Table of Content

15 March 2014, Volume 52 Issue 1

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Reinterpretation of the Early Cretaceous maniraptoran (Dinosauria: Theropoda) Zhongornis haoae as a scansoriopterygid-like non-avian, and morphological resemblances between scansoriopterygids and basal oviraptorosaurs

Jingmai K. O’CONNOR, Corwin SULLIVAN

2014, 52(1):  3-30. 

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 The recently described maniraptoran theropod Zhongornis haoae, known from a single juvenile specimen, was originally identified as a bird. However, morphological re-evaluation reveals striking resemblances to both Oviraptorosauria and Scansoriopterygidae. The reduced, but still long, boney tail is reinterpreted as having approximately twenty vertebrae and is reminiscent of the tails of Caudipteryx and Epidexipteryx in its proportions and morphology. Other morphological similarities with basal oviraptorosaurs include a short and deep skull, and a reduced minor digit. Zhongornis also differs strikingly from other Mesozoic birds, and resembles scansoriopterygids, in the size of the alular metacarpal, the proportions of the manual digits, and the lack of processes on the ischium. These similarities, together with resemblances between basal oviraptorosaurs and previously described scansoriopterygids, may point to a close relationship between these two clades. Cladistic analysis confirms a close relationship between Zhongornis and Scansoriopterygidae, which share forelimbs and pedal unguals that are elongate compared to those of oviraptorosaurs, but does not support oviraptorosaur affinities for this clade. Additional specimens will be required in order to determine both the taxonomic placement of this species and the affinities of Scansoriopterygidae, highlighting the drawbacks of basing new species on juvenile material.

A new diverse enantiornithine family (Bohaiornithidae fam. nov.) from the Lower Cretaceous of China with information from two new species

WANG Min, ZHOU Zhong-He, Jingmai K. O’CONNOR, Nikita V. ZELENKOV

2014, 52(1):  31-76. 

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Two new enantiornithine birds, Parabohaiornis martini gen. et sp. nov., and Longusunguis kurochkini gen. et sp. nov., are reported here based on three nearly complete skeletons from the Lower Cretaceous lacustrine deposits of the Jiufotang Formation in Liaoning, northeastern China. The two new species share several unique features with Bohaiornis, Shenqiornis, Sulcavisand Zhouornis, including a robust rostrum with robust, subconical teeth, furcula with blunt omal expansions, sternal trabeculae caudolaterally directed, short and stout tarsometatarsus with hypertrophied ungual on digit Ⅲ. A close relationship among the two new species and four previously described taxa is confirmed by a comprehensive phylogenetic analysis, leading us to erect Bohaiornithidae fam. nov. With six known taxa, Bohaiornithidae is the most diverse recognized enantiornithine family. The robust morphology of the rostrum and foot suggests bohaiornithids occupied a specialized ecological niche compared to other Early Cretaceous enantiornithines.

A subadult specimen of Pengornis and character evolution in Enantiornithes

HU Han, ZHOU Zhong-He, Jingmai K. O’CONNOR

2014, 52(1):  77-97. 

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Previously known only from the holotype specimen, Pengornis houi is the largest known Early Cretaceous enantiornithine bird and important for understanding body size and character evolution in Ornithothoraces. We report on a new subadult specimen from the Lower Cretaceous Jiufotang Formation referred to Pengornis sp. The specimen preserves a nearly complete sternum, reminiscent of that in Protopteryx and the basal ornithuromorph Archaeorhynchus, confirming the basal position of Pengornis and shedding new light on the evolution of the sternum in ornithothoracines. Anatomical information suggests that despite its size, Pengorniswas arboreal, like other enantiornithines.

Large anseriform (Aves: Anatidae: Romainvilliinae?) fossils from the Late Eocene of Xinjiang, China

Thomas A. STIDHAM, NI Xi-Jun

2014, 52(1):  98-111. 

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Two new avian fossils from the Late Eocene of Xinjiang in western China appear to document the possible first occurrence of the extinct anseriform group Romainvilliinae (Anatidae) within China and Asia. The tarsometatarsus has several anseriform and anatid characters, and a combination of traits only reported from the romainvilliines among waterfowl. The absence of a medial flange on the second trochlea, its large size similar to extant swans, and asymmetrical proximal end of the plantar side of the third trochlea indicate that this specimen represents a new unnamed taxon. The equally large femur specimen exhibits morphology consistent with the anatid, and possible romainvilliine, Cygnopterus affinis from the Early Oligocene of Belgium. If these unnamed fossils represent Asian romainvilliines, they support a geographic range extension of the group, the occurrence of large body-sized romainvilliines in the Eocene, and an avifaunal biogeographic link between Europe and Asia during the Eocene prior to the end of the Turgai Strait as a dispersal barrier to most mammals.

The histology of two female Early Cretaceous birds

Jingmai K. O’CONNOR, WANG Min, ZHENG Xiao-Ting, WANG Xiao-Li, ZHOU Zhong-He

2014, 52(1):  112-128. 

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We conduct histological analysis of two sexually mature fossil birds from the Lower Cretaceous Jehol Group referable to Jeholornis sp. and Enantiornithes indet. Histology confirms that in these lineages of basal birds, sexual maturity was achieved before skeletal maturity. The samples reveal structural differences from previously described relevant specimens, indicating that the ontogenetic changes in bone tissue that occur in Mesozoic birds are more complicated than previously recognized. The female specimen ofJeholornis sectioned here is more vascularized than previously described specimens, with both reticular and longitudinal canals. The enantiornithine bone tissue is most similar to that reported for the Early Cretaceous Concornis, primarily formed by parallel-fibered bone but more vascularized than other reported adult enantiornithine specimens. The bone shows a distinct decrease in the rate of bone deposition, inferred to represent the onset of sexual maturity.

A behavioral analysis of fossil bird tracks from the Haman Formation (Republic of Korea) shows a nearly modern avian ecosystem

Amanda R. FALK, Jong-Deock LIM, Stephen T. HASIOTIS

2014, 52(1):  129-152. 

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The Lower Cretaceous Haman Formation of the Republic of Korea has yielded several localities with thousands of dinosaur, bird, and pterosaur tracks. One such tracksite is found at the Gyeongsangnam-do Institute of Science Education (GISE) in Jinju, Republis of Korea. More than 1000 bird tracks are exposed on a single bedding plane, and thousands more are found in smaller float blocks on exhibit around the museum or in storage. The morphologic and behavioral diversity is extremely high; there are more than seven different morphologies described herein, with behaviors ranging from feeding––including pecking, probing, predator-prey interactions, and scything traces––to landing and running. Arcuate traces and associated webbed-footed trackways are identical to scything feeding traces produced by the extant black-faced spoonbill (Palatea minor). Individual peck and probe marks have also been reported, and clustered probing has been observed. The behaviors at this site are strikingly modern in respect to morphology and diversity, indicating that ornithurine birds had a very modern set of behaviors and anatomy. The high morphologic diversity of track morphotypes indicates that Early Cretaceous ornithurine birds were actually very diverse, compared to previous assumptions based on the body fossil record, which is dominated by enantiornithines.