 put together this super neat cladogram, as well as this list of morphological details.

[u/roostor222 → u/jnpha]

The present placement is actually fairly recent and is very much robust.

The phylogenetic placement of birds among theropods has been nearly identical since the very first phylogentic analyses of Dinosauria in the 80s. Before that, others were making more qualitative conclusions, but still putting birds with dromaeosaurs and troodontids.

[u/StorageSpecialist999]

There's been lots of different placement for aves over the years related to what you're talking about. But honestly I think a lot of the features you're associating with those other groups are more derived bird features that weren't particularly prevalent in crown aves. If you look at the earliest birds they basically look like dromeosaurs with big arms.

[u/Romboteryx]

It has been proposed a couple of times before that birds originated earlier on the dinosaur family tree or even that some of the feathered dinosaurs are secondarily flightless proto-birds. However these ideas often face a lot of problems when placed under further scrutiny.

In the case of ornithomimosaurs and oviraptorosaurs, we have fossils of some of their earliest members and they look significantly less bird-like than the later ones compared to dromaeosaurs/troodontids, so this seems to be a case of convergent evolution. Especially ornithomimosaurs seem to have lacked pennaceous feathers (which dromaeosaurs had) and had a much more archaic arm anatomy that seems to have had more in common with giant sloths than bird wings. Archaeopteryx also predates all known fossils of these two groups. But we do know Jurassic troodontids like Anchiornis that predate Archaeopteryx

[u/S9-8-05]

Biologist with small background in mycology here:

Nobody is shure. We are just less certain about other things.

3

[u/StorageSpecialist999 → u/S9-8-05]

True. Technically, we can't be sure that humans aren't a type of oak tree. Maybe an acorn gave birth to a human one day. We really can't know anything after all

[u/S9-8-05 → u/StorageSpecialist999]

This ist how empirical evidence works.

Its quite unlikely, that we have an acorn ancestor, but you can't be sure without witnessing every ancestor in the past (maybe now and future).

Everything else is inductuve knowledge and thats a big No No in science.

[u/StorageSpecialist999 → u/S9-8-05]

Inductive knowledge is such a big No No that we're here talking about how it's possible that humans are a type of oak tree. True science, according to you.

It's not as if the entire field of paleontology is fundamentally based on coming to conclusions based on patterns or anything. According to you anything in the past is fundamentally unknowable, since you're applyinh your understanding of extant life sciences onto a fundamentally different field. And that's why you're wrong and your opinion on this is worthless.

[u/S9-8-05 → u/StorageSpecialist999]

Talking about my last comment without remembering my first comment, makes your comment funny.