I dont know about birds being immature dinos.
During the Megafauna era, only 100,000 years or so ago, there were GIANT flightless birds.
15 foot tall Ostrich types etc etc.
Even now were have 8 foot Ostriches, 6 foot + Emus, 5 foot Cassowarys etc.
I still believe Dinosaurs images are misrepresented.
Skin, fur etc has not survived in fossils, but some feathers have.
There is NO reason to believe that Dinosaurs were not just Naked skin things, but ACTUALLY could have been covered with fur, or maybe decorative
plumes of feathers or skin stuff (eg chickens/roosters head things)
They may have been brightly coloured to attract mates (like birds) or have camoflage fur, like tigers etc.
Only recently a scientist has come forward and said many of the "Identified" Dinosaurs are in fact NOT separate creatures, BUT are in fact,
different stages of the same creature.as in ..Infant, Juvenile, Adult.
This makes sense, as we see it in life now, different appearances for different stages of growth.
I dont believe they use to Roar (like an Elephant or Lion) as portrayed in the movies.
As there are a myriad of bird sounds, i believe they may have chirped, hissed, deep guttural moans etc that would have been heard in the jungles and
plains of the time. Hollywood has distorted people's thoughts...thru ignorance.
Many people show fascination on how these large predators had such tiny arms but huge legs and tails....Why???
Look at the Mammal/Marsupial Kangaroo today...it has Small arms and Large legs and very strong tail....and furry.
A Giant kangaroo of the megafauna era stood over 10 feet tall!!
Who says all the Dinosaurs ran??
Maybe some Hopped, Jumped etc to travel faster than running.
Eg, Kangaroos, some Mice, some birds etc etc.
Too much of a closed mind with these so called "experts".
The only positive, is they HAVENT got a clue.....Until we invent that time machine, wild theories are probably closer to the truth, than what they
Think they know and call it science.