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Iberomesornis romerali (Aves, Ornithothoraces) reevaluated as an Early Cretaceous enantiornithine
Abstract
Recent cladistic analyses have placed the Early Cretaceous avian, Iberomesornis romerali, outside the enantiornithine radiation at the base of Ornithothoraces. This conclusion is based on erroneous interpretations of the holotypic skeleton, which is shown here to exhibit ten enantiornithine synapomorphies. Revised diagnoses are presented for Enantiornithes and Iberomesornis romerali, which is very close in skeletal form to the Spanish and Chinese enantiornithines Concornis lacustris and Sinornis santensis, respectively.
... 129-126 Ma; Fig. 1) is the most exceptional source of Cretaceous birds in Europe. All collected specimens are referable to Enantiornithes; cumulatively these fossils provide key information regarding phylogeny, ecology, locomotion, and life Buscalioni, 1992;Sereno, 2000;Chiappe, 2002). More recent analyses including a much higher number of Cretaceous avian taxa differ with regards to the relative position of Iberomesornis within Enantiornithes: embedded in an enantiornithine polytomy (O'Connor et al., 2011); basal and closest to Protopteryx (Atterholt et al., 2018); or more derived and closer to Longipterygidae (O'Connor and Zhou, 2013;Wang et al., 2022b). ...
... More recent analyses including a much higher number of Cretaceous avian taxa differ with regards to the relative position of Iberomesornis within Enantiornithes: embedded in an enantiornithine polytomy (O'Connor et al., 2011); basal and closest to Protopteryx (Atterholt et al., 2018); or more derived and closer to Longipterygidae (O'Connor and Zhou, 2013;Wang et al., 2022b). The last anatomical studies describing the holotype of I. romerali were published more than 20 years ago (Sereno, 2000;Sanz et al., 2002). Like many other fossil birds preserved in slabs, the skeleton is two-dimensionally preserved and crushed, and many characters could not be observed originally due to its preservation in a slab which leaves a considerable portion of the skeleton hidden in the matrix. ...
... High-resolution images of the fossil were obtained using a macro lens (Canon EOS EF 50 mm F/1.8) of a camera Canon EOS 6D. The terminology regarding anatomy primarily follows , and also Sereno (2000), Panteleev (2018), and Wang et al. (2022a). ...
... In addition to the aforementioned plesiomorphic features, K. mater also shares with Enantiornithes a proportionally narrow shaft and small trochlea of metatarsal IV (also shared with confuciusornithids and the basal ornithuromorph Khinganornis hulunbuirensis Wang, Cau, Kundrát, Chiappe, Ji, Wang, Li and Wu, 2020;O'Connor et al., 2014), distally expanded metatarsal II trochlea with respect to metatarsal shaft (in K. mater this trochlea is smaller than that of metatarsal III, whereas in most Enantiornithes and confuciusornithids the trochlea of metatarsal II is wider than that of metatarsal III; Sereno, 2000;O'Connor et al., 2014), and proportionally large ungual phalanges (Chiappe and Calvo, 1994;Sereno, 2000;Zhang et al., 2001;Wang et al., 2014;Fig. 6). ...
... In addition to the aforementioned plesiomorphic features, K. mater also shares with Enantiornithes a proportionally narrow shaft and small trochlea of metatarsal IV (also shared with confuciusornithids and the basal ornithuromorph Khinganornis hulunbuirensis Wang, Cau, Kundrát, Chiappe, Ji, Wang, Li and Wu, 2020;O'Connor et al., 2014), distally expanded metatarsal II trochlea with respect to metatarsal shaft (in K. mater this trochlea is smaller than that of metatarsal III, whereas in most Enantiornithes and confuciusornithids the trochlea of metatarsal II is wider than that of metatarsal III; Sereno, 2000;O'Connor et al., 2014), and proportionally large ungual phalanges (Chiappe and Calvo, 1994;Sereno, 2000;Zhang et al., 2001;Wang et al., 2014;Fig. 6). ...
... In K. mater as in Enantiornithes, Mystiornis cyrili Kurochkin et al., 2011 and confuciusornithids, the metatarsal II trochlea is mediolaterally expanded and dorsoplantarly compressed and is notably medially angled (also present in confuciusornithids and the ornithuromorph Schizooura lii; Sereno, 2000;O'Connor et al., 2014;Wang, O'Connor et al., 2020). ...
