Artist's reconstruction of Sonselasuchus cedrus in its environment in what is now Petrified Forest National Park, 215 million years ago.
Artwork by Gabriel Ugueto.
In Greek mythology, Oedipus solved the riddle of the Sphinx and so saved the city of Thebes. The riddle asked, “What goes on four legs in the morning, two in the afternoon and three in the evening?” Oedipus correctly answered “Man” (crawling as a baby, walking upright as an adult and using a walking stick in old age.)
Of course, that myth is no less plausible than the Hebrew origin myths that creationists regard as literal history but, in a way, Oedipus was lucky. Not only did the Sphinx allow the stretch of regarding a walking stick as a leg (for poetic licence?), but the riddle did not stop at two legs, as there are very many bipedal species, and at least one went on four legs in infancy.
Researchers, Elliott Armour Smith from the University of Washington Department of Biology and Professor Christian A. Sidor of the Washington University Burke Museum, have just published the results of a study in the Journal of Paleontology showing that an ancient relative of crocodiles, the poodle-sized Sonselasuchus cedrus, probably began life as a quadruped and later had to learn to walk upright because of different growth patterns in different bones.
This creates a problem for creationists, not so much because other mythologies contain legends such as the riddle of the Sphinx that, treated as a metaphor, describe the human condition better than any of the implausible tales in the Bible, but because the myths it does contain preclude learning any of the fascinating history of life on Earth that requires a realistic timeline running into hundreds of millions, even billions of years. These peculiar crocodiliform shuvosaurids lived between about 225 and 201 million years ago and were contemporaneous with the bipedal ornithomimid dinosaurs that eventually gave rise to birds.
The interesting question then—and something creationists are precluded from considering—is what about the earthly environment made bipedalism such an advantage that it evolved independently in two distantly related groups of reptiles?
This conclusion comes from the examination of 950 Sonselasuchus fossils unearthed in Arizona’s Petrified Forest National Park—a fossil site which has yielded more than 3,000 fossil bones since 2014.










































