Article

Erratum: Phylogentic support for a specialized clade of cretaceous enantiornithine birds with information from a new species (Journal of Vertebrate Paleontology (2009) 29:1 (188-204))

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

A new species of enantiornithine bird from the Lower Cretaceous Yixian Formation of northeastern China is reported. The new taxon, Shanweiniao cooperorum, possesses several enantiornithine synapomorphies as well as the elongate rostral morphology (rostrum equal to or exceeding 60% the total length of the skull) of the Chinese early Cretaceous enantiornithines, Longipteryx chaoyangensis and Longirostravis hani. The discovery of this new specimen highlights the existence of a diverse clade of trophically specialized enantiornithines, Longipterygidae, for which we present phylogenetic support in a new comprehensive cladistic analysis of Mesozoic birds. Shanweiniao provides new information on the anatomy of longipterygids, and preserves a rectricial morphology previously unknown to enantior-nithines, with at least four tail feathers closely arranged. This supports the hypothesis that enantiornithines were strong fliers and adds to the diversity of known tail morphologies of these Cretaceous birds.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Despite the large number of specimens uncovered from the Jehol Biota over the past several decades (Zhou, 2004Zhou, , 2014 Xu et al., 2014), the early evolution of the avian tail complex is poorly understood. Several short discussions have been published regarding specific taxa: Jeholornis (O'Connor et al., 2012), Eopengornis (Wang X et al., 2014), Shanweiniao (O'Connor et al., 2009), Yixianornis (Clarke et al., 2006) and Iteravis (Zhou et al., 2014). However, the only research focused on the morphological changes that occur in the derived maniraptoran tail during early avian evolution predates most important discoveries ( Dial, 1993, 1996a, b). ...
... In order to reduce the effects of body size, we normalized the TLP using the total length of the humerus (TLH) and the total length of femurs (TLF), two most reliable and widely used proxies for body size and mass in most birds (Liu et al., 2012; Hone, 2012). Most of the data (27 specimens) were collected directly from specimens measured using stainless hardened digital calipers; measurements from four specimens were taken from the literature (Sapeornis CAGS-03-07-08 (Yuan, 2005), Zhouornis (Zhang et al., 2013), Sulcavis (O'), Shanweiniao (O'Connor et al., 2009)). A d v a n c e d o n l i n e p u b l i c a t i o n ...
... Clades cannot be easily distinguished by MLW/TLP values (Table 1; Fig. 7C). Because the data of sapeornithiforms and ornithuromorphs are too questionable and limited (only one datum of each) to be considered, and the ratio of MLW/TLP present in confuciusornithiforms Fig. 7Scatter diagram of metrical data (Citations: Sapeornis CAGS-03-07-08 (Yuan, 2005), Zhouornis (Zhang et al., 2013), Sulcavis (O'), Shanweiniao (O'Connor et al., 2009). (0.12–0.24) and enantiornithines (0.15–0.53) are indistinguishable. ...
Article
Full-text available
The transformation from a long reptilian tail to a shortened tail ending in a pygostyle and accompanied by aerodynamic fanning rectrices is one of the most remarkable adaptations of early avian evolution. However, no fossils directly capture this transition, and information regarding the structural morphology and the early evolution of the pygostyle in Mesozoic birds and their integuments is relatively limited. Here we provide a review of the pygostyle morphology of Early Cretaceous birds with comparison to the structure in living birds. This study emphasizes the convergent evolution of distally co-ossified caudal vertebrae in non-avian maniraptorans and early birds. There further exist distinct differences in pygostyle morphology between Sapeornithiformes, Confuciusornithiformes, Enantiornithes, and Ornithuromorpha. The morphology of the pygostyle and rectrices in early ornithuromorphs appear similar to that of extant birds, whereas the pygostyle in more primitive birds does not appear morphologically capable of supporting the rectricial bulbs and musculature necessary to control an aerodynamic fan-shaped tail. The rectricial bulbs and rectricial fan appear to have coevolved with the plough-shaped pygostyle early in the evolution of the Ornithuromorpha. This study also shows that the confuciusornithiform pygostyle was more similar to that of enantiornithines than previously recognized, consistent with the presence of nearly identical ornamental tail feathers in both groups.
... This bone is short and broad as in other enantiornithines with the maximum width measuring approximately 1.2 times the maximum length (the ratio is 1.06 in Protopteryx (Zhang and Zhou, 2000) and 1.1 in Longipteryx (Zhang et al., 2001)). The rostral margin is slightly broken but it appears to be minimally vaulted, as in Shanweiniao (O'Connor et al., 2009). The preserved craniolateral corner forms an obtuse angle of approximately 105°. ...
... As in most enantiornithines, metatarsal III extends farther distally than metatarsal IV, which in turn extends farther distally than metatarsal II. The left metatarsus preserves a bone that we tentatively identify as metatarsal V, although this element has never been preserved in any other enantiornithine (O'Connor et al., 2009). This bone, situated near the proximal tarsals, is short, approximately 17.5% of the length of metatarsal II, and very thin (Fig. 7). ...