The fossil record of Early Cretaceous birds in South America has been restricted to members of Enantiornithes from the Crato Formation (Aptian) of Brazil. Here we describe a new genus and species of bird discovered at Pedra Branca Mine, Nova Olinda County, Ceará State, Brazil, which adds to the avian fossil record from the Crato Formation. The specimen is represented by an isolated foot that is exposed in plantar view. A plantarly displaced metatarsal III with a well-developed hypotarsus supports its referral to Ornithuromorpha, representing the oldest member of the clade reported for Gondwana. Its unique foot conformation indicates that it may belong to an unknown ornithuromorph clade with some cursory similarities to extant flightless ratites. The presence of Early Cretaceous ornithuromorphs in Brazil indicates that the clade was widespread in Gondwana during the Mesozoic.
http://zoobank.org/urn:lsid:zoobank.org:pub:08333BA3-F231-4E61-9E89-105C7478AE31
... gen. is referred as Enantiornithes on the basis of the following synapomorphies (Carvalho et al. 2015): proximally forked and distally constricted pygostyle with a ventrolateral process, convex lateral margin of coracoid, scapulocoracoid articulation with scapular pit and coracoid tuber, distal end of metacarpal III more distally extended than the metacarpal II, distal tarsals fused to proximal metatarsus, but remaining portion of metatarsals free. Sereno (2000) also added a suite of purported synapomorphies that may allow to reinforce the inclusion of Cratoavis nov. gen. to Enantiornithes: metatarsal I with posteriorly reflected distal condyles ("J" shaped) and the distal condyles joined along its dorsal margin. ...
... gen. resembles Iberomesornis in having plesiomorphically anteroposteriorly short cervical and dorsal vertebral centra, and a simple proximal humeral morphology (Sanz & Bonaparte 1992;Sereno 2000). However, Cratoavis nov. ...
... gen. differs in having fan-shaped distal margin of dorsal neural spines, in contrast to Iberomesornis in which they are low and with a subcuadrangular contour (Sereno 2000), well-developed neural spines on caudal vertebrae, ulna as long as humerus (longer than humerus in Iberomesornis; Sereno, 2000), and gracile pedal phalanges. Furthermore, Cratoavis nov. ...
The fossil record of birds in Gondwana is almost restricted to the Late Cretaceous. Herein we describe a new fossil from the Araripe Basin, Cratoavis cearensis nov. gen et sp., composed of an articulated skeleton with feathers attached to the wings and surrounding the body. The present discovery considerably extends the temporal record of the Enantiornithes birds at South America to the Early Cretaceous. For the first time, an almost complete and articulated skeleton of an Early Cretaceous bird from South America is documented.
... gen. is referred as Enantiornithes on the basis of the following synapomorphies (Carvalho et al. 2015): proximally forked and distally constricted pygostyle with a ventrolateral process, convex lateral margin of coracoid, scapulocoracoid articulation with scapular pit and coracoid tuber, distal end of metacarpal III more distally extended than the metacarpal II, distal tarsals fused to proximal metatarsus, but remaining portion of metatarsals free. Sereno (2000) also added a suite of purported synapomorphies that may allow to reinforce the inclusion of Cratoavis nov. gen. to Enantiornithes: metatarsal I with posteriorly reflected distal condyles ("J" shaped) and the distal condyles joined along its dorsal margin. ...
... gen. resembles Iberomesornis in having plesiomorphically anteroposteriorly short cervical and dorsal vertebral centra, and a simple proximal humeral morphology (Sanz & Bonaparte 1992;Sereno 2000). However, Cratoavis nov. ...
... gen. differs in having fan-shaped distal margin of dorsal neural spines, in contrast to Iberomesornis in which they are low and with a subcuadrangular contour (Sereno 2000), well-developed neural spines on caudal vertebrae, ulna as long as humerus (longer than humerus in Iberomesornis; Sereno, 2000), and gracile pedal phalanges. Furthermore, Cratoavis nov. ...
