Paraphysornis is an extinct genus of giant flightless terror birds that inhabited Brazil during Late Oligocene or Early Miocene epochs.

[2] Following closer examination of various phorusrhacid remains held in institutions across Europe, North America and Argentina; Alvarenga came to the conclusion that his taxon displays enough unique features to warrant a new genus distinct from Physornis, naming it Paraphysornis in a publication in 1993.

Only few elements of the cranium are preserved including the quadrates and their articulation with the mandible as well as the front of the premaxilla, which shows a strongly hooked tip as known from other phorusrhacids.

Unlike other phorusrhacids, Paraphysornis preserves no indication of quill knobs, attachment points for strong pennacious feathers.

[2] The femur preserves both the proximal and distal ends but is missing the shaft, making it impossible to determine the exact length of the bone.

[5] Paraphysornis shares several characteristics with Brontornis including the shortend tarsometatarsus (only half the length of the tibiotarsus) and the morphology of the vertebrae.

[8] The following phylogenetic tree shows the internal relationships of Phorusrhacidae under the exclusion of Brontornis as published by Degrange and colleagues in 2015, which recovers Paraphysornis as basal to clade that contains Physornis, Phorusrhacos and Andalgalornis, among others.

Applying this method likewise gives results suggesting a heavyset graviportal animal, with calculated values being similar to those of moas and elephant birds.

[10] However, according to recent calculations by Rubén Molina-Pérez and Asier Larramendi, Paraphysornis may have still been capable of reaching speeds of up to 55.1 kilometres per hour (34.2 mph).

[10] Paraphysornis lived during the Late Oligocene or Early Miocene in the Tremembé Formation, which preserves what's thought to be a shallow lake.

Other animals present in the formation include a variety of fish, flamingos, a species of screamer,[13] teratorns and leontiniid notoungulates.