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| Neobohaiornis lamadongensis Shen, Clark, Fang, Chen, Jiang, Ji & O’Connor, 2024 |
Abstract
Enantiornithes are the most successful early-diverging avian clade, their fossils revealing important information regarding the structure of Cretaceous avifaunas and the parallel refinement of flight alongside the ornithuromorph lineage that includes modern birds. The most diverse recognized family of Early Cretaceous enantiornithines is the Bohaiornithidae, known from the Jehol Biota in northeastern China. Members of this clade enhance our understanding of intraclade morphological diversity and elucidate the independent evolution of this unique lineage. Here, we report on a new specimen of bohaiornithid, Neobohaiornis lamadongensis gen. et sp. nov., from the Lower Cretaceous Jiufotang Formation in western Liaoning, China. The holotype specimen is considerably smaller than all other known bohaiornithids (roughly half the size of Bohaiornis). The presence of complete fusion in compound elements strongly suggests it represents a mature or nearly mature individual, and therefore substantially increases the known size range of this clade. This specimen further differs from known bohaiornithids in that it exhibits reduced manual unguals and an increased number of sacral vertebrae, which indicates bohaiornithids evolved increased flight capabilities in parallel to other enantiornithine lineages, such as the Longipterygidae. Traces of the plumage, which are rarely preserved in bohaiornithids, reveal the presence of remiges with rounded distal margins and short crural feathers.
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| Holotype of Neobohaiornis lamadongensis gen. et sp. nov. (MHGU-0288). (A) Photograph; (B) line drawing. al alular metacarpal, ce cervical vertebrae, co coracoid, d dentary, fr frontal, fe femur, fi fibula, fs fish, fu furcula, h humerus, hy hyoid, il illium, is ischium, mac major metacarpal, mic minor metacarpal, mt I-IV metatarsal I-IV, n nasal, pm premaxilla, pu pubis, py pygostyle, r radiale, sc scapula, st sternum, ti tibiotarsus, u ulna. |
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| Plumage preserved in the holotype of Neobohaiornis lamadongensis gen. et sp. nov. (MHGU-0288). (A) apices of the feathers extending from the caudal margin of the external nares down the neck; (B) distribution of crural feathers along the left tibiotarsus; (C) A pair of rachis-dominated rectrices (blue arrows); (D) The primary wing feathers preserved on the left wing. ms medial stripe, rd rachis in ‘rachis-dominated’ feathers. |
Aves Linnaeus, 1758; [sensu Sereno, 1999].
Ornithothoraces Chiappe, 1995.
Enantiornithes Walker, 1981.
Bohaiornithidae Wang et al., 2014.
Neobohaiornis lamadongensis gen. et sp. nov.
Diagnosis: Referrable to Enantiornithes based on the presence of the following diagnostic features: a furcula with a ventral margin wider than dorsal margin; a proportionately elongate hypocleidium of the furcula; minor metacarpal projecting distally farther than major metacarpal; metatarsal IV mediolaterally thinner than both metatarsals II and III with the trochlea reduced to a single condyle; and a J-shaped metatarsal I. Referred to the enantiornithine clade Bohaiornithidae based on the presence of ...
Etymology: The generic name refers to the derived morphology (e.g., reduced alular digit, increased number of sacral vertebrae) of this taxon relative to other bohaiornithids. The specific name refers to the town of Lamadong, near where the fossil was found.
Caizhi Shen, Alexander D. Clark, Hui Fang, Shaokun Chen, Hongxia Jiang, Qiang Ji and Jingmai K. O’Connor. 2024. A New diminutive Species of bohaiornithid enantiornithine (Aves: Ornithothoraces) from the Lower Cretaceous Jehol Group, northern China. Scientific Reports. 14: 31363. DOI: doi.org/10.1038/s41598-024-82869-8
