The Megafauna of the day for this Tuesday, the 9th of April 2013 is the terribly under-appreciated Phorusrhacos longissimus, of the clade Phorusrhacidae, better known as the Terror Birds.
Extant in the mid-Miocene epoch, P.longissimus stood at up to 2.5m tall and may have weighed as much as 130kg. Its vicious-looking skull was enormous up to 60 cm long, and equipped with a deadly hooked beak.
P. longissimus is thought to have killed its prey by similar action to its only living relatives, the Seriemas - by grabbing the prey in the beak and burdening it against the ground until dead. It has been speculated that it may have also been capable of administering a fatal stabbing blow with the hook of the beak.