Bird Evolution ..?

How did these creatures so called birds come into existence ?
Why are they called as birds ?
Are they evolved from the Jurassic Era !!

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Challenging topic … Yet this is the best simplest explanation I found : birds are just vertebrates that invested everything in muscles, contrary to mammals that apparently invested in brain. I am not sure about “lower” vertebrates – probably on other organs and tissues…

See Thermogenesis, muscle hyperplasia, and the origin of birds

All my apologies to the bird lovers…

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To answer your third question, birds are a branch of the tree of life, so their lineage stretches back to the dawn of life billions of years ago just like all other living organisms - all living organisms have been evolving for the exact same amount of time. But if you’re wondering when the bird lineage started to look like birds, then you are right, it was probably in the Jurassic. Birds are dinosaurs that evolved flight and a variety of other unique adaptations, and managed to survive the mass extinction that killed off all of the other dinosaur lineages.
The group of dinosaurs that includes birds is called the Theropods, which includes dinosaurs like Velociraptor and T. rex, so birds are just very specialized theropod dinosaurs.

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This is an interesting topic to discuss.
Every day you see flying dinosaurs. Yes, birds are legit dinosaurs. Birds evolved from dinosaurs from theropods, which included T. rex, Spinosaurus and Velociraptor. And believe it or not, some dinosaurs of the Therepods already had (or developed) feathers.

The well-known evidence that birds are dinosaurs is Archeopteryx. You can read the article on Wikipedia.

I still have a hard time imagining that we are surrounded by tiny, feathered dinosaurs :grinning_face_with_smiling_eyes:

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@muhmalikali ,you are right about the evidence but I still doubt that how is it possible for Archeopteryx (this one specie) to have developed into various forms of birds that we see today.
It did not develop to 10 or 100 or 1000 species but to 9,000 /10,000 species.
That’s a huge number

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Is it something to do with cell biology ?
Did we create some species by hybradisation ?
How did 9,000 to 10,000 species of birds develop ?

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I dont think a T-rex would have made a difference or maybe it did make a difference
I think its cells tried to develop over a period of time and turned into some specie that it never meant to be. :thinking:

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most scientists accept that birds are a specialised subgroup of theropod dinosaurs,[41] and more specifically, they are members of Maniraptora, a group of theropods which includes dromaeosaurids and oviraptorosaurs, among others

As quoted by wikipedia

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And If you see cassowary I am sure your heart will tremble same as that of dinosaur. That bird really looks prehistoric

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the word bird originated from the Anglo Saxon word “bredan,” meaning “to breed,” which gave “bird ” its original meaning–a young bird (what we now call a chick).
I just got the origin of word bird, I think it was connected to birds long before we started calling them birds.

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And about breeds …

If you consider that there may be some 360 breeds of dogs and some 70 breeds of cats, waiting for some more time in a human-led environment, there might be as many species (depending if they are kept apart or not…). And it is just from two species…

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It definitely is a huge number! These species accumulated slowly over time: an ancient Archaeopyeryx-like bird first split into two species, and then those species started to split, until the numbers started to add up. Some ancient species went extinct, while others were very successful and eventually gave rise to many more species. Remember that this did not happen all at once: Archaeopteryx live 150 million years ago, so there has been a very long time for bird species to evolve. Usually it takes just about 1-4 million years for one species of bird to evolve into a new species, but sometimes it can be much much faster.

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yup its heart trembling but as studies say chickens are the closest relatives to the T-Rex.
I think some of the cells of the T-rex transformed into a chicken and gave rise to a new specie,then the breeding of the chicken started,then the age of homosapians(humans) came into existence.

Other than cassowary,even Turkey’s and chicken’s resemble some instincts same as the Dinosaur so we can also say Turkey’s and Chickens are prehistoric.

