Wellnhopterus is a genus of azhdarchid pterosaur that lived during the Maastrichtian age of the Late Cretaceous period in what us now Texas, United States.

Its fossil remains were discovered in the Javelina Formation at Big Bend National Park, located in Brewster County, Texas.

The fossils consist of a set of upper and lower jaws, several cervical (neck) vertebrae, and a fragmentary long bone.

Originally referred to an indeterminate species of Quetzalcoatlus, these remains would receive various interpretations ranging from a tapejarid to an azhdarchid identity.

Back in July 2021, the jaw remains of Wellnhopterus had actually been given a separate genus and type species, "Javelinadactylus sagebieli", named and described by paleontologist Hebert Campos.

This anatomy of Wellnhopterus has been compared to other "blunt-jawed" azhdarchids, such as Hatzegopteryx, which are more adapted to hunt proportionally large prey in a raptorial manner.

In March 1986, the remains of jaws and cervical (neck) vertebrae of a large pterosaur were discovered in the Javelina Formation at Big Bend National Park in Brewster County, western Texas, by preparator Robert Rainey.

In 1996, paleontologists Alexander Kellner and Wann Langston Jr. pointed out that the remains dated from older layers than those which had produced Quetzalcoatlus sp.

The complete specimen, including the jaws and the cervical vertebrae, were given the new genus and type species Wellnhopterus brevirostris in December 2021.

[2] Back in July 2021, the genus and type species "Javelinadactylus sagebieli" had been named and described by Brazilian paleontologist Hebert Campos based only on specimen TMM 42489-2.

The specific name sagebieli honors James Sagebiel, head of the vertebrate fossils collection of the University of Texas.

Campos had assigned it to the subfamily Thalassodrominae within Tapejaridae, which would make "Javelinadactylus" the first known tapejarid from North America and would extend the range of the group to the Maastrichtian.

Azhdarcho lancicollis Albadraco tharmisensis Aerotitan sudamericanus Mistralazhdarcho maggii Aralazhdarcho bostobensis Phosphatodraco mauritanicus Eurazhdarcho langendorfensis Zhejiangopterus linhaiensis Wellnhopterus brevirostris Cryodrakon boreas Hatzegopteryx thambema Arambourgiania philadelphiae Quetzalcoatlus lawsoni Quetzalcoatlus northropi Topology 2: Pêgas and colleagues (2023).