The fossil record of birds in Gondwana is almost restricted to the Late Cretaceous. Herein we describe a new fossil from the Araripe Basin, Cratoavis cearensis nov. gen et sp., composed of an articulated skeleton with feathers attached to the wings and surrounding the body. The present discovery considerably extends the temporal record of the Enantiornithes birds at South America to the Early Cretaceous. For the first time, an almost complete and articulated skeleton of an Early Cretaceous bird from South America is documented. KEYWORDS: Cratoavis cearensis nov. gen et sp.; Araripe Basin; Fossil bird. RESUMO: No Gondwana, o registro fóssil de aves está praticamente restrito ao Cretáceo Superior. Neste estudo é descrito um novo fóssil da Bacia do Araripe, Cratoavis cearensis nov. gen. et sp., composto por um esqueleto articulado com penas conectadas às asas e circundando o corpo. A presente descoberta amplia consideravelmente o intervalo temporal de registro das aves Enantiornithes na América do Sul ao Cretáceo Inferior. Pela primeira vez, um esqueleto articulado e quase completo de uma ave do Cretáceo Inferior da América do Sul é documentado. PALAVRAS-CHAVE: Cratoavis cearensis nov. gen. et sp.; Bacia do Araripe; Ave fóssil. A new genus and species of enantiornithine bird from the Early Cretaceous of Brazil
... A minimum of six are present in the specimen. Gastralia are commonly found throughout many groups of Early Cretaceous birds including Enantiornithes (Chiappe et al., 1999;Sereno, 2000;Zhang et al., 2001;Zhang et al., 2004;Zhou et al., 2005). The ventrally exposed sacrum consists of six fully fused vertebrae (Fig. 2B). ...
... The ventrally exposed sacrum consists of six fully fused vertebrae (Fig. 2B). In contrast, Sinornis santensis (Sereno et al., 2002), Iberomesornis romerali (Sereno, 2000), Longiperyx (Zhang et al., 2001) and Vescornis all have eight. Sereno (2000) states that the possession of eight sacrals and six caudals is a common pattern among Enantiornithes. ...
... In contrast, Sinornis santensis (Sereno et al., 2002), Iberomesornis romerali (Sereno, 2000), Longiperyx (Zhang et al., 2001) and Vescornis all have eight. Sereno (2000) states that the possession of eight sacrals and six caudals is a common pattern among Enantiornithes. Contradicting this trend L. hani has seven sacral vertebrae (Hou et al., 2004). ...
The lacustrine deposits of the Jiufotang Formation, Liaoning Province, China have yielded a diverse avifauna representing a wide spectrum of basal lineages. Here we add to this diversity by describing the longirostrine enantiornithean taxon Rapaxavis pani gen. et sp. nov. The specimen possesses the following autapomorphies: (1) caudoateral processes of the sternum with two prominent branches and a smaller third branch, (2) paired triangular thoracic elements of unknown homology, and (3) the combination of six sacral vertebrae and six free caudal vertebrae. Otherwise, this genus is closely allied with the Yixian Formation species Longirostravis hani, sharing elongate, curving rostrum with teeth restricted to the premaxilla and rostral-most dentary, and a derived manus lacking unguals. The holotype of Rapaxavis is exquisitely preserved, with such details as distal tarsals, keratinous sheaths of the pedal unguals and some three-dimensional features of the bones intact. The holotype appears to lack a fused tibiotarsus and a fused carpometa-carpus. These features may indicate that the specimen is not yet fully grown, though the life stages of members of the Enantiornithes will not be clear until a complete ontogenetic series can be constructed. A comparison of the proportions of the pedal phalanges of Rapaxavis to modern birds shows Rapaxavis to be highly adapted to a grasping, arboreal lifestyle. The combination of strongly arboreal pedal adaptations and the probing adaptations in the rostrum is here confirmed in a member of the Enantiornithes for the first time in the literature, adding to their already impressive known functional diversity.
... Phalanges MACN PV RN 1103 and MACN PV RN 1104 are reminiscent of Enantiornithes in having the distal articular surface ovoid in lateral view, a well constricted shaft, dorsally oriented distal articular trochleae, and ellipsoidal and dorsally positioned distal flexor pits. This suite of features is present in known Enantiornithes such as Iberomesornis, Sinornis, and Soroavisaurus (Chiappe, 1993; Sereno, 2000; Sereno et al., 2002), but absent in the basal ornithuromorph Patagopteryx (Chiappe, 2002), and in Ornithurae such as Ichthyornis (Clarke, 2004), Hesperornithes (Martin and Tate, 1976), and Neornithes. The combination of features present in the distal end of the phalanges (MACN PV RN 1103 and MACN PV RN 1104) are also exhibited in the pedal phalanx II-2 of the non-avian theropod clade Dromaeosauridae (see Rauhut, 2003 ). ...
... Moreover, Alamitornis is reminiscent of Enantiornithes and Patagopteryx in having a very well developed humeral ventral tubercle. However, Alamitornis lacks most diagnostic features of enantiornithes, i.e., the head is not saddle-shaped, the ventral tubercle lacks any pneumatization, the humeral trochanter is absent, and there is no pneumatic foramen distal to the humeral head (Sereno, 2000). Additionally, Alamitornis resembles Vorona and Patagopteryx in having an expanded lateral supracondylar ridge of the femur, which ends in a well developed proximal tubercle . ...