It’s not like some of cells of t-rex change into chicken, it does not work that way, there are some small changes which takes a lot of time. By small changes like developing limbs then after some time fingers started growing longer coverd with skin and process of getting lighter legs from hairy muscular legs.
My point of saying is that if a dinosaur converted into birds it’s not like that cells will transform of that of chicken,
But dinosaur will have slow variation like lighter body than before, which will take millions of year then they will transform into something that is a link between dinosaur and chicken

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This is a common idea but it is a myth: all birds are equally related to non-bird dinosaurs, because all birds are descended from the same ancestor. For example, it is like with human families: me and my cousins are all equally related to our grandma, just the same way all birds are all equally related to other dinosaurs.

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Modern birds, Aves, are just one of three previously existing, but very different types of “birds” that existed prior to the K-Pg extinction. The other two were enantiornithines and hesperornithiforms. Of those the enantiornithes were by far the most successful, but it was the Aves that survived, although even they nearly went extinct.

A very small number of bird species survived the K-Pg extinction, possibly as few as 6 species of ground dwelling birds, and it’s thought that part of why the birds we are familiar with survived is due to having beaks instead of jaws and teeth. (NOTE: “lineages” is probably a better descriptor than species in this case, regardless, the point is that birds nearly went extinct and it was a very small number that made it through the extinction event)

Following this extinction birds diversified rapidly, spreading to occupy a wide range of niches made available after the extinction event. This may have led to an increase in bird the pace of evolution, which would be unsurprising as that’s what tends to happen when new niches are available for exploitation.

It’s worth mentioning that not long after the non-avian dinosaurs went extinct 64 million years ago there was a period where birds briefly became the dominant land animals, and in some parts of the world they remained large apex ground predators until recently.

As for the ultimate origin of birds, as others have said, the consensus is that they evolved from small theropods, specifically the Maniraptora (as has been mentioned elsewhere).

The specific details of exactly how these dinosaurs evolved into birds, and how many times, is extremely contentious, with new discoveries constantly adding both detail and complexity.

There are two basic arguments, one is that birds evolved from small dinosaurs that glided from high points, much like modern flying squirrels, flying snakes, draco lizards, coalingas, flying frogs, etc do. The criticism of this is that gliding flight is essentially passive and it’s difficult to see how it would lead to the evolution of the massive breast muscles powered flight requires.

The second popular hypothesis is that flight evolved initially from the need to keep fast moving and agile animals on the ground and enhanced traction when running. This is called “wing assisted running” and is seen in present day birds, especially juveniles of certain species, and has the advantage of providing a mechanism for evolving the breast muscles needed for flight.

There is a third hypothesis that’s often called the “Cursorial Theory” dating back to the late 1800s which proposes that flight evolved from animals running and making hops into the air (a little like flying fish and flying squid), which eventually were extended into flight. This idea has largely been abandoned now.

In short, while the general picture of the evolution of birds is agreed upon, the specific details are still being vigorously debated. Increasingly it’s looking like dinosaurs evolved flight repeatedly, and possibly via different mechanisms each time as well.

Not only were there two other very successful “birds” clades in existence prior to the K-Pg extinction, fossils of bat-winged dinosaurs like Ambopteryx have been found which had both feathers and bat-like membrane wings.

It’s interesting to think what things would have been like if the the more widespread and successful enantiornithines or the less widespread hesperornithiforms had been the ones to make it through the K-Pg extinction. Or how different life today would be if none of these birds and near-birds survived the extinction event.

EDITS:

Minor ones to correct spelling and grammar. Likely still missed a few.

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Did you mean wing-assisted (inclined) running?

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This always bothers me as it’s so inaccurate. Possibly as few as 6 bird species survived the K-Pg extinction, and all modern birds evolved from those species.

It’s utterly ridiculous on a number of levels to try to claim that one of those descendents is more closely related to a distant animal that had diverged from the line leading to modern birds long before the extinction event.

Not only are all existing birds equally related to T-rex, we have no genetic samples from T-rex to analyze, so even if all modern birds were not equally related to T-rex we would have no way of determining which was more closely related.

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Ah, yeah, typo when writing. It’s not just incline running, it’s useful for cornering and such too.

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That’s why I put incline in parentheses

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