Feathers, once thought unique to birds, must have evolved in dinosaurs long before birds developed. Sophisticated new analyses of these fossils, which track structural changes and map how the specimens are related to each other, support the idea that avian features evolved over long stretches of time.

In the view of most paleontologists today, birds are living dinosaurs. The best explanation for the presence of these shared characteristics is that they existed in a common ancestor, from which both dinosaurs and birds are descended.

okapi
Some scientists have long presumed today’s giraffe (Giraffa camelopardalis, right), which includes a handful of subspecies scattered throughout sub-Saharan Africa, evolved from an animal that looked like its close cousin the okapi (Okapia johnstoni, left), which lives in the tropical forests of central Africa.

In phylogenetic taxonomy, the genus Triceratops has been used as a reference point in the definition of Dinosauria; dinosaurs have been designated as all descendants of the most recent common ancestor of Triceratops and modern bird.

Fossil records suggest that modern birds originated 60 million years ago, after the end of the Cretaceous period about 65 million years ago when dinosaurs died off. But molecular studies suggest that the genetic divergences between many lineages of birds occurred during the Cretaceous period.

Among the survivors were a small group of ground-dwelling birds: the ancient ancestors of modern day chickens. Chickens are actually direct – albeit petite – descendents. As a result, chicken DNA is surprisingly most closely related to dinosaur DNA.

As far as reptiles go, crocodiles are closely related to dinosaurs. But they’re incredibly complex biological organisms that survived the meteor impact that ended the Cretaceous period roughly 66 million years ago — and did in their dinosaur relatives.

Research paper says the avians gave up teeth to speed up egg hatching. Previous studies had concluded that birds — living descendants of avian dinosaurs — lost their teeth to improve flight.

No. Brachiosaurus was a dinosaur that lived around 150 million years ago. Confusion might arise from the name of one of these great sauropods: Brachiosaurus giraffatitan. This means ‘giant giraffe’, but the physical resemblance between the two animals is actually quite superficial.

There are many animals that defy evolution and the bull giraffe is one of them. The circulatory system of only its neck is made with complexity in which evolution cannot create. The bull giraffe has a huge heart that pumps blood up its long neck. The blood pumped to its brain up the neck defies gravity.

Vestigial Structures Definition Vestigial structures are various cells, tissues, and organs in a body which no longer serve a function. A vestigial structure can arise due to a mutation in the genome. This mutation will cause a change in the proteins that are required for the formation of the structure.

Vestigial organs have demonstrated remarkably how species are related to one another, and has given solid ground for the idea of common descent to stand on. From common descent, it is predicted that organisms should retain these vestigial organs as structural remnants of lost functions.

These vestigial organs, Darwin argued, are evidence of evolution and represent a function that was once necessary for survival, but over time that function became either diminished or nonexistent.

Webster’s Third New International Dictionary defines a vestige as “a small and degenerate or imperfectly developed bodily part or organ that remains from one more fully developed in an earlier stage of the individual, in a past generation, or in closely related forms.”