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Scientists trying to establish the evolutionary explanation for massive prehistoric reptiles eventually becoming modern-day birds have manipulated the proteins of embryonic chickens to make their beaks take the form of a dinosaur snout, according to a study published in the journal Evolution this Tuesday.
According to lead author Bhart-Anjan Bhullar, a Yale paleontologist, reversing the process by which chickens develop beaks so that they would grow a “snout” wasn’t difficult to do at all. He says the beak was a fairly recent development in bird evolution, coming long after birds developed the ability to fly. Beaks come in all shapes and sizes, and represent the specialization that species come to adapt in order to survive in unique habitats. Before beaks emerged, bird noses were blunt and primitive.
Bones called premaxillae, situated near the front of most animal jaws, eventually came to form what we know as beaks today. Over the course of thousands of years, chickens’ premaxillae fused and elongated, morphing into something that more resembles the beaks we recognize today.
The avian beak is a key evolutionary innovation whose flexibility has permitted birds to diversify into a range of disparate ecological niches. We approached the problem of the mechanism behind this innovation using an approach bridging paleontology, comparative anatomy, and experimental developmental biology. First we used fossil and extant data to show the beak is distinctive in consisting of fused premaxillae that are geometrically distinct from those of ancestral archosaurs. To elucidate underlying developmental mechanisms, we examined candidate gene expression domains in the embryonic face: the earlier frontonasal ectodermal zone (FEZ) and the later midfacial Wnt-responsive region, in birds and several reptiles. This permitted the identification of an autapomorphic median gene expression region in Aves. In order to test the mechanism, we used inhibitors of both pathways to replicate in chicken the ancestral amniote expression. Altering the FEZ altered later Wnt responsiveness to the ancestral pattern. Skeletal phenotypes from both types of experiments had premaxillae that clustered geometrically with ancestral fossil forms instead of beaked birds. The palatal region was also altered to a more ancestral phenotype. This is consistent with the fossil record and with the tight functional association of avian premaxillae and palate in forming a kinetic beak.
The Southern Cassowarry is a rainforest dwelling member of the ratite family, native to Northwestern Australia and New Guinea. Cassowaries have black plumage and blue skin patches, with a bony head plate that gives it a saurian appearance. These birds weigh over 130 pounds, stand nearly 6 feet tall, and are fiercely territorial.
Armed with razor sharp spurs and one of the strongest kick forces of any animal, Cassowaries will not hesitate to challenge a perceived threat. Human intruders into Cassowary habitat have been ripped open, disemboweled or killed instantly by the force and slicing effect of a Cassowary attack
originally posted by: GothmogThe scientists involved were or are trying to genetically modify the chicken back to its velociraptor beginnings. Dont know whether this bodes well for mankind or not
Hesperornis was a large flightless bird that swam in the oceans and snared fish with a tooth-lined beak. Its small wings were held close in to the body and were of little use beyond possibly helping it steer through the water. Instead, Hesperornis relied on its powerful hind legs and webbed feet to chase prey and evade predators in the Cretaceous seas. A flattened tail may have helped the bird change depth and direction underwater.
originally posted by: Barcs
It's funny how obvious it becomes when you actually observe and analyze chickens. The head movement, the way they interact, it's almost exactly how velociraptors are portrayed by scientists. I was on a farm over the weekend, to visit my mom for mother's day, and they have chickens, geese and ducks. When you sit back and watch how they interact, it's almost uncanny that they came from dinosaurs. Just imagine a raptor with feathers and you have a bigger, meaner looking, smarter chicken. Scientists have found that the ancestor of raptors had feathers and recently an arm was discovered with quills, so there's a good chance that velociraptor was actually fully feathered.
originally posted by: SuperFrog
a reply to: Gothmog
Thank you for pointing to mistake in my post, I've sent U2U to moderator to see if they can fix it in opening post.
I am sure we will do just fine... as long as we don't destroy ourselves by other means.
Quote from Dr. Sagan always comes into mind, when he tells what he wonders about aliens and one of question is - Are they also dangers to themselves.