Like all phorusrhacids, Titanis had elongated hind limbs, a thin pelvis, proportionally small wings, and a large skull with a hooked beak.

Titanis is known from the Pliocene deposits of Florida, southern California, and southeastern Texas, regions that had large open savannas and a menagerie of mammalian megafauna.

[1][2][3] The two collectors donated their discoveries to the Florida Museum of Natural History (UF) later along with bones of equids, proboscideans, and many other Floridan fossils from the late Pliocene and latest Pleistocene.

[6][7][1][8] Ray presented the Santa Fe fossils to the museum's ornithologist Pierce Brodkorb, who mistakenly believed that they were from Rancholabrean strata, an error which made it to the final publication.

[2] Inglis 1b was originally a sinkhole during the Pliocene,[11][12][5] but became a sedimentary layer of clay that was uncovered during construction of the Cross Florida Barge Canal by the federal government during the 1960s.

[5]A newer discovery of Titanis was described in 1995; an isolated pedal phalanx that had been recovered from a sand and gravel pit near Odem along the Nueces River in San Patricio County, Texas.

Later analyses of rare-earth elements within the fossil demonstrated that the Texan Titanis derived from Pliocene rocks of the Hemphillian stage, a period preceding the formation of the Isthmus of Panama.

[20] This was supported by later studies,[19] but a 2013 paper by paleontologist Robert Chandler and colleagues assigned the premaxilla to Titanis, the authors citing the bone's age and phorusrhacid features.

[17] The age of the Anza-Borrego premaxilla is estimated at 3.7 million years old, making it the oldest confirmed fossil of Titanis, though the Texan specimen may be older.

[16][6][17] During the early Cenozoic, after the extinction of the non-avian dinosaurs, mammals underwent an evolutionary diversification, and some bird groups around the world developed a tendency towards gigantism; this included the Gastornithidae, the Dromornithidae, the Palaeognathae, and the Phorusrhacidae.

[22] A lineage of related predatory birds, the bathornithids, occupied North America before the arrival of phorusrhacids, living from the Eocene to Miocene and filling a similar niche to cariamids.

[24][25] It is unclear where the group originated; both cariamids and phorusrhacids may have arisen in South America, or arrived from elsewhere when southern continents were closer together or when sea levels were lower.

[27] Titanis itself coexisted with a variety of placental mammalian predators, including carnivorans like the saber-toothed cat Smilodon, cheetah-like Miracinonyx, wolf-like Aenocyon,[28][29] and the short-faced bear Arctodus.

[26][22] Brazilian paleontologist Herculano Alvarenga and colleagues published a phylogenetic analysis of Phorusrhacidae in 2011 that did not separate Brontornithinae, Phorusrhacinae, and Patagornithinae, resulting in Titanis in a polytomy (topology 1).

[9] In their 2015 description of Llallawavis, the Argentinian paleontologist Federico J. Degrange and colleagues performed a phylogenetic analysis of Phorusrhacidae, wherein they found Phorusrhacinae to be polyphyletic, or an unnatural grouping (topology 2).

[33] Topology 1: Alvarenga et al. (2011) results[9] Mesembriornithinae Psilopterinae Patagornis Andrewsornis Andalgalornis Phorusrhacos Titanis Devincenzia Kelenken Brontornis Physornis Paraphysornis

Topology 2: Degrange et al. (2015) results[33] Mesembriornithinae Psilopterinae Kelenken guillermoi Devincenzia pozzi Titanis walleri Phorusrhacos longissimus Andalgalornis steulleti Andrewsornis abbotti Patagornis marshi Physornis fortis Paraphysornis brasiliensis

Titanis is distinguished from other phorusrhacines by the anatomy of its tarsometatarsus; the distal end of the mid-trochlea is spread out onto its sides and its slenderness compared to related genera of the same size.

These researchers pointed out that the narrowing of the pelvis, upper maxilla, and thorax could have been adaptations to enable the birds to search for and take smaller animals in tall plant growth or broken terrain.

[26] In 2005, Rudemar Ernesto Blanco and Washington W. Jones examined the strength of the tibiotarsus (shin bone) of phorusrhacids to determine their speed, but conceded that such estimates can be unreliable even for extant animals.

This strength could be used for accessing the marrow inside the bones, or by using the legs as kicking weapons (like some modern ground birds do), consistent with the large, curved, and sideways compressed claws known in some phorusrhacids.

[34] In a 2006 news article, Luis Chiappe, an Argentine paleontologist, stated that Kelenken, a similar genus to Titanis, would have been as quick as a greyhound, and that while there were other large predators in South America at the time, they were limited in numbers and not as fast and agile as the phorusrhacids, and the many grazing mammals would have provided ample prey.

Chiappe remarked that phorusrhacids crudely resembled earlier predatory dinosaurs like Tyrannosaurus, in having gigantic heads, very small forelimbs, and very long legs, and thereby similar carnivore adaptations.

[41] A 2010 study by Degrange and colleagues of the medium-sized phorusrhacid Andalgalornis, based on Finite Element Analysis using CT scans, estimated its bite force and stress distribution in its skull.

Due to the relative weakness of the skull at the sides and midline, these researchers considered it unlikely that Andalgalornis engaged in potentially risky behavior that involved using its beak to subdue large, struggling prey.

Alternatively, if Andalgalornis did target large prey, Degrange et al. conjectured that it probably used a series of well-targeted repetitive strikes with the beak in an "attack-and-retreat" strategy.

[16][14][17] In Inglis 1a specifically, previous studies have reported that longleaf pine flatwoods and pine-oak scrub are known to have occupied the area, similar to the modern flora.

[54] This period of separation from the rest of the Earth's continents led to an age of unique mammalian and avian evolution, with the dominance of phorusrhacids and sparassodonts as predators in contrast to the North American placental carnivores.

The fauna of North America was composed of living groups like canids, felids, ursids, tapirids, antilocaprids, and equids populating the region alongside now extinct families like the gomphotheres, amphicyonids, and mammutids.

[62] The extinction of Titanis and other phorusrhacids throughout the Americas was originally theorized to have been due to competition with large placental (canid, felid, and possibly ursid) carnivores that occupied the same ancient terrestrial ecosystems during the Great American Interchange.