A new fossil from Australia pushes back the origin of tetrapods, or four-limbed animals, more than two million years.
The creature, Ossinodus, lived during the Devonian Period 333 million years ago in what would have been temperate forests.
Researchers analyzed only one Ossinodus radius bone from the front leg but this was a special and rare bone. The scientists used CT imaging to examine the structure of the bone to discover that it contained a partially healed fracture. But how did it become fractured?
Because the force of the trauma to the bone was upward of 11 times the animal’s body weight, the researchers find it highly unlikely that a water-dwelling animal could sustain a force that high. Generally, water cushions the blow of any object. This animal must have fallen from a height of almost three feet, possibly from a rock. Based on the nature of the fracture, researchers ruled out an attack from a predator.
Ossinodus now takes the title of oldest known tetrapod from the previous owners, its relatives from Scotland. But the search for the first true tetrapod continues.
