The toothless pterosaur Jidapterus edentus (Pterodactyloidea: Azhdarchoidea) from the Early Cretaceous Jehol Biota and its paleoecological implications

Abstract

BackgroundIn the Early Cretaceous Jehol Biota, the toothless pterosaurs flourished with the chaoyangopterids and tapejarids playing a key role in understanding the early diversity and evolution of the Azhdarchoidea. Unlike the more diverse tapejarids, the rarer chaoyangopterids are characterized by a long and low rostrum, supporting a close relationship with the huge azhdarchids. Unfortunately, our knowledge is still limited in the osteology, paleoecology, and taxonomy of the Chaoyangopteridae. As one of the best preserved skeletons, the type and only specimen of Jidapterus edentus provides an opportunity to understand the morphology and paleoecology of the chaoyangopterids.ResultsOur study of the osteology of Jidapterus edentus reveals valuable information about the morphology of the Chaoyangopteridae such as a rostrum with a curved dorsal profile, high Rostral Index (RI), larger angle between the dorsal and postorbital processes of the jugal, sequentially shorter fourth to seventh cervical vertebrae, sternum with a plate wider than long, contact of the metacarpal I with the distal syncarpal, pneumatic foramen on first wing phalanx, hatchet-like postacetabular process with unconstricted neck and small dorsal process, distinctly concave anterior margin of pubis, subrectangular pubic plate with nearly parallel anterior and posterior margins, longer proximal phalanges of pedal digits III and IV, as well as reduced and less curved pedal unguals. These features further support the validity of Jidapterus edentus as a distinct species and the close relationship of the chaoyangopterids with the azhdarchids. Paleoecologically, the chaoyangopterids are probably like the azhdarchids, more terrestrial than the contemporaneous and putatively arboreal tapejarids, which may have been limited to the forest-dominated ecosystem of the Jehol Biota.DiscussionThe osteology of Jidapterus edentus further supports the close relationship of the Chaoyangopteridae with the Azhdarchidae in sharing a high RI value and reduced and mildly-curved pedal unguals, and it also implies a possible paleoecological similarity in their terrestrial capability. Combined with the putatively arboreal and herbivorous tapejarids, this distinct lifestyle of the chaoyangopterids provides new insights into the diversity of pterosaurs in the ecosystem of the Jehol Biota.

Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary

“…dobruskii [ 16 ] from the Turonian-Campanian of Brazil shows that tapejarids survived into the Late Cretaceous. Our analysis also follows previous analyses [ 24 , 85 ] in recovering B . galaczi , previously referred to Azhdarchidae [ 23 ], as a Late Cretaceous tapejarid.…”

A new darwinopteran pterosaur reveals arborealism and an opposed thumb

“…In our phylogenetic analyses (Supplemental information), we have included all darwinopteran species into three different datasets. [12][13][14] Our results corroborate the placement of K. antipollicatus as the sister species of K. sinensis (Figures 1C and S4). Opposition of the pollex K. antipollicatus sp.…”

“…In contrast, the other Linglongta strata wukongopterids (Darwinopterus and Wukongopterus) nest within scansorial mammals, plotting next to Gulo (wolverine) (Figure 3). Other pterosaurs previously viewed as possibly arboreal were recovered within the morphospace of scansorial quadrupeds (Vesperopterylus, which possibly bears a reversed hallux 33 ) or within the intersection between terrestrial and scansorial quadrupeds (such as the small-sized Nemicolopterus, robust-clawed tapejarids, and Dendrorhynchoides 3,12,34 ).…”

Sinomacrops bondei, a new anurognathid pterosaur from the Jurassic of China and comments on the group

“…Dendrorhynchoides curvidentatus fell at the base of the group, while Luopterus mutoudengensis fell as the sister-group of Batrachognathus volans . In this analysis ( Wu, Zhou & Andres, 2017 ), the clade comprising all other anurognathids to the exclusion of D. curvidentatus was supported by one synapomorphy: a fifth pedal digit phalanx 2 straight, instead of curved as in D. curvidentatus . This bone is clearly curved in D. curvidentatus (see Ji & Ji, 1998 ) and straight in Luopterus mutoudengensis , Anurognathus ammoni and Jeholopterus ningchengensis ( Wang et al, 2002 ; Bennett, 2007 ; Lü & Hone, 2012 ), however, it is unknown in Batrachognathus volans (see Riabinin, 1948 ), as well as in Sinomacrops bondei , and thus is not informative concerning the position of Batrachognathus .…”

“…In the analysis by Wu, Zhou & Andres (2017) , a polytypic genus Dendrorhynchoides (encompassing D. curvidentatus and D. mutoudengensis ) was not recovered as monophyletic. Dendrorhynchoides curvidentatus fell at the base of the group, while Luopterus mutoudengensis fell as the sister-group of Batrachognathus volans .…”