Camptodontus yangi, Li, Gong, Zhang, Yang, and Hou, 2010, Li, Gong, Zhang, Yang, and Hou, 2010

Yun, Chan-Gyu, 2019, Comments on the taxonomic validity of Camptodontornis yangi (Li, Gong, Zhang Yang, and Hou, 2010) and its relationships to Longipteryx chaoyangensis Zhang Zhou, Hou, and Gu, 2000 and Boluochia zhengi Zhou, 1995, Zootaxa 4652 (2), pp. 391-392 : 391

Although

the nomenclature of the longipterygid bird Camptodontus yangi Li, Gong, Zhang, Yang, and Hou, 2010 may have been clouded by the finding that its generic name was preoccupied by Camptodontus Dejean, 1826 in the carabid beetles, necessitating its replacement by Camptodontornis Demirjian, 2019 , the taxonomic status of this species has become even more debatable.

Martyniuk (2012) firstly considered the taxon as possibly synonymous with Boluochia zhengi Zhou, 1995 , based on similarities on snout and tooth morphology.

Wang et al. (2014) subsequently noted that the diagnostic features of yangi (e.g. carina restricted to caudal part of sternum, cranial cervicals heterocoelous, ulna longer than humerus) were actually widespread among enantiornithine birds, and that other morphological features (large teeth strongly curved caudally, lateral trabecula of sternum slightly laterally directed with simple distal expansion) closely matched the condition of Longipteryx Zhang, Zhou, Hou and Gu, 2000 . Based on these shared features and absence of any autapomorphies or unique character combination, Wang et al. (2014) referred the holotype of yangi (SG2005-B1; Shenyang Institute of Geology and Mineral Resources, Shenyang, China) to Longipteryx . Wang et al. (2015) then investigated this issue further, pointing out that the incomplete and disarticulated nature of the type specimen and lack of any detail concerning dentition in the protologue. Moreover, at least one referred specimen of Longipteryx chaoyangensis Zhang, Zhou, Hou and Gu, 2000 (DNHM-D 2889; Dalian Natural History Museum, Dalian, China) showed tooth morphology (presence of longitudinal groove in the anterolateral facet of each premaxillary tooth) identical to that in the holotype of “ Camptodontus yangi ”; and the holotype of Longipteryx chaoyangensis (IVPP V 12325 ; Institute of Vertebrate Paleontology and Paleoanthropology , Beijing, China) was found to bear a similar feature in teeth as well. Therefore , Wang et al. (2015) treated yangi as the junior synonym of Longipteryx chaoyangensis .

In summary, Camptodontornis yangi not only has no diagnostic features of its own but is also probably referable to a previously named longipterygid bird, Longipteryx chaoyangensis . Furthermore, the holotype of Boluochia zhengi (IVPP V9770) is very similar to specimens referred to Longipteryx chaoyangensis , and the only obvious difference is lateral deflection of the distal end of metatarsal IV (O’Connor et al., 2010). Such a difference is minor, and possibly due to individual or ontogenetic variation, or sexual dimorphism. If the two taxa are synonymous, Boluochia zhengi has priority as it was named five years prior to Longipteryx chaoyangensis . In such circumstances, Camptodontornis Demirjian, 2019 and Longipteryx Zhang, Zhou, Hou and Gu, 2000 are generic synonyms of Boluochia Zhou, 1995 ; and yangi Li, Gong, Zhang, Yang, and Hou, 2010 and chaoyangensis Zhang, Zhou, Hou and Gu, 2000 are specific synonyms of zhengi Zhou, 1995 .