The discovery, local distribution, and curation of the giant azhdarchid pterosaurs from Big Bend National Park

Abstract

ABSTRACT Field crews from The University of Texas at Austin first identified pterosaur remains from the Upper Cretaceous Javelina Formation of Big Bend National Park in 1971 and continued excavation of these animals for decades. The announcement of the giant Quetzalcoatlus northropi in 1975 by graduate student Douglas Lawson drew worldwide attention, and fossil preparators William Amaral and Robert Rainey discovered several key localities in a region informally called Pterodactyl Ridge that have been thoroughly collected and documented. The Pterodactyl Ridge sites produced hundreds of bones from surface collection and quarries through 1986, but later surface collection yielded poorer results. The majority of these elements represent an animal substantially smaller than Q. northropi, Quetzalcoatlus lawsoni Andres and Langston, 2021—historically referred to as Quetzalcoatlus sp. These and subsequent field expeditions from several institutions have reported occurrences of pterosaurs from both the Aguja and Javelina formations, but this study limits only the Javelina Formation material to pterosaurs. Quetzalcoatlus northropi is known within Big Bend National Park only from stream channel facies, and the smaller Q. lawsoni from the upper abandoned channel-lake facies at Pterodactyl Ridge. The lower abandoned channel-lake facies strata of Pterodactyl Ridge produce a third genus and species, Wellnhopterus brevirostris Andres and Langston, 2021. In addition, a smaller azhdarchid is found in the overbank floodplain facies.