Article
Full-text available
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, Pengornis was arboreal, like other enantiornithines. Since Enantiornithes was first recognized over three decades ago (Walker, 1981), dozens of new enantiornithine taxa have been discovered from the Lower Cretaceous Jehol Group of northeastern China (Benton et al., 2008). This fossil-rich lacustrine unit consists of the lower Dabeigou Formation, exposed only in Hebei, the middle Yixian Formation, and the overlying Jiufotang Formation (Zhou et al., 2003). Pengornis is the largest known Early Cretaceous enantiornithine bird. The holotype and only previously known specimen of Pengornis houi (IVPP V 15336) preserves features previously considered unique to Ornithuromorpha such as the relatively more globose humeral head and the hooked acromion process on the scapula, providing evidence for a complex pattern of character evolution in ornithuromorph and enantiornithine birds (Zhou et al., 2008). Although the holotype specimen of P. houi preserves a great deal of anatomical information, particularly regarding the skull, preservation obscures many anatomical details of the disarticulated forelimb and hindlimb, the thoracic and pelvic girdles are incomplete, and no plumage is preserved. Recently, a nearly complete subadult specimen (IVPP V 18632) was recovered from the Jiufotang Formation of Lingyuan, western Liaoning, very near the locality that produced the holotype of P. houi. Morphological comparisons between this new specimen and the holotype of P. houi show that the new specimen can be referred to Pengornis, and may
... Caudally, the ventral margin of the dentary often expands ventrally at the level of the lacrimal while the dorsal margin remains straight (e.g.Hebeiornis, Shenqiornis, Eocathayornis). In the longipterygids Longirostravis, Rapaxavis and Longipteryx, the dentary is overall slightly concave ventrally (Hou et al. 2004;Morschhauser et al. 2009;O'Connor et al. 2009). Gobipteryx reportedly differs from Early Cretaceous enantiornithines in that the mandibular bones are nearly completely fused (dentaries strongly ankylosed in IGM100/1011;Chiappe et al. 2001) and the caudal articulation of the dentary is forked, as in more advanced birds (Elzanowski 1977). ...
... Enantiornithines display a unique mosaic of primitive and derived characters, reflecting their intermediate phylogenetic position between the basal-pygostylians and modern birds, and the scale of their Cretaceous evolutionary radiation (an alternative phylogenetic proposal for Enantiornithines—sharing a most common recent ancestor with Archaeopteryx[Martin 1983[Martin , 2004—has been shown to be less parsimonious by phylogenetic analyses over the last two decades [e.g.Chiappe 1995aChiappe , 2002Clarke and Norell 2002;O'Connor et al. 2009]). However, the pattern of character loss and/or plesiomorphic retention in certain areas of the skeleton is intriguing. ...
Article
Full-text available
Enantiornithines are the most speciose avian clade in the Mesozoic, with a fossil record that nearly spans the Cretaceous; however, with less than half of known taxa preserving skull material, our understanding of their cranial morphology remains incomplete. Here we present a comprehensive overview of the current knowledge of enantiornithine skull anatomy and discuss the range of morphologies known for each of the main cranial elements. The typical enantiornithine skull retains numerous ancestral features such as the absence of fusion among bones, the presence of a postorbital bone, a primitive quadrate with a single headed otic process, an unforked dentary, and teeth. The postorbital in at least one taxon is unreduced, suggesting the existence of a complete infratemporal fenestra and thus an unmodified diapsid skull as in confuciusornithids. The rostrum is well known and shows considerable variation, typical of theropods; however, in terms of rostral proportions, enantiornithines are extremely limited within the modern avian spectrum. Although Late Cretaceous skull material is extremely fragmentary, when compared to Early Cretaceous material it reveals a trend towards more specialized morphologies in younger taxa. The foramen magnum in all taxa points caudally, indicating that the ‘flexed’ type skull morphology may not have evolved in this group. Enantiornithine teeth show considerable diversity in numbers, size, morphology and placement, ranging from taxa with large teeth found throughout the jaws to taxa with small, rostrally restricted teeth, to the fully edentulous. Despite limited preservation of skull material, a number of trophic specializations can be deduced from the range of preserved morphologies, further hinting at the morphological and ecological diversity of the Cretaceous Enantiornithes.
... Zhou 2006; Z.-H.Zhou & Zhang 2006). Only in the most diverse clade, the Enantiornithes, were significant excursions in rostral proportions observed (Zhang et al. 2000;Hou et al. 2004;Morschhauser et al. 2009;O'Connor et al. 2009). However, even these departures remained within the mesorostrine morphospace with the rostrum of Longipteryx representing the upper known limit, contributing to 65% of the skull length (O'Connor & Chiappe 2011). ...
Article
Full-text available
A new species of Early Cretaceous ornithuromorph with an elongate rostrum is described from the Sihedang locality of the Lower Cretaceous Yixian Formation in north-eastern China. Like the longipterygid enantiornithines, rostral elongation in Dingavis longimaxilla gen. et sp. nov. is achieved primarily through the maxilla, whereas neornithines elongate the premaxilla and rostralization is far more extreme than observed in early birds. Notably, in the rostrum of Xinghaiornis, the most ‘longirostrine’ Early Cretaceous ornithuromorph, the premaxilla and maxilla contribute to the rostrum equally. These lineages together highlight the diversity of configurations in which early birds experimented with rostralization of the skull. The 65% upper limit in rostral proportions of Early Cretaceous taxa with elongate maxillae and the fact that this morphology was abandoned in more derived taxa suggests that in Aves this skull configuration provided less structural stability.
Article
Recently reported specimens from the Mid-Late Jurassic Yanliao (or Daohugou) Biota and Early Cretaceous Jehol Biota of Northeast China suggest that the early evolution of avian flight involved a surprising amount of homoplasy and evolutionary experimentation. Pennaceous feathers of variable size, structure, and extent occur on the hindlimbs of numerous Jehol and Yanliao paravian theropods, including some basal birds, and clearly had an aerodynamic function at least in the dromaeosaurid Microraptor. However, their function in many cases may have been primarily ornamental, and it is unclear whether aerodynamically useful hindwings represent a widespread paravian feature or an evolutionary novelty limited to Microraptor and possibly a few other taxa. Clearer examples of novelties related to aerial locomotion are the tail plumage of the basal bird Jeholornis, in which a proximal fan of feathers is present and the ancestral distal frond is somewhat reduced, and the membranous wings of the Yanliao scansoriopterygid Yi. Early paravian evolution evidently involved a rapid diversification of aerodynamic structures, and ancestral paravians may have been volant. It is also possible that the avian lineage passed through a four-winged “tetrapterygian” stage, but current phylogenies suggest that aerodynamic hindwings were more likely acquired independently by different paravian groups.
