Thursday, April 1, 2021

[Paleontology • 2021] Sinomacrops bondei • A New Anurognathid Pterosaur (Anurognathidae: Batrachognathinae) from the Jurassic of China and Comments on the Group

Sinomacrops bondei  
Wei, Pêgas, Shen, Guo, Ma, Sun & Zhou,. 2021

Paleoart courtesy of Zhao Chuang

Anurognathids are an elusive group of diminutive, potentially arboreal pterosaurs. Even though their monophyly has been well-supported, their intrarelationships have been obscure, and their phylogenetic placement even more. In the present work, we present a new genus and species from the Middle-Late Jurassic Tiaojishan Formation, the third nominal anurognathid species from the Jurassic of China. The new species provides new information concerning morphological diversity for the group. Furthermore, we provide a new phylogenetic analysis incorporating into a single data set characters from diverging phylogenetic proposals. Our results place them as the sister-group of Darwinoptera + Pterodactyloidea, as basal members of the Monofenestrata.

Systematic Paleontology

Pterosauria Owen, 1842
Novialoidea Kellner, 2003
Breviquartossa Unwin, 2003
Monofenestrata Lü et al., 2009

Anurognathidae Kuhn, 1937
Batrachognathinae Kellner et al., 2010

Definition. The most inclusive clade containing Batrachognathus volans but not Anurognathus ammoni (Kellner et al., 2010).

Synapomorphies. Humeral deltopectoral crest reduced (less wide than humeral shaft; and less wide than proximodistally long), humeral deltopectoral crest subrectangular, ulnar crest of humerus rounded, humeral/femoral length ratio over 1.60, tibial/femoral length ratio over 1.70.

Included species. Batrachognathus volans and Sinomacrops bondei gen. et sp. nov.

Figure 2: Sinomacrops bondei tax. nov., holotype (JPM-2012-001) overview.
(A) Photograph; and (B) schematic drawing.
Abbreviations: ca, caudal vertebrae; co, coracoid; cv, cervical vertebrae; d, dentary; fe, femur; fi, fibula; hu, humerus; mcIV, metacarpal IV; pip, puboischiadic plate; prap, preacetabular process of the illium; rd, radius; sca, scapula; sk, skull; ul, ulna; wp, wing phalanx. Scale bar equals 20 mm.

Sinomacrops bondei gen. et sp. nov.

Etymology. The generic name is a combination of Sino, macro and ops; which are Ancient Greek for China, large, and eyes/face, respectively. This is in reference to both the large eyes and the broad faces that are typical of anurognathids, and to the Chinese origin of the new species. The specific epithet honors paleontologist Niels Bonde, for his many scientific contributions and being an inspiration for us.

Locality and horizon. Mutoudeng, Qinglong County of Hebei Province. Daohugou Beds (Callovian-Oxfordian 164-158 Ma) of the Tiaojishan Formation (see Liu, Zhao & Liu 2006; Liu et al., 2006; Gao & Shubin, 2012).

Diagnosis. The new taxon exhibits two autapomorphies: first three maxillary alveoli closely spaced, and tibiotarsus twice as long as the femur.

Figure 14: Life reconstruction of Sinomacrops bondei.
Paleoart courtesy of Zhao Chuang, 
reproduced with permission.

Phylogenetic analysis results.
Strict consensus tree showing the phylogenetic relationships of Sinomacrops bondei and anurognathids. Dashed line indicates result exclusive to the semi-strict consensus tree.

JZMP-2107500095 represents a new anurognathid, here named Sinomacrops bondei (Fig. 14). It is the second anurognathid from the Tiaojishan Formation, and the first anurognathid specimen to exhibit a skull exposed in lateral view. In our new phylogenetic analysis, it is recovered as the sister-group of Batrachognathus volans, with which it comprises the Batrachognathinae. All other taxa were recovered as closer to Anurognathus. The exclusion of Luopterus mutoudengensis from the genus Dendrorhynchoides is corroborated. Vesperopterylus lamadongensis is recovered as the sister-group of Anurognathus ammoni, with Jeholopterus ningchengensis as their successive sister-group.
Some previous interpretations of anurognathid morphology and systematics have relied on limited available information. With time and new specimens being discovered, new data have been provided and new interpretations were presented. For this reason, each new specimen is crucial for the understanding of the group. The present information available leads us to interpret anurognathids as basal members of the Monofenestrata, as the sister-group of Darwinoptera + Pterodactyloidea.

Xuefang Wei, Rodrigo Vargas Pêgas, Caizhi Shen, Yanfang Guo, Waisum Ma, Deyu Sun and Xuanyu Zhou​. 2021. Sinomacrops bondei, A New Anurognathid Pterosaur from the Jurassic of China and Comments on the Group.  PeerJ. 9:e11161. DOI: 10.7717/peerj.11161