Tropeognathus

specimen of Tropeognathus mesembrinus (BSP 1987 I 46) in lateral (A1), palatal (A2), and anterior (A3) views In the 1980s the German paleontology museum Bayerische Staatssammlung für Paläontologie und historische Geologie in Munich acquired a pterosaur skull from Brazilian fossil dealers that had probably been found in Ceará, in the geological group called the Santana Group, which is located in the Araripe Basin (Chapada do Araripe) of Brazil. The holotype, BSP 1987 I 46, was discovered in a layer of the Romualdo Formation within the Santana Group, dating to the latest Aptian and earliest Albian stages. Along with the holotype, several other pterosaur specimens were found in the fossil site, these specimens however, were referred to genera such as Anhanguera and Cearadactylus. The uncovered holotype consists of a skull with lower jaws. A second specimen was referred by André Jacques Veldmeijer in 2002: SMNS 56994, which consists of a partial mandible. In 2013, Brazilian paleontologist Alexander Kellner referred a third, larger, specimen: MN 6594-1, a skeleton with skull, with extensive elements of all body parts, except the tail and the lower hindlimbs. It was considered an Anhanguera mesembrinus by Alexander Kellner in 1989, a Criorhynchus mesembrinus by Veldmeijer in 1998 and a Coloborhynchus mesembrinus by Michael Fastnacht in 2001. In 2006, Veldmeijer accepted that Tropeognathus and Ornithocheirus were cogeneric, but rejected O. simus as the type species of Ornithocheirus in favor of O. compressirostris, which was named as Lonchodectes by Unwin due to an analysis by English paleontologist Reginald Walter Hooley in 1914. This made Veldmeijer use the names Criorhynchus simus and Criorhynchus mesembrinus instead. Back in 1987, Wellnhofer had named a second species called Tropeognathus robustus, based on specimen BSP 1987 I 47, which is a more robust lower jaw. In 2013 however, T. robustus was considered as a species of Anhanguera, resulting in an Anhanguera robustus. == Description ==

Size of three flying individuals Tropeognathus is known to have reached wingspans of about , as can be inferred from the impressive size of the specimen MN 6594-V, identified as Tropeognathus cf. T. mesembrinus. The maximum wingspan estimate for Tropeognathus reaches , Skull and crests of Tropeognathus; note the prominent, keel-like snout-crests. ns, notice Tropeognathus (E and F) with a well-developed "keeled" crest The skull of Tropeognathus bore a distinctively convex, "keeled" crests on the lower end of its snout, with an opposing, smaller mass on the underside of the lower jaws. This structure was prominent, well-developed, and relatively large in Tropeognathus (especially in males); however, by comparison, these crests were somewhat weakly-formed as opposed to the thicker skull crests of other pterosaurs, such as Ornithocheirus. The upper crests arose from the snout tip and extended back to the fenestra nasoantorbitalis, the large opening in the skull side. An additional, smaller crest projected down from the lower jaws at their symphysis ("chin" area). The similar anhanguerid Anhanguera possessed jaws that were tapered in width, but expanded into a broad, spoon-shaped rosette at the tip, which differed from Tropeognathus for having a narrower appearance. The jaws can be distinguished from its relatives by a few differences in the crest: unlike its close relatives Coloborhynchus and Ornithocheirus, the crest on the upper jaw of Tropeognathus was more prominent and much larger, and therefore resulting in a broader skull. Vertebrae The first five dorsal vertebrae of Tropeognathus are fused into a notarium, with five sacral vertebrae fused into a synsacrum, and the third and fourth sacral vertebrae are keeled within. The front blade of the ilium is strongly directed upwards, resulting in a narrow structure. == Classification ==

of Tropeognathus (B) compared to the palates of Ferrodraco (A) and Siroccopteryx (C), all of them are in occlusal view In 1987, Wellnhofer assigned Tropeognathus to a Tropeognathidae. However, many subsequent analyses made in 2019 and 2020 have recovered Tropeognathus within the family Anhangueridae, with a specific one by Borja Holgado and Rubi Pêgas in 2020, placing Tropeognathus more specifically within the subfamily Tropeognathinae, sister taxon to Siroccopteryx. Topology 1: Andres & Myers (2013). Topology 2: Holgado & Pêgas (2020). }} }} }} }} }} }} }} }} }} }} }} == In popular culture ==

Tropeognathus mesembrinus was the subject of an entire episode of the award-winning BBC television program Walking with Dinosaurs (which used the first name of its cousin Ornithocheirus but was incorrectly named as a species of it, as Ornithocheirus mesembrinus). However, the largest definite Ornithocheirus mesembrinus specimens described at the time measured , in terms of wingspan. Nevertheless, specimen MN 6594-V in 2013 was, at its degree of completeness, the largest known pterosaur individual. == See also ==