Terror Birds “Phorusrhacidae”

TAXONOMY AND PHYLOGENY ORIGINS OF FLIGHTLESSNESS IN BIRDS ADAPTATIONS ● Named in Diet and Hunting: (3) 1887 by The graphic to the left compares the skulls of Florentino Origin: (5) three species of terror birds including Ameghino, A theory commonly accepted by scientist is that all Andalgalornis steulleti, Haliaeetus albicilla and after the first birds that cannot fly today descended from birds that Cariama cristata. Each skull is placed under member of could fly. Some scientist argue that the birds that can different load cases. the group no longer fly lost that ability because there wasn’t any discovered, evolutionary advantage to flying in their environment. If Andalgalornis steulleti hunted small prey: Phorusrhacos Relation to Phorusrhacidae: (9) ● Less precision necessary ● Upon naming, Phorusrhacidae evolved to be menacing predators ● Easier to kill no precedent despite not having the ability to fly. Part of what made ● More safe to consume for a large them such a formidable predator is their small wings. If Andalgalornis steulleti hunted large prey: carnivorous bird had existed in South America (6) The size of the wings of Phorusrhacidae allowed for ● More precision ● SIlhouettes in the above diagram indicate body size, them to make quick maneuvers while moving at top ● Avoiding high lateral loads and dark silhouettes indicate a body mass over 70kg. speeds. This ultimately enabled them to out maneuver ● Used attack-and-retreat strategy ● Easily identified in the tree is the divergence from their prey more often than not. ● Possible use of talons to hold down prey smaller terror birds to those that are very large, the 3 ones we are familiar with, like Phorusrhacos. (2) Habitat: (4) Based on the hip bone structures, most PHYSICAL FEATURES Phorusrhacidae were very maneuverable. This tells that they lived in a region of high Phorusrhacidae have plenty of physical attributes that vegetation and were still very agile. This helped them earn the name “terror birds”. These supports the idea that they were able to hunt attributes include: for smaller prey under rocks and foliage. With ● Height of 3 to 10 feet vision similar to hawks, it can be assumed ● Weight of up to 300 pounds Phorusrhacidae hunted by sight thus requiring ● Running speed of up to 30 mph sunlit areas to hunt and not hunting at night. ● Ability to make quick strikes with great power The habitat for Phorusrhacidae must of had ● Sharp beak with a downward curving slope sunlight and high vegetation. (advantage when killing prey) NEW DISCOVERIES IN TERROR BIRD ● Sharp talons ● Small wing size RESEARCH AND SCIENTIFIC RELEVANCE Running: (4) Discovery: (1) Based off toe morphology, we can conclude Although flying ● First discovered in Tertiary of Argentina during may not be a that Phorusrhacidae were similar to our the 1880s possibility, the modern day ostriches. Phorusrhacidae had long ● Carlos Ameghino, Florentino Ameghino, and balance that the hind limbs which enabled a long stride when Fransico Pascasio Moreno were the founders of wings provide the Phorusrhacidae running therefore making them faster than aided the terror Scientific Relevance: (1) other animals with shorter hind limbs. birds in ● The discovery of Phorusrhacidae dramatically maneuvering. helps our understanding of avian paleontology (6) (7) (8) ● Helped discover many new taxa of birds. ● Helped us further understand the behavior of predatory birds. 4

Brett Puleo, Ryan Sabini, Jack Hennigan, Lily Harrington GEOL 204 The Fossil Record, Spring 2019 Section 010