how have birds evolved over time

Because fully preserved animal skeletons are exceedingly rare, comparative analyses of fossil material typically concentrate on a specific body region. The reason the team studied skulls is that they are multifunctional, supporting sense organs, facilitating feeding, luring mates, and enabling self-defense. Felice notes, “The shape of a bird’s skull varies incredibly among them.” Consider hawks versus hummingbirds, he says, or pigeons versus pelicans. “Did birds evolve more quickly than their nonavian dinosaur ancestors to produce their highly variable skulls?” Felice queries. Although it may seem like a specific question, he says that it “gets toward an understanding of how diversity evolves.” “Is the diversity of a group of organisms really achieved slowly over time, or is it achieved quickly in an explosive burst?”

However, it is evident that some dinosaur groups had extraordinarily high rates of skull evolution. Every species in the ceratopsians, which includes Triceratops and its relatives, possesses a distinct configuration of horns and crests. And because they are useful for luring mates, these appear to have developed quickly, according to Ksepka. “These intricate skull decorations were present on so many dinosaurs, but they are extremely uncommon in birds—the cassowary is one amazing exception,” he continues. A prominent bony crest sits atop the head of the large, flightless cassowary, a relative of the emu that lives in the tropical forests of northeastern Australia and Papua New Guinea. “Feathers took over the role of display, as evidenced by the abundance of contemporary birds with simple skulls and exquisite feathered head crests. Just look at your friendly backyard cardinals and blue jays. ”.

Different body parts evolve at different rates in a phenomenon known as mosaic evolution, which has been observed in many organisms, including humans. Ksepka observes that the rapid evolution of the ceratopsians’ skulls contrasts sharply with the barely perceptible changes in their limb bones. In the meantime, he claims that modern warblers have developed “a kaleidoscope of color patterns,” but their skull shapes have changed very little. ”.

According to another outside expert, Stephen Brusatte of the University of Edinburgh, the finding that bird skulls originated from relatively low evolutionary rates “is essentially opposite from what we know of the rest of the skeleton.” Other body regions than the skull were the subject of earlier research by Brusatte and colleagues, who discovered that these areas evolved more quickly in birds than in other dinosaurs. This suggests, in my opinion, that the skeleton underwent quick and striking alterations during the emergence of birds, most notably the conversion of the arms into wings for flight. The heads were probably behind the rest of the skeleton in this transition, as they were less significant. “With characteristics like a beak, large eyes, and a brain, birds seem to have figured out early on in their evolution that worked for them,” he says. “Birds didn’t need to radically change any of these things in order to adapt to different niches.” Brusatte contends that instead, “birds adapted to new niches by changing their body sizes, wing shapes, and flying styles more than their heads after splitting off from other dinosaurs and going into the skies.” ”.

The majority of bird groups and 75 percent of plant and animal species, including the nonbird dinosaurs, were wiped out by an asteroid impact that struck Earth 66 million years ago. Since then, scientists have tended to believe that the diversity of birds today is the result of a surge of evolutionary activity that followed the event. Although it’s unclear exactly why only the neornithine lineage survived this apocalypse, the discovery of a 66 Asteriornis, a 7-million-year-old neornithine bird fossil from Belgium that is related to modern ducks and chickens, suggests that being small and residing near a shoreline may have been advantageous. Either way, the theory was that the neornithine birds had the area mostly to themselves following the mass extinction. Birds suddenly exploded into a multitude of forms to fill the numerous newly empty ecological niches, free from competition from other dinosaurs (not to mention a whole bunch of other vertebrates that also perished, including the pterosaurs, those flying reptiles that had long ruled the skies).

There has long been discussion regarding the evolutionary roles of feathers. It is evident that the initial, most basic feathers resembled hairs had an insulating purpose. However, even though the forelimbs of later theropods, like some oviraptorosaurs, are short, the arms and hands have long feathers. One theory regarding the function of these animals with long feathers on short arms comes from some amazing fossils of oviraptorosaurs found in the Cretaceous sediments of the Gobi Desert. The animal’s skeleton is hunched over an egg nest, resembling a protective chicken. The hands are positioned so that they appear to be protecting the eggs. It is possible that these feathers provided warmth and protection for the eggs.

Take feathers, for example. Small theropods related to Compsognathus (e. g. , Sinosauropteryx) probably evolved the first feathers. Their heads, necks, and bodies were covered in these short, hair-like feathers that served as insulation. The feathers appear to have had distinct color patterns as well, though it’s unclear if these were for show, camouflage, species identification, or some other purpose.

Following Archaeopteryx, birds continued to evolve in some ways similar to those of their theropod ancestors. Their reduced and fused bones may have contributed to their increased flight efficiency. Likewise, the feathers grew longer and their vanes asymmetrical, and the bone walls became even thinner, all of which likely improved flight. After the bony tail became a stump, a spray of feathers at the tail began to serve as a stabilizing and maneuvering aid. The wishbone, which was present in dinosaurs other than birds, developed into a more robust and complex structure, and the shoulder girdle’s bones changed to join the breastbone, stabilizing the forelimb’s flight mechanism. The breastbone grew in size and developed a central keel along the breast’s midline, which supported the muscles used for flight. As the primary means of locomotion changed from running to flying, the arms became longer than the legs, and in different lineages of early birds, teeth were repeatedly lost. The Late Cretaceous is when the ancestor of all living birds lived. In the 65 million years that have passed since the other dinosaurs went extinct, this ancestral lineage has diversified into the main species of birds that are still alive today.

A lot of the features that birds inherited from these theropod dinosaurs changed as they evolved. But it’s crucial to keep in mind that the animals weren’t in any way “trying” to be birds. In actuality, it becomes increasingly clear the closer we examine that the collection of traits that define birds evolved via a convoluted process and fulfilled various roles along the way.

We find several new types of feathers in theropods even more closely related to birds, such as the oviraptorosaurs. One is branched and downy, as pictured below. Others have developed an unstructured base and a central stalk with branches branching off of it. Others (such as the Archaeopteryx and Dromaeosauridae) have a structure resembling a vane, with barbules holding the well-organized barbs together. This is identical to the feather structure of living birds.

FAQ

How did birds evolve?

Many scientists are convinced that birds evolved from the dinosaurs. Numerous finds in recent years have seemed to support the hypothesis that birds descended from two-legged, running dinosaurs called theropods.

What is said that birds have evolved from?

Note: The paleontological studies of the fossil Archaeopteryx is the link between reptiles and birds. This provides evidence that birds have originated from the reptiles.

Did birds evolve more than once?

“A bird didn’t just evolve from a T. rex overnight, but rather the classic features of birds evolved one by one; first bipedal locomotion, then feathers, then a wishbone, then more complex feathers that look like quill-pen feathers, then wings,” Brusatte said.

What are the evidence of birds evolution?

The discovery that birds evolved from small carnivorous dinosaurs of the Late Jurassic was made possible by recently discovered fossils from China, South America, and other countries, as well as by looking at old museum specimens from new perspectives and with new methods.