Phorusrhacids, also known as terror birds, are an extinct clade of carnivorous, generally flightless birds that lived in South America, North America, Africa, Europe and possibly Antarctica during the Cenozoic era between 53 million and ~96,040 years ago.
Description[]
Phorusrhacids are predaceous avians. They are thought to have used their large hooked beaks to crack the skulls of their victims or injure them enough to cause fatal blood loss. To support such large beaks, phorusrhacids had long thick necks that also provide better visibility during hunting. The other main feature of the so-called terror birds are their long powerful legs, which can carry them up to astonishing speeds despite their size, and are also thought to be used in a similar manner to the extant secretary bird. Some members, like Kelenken, would have used their feet to immobilize prey and use beaks to rip them apart.
Paleobiology[]
Phorusrhacids had very large heads with giant beaks which may have been used to disembowel their prey or even crush their skulls with the hooks at the end of their beaks. They were unable to fly due to their build, similar to modern day ratites. Likewise, they were also very fast compared to their size due to their powerfully built legs. Terror birds could likely also hunt smaller prey in a similar manner to their closest living relatives the seriemas - picking up the prey with their large beaks and repeatedly throwing them to the ground until they are either stunned or dead.
Extinction[]
The extinction of the phorusrhacids is still unknown and heavily theorized by paleontologists and researchers alike. It's been thought that they were outcompeted to extinction by more advanced predatory mammals with the emergence of the Panama Isthmus, however more recent evidence seems to suggest otherwise, as the decline in population of native South American predators did not seem to correlate with the arrival of new competitors. In fact, large numbers of them have already died out even before the arrival of more derived placental carnivores. The phorusrhacid Titanis also seems to disprove such theory, as their range expanded well into North America during the interchange, making them coexist with the aforementioned carnivores for several million years until the species's extinction at the end of the Blancan stage in the Early Pleistocene.
Recent skull discoveries[]
Classification[]
Phorusrhacids are classified as part of the Cariamiformes clade of birds, making their closest living relatives the seriemas, which are similarly predatory flightless birds. Terror birds are divided into five subfamilies, the Physornithinae, Mesembriornithinae, Patagornithinae, Phorusrhacinae (also known as "true" terror birds), and Psilopterinae. Until newer species are discovered, Phorusrhacinae would remain the largest subfamily within Phorusrhacidae.
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