A New Ornithuromorph (Aves: Ornithothoraces) Bird from the Jehol Group Indicative of Higher-Level Diversity

The Dinosaur Institute, Natural History Museum of Los Angeles County, 90007, Los Angeles, California
Journal of Vertebrate Paleontology (Impact Factor: 1.98). 04/2010; 30:311-321. DOI: 10.1080/02724631003617498


Basal Ornithuromorpha, until recently, was one of the most poorly documented segments of early avian evo-lution. The known species diversity of the ornithuromorph clade has increased rapidly with the addition of new discoveries from the Early Cretaceous deposits of northeastern China. Reported in this paper is the discovery of a new bird from the Lower Cretaceous Yixian Formation, Liaoning Province, China. The specimen represents a new species, Longicrusavis houi, but bears similarities to Hongshanornis longicresta from the same formation of Inner Mongolia. The two birds are compa-rable in size and share an unusual sigmoid mandible and elongate hindlimbs relative to their forelimbs. Together these taxa represent a clade (Hongshanornithidae, new taxon) of specialized 'shorebirds' whose elongate hindlimbs indicate ecological adaptations different from those of other Jehol ornithuromorphs. Phylogenetic relationships of Mesozoic birds are discussed based on the results of a comprehensive cladistic analysis. New morphological information on Ornithuromorpha is provided through the detailed description of the new taxon together with new information on Hongshanornis.

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Available from: Luis M. Chiappe, Sep 03, 2014
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    • "Mesozoic birds show the same relationship between crop and gizzard morphology as living birds, namely a large distally located crop is found in specimens also preserving gizzard stones indicative of a well developed ventriculus (Sapeornis, Hongshanornis), whereas a simple crop is found in taxa lacking gizzard stones (Yanornis). Indeed, teeth are reduced in Hongshanornis and Sapeornis, but not absent [31], [32], and thus grinding gizzards are correlated with tooth reduction. Yanornis neither required (based on diet) nor had a grinding gizzard and its teeth are hypertrophied, thus natural selection on the teeth must have been driven by another function, which we have suggested may be prey capture. "
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    ABSTRACT: A crop adapted for an herbivorous diet of seeds has previously been documented in the Early Cretaceous birds Sapeornis and Hongshanornis. Here we report on several specimens of Yanornis that preserve a crop containing fish. One specimen preserves two whole fish in the oesophagus, indicating that Early Cretaceous birds shared trophic specializations with Neornithes for the increased energetic demands of flight - namely the storing of food for later consumption when the stomach is full. Whole fish also indicate that despite their presence, teeth were not used to orally process food, suggesting the hypertrophied dentition in this taxon were utilized in prey capture. The presence of macerated fish bones in the crop of other specimens indicates the highly efficient advanced muscular system of peristalsis responsible for moving ingested items between different segments of the alimentary canal was also in place. Despite the fact many features of the modern avian alimentary canal are inferred to compensate for the absence of teeth in birds (expandable oesophagus, grinding gizzard), the derived alimentary canal was apparently present in toothed Cretaceous birds. Although Yanornis was considered to have switched their diet from piscivorous to herbivorous, based on position and morphology we reinterpret the gastroliths reported in one specimen as sand impacted in the intestines, and reconstruct the taxon as primarily piscivorous. This is a novel interpretation for fossilized gastroliths, and the first documentation of this condition in the fossil record.
    Full-text · Article · Apr 2014 · PLoS ONE
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    • "The fragmentary remains of two to four teeth are preserved set in the dentary. This confirms the presence of teeth in the dentary of hongshanornithids, which was hypothesized by O’Connor, Gao & Chiappe (2010). Crowns cannot be discerned, but the dentary teeth appear to be smaller than those preserved in the maxilla. "
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    ABSTRACT: The discovery of Hongshanornis longicresta, a small ornithuromorph bird with unusually long hindlimb proportions, was followed by the discovery of two closely related species, Longicrusavis houi and Parahongshanornis chaoyangensis. Together forming the Hongshanornithidae, these species reveal important information about the early diversity and morphological specialization of ornithuromorphs, the clade that contains all living birds. Here we report on a new specimen (DNHM D2945/6) referable to Hongshanornis longicresta that contributes significant information to better understand the morphology, trophic ecology, and aerodynamics of this species, as well as the taxonomy of the Hongshanornithidae. Most notable are the well-preserved wings and feathered tail of DNHM D2945/6, which afford an accurate reconstruction of aerodynamic parameters indicating that as early as 125 million years ago, basal ornithuromorphs had evolved aerodynamic surfaces comparable in size and design to those of many modern birds, and flight modes alike to those of some small living birds.
    Full-text · Article · Jan 2014 · PeerJ
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    • "Evolutionary patterns were reconstructed for each of these three tail portions using Mesquite (v2.7.5) software [97] on an up-to-date composite phylogeny for non-avian coelurosaurs and basal and modern birds [47], [57], [58], [98], [99], [100], with additional dinosaurian taxa and non-dinosaurian outgroups [101] (Fig. 1). While much of the theropod phylogeny used here has reached a relative consensus, some areas such as maniraptoran or basal bird relationships should be re-examined once consensus is reached. "
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    ABSTRACT: Theropod dinosaurs show striking morphological and functional tail variation; e.g., a long, robust, basal theropod tail used for counterbalance, or a short, modern avian tail used as an aerodynamic surface. We used a quantitative morphological and functional analysis to reconstruct intervertebral joint stiffness in the tail along the theropod lineage to extant birds. This provides new details of the tail's morphological transformation, and for the first time quantitatively evaluates its biomechanical consequences. We observe that both dorsoventral and lateral joint stiffness decreased along the non-avian theropod lineage (between nodes Theropoda and Paraves). Our results show how the tail structure of non-avian theropods was mechanically appropriate for holding itself up against gravity and maintaining passive balance. However, as dorsoventral and lateral joint stiffness decreased, the tail may have become more effective for dynamically maintaining balance. This supports our hypothesis of a reduction of dorsoventral and lateral joint stiffness in shorter tails. Along the avian theropod lineage (Avialae to crown group birds), dorsoventral and lateral joint stiffness increased overall, which appears to contradict our null expectation. We infer that this departure in joint stiffness is specific to the tail's aerodynamic role and the functional constraints imposed by it. Increased dorsoventral and lateral joint stiffness may have facilitated a gradually improved capacity to lift, depress, and swing the tail. The associated morphological changes should have resulted in a tail capable of producing larger muscular forces to utilise larger lift forces in flight. Improved joint mobility in neornithine birds potentially permitted an increase in the range of lift force vector orientations, which might have improved flight proficiency and manoeuvrability. The tail morphology of modern birds with tail fanning capabilities originated in early ornithuromorph birds. Hence, these capabilities should have been present in the early Cretaceous, with incipient tail-fanning capacity in the earliest pygostylian birds.
    Full-text · Article · May 2013 · PLoS ONE
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