Titanis

Credit: Julio Lacerda.

*Titanis* is an extinct genus of phorusrhacid that lived in South America during the Pliocene to the Early Pleistocene.

## Description

*Titanis* was about 8 feet (2.5 meters) tall, with a large head, and a sharp, hooked beak and long legs tipped by powerful talons. *Titanis* was one of the last phorusrhacids, which crossed the Panama Isthmus land bridge into North America when the continents joined 3 million years ago. *Titanis* likely hunted on open plains, catching prey with wings that had sharp re-evolved digits tipped with talons, before pinning it with its strong legs and ripping chunks of flesh from its prey with its serrated beak. *Titanis*’ arms are unique to its genus; sharp-clawed wings, where earlier members had stubby and useless wings. Evidence suggests a large size variation in multiple individuals, possibly a drastic sexual dimorphism. *Titanis* was likely a fast cursorial animal. No skull material of this genus is known. Morphologically, *Titanis* is similar to *Phorusrhacos* and *Devincenzia*. However, the animal is differentiated via two autapomorphies: a short thick neck and an overall stockier body. Little is known of the body, and *Titanis* seems to have been less wide-footed with a stronger middle toe than *Devincenzia*.

*Titanis*' wings were unusual, being flightless, yet having a strange joint-like articulation, suggesting the fingers bore some degree of flexion. The animals wrists are also rigid, which would not have allowed the hands to fold along the arm to the degree some birds can. R.M. Chandler hypothesizes that *Titanis* had hands similar to non-avian dinosaurs, like those in dromaeosaurs. However, a similar joint exists in seriemas (the group that *Titanis* and all terror birds fit into), which do not have grasping hands.

## Paleobiology

### Distribution

*Titanis* occurs ~5-12 million years ago in Florida and Texas. In Gilchrist County, Florida, fossils are found dating to ~3-2.9 million years ago. In Santa Fe River, 27 specimens have been recovered. Titanis is also known from Port Charlotte and Inglis, Florida. One specimen has been found in Neuces River, Texas. 41 specimens are known.

### Biomechanics

Studies on *Andalgalornis steulleti*, a phorusrhacid, finds new information about neck and head movement all terror birds, including *Titanis*. A series of biomechanics tests found they had difficulty moving their heads laterally, but could move it's head back-and-forth tremendously. It is theorized *Titanis* likely pummeled prey to death.

### Extinction

*Titanis*' extinction and other terror birds in the Americas was caused by competition with large placental carnivores such as canids, felids and maybe ursids. These radiated into their ecosystems during the Great American Faunal Interchange. Circumstantial evidence, such as bone fractures, suggests *Titanis* did not go extinct 15,000 years ago. More precise dates by McFadden et al. refutes this, stating all remains appear 2 million years old, at the least.

## Classification

*Titanis* is a terror bird (family Phorusrhacidae), and was thought to be the youngest in the lineage. However, a South American taxon has been reported to be much earlier. *Titanis* is the only known member to have migrated during the Great American Interchange. Predatory birds called bathornithids also occurred in North America from the Paleocene to the Miocene. However, these were not ancestors of *Titanis* or any Phorusrhacidae, but instead a convergent group that filled similar niches and attained similar size. For example, *Paracrax* reached 2 meters in height. These went extinct ~15 million years before *Titanis* crossed into North America. seriemas are the only living relatives of *Titanis*.

## Reference

* Dorling Kindersley Encyclopedia of Dinosaurs and Prehistoric Life, p. 145
* https://en.wikipedia.org/wiki/Titanis