... However, the femur of the new species differs from that of Vorona in having more gracile proportions, in lacking sharp intermuscular lines, and in having distal condyles that are only weakly directed caudally (see Forster et al., 2002). On the other hand, Alamitornis resembles Patagopteryx in several derived traits, such as: 1) the absence of proximal humeral pneumatization [although the humerus is also apneumatic in several basal birds, such as Archaeopteryx, Gansus, Apsaravis, most basal and derived birds exhibit different kinds of humeral pneumatization, including the peculiar humeral fenestra present in Sapeornis and Confuciusornithidae (Chiappe et al., 1999; Zhou and Zhang, 2003), the fossae present on the internal tuberosity of Enantiornithes (Sereno, 2000), and the pneumotricipital fossa of Enantiornithes, Ichthyornis and Neornithes (Hope, 2002)], 2) head globe-shaped in caudal view, 3) well excavated cranial humeral surface, and 4) deltopectoral crest directed nearly at a right angle with respect to the main axis of the bone (Chiappe, 2002; personal observations). Nevertheless , the humerus of Alamitornis differs from that of Patagopteryx in several features, such as the position and morphology of the internal tubercle and its extremely gracile proportions. ...
In this note we report new avian remains from the Late Cretaceous Los Alamitos Formation (Campanian-Maastrichtian) at the Los Alamitos locality, Río Negro Province, Argentina. Isolated remains referable to indeterminate Aves, ?Patagopterygiformes, indeterminate Ornithurae, cf. Hesperornithes and cf. Neornithes are described and discussed. The new genus and species Alamitornis minutus is erected to include a minute-sized and gracile bird, probably related to the non-volant ratite-like bird Patagopteryx. If correctly identified, the record of Hesperornithes may be the first for this group in the Southern Hemisphere. The Los Alamitos paleoavifauna represents one of the most diverse fossil bird assemblage from the Mesozoic of Gondwana known to date.
... These bones remain unfused to the metatarsals in adult specimens of Archaeopteryx (Wellnhofer, 1992) and Rahonavis (Forster et al., 1998). Free tarsals were also reported for the Spanish Early Cretaceous Iberomesornis (Sanz and Bonaparte, 1992), although this claim was refuted by Sereno (2000), who argued that the proximal ends of the metatarsals of this bird were fused to one another and to the distal tarsals. While the presence of these individual ossifications in Iberomesornis is inconclusive, Sereno's (2000) assertion that the metatarsals of this taxon were proximally fused is undoubtedly mistaken. ...
... Free tarsals were also reported for the Spanish Early Cretaceous Iberomesornis (Sanz and Bonaparte, 1992), although this claim was refuted by Sereno (2000), who argued that the proximal ends of the metatarsals of this bird were fused to one another and to the distal tarsals. While the presence of these individual ossifications in Iberomesornis is inconclusive, Sereno's (2000) assertion that the metatarsals of this taxon were proximally fused is undoubtedly mistaken. ...
Mesozoic remains of embryonic and early juvenile birds are rare. To date, a handful of in ovo embryos and early juveniles of enantiornithines from the Early Cretaceous of China and Spain and the Late Cretaceous of Mongolia and Argentina have comprised the entire published record of perinatal ontogenetic stages of Mesozoic birds. We report on the skeletal morphology of three nearly complete early juvenile avians from the renowned Early Cretaceous Yixian Formation of Liaoning Province in northeastern China. Evidence of the immaturity of these specimens is expressed in the intense grooving and pitting of the periosteal surfaces, the disproportionately small size of the sterna, and the relative size of the skull and orbits. Size notwithstanding, anatomical differences between these three specimens are minimal, leaving no basis for discriminating them into separate taxa. Numerous osteological synapomorphies indicate that they are euenantiornithine birds, the most diverse clade of Enantiornithes, but their identification as members of a particular euenantiornithine taxon remains unclear. Their early ontogenetic stage, however, provides important information about the postnatal development of this specious clade of Cretaceous birds. The presence of pennaceous wing feathers suggests that fledging occurred very early in ontogeny, thus supporting a precocial or highly precocial strategy for enantiornithine hatchlings. The morphology of these new early-stage juveniles is also significant in that they allow a better understanding of the homologies of several avian compound bones because the components of these skeletal compounds are preserