Building a dinosaur from a chicken Can scientists convince birds to evolve backward .. into dinosaurs?

 Archaeopteryx lithographica at the Museum für Naturkunde in Berlin, Germany. (This is the original fossil -- not a cast.)

One of the most controversial topics in science during the past many decades has been the debate over the origin of birds: did they evolve from dinosaurs or reptiles? This debate quieted down for awhile until the discovery of an important new fossil in the nineteenth century. This fossil, known today as the Berlin specimen of Archaeopteryx (pictured above), led to fresh insights, thus reigniting this debate. Today, it is fairly well-accepted by the scientific community that birds are a special lineage of theropod dinosaurs.


When you look closely at the above fossil, you can see similarities as well as clear morphological differences between Archaeopteryx and, say, a chicken. Archaeopteryx has fingers instead of wings, Archaeopteryx has a long bony tail instead of a short bony nubbin and, if you look closely, you can also see that Archaeopteryx has teeth -- all of which birds lack.

But ornithologists and birders are familiar with one peculiar South American bird, the hoatzin, Opisthocomus hoazin, whose chicks possess claws on two of their wing digits -- almost like Archaeopteryx! But hoatzins aren't unique: curious traits, traits that had been lost during evolution, sometimes pop up in domestic livestock and even in humans -- chickens with teeth, horses with extra toes and humans with tails, for example. These features, known as atavisms, result from errors in gene regulation: genes are either "turned on" (expressed) or "turned off" (suppressed) at the incorrect times during development. Atavistic traits are reminders of the evolutionary past.

Knowing this, renown paleontologist Jack Horner has spent much of his career trying to turn back the evolutionary clock by reconstructing a dinosaur. He's found dinosaur fossils with extraordinarily well-preserved blood vessels and soft tissues, but never intact DNA. So instead of using the Jurassic Park method to recreate dinosaurs, he's taking a different approach. Mr Horner is taking a living descendant of the dinosaur -- chickens -- and genetically engineering them to reactivate ancestral traits -- including teeth, tails, and even hands. He's making a "chickenosaurus". In this fascinating video, Mr Horner reviews recent dinosaur discoveries and talks about his plans for recreating a "chickenosaurus":


Jack Horner studied geology and zoology but did not complete his bachelor's degree due to his inability to pass the required foreign language courses (he is somewhat dyslexic and could not read adequately in German). However, he did complete his senior thesis on the fauna of the Bear Gulch Limestone in Montana, which is one of the most famous Mississippian fossil sites in the world. He currently is Curator of Paleontology at the Museum of the Rockies and also serves in a number of academic capacities. In recognition of his achievements and contributions to the field of paleontology, he was awarded an Honorary Doctorate of Science in 1986 by the University of Montana and in 2006 by the Pennsylvania State University. In 1986, he was also awarded the prestigious MacArthur Fellowship. Mr Horner further discusses his plans to reconstruct a "chickenosaurus" in his 2009 book, How to Build a Dinosaur: Extinction Doesn't Have to Be Forever [Amazon UK; Amazon US].


Source The Guardian