News Finding: "While this explanation of the second and fourth digits is viable, it is incomplete and fails to account for the animal's first and fifth digits," the paleontologists said.
Paper Finding: This proposed location of metacarpals I and V is consistent with the extinct tridactyl Hypohippus, where all five digits are present proximally towards the wrist.
News Context: For the first time, Professor Solounias and colleagues propose that the reduction in the number of digits is not a matter of simple attrition; instead, they believe that all five digits have merged to form the compacted forelimbs with hooves that we know today. "While this explanation of the second and fourth digits is viable, it is incomplete and fails to account for the animal's first and fifth digits," the paleontologists said. Fragments of the 'missing' digits can be found in the form of ridges on the backside of the splints."
Paper Context: Metacarpals III-V of Hyracotherium are, therefore, singular and do not contain remnants of other digits, as is seen in later equids. This proposed location of metacarpals I and V is consistent with the extinct tridactyl Hypohippus, where all five digits are present proximally towards the wrist. In Hypohippus, metacarpals I and V are present at the proximal shaft, as ovoid bony elements positioned on the ventral surface of metacarpals II and IV.