Article
Full-text available
A careful reappraisal of the only known specimen of the poorly understood fossil enantiornithine bird Boluochia zhengi reveals numerous morphological similarities that suggest this taxon is closely related to the well-known Longipteryx chaoyangensis, and so is assignable to the most diverse recognized clade of Early Cretaceous enantiornithines, the Longipterygidae. This new study of the holotype of B. zhengi reveals new longipterygid synapomorphies and expands our knowledge of the temporal and geographical ranges and diversity of the clade. We suggest that the trophic specialization that characterizes longipterygids may have been a major factor contributing to the success of this clade.
Article
Full-text available
In the last twenty years, the extraordinary discoveries of vertebrate fossils from the Jehol Biota not only have important implications for studying the evolution of major Mesozoic vertebrate groups, their paleobiostratigraphy and paleoenvironmentology, but also provide critical evidence for understanding the biodiversity changes of the Early Cretaceous ecosystem. Currently, the Jehol Biota in a narrow sense (i.e., distribution limited to western Liaoning, northern Hebei, and southeastern Inner Mongolia) comprises a vertebrate assemblage of at least 121 genera and 142 species. Among them are 13 genera and 15 species of mammals, 33 genera and 39 species of birds, 30 genera and 35 species of dinosaurs, 17 genera and species of pterosaurs, 5 genera and species of squamates, 5 genera and 7 species of choristoderes, 2 genera and species of turtles, 8 genera and species of amphibians, 7 genera and 13 species of fishes as well as 1 genus and species of agnathan. All these known 121 genera are extinct forms, and only a small percentage of them (e.g., agnathans, some fishes and amphibians) can be referred to extant families. The Jehol vertebrate diversity already exceeds that of the contemporaneous lagerstätten such as Santana Fauna from Brazil and the Las Hoyas Fauna from Spain, and is nearly as great as that of the Jurassic Solnhofen Fauna and the Eocene Messel Fauna from Germany. Therefore, The Jehol Biota undoubtedly represents a world class lagerstätte in terms of both fossil preservation and vertebrate diversity. The success of the Jehol vertebrate diversity had a complex biological, geological, and paleoenvironmental background. Analysis of the habitat and diet of various vertebrate groups also indicates that the habitat and dietary differentiation had played a key role in the success of the taxonomic diversity of vertebrates of various ranks. Furthermore, the interactions among vertebrates, plants, and invertebrates as well as the competitions among various vertebrate groups and some key morphological innovations also contributed to the success of the Jehol vertebrate diversity. KeywordsJehol Biota-Early Cretaceous-vertebrate-diversity-lagerstätten
Article
Full-text available
Shared behavioural, morphological and physiological characteristics are indicative of the evolution of extant birds from nonavian maniraptoran dinosaurs. One such shared character is the presence of uncinate processes and respiratory structures in extant birds. Recent research has suggested a respiratory role for these processes found in oviraptorid and dromaeosaurid dinosaurs. By measuring the geometry of fossil rib cage morphology, we demonstrate that the mechanical advantage, conferred by uncinate processes, for movements of the ribs in the oviraptorid theropod dinosaur, Citipati osmolskae, basal avialan species Zhongjianornis yangi, Confuciusornis sanctus and the more derived ornithurine Yixianornis grabaui, is of the same magnitude as found in extant birds. These skeletal characteristics provide further evidence of a flow-through respiratory system in nonavian theropod dinosaurs and basal avialans, and indicate that uncinate processes are a key adaptation facilitating the ventilation of a lung air sac system that diverged earlier than extant birds.
Article
We examine the relationships between primary feather length (f(prim)) and total arm length (ta) (sum of humerus, ulna and manus lengths) in Mesozoic fossil birds to address one aspect of avian wing shape evolution. Analyses show that there are significant differences in the composition of the wing between the known lineages of basal birds and that mean f(prim) (relative to ta length) is significantly shorter in Archaeopteryx and enantiornithines than it is in Confuciusornithidae and in living birds. Based on outgroup comparisons with nonavian theropods that preserve forelimb primary feathers, we show that the possession of a relatively shorter f(prim) (relative to ta length) must be the primitive condition for Aves. There is also a clear phylogenetic trend in relative primary feather length throughout bird evolution: our analyses demonstrate that the f(prim)/ta ratio increases among successive lineages of Mesozoic birds towards the crown of the tree ('modern birds'; Neornithes). Variance in this ratio also coincides with the enormous evolutionary radiation at the base of Neornithes. Because the f(prim)/ta ratio is linked to flight mode and performance in living birds, further comparisons of wing proportions among Mesozoic avians will prove informative and certainly imply that the aerial locomotion of the Early Cretaceous Confuciusornis was very different to other extinct and living birds.
Chapter
Full-text available
Although more than half of the evolution of birds occurred during the Mesozoic Era our understanding of this long history focused on the spectacular specimens of the Late Jurassic Archaeopteryx lithographica and the more derived Late Cretaceous hesperornithiforms and ichthyornithiforms for over a century of paleontological research. In the last decade, however, a tremendous burst of new evidence—perhaps unparalleled in the field of vertebrate paleontology—has been uncovered. Indeed, the number of species of early birds described during the 1990s nearly tripled the number of taxa discovered during the previous 130 years elapsed since the discovery of Archaeopteryx in the mid-1800s.
