Kaitlyn the fracture originated in a high force scenario,

Kaitlyn SmithJanuary 20, 2018Biology 181Tonya BaxleyChapter 18: Article Summary The evolutionary history of vertebrate animals has always been one of the most difficult to study (and prove) areas of paleontology. Most people simply refuse to accept that all higher animals have a fishy aquatic ancestor. Another point of contention is the “missing link” debate, which exploits the holes in the paleobiological record where yet to be discovered creatures would fit; this approach is not fair, however, because of how rare fossilization events really are, along with the fact that not everything has been discovered yet. Despite these challenges, new methods for where discerning early vertebrates spent their lives, whether it be at sea or on land. In a study by a group of Paleopathologists (Peter J. Bishop,  Christopher W. Walmsley, Matthew J. Phillips, Michelle R. Quayle, Catherine A. Boisvert, and Colin R. McHenry), specialized researchers who examine prehistoric illnesses and ailments ranging from broken bones to cancers to viruses, it was found that how terrestrial a tetrapod was could be determined by types of bone fractures occur in the animal’s limbs. This not only allows for the examination of an animal’s lifestyle, this experiment also helps pinpoint which creatures became terrestrial and when they did it. These scientists examined the oldest recorded broken tetrapod bone for analysis: the radius of the tetrapod Ossinodus pueri from the Mid Visean Era (333 million years ago). After studying the shape of the fracture using “high resolution finite element analysis”, they determined that the fracture originated in a high force scenario, like from an impact accrued on land (likely a fall). This combined with osteological studies of the bone, which examined the internal structures and deemed them cancellous (having a porous, cavity featuring structure), allowed the scientists to determine that the Ossinodus was among the first tetrapods to live a majority of its life on land. This also allows the paleopathology team to determine that the first land dwelling tetrapods were evolved on the supercontinent Gondwana, far from the existing theories that smaller tetrapods in prehistoric Europe were the first to live on land.ReferencesBishop, P. J., Walmsley, C. W., Phillips, M. J., Quayle, M. R., Boisvert, C. A., & McHenry, C. R. (2015). Oldest Pathology in a Tetrapod Bone Illuminates the Origin of Terrestrial Vertebrates. Plos ONE, 10(5), 1-18. doi:10.1371/journal.pone.0125723