A Giant Flightless Bird from the Pleistocene of Florida

Tin; large, flightless birds of the superfamily Phorusrhacoidea have had a known history confined, until now, to Argentina and Uruguay, and, in time, to the period from the Oligocene to the early Pleistocene.This paper extends the known geographic occurrence of the group to North America and its known geologic range into the late Pleistocene.The fossil here described, from a fluvial deposit in northern Florida, is a bird of tremendous size, larger than the African ostrich and more than twice the size of the South American rhea.Titanis, new genus Type of Genus.Titanis walleri, new species.Diagnosis.Referable to the family Phorusrhacidae, subfamily Phorusrhacinae, on the basis of: gigantic size; distal foramen of tarsometatarsus bifurcate, with foramen for extensor brevis digiti IV opening through distal end of shelf bounding outer intermetatarsal space (confluent with foramen for tibialis anticus artery on plantar surface of shaft in Brontornithidae, separate but on plantar face in Rheidae); lower end of shaft not bilaterally expanded (flaring toward roots of trochleae in Rheidae); plantar surface of shaft flat above trochleae (concave in comparable groups); trochleae nearly on a plane (strongly arched in Psilopteridae and Rheidae); posterior wings of trochleae obsolete (well developed in Psilopteridae).Distal portion of tarsometatarsus similar to that of Phorusrhacos Ameghino (1887),* but middle trochlea somewhat expanded distally (without distal expansion in Phorusrhacos), vertical in distal view (medially inclined in Phorusrhacos), and with inner margin of plantar face abruptly * This is the original spelling, although at least six emendations have been proposed, three by Lydekker, two by Ameghino himself, and one by Sdater.The family-group names are here accordingly altered to conform with the spelling Phorusrhacos.