Article
Full-text available
The osteology and plumage of Confuciusornis sanctus and Changchengornis hengdaoziensis from the Chaomidianzi Formation (previously referred to as the lower section of the Yixian Formation) of western Liaoning Province (China) are described in detail. Confuciusornis sanctus and Changchengornis hengdaoziensis have toothless, beaked skulls (the tomial crest is straight in the former species and strongly curved in the latter) and retain the dorsal portion of the nasal process of the maxilla. The skull of Confuciusornis sanctus is of typical diapsid plan. It possesses a triradiate postorbital that with the squamosal forms a complete supratemporal arcade. Furthermore, a robust jugal-postorbital contact completely separates the infratemporal fenestra from the orbit. Although the postorbital region is not preserved in Changchengornis hengdaoziensis, it likely resembles that of Confuciusornis sanctus. Both species have abbreviated tails with long pygostyles, not the long, bony tail originally reconstructed in Confuciusornis sanctus. Scapulae and coracoids are fused to form scapulocoracoids. The coracoids are strutlike but much shorter than the scapulae. The furculae are robust and boomerang shaped. The sterna are long and nearly flat. A complete basket of gastralia follows the sternum caudally. The wing elements are short, and proportions among individual bones are primitive in that the hand is longer than either the humerus or the ulna and the ulna is shorter than the humerus. The pelvis is opisthopubic. The postacetabular wing of the ilium is much shorter than the preacetabular wing. Differences in plumage, namely the presence or absence of two very long tail feathers, are observed among several well-preserved specimens of Confuciusornis sanctus. This difference is likely the expression of sexual dimorphism, although other biological attributes known for extant populations (e.g., differential molting, correlation between sexual maturity and ornamental plumage) indicate that alternative explanations may also account for the observed plumage variation among specimens of Confuciusornis sanctus. Given the latest Jurassic-earliest Cretaceous age of the Chaomidianzi Formation, Confuciusornis sanctus and Changchengornis hengdaoziensis are surely among the oldest known birds after the Early Tithonian Archaeopteryx lithographica. Confuciusornis sanctus and Changchengornis hengdaoziensis thus furnish the earliest record of beaked birds. The fully diapsid skull of Confuciusornis sanctus, and presumably of Changchengornis hengdaoziensis, and the absence of a bending zone on the base of the snout suggest that earlier interpretations of the skull of Confuciusornis sanctus as prokinetic are incorrect. Confuciusornis sanctus probably had very limited cranial kinetic capabilities, if any. Optimization of the postorbital-jugal contact, a character intimately correlated with intracranial kinesis, in a phylogeny of basal avians indicates that the essentially akinetic condition of the skull of Confuciusornis sanctus is a reversal derived from forms possessing kinetic properties. Recent recognition of two additional species of Confuciusornis - Confuciusornis chuonzhous and Confuciusornis suniae - are based on anatomical misinterpretations. Thus, Confuciusornis suniae and Confuciusornis chuonzhous are regarded as junior synonyms of Confuciusornis sanctus. Confuciusornis sanctus is the sister-taxon of Changchengornis hengdaoziensis, and both are placed within the Confuciusornithidae. Some of the synapomorphies supporting this grouping include the presence of edentolous jaws, a rostrally forked mandibular symphysis, a reduced claw of manual digit II, and a V-shaped caudal margin of the sternum. The Confuciusornithidae is considered to be the sister-group of a clade composed of the Enantiornithomorpha and the Ornithuromorpha. This phylogenetic interpretation is far more parsimonious than previous systematic hypotheses placing the Confuciusornithidae as either within the Enantiornithes or as its sister-group. Purported climbing specializations of Confuciusornis sanctus are evaluated in light of the available anatomical evidence. We conclude that both Confuciusornis sanctus and Changchengornis hengdaoziensis were ill suited for tree climbing. The foot of Changchengornis hengdaoziensis, however, suggests a greater grasping ability than that of Confuciusornis sanctus. It is argued that both Confuciusornis sanctus and Changchengornis hengdaoziensis were able to fly and take off from the ground. The remarkable concentration of specimens of Confuciusornis sanctus from a relatively small quarry near the village of Sihetun (Liaoning Province) suggests several events of mass mortality and, perhaps, a gregarious behavior.
Article
Full-text available
The timing of the Jiufotang Formation remains speculative despite recent progress in the study of the Jehol Biota. In this paper we contribute to this topic with 40Ar/39Ar dating on K-feldspar (sanidine and orthoclase) from tuffs interbedded within the fossil-bearing shales of the Jiufotang Formation, from the upper part of the Jehol Group in Chaoyang, Liaoning, northeastern China. 40Ar/39Ar step heating analyses of K-feldspar and the SHRIMP U-Pb zircon data indicate that tuffs at the Shangheshou section erupted at 120.3 +/- 0.7 million years ago. This result confirms an Aptian age for the Jiufotang Formation that was mainly based on biostratigraphic evidence. It also places stringent controls on the age of the fossils from the formation, providing a minimum age (120 Ma) for the four-winged dinosaur, Microraptor, and the seed-eating bird, Jeholornis.
Article
Full-text available
We report new 40Ar÷39Ar dating results obtained from total fusion and incremental-heating analyses of sanidine and biotite from three tuffs found interbedded within the fossil-bearing deposits of Liaoning, northeast China. The first is a new sample of the Bed 6 Sihetun tuff from the Yixian Formation, previously dated by our team as middle Early Cretaceous, and recently considered by Lo et al., partially reset due to metamorphism from a nearby basaltic sill. The second is the Yixian Bed 9 tuff from Hengdaozi considered by Lo et al. to be unaffected by metamorphism and whose age, based on total fusion 40Ar÷39Ar dating of biotite, argues for a Jurassic age for the Yixian Formation. The third tuff is a previously undated tuff from the upper part of the underlying Tuchengzi Formation. Single crystal total fusion 40Ar÷39Ar analyses of the Sihetun sanidine showed homogeneous radiogenic Ar, Ca÷K ratios, excellent reproducibility and gave a mean age of 125.0±0.18 (1SD)±0.04 (SE) Ma. Single sanidine crystal total fusion 40Ar÷39Ar analyses of the Hengdaozi tuff gave a mean age of 125.0±0.19 (1SD)±0.04 (SE) Ma, which is indistinguishable from the Sihetun tuff. The Tuchengzi Formation tuff gave a mean age of 139.4±0.19 (1SD)±0.05 (SE) Ma. Detailed laser incremental-heating analyses of biotite from Sihetun, Hengdaozi, and Tuchengzi tuffs show disturbed Ar release patterns and evidence of trapped argon components. We conclude from these analyses that the total fusion dates on biotite by Lo et al. are erroneously old and isotopic dating of both biotite and sanidine from tuffs of the Yixian Formation point to a middle Early Cretaceous age. The upper part of the Tuchengzi Formation can be referred to the Early Cretaceous.
Article
Full-text available
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.
Article
Full-text available
AVIAN flight is one of the most remarkable achievements of vertebrate evolution, yet there is little evidence of its early phases. Specimens of Archaeopteryx shed important (albeit controversial) light on this evolutionary phenomenon, but the large morphological (and almost certainly functional) gap between Archaeopteryx and modern avians remained virtually empty until recently. Here we report a new, exquisitely preserved, bird from the Lower Cretaceous Konservat-Lagerstätte of Las Hoyas (Cuenca, Spain) which provides evidence for the oldest known alula (bastard wing). Crustacean remains found inside its belly also provide the oldest direct evidence of feeding habits in birds. The new specimen has numerous synapomorphies with the Enantiornithes, but its unique sternal morphology, along with other autopomorphies in the furcula and vertebral centra, support the recognition of a new enantiornithine taxon, Eoalulavishoyasi. The combination in Eoalulavis of a decisive aerodynamic feature, such as the alula, with the basic structures of the modern flight apparatus indicates that as early as 115 million years ago, birds had evolved a sophisticated structural system that enabled them to fly at low speeds and to attain high manoeuvrability.
Article
Full-text available
We report on a new Mesozoic bird, Longirostravis hani, from the Early Cretaceous Jehol Biota of northeastern China. The new taxon has a long, slender rostrum and mandible, and a small number of rostralmost teeth. Postcranial characters such as a furcular ramus wider ventrally than dorsally, a centrally concave proximal margin of the humeral head, and a minor metacarpal that projects distally more than the major metacarpal, support the placement of Longirostravis within euenantiornithine Enantiornithes, the most diverse clade of Mesozoic birds. The morphology of the skull, however, suggests that Longirostravis had a probing feeding behavior, a specialization previously unknown for Enantiornithes. Indeed, this discovery provides the first evidence in support of the existence of such a foraging behavior among basal lineages of Mesozoic birds.
Article
Birds evolved from and are phylogenetically recognized as members of the theropod dinosaurs; their first known member is the Late Jurassic Archaeopteryx, now represented by seven skeletons and a feather, and their closest known non-avian relatives are the dromaeosaurid theropods such as Deinonychus. Bird flight is widely thought to have evolved from the trees down, but Archaeopteryx and its outgroups show no obvious arboreal or tree-climbing characters, and its wing planform and wing loading do not resemble those of gliders. The ancestors of birds were bipedal, terrestrial, agile, cursorial and carnivorous or omnivorous. Apart from a perching foot and some skeletal fusions, a great many characters that are usually considered ‘avian’ (e.g. the furcula, the elongated forearm, the laterally flexing wrist and apparently feathers) evolved in non-avian theropods for reasons unrelated to birds or to flight. Soon after Archaeopteryx, avian features such as the pygostyle, fusion of the carpometacarpus, and elongated curved pedal claws with a reversed, fully descended and opposable hallux, indicate improved flying ability and arboreal habits. In the further evolution of birds, characters related to the flight apparatus phylogenetically preceded those related to the rest of the skeleton and skull. Mesozoic birds are more diverse and numerous than thought previously and the most diverse known group of Cretaceous birds, the Enantiornithes, was not even recognized until 1981. The vast majority of Mesozoic bird groups have no Tertiary records: Enantiornithes, Hesperornithiformes, Ichthyornithiformes and several other lineages disappeared by the end of the Cretaceous. By that time, a few Linnean ‘Orders’ of extant birds had appeared, but none of these taxa belongs to extant ‘families’, and it is not until the Paleocene or (in most cases) the Eocene that the majority of extant bird ‘Orders’ are known in the fossil record. There is no evidence for a major or mass extinction of birds at the end of the Cretaceous, nor for a sudden ‘bottleneck’ in diversity that fostered the early Tertiary origination of living bird ‘Orders’.
Article
Modern birds have extremely short tail skeletons relative to Archaeopteryx and nonavialian theropod dinosaurs. Long- and short-tailed birds also differ in the conformation of main tail feathers making up the flight surface: frond shaped in Archaeopteryx and fan shaped in extant fliers. Mechanisms of tail fanning were evaluated by electromyography in freely flying pigeons and turkeys and by electrical stimulation of caudal muscles in anesthetized birds. Results from these experiments reveal that the pygostyle, rectrices, rectricial bulbs, and bulbi rectricium musculature form a specialized fanning mechanism. Contrary to previous models, our data support the interpretation that the bulbi rectricium independently controls tail fanning; other muscles are neither capable of nor necessary for significant rectricial abduction. This bulb mechanism permits rapid changes in tail span, thereby allowing the exploitation of a wide range of lift forces. Isolation of the bulbs on the pygostyle effectively decouples tail fanning from fan movement, which is governed by the remaining caudal muscles. The tail of Archaeopteryx, however, differs from this arrangement in several important respects. Archaeopteryx probably had a limited range of lift forces and tight coupling between vertebral and rectricial movement. This would have made the tail of this primitive flier better suited to stabilization than maneuverability. The capacity to significantly alter lift and manipulate the flight surface without distortion may have been two factors favoring tail shortening and pygostyle development during avian evolution.
Article
The anatomy of a new articulated enantiornithine bird skeleton from the Late Cretaceous of Patagonia clearly indicates a capacity for powered flight, approaching that of modern birds. Enantiornithines possess some of the synapomorphies of the Ornithurae, although they retain plesiomorphic states for many other characters, mainly in the hind limb. Such a mosaic character combination suggests a sister-group relationship between Enantiornithes and Ornithurae. Derived features of the pectoral girdle are here considered as diagnostic for a major avian clade, the Ornithopectae, comprising all known birds other than Archaeopteryx. The combination of derived and primitive traits in the fore and hind limbs and their girdles in early ornithopectines reflects mosaic evolution, with flight-related modifications of the fore limb and pectoral girdle preceding those in the hind limb and pelvic girdle.
Article
We report on a new species of enantiornithine bird from the Late Cretaceous of the Mongolian Gobi Desert, which adds to the meager record of birds from the latest part of the Mesozoic in this region. The exceptional, three‐dimensional bones of the new fossil increase the known anatomical diversity of enantiornithine birds, providing information about previously unreported morphologies such as a pneumatised furcula. Several synapomorphies nest the new bird within an enantiornithine clade of proficient fliers, but the anatomy and proportions of its flight apparatus imply significant aerodynamic restrictions. The combination of phylogeny and our functional interpretation suggests that this new fossil bird is a representative of a flightless lineage. This discovery thus provides the first evidence of a trend towards more limited flying capabilities among Enantiornithes, a group of Cretaceous birds otherwise believed to be represented by competent fliers.
Article
Current classification of birds recognizes three subclasses which are morphologically distinct: the Archaeornithes for Archaeopteryx, the Odontornithes for the Hesperornithiformes and the Ichthyornithiformes, and the Neornithes for all modern birds and their extinct immediate relatives. (Some authorities1 prefer different names for some of these taxa.) I have examined new material recently discovered in the Upper Cretaceous rocks of Argentina which indicates the existence of a group of birds having features so different from those of the currently recognized subclasses that they seem to represent a fourth subclass, here named the Enantiornithes (‘opposite birds’). I describe unique features of the Enantiornithes which include a reduced outer metatarsal, in some forms an extreme modification of the remaining elements of the tarsometatarsus, a highly modified pectoral girdle, and sometimes a characteristic perforation in the proximal end of the humerus.
Article
The avialan taxon Apsaravis ukhaana from the Late Cretaceous of southern Mongolia is completely described and its phylogenetic position is evaluated. Apsaravis ukhaana is from continental sandstones exposed at the locality of Ukhaa Tolgod, Omnogov Aimag, Mongolia. The holotype specimen consists of the nearly complete, articulated skeleton of a small volant avialan. Apsaravis ukhaana is unambiguously differentiated from other avialans based on the presence of several unique morphologies: a strong tubercle on the proximal humerus, a hypertrophied trochanteric crest on the femur, and extremely well-projected posterior wings of a surface of the distal tibiotarsus that in Aves articulates with the tibial cartilage. Ten other homoplastic characters optimize as autapomorphies of Apsaravis ukhaana in the phylogenetic analysis. They are as follows: ossified mandibular symphysis; dentary strongly forked posteriorly; hooked acromion process on scapula; highly angled dorsal condyle of humerus; humeral condyles weakly defined; distal edge of humerus angling strongly ventrally; humerus flared dorsoventrally at its distal terminus; lateral condyle of tibiotarsus wider than medial one; neither condyle of tibiotarsus tapering toward the midline; and metatarsal II trochlea rounded rather than ginglymoid. Phylogenetic placement of Apsaravis ukhaana as the sister taxon of Hesperornithes + Aves resulted from analysis of 202 characters scored for 17 avialan ingroup taxa. The implications of Apsaravis ukhaana, and the results of the phylogenetic analysis, for the evolution of flight after its origin and character support for enantiornithine monophyly are extensively discussed.
Article
Abstract  Enantionithine birds are the most blooming branch of early birds and have distinct diversities. A large number of enantionithine birds have been reported from the Early Cretaceous Jiufotang Formation in western Liaoning, China. Recently, we discovered a new eoenantiornithid bird from the Jiufotang Formation in Dapingfang Town, western Liaoning. A new eoenantiornithid bird, Dapingfangornis sentisorhinus gen. et sp. nov., is erected based on this complete skeleton with a skull. The new bird is distinguished from other known Mesozoic birds in a medium to small size, a distinct thorn-like process on the nasals, a sternum with a long and a short lateral processes. The thorn-like process on the nasal has not been discovered among known fossil birds, thus the discovery also provides new materials on the diversities of early birds.
Article
A metric comparison of 155 fossil and extant species in lateral view based on the proportions of three homologous units (braincase, orbit and rostrum) reveals the existence of an archosaurian skull geometry. An empirical morphospace depicting skull proportions shows that the most variable unit is the rostrum. Three skull types based on rostral proportion are proposed: meso-, longi- and brevirostral. These types depend, on one hand, on a direct numerical relationship between the braincase and the orbit, with a mean ratio of 1:1; never surpassing a 2:1 or 1:2 ratio limit. On the other hand, skull types show a significant negative correlation between braincase and rostrum proportions. Close relationships have been obtained between orbit and the rostrum, although with lower significance and a geometric meaning specific to each group. Skull types depend mainly on the proportional relationship between the rostrum and the braincase. Mesorostral types account for more natural occurrences within morphospace, implying a plesiomorphic condition in Archosauria. Skulls with highest longirostral values (flying forms) display a more restrictive braincase–orbit ratio relationship. Brevirostrals are limited to the smallest skull lengths, up to approximately 180 mm. 85% of brevirostral modern birds have altricial post-hatchling development. General allometric pattern is very similar for all sampled archosaurs, although giant taxa (i.e. non-avian theropods) display a different type of skull proportional growth, closer to isometry. Results reveal the existence of a constructional skull geometry, highlighting the importance of the deviance of the structural design from adaptive explanations on craniofacial morphology in macroevolution. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 80, 67–88.
Article
A new enantiornithine birdLongipteryx chaoyangensis gen. et sp. nov. is described from the Early Cretaceous Jiufotang Formation in Chaoyang, western Liaoning Province. This new bird is distinguishable from other known enantiornithines in having uncinate processes in ribs, elongate jaws, relatively long wings and short hindlimbs, and metatarsal IV longer than metatarsals II and III. This new bird had probably possessed (i) modern bird-like thorax which provides firm attachment for muscles and indicates powerful and active respiratory ability; (ii) powerful flying ability; (iii) special adaptation for feeding on aquatic preys; and (iv) trochleae of metatarsals I–IV almost on brate heterocoelous. Distal region of sternum with well developed carina and lateral processes. Uncinate processes present but not fused with ribs. At least 6 rows of gastraliae present. Carpometacarpus not completely fused, minor metacarpal longer than major one; second phalanx the same level, an adaptation for perching. The new bird represents a new ecological type different from all known members of Enantiornithes. It shows that enantiornithines had probably originated earlier than the Early Cretaceous, or this group had experienced a rapid radiation right after it first occurred in the early Early Cretaceous.
Article
Birds evolved from and are phylogenetically recognized as members of the theropod dinosaurs; their first known member is the Late Jurassic Archaeopteryx, now represented by seven skeletons and a feather, and their closest known non-avian relatives are the dromaeosaurid theropods such as Deinonychus. Bird flight is widely thought to have evolved from the trees down, but Archaeopteryx and its outgroups show no obvious arboreal or tree-climbing characters, and its wing planform and wing loading do not resemble those of gliders. The ancestors of birds were bipedal, terrestrial, agile, cursorial and carnivorous or omnivorous. Apart from a perching foot and some skeletal fusions, a great many characters that are usually considered 'avian' (e.g. the furcula, the elongated forearm, the laterally flexing wrist and apparently feathers) evolved in non-avian theropods for reasons unrelated to birds or to flight. Soon after Archaeopteryx, avian features such as the pygostyle, fusion of the carpometacarpus, and elongated curved pedal claws with a reversed, fully descended and opposable hallux, indicate improved flying ability and arboreal habits. In the further evolution of birds, characters related to the flight apparatus phylogenetically preceded those related to the rest of the skeleton and skull. Mesozoic birds are more diverse and numerous than thought previously and the most diverse known group of Cretaceous birds, the Enantiornithes, was not even recognized until 1981. The vast majority of Mesozoic bird groups have no Tertiary records: Enantiornithes, Hesperornithiformes, Ichthyornithiformes and several other lineages disappeared by the end of the Cretaceous. By that time, a few Linnean 'Orders' of extant birds had appeared, but none of these taxa belongs to extant 'families', and it is not until the Paleocene or (in most cases) the Eocene that the majority of extant bird 'Orders' are known in the fossil record. There is no evidence for a major or mass extinction of birds at the end of the Cretaceous, nor for a sudden 'bottleneck' in diversity that fostered the early Tertiary origination of living bird 'Orders'.
Article
Thesis (Ph.D.)--Yale University, 2002. Includes bibliographical references (p.337-359). Photocopy.
Article
Plates preceded by guard-sheets with descriptive letterpress. Thesis (Ph. D.)--University of California, Berkeley, Dec. 1928. Bibliography: p. 138-144.
Article
A fossil enantiornithine bird, Protopteryx fengningensis gen. et sp. nov., was collected from the Early Cretaceous Yixian Formation of Northern China. It provides fossil evidence of a triosseal canal in early birds. The manus and the alular digit are long, as in Archaeopteryx and Confuciusornis, but are relatively short in other enantiornithines. The alula or bastard wing is attached to an unreduced alular digit. The two central tail feathers are scalelike without branching. This type of feather may suggest that modern feathers evolved through the following stages: (i) elongated scale, (ii) central shaft, (iii) barbs, and finally (iv) barbules and barbicel.
Article
In studies of the evolution of avian flight there has been a singular preoccupation with unravelling its origin. By contrast, the complex changes in morphology that occurred between the earliest form of avian flapping flight and the emergence of the flight capabilities of extant birds remain comparatively little explored. Any such work has been limited by a comparative paucity of fossils illuminating bird evolution near the origin of the clade of extant (i.e. 'modern') birds (Aves). Here we recognize three species from the Early Cretaceous of China as comprising a new lineage of basal ornithurine birds. Ornithurae is a clade that includes, approximately, comparatively close relatives of crown clade Aves (extant birds) and that crown clade. The morphology of the best-preserved specimen from this newly recognized Asian diversity, the holotype specimen of Yixianornis grabaui Zhou and Zhang 2001, complete with finely preserved wing and tail feather impressions, is used to illustrate the new insights offered by recognition of this lineage. Hypotheses of avian morphological evolution and specifically proposed patterns of change in different avian locomotor modules after the origin of flight are impacted by recognition of the new lineage. The complete articulated holotype specimen of Yixianornis grabaui, from the Early Cretaceous Jiufotang Formation of Liaoning Province, in north-eastern China, arguably the best-preserved basal ornithurine specimen yet discovered, provides the earliest evidence consistent with the presence of extant avian tail feather fanning.
NONA: a tree searching program. Program and documentation distributed by
  • P Goloboff
Goloboff, P. 1993. NONA: a tree searching program. Program and documentation distributed by P. Goloboff, San Miguel de Tucumá n, Argentina.
trochlea in plantar view, proximal extent of lateral and medial edges of trochlea: trochlear edges approximately equal in proximal extent (0)
  • Iii Metatarsal
Metatarsal III, trochlea in plantar view, proximal extent of lateral and medial edges of trochlea: trochlear edges approximately equal in proximal extent (0); medial edge extends farther (1).
Mesozoic Pompeii The Jehol Biota
  • X.-L Wang
  • Z.-H Zhou
Wang, X.-L., and Z.-H. Zhou. 2003. Mesozoic Pompeii; pp. 19–35 in M.-M. Chang, P.-J. Chen, Y.-Q. Wang, Y. Wang, and D.-S. Miao (eds.), The Jehol Biota. Shanghai. China: Shanghai Scientific and Technical Publishers.
The Jehol Biota: the Emergence of Feathered Dinosaurs, Beaked Birds and Flowering Plants
  • F.-C Zhang
  • Z.-H Zhou
  • L.-H Hou
Zhang, F.-C., Z.-H. Zhou, and L.-H. Hou. 2003. Birds; pp. 129–150 in M.-M. Chang (ed.), The Jehol Biota: the Emergence of Feathered Dinosaurs, Beaked Birds and Flowering Plants. Shanghai, China: Shanghai Scientific and Technical Publishers. well-discernable) (1); vertebrae completely fused into a pygostyle (2). (ORDERED)
with the insertion of the tendon of the m. tibialis cranialis in Aves): absent (0); present, on approximately the center of the proximodorsal surface of metatarsal II (1); present, developed on lateral surface of metatarsal II, at contact with metatarsal III or on lateral edge of metatarsal III
  • Ii Metatarsal
Metatarsal II tubercle (associated with the insertion of the tendon of the m. tibialis cranialis in Aves): absent (0); present, on approximately the center of the proximodorsal surface of metatarsal II (1); present, developed on lateral surface of metatarsal II, at contact with metatarsal III or on lateral edge of metatarsal III (2). (ORDERED)
Systema naturae, sistens regna tria naturae, in classes et ordines genera et species redacta tabulis que aeneis illustrata
  • C Linnaeus
Linnaeus, C. 1758. Systema naturae, sistens regna tria naturae, in classes et ordines genera et species redacta tabulis que aeneis illustrata. G. Kiesswetteri, Stockholm.
widely separated mediolaterally (0); adjacent (1); crossed on midline (2) In taxa such as Eoalulavis in which the preserved sternum does not bear actual sulci, the placement of the coracoids can be used to infer their position relative to the sternum
  • Sternum
Sternum, coracoidal sulci spacing on cranial edge: widely separated mediolaterally (0); adjacent (1); crossed on midline (2). In taxa such as Eoalulavis in which the preserved sternum does not bear actual sulci, the placement of the coracoids can be used to infer their position relative to the sternum.
relative mediolateral width: metatarsal IV approximately the same width as metatarsals II and III (0); metatarsal IV narrower than metatarsals II and III (1); metatarsal IV greater in width than either metatarsal II or III
  • Metatarsals
Metatarsals, relative mediolateral width: metatarsal IV approximately the same width as metatarsals II and III (0); metatarsal IV narrower than metatarsals II and III (1); metatarsal IV greater in width than either metatarsal II or III (2).
deltopectoral crest: projected dorsally (in line with the long axis of humeral head) (0)
  • Humerus
Humerus, deltopectoral crest: projected dorsally (in line with the long axis of humeral head) (0); projected cranially (1).
1111???01 1111000??? ?1?111130
  • Neuquenornis
Neuquenornis ?????????? ?????????? ?????????? ?????????? ?????????? ???????0?? ?1???????? ?????????? ?1111???01 1111000??? ?1?111130[12] ?1???????? Vescornis ?0?????0?? ?????????? ?????????? ????000??? ?00[12]001?1? ?21?1??0?? ?1??0????2
humeral articular (glenoid) facet: dorsal to acrocoracoid process
  • Coracoid
Coracoid, humeral articular (glenoid) facet: dorsal to acrocoracoid process/ " biceps tubercle " (0); ventral to acrocoracoid process (1).
  • H.-Y., X.-L He
  • Z.-H Wang
  • F Zhou
  • A Wang
  • G.-H Boven
  • R.-X Shi
  • Zhu
He, H.-Y., X.-L. Wang, Z.-H. Zhou, F. Wang, A. Boven, G. -H. Shi, and R.-X. Zhu. 2004. Timing of the Jiufotang Formation (Jehol Group) in Liaoning, northeastern China and its implications. Geophysics Research Letters 31:L12605.
infratrochlear fossa deeply excavating proximal surface of pisiform process: absent (0)
  • Carpometacarpus
Carpometacarpus, ventral surface, infratrochlear fossa deeply excavating proximal surface of pisiform process: absent (0); present (1).
Archaeopterygidae (Upper Jurassic of Germany)
  • A Elzanowski
Elzanowski, A. 2001. Archaeopterygidae (Upper Jurassic of Germany);
approximately 90 (0); less than 70 (1) The interclavicular angle is measured as the angle formed between three points, one at the omal end of each rami and the apex located at the clavicular symphysis
  • Furcula
Furcula interclavicular angle: approximately 90 (0); less than 70 (1). The interclavicular angle is measured as the angle formed between three points, one at the omal end of each rami and the apex located at the clavicular symphysis.
cuppedicus fossa as broad, mediolaterally oriented surface directly cranioventral to acetabulum: present (0); surface absent, insertion variably marked by a small entirely lateral fossa cranial to acetabulum
  • M Ilium
Ilium, m. cuppedicus fossa as broad, mediolaterally oriented surface directly cranioventral to acetabulum: present (0); surface absent, insertion variably marked by a small entirely lateral fossa cranial to acetabulum (1).
or nearly completely) fused to each other: absent (0)
  • Ii-Iv Metatarsals
  • Completely
Metatarsals II-IV completely (or nearly completely) fused to each other: absent (0); present (1).
length: shorter than humerus (0); as long as or longer than humerus
  • Scapula
Scapula, length: shorter than humerus (0); as long as or longer than humerus (1).
iliofibularis: craniolaterally directed (0); laterally directed (1)
  • Fibula
Fibula, tubercle for m. iliofibularis: craniolaterally directed (0); laterally directed (1); caudolaterally or caudally directed (2). (OR-DERED)
humerotricipitalis groove: absent (0); present as a welldeveloped ventral depression contiguous with the olecranon fossa
  • M Humerus
Humerus, m. humerotricipitalis groove: absent (0); present as a welldeveloped ventral depression contiguous with the olecranon fossa (1).