Fossil remains of Tropeognathus have been recovered from the Romualdo Formation, which is a Lagerstätte located in the Santana Group of the Araripe Basin in northeastern Brazil.

[2] 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.

[3] 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.

[6] 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.

[7] After Tropeognathus mesembrinus was named by Peter Wellnhofer in 1987, other researchers tended to consider it part of several other genera, leading to an enormous taxonomic confusion.

[7] 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.

[2] The upper crests arose from the snout tip and extended back to the fenestra nasoantorbitalis, the large opening in the skull side.

[14] 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.

[23] Siroccopteryx Tropeognathus Mythunga Ferrodraco Aerodraco Coloborhynchus Nicorhynchus Uktenadactylus Caulkicephalus Guidraco Ludodactylus Liaoningopterus Cearadactylus Maaradactylus Anhanguera

[8] The specimens which the producers of the program used to justify such a large size estimate were described in 2012, and were under study by Dave Martill and David Unwin at the time of Walking With Dinosaurs' production.