The snout of a medium-sized pterosaur from the Santana Formation in northeastern Brazil is the only known fossil of Unwindia trigonus. Described by David Martill in 2010, Unwindia is named for fellow paleontologist David Unwin.
The specimen is very long and tapering, measuring 22 cm (8.5 inches) long, but less than 4 cm (1.5 inches) tall. The specimen is from the snout region of the skull, from the tip of the upper jaw to the nasoantorbital fenestra, a prominent window in the snout housing the nostrils and a large facial sinus. The snout is notably narrow, being twice as tall as wide, with a triangular cross-section. When complete, it’s likely the skull would have been around 30 cm (12 inches) long and 6 cm (2.5 inches tall).
Despite having very long jaws, Unwindia appears to have just 7 pairs of teeth in the upper jaws, restricted to the distal-most 6 cm (2.5 inches). The tooth sockets, or alveoli, are unusual, with each tooth emerging from a low “pedestal” of bone at the base. The teeth themselves are barely 1 cm (0.38 inch) long, and shaped like slightly compressed cones that curve inward.
Although the specimen is just known from skull bones, it is possible to estimate the wingspan of the whole animal at approximately 2.3 m (7.5 feet) by comparison to similar species.
When first described, Martill compared Unwindia to Lonchodectes and Yixianopterus, two mysterious pterosaurs that share several features with it. In all three species the alveoli are on bony “pedestals” and the teeth are small compressed cones. What’s more, they have long and extremely narrow snouts resembling swords.
While Martill considered Unwindia a close relative of Yixianopterus, he didn’t consider it to be lonchodectid because some other lonchodectid species have more extensive tooth rows. Instead, he thought it to be part of the archaeopterodactyloid lineage most similar to the gallodactylids. Later authors have considered Unwindia and Yixianopterus to be lonchodectids due to their long and narrow snouts, similar teeth, and alveoli on pedestals.
But just where lonchodectids lie on the family tree of pterosaurs is unclear. Lü Junchang considered them to members of the mostly toothless azhdarchoid lineage. More recent phylogenetic analyses by Brian Andres have found them to be ornithocheiroids closer to ornithocheirids than to istiodactylids.
Unwindia, Lonchodectes, and most other lonchodectids are known just from skull bones, all showing similar unusual and distinctive anatomy. Yixianopterus is the only lonchodectid known from a partially articulated skeleton. This skeleton has been described only in a preliminary fashion, and is used as a guide for the Unwindia life reconstruction and size comparison. When fully described Yixianopterus will greatly increase our knowledge about lonchodectids.
Because Unwindia and other lonchodectids are so unique and poorly known, it is difficult to say much about their lifestyle. Based on the teeth, it’s clear that Unwindia was carnivorous, but it’s not entirely clear what they ate. The very long and narrow snouts with teeth restricted to the ends suggests that Unwindia used its snout to probe in tight spaces and grasp food. It may have probed in burrows looking for food, or even scavenged dinosaur carcasses. One hundred fifteen million years ago, at the time Unwindia lived, this part of Brazil was made up deltas and lagoons at the edge of the incipient Atlantic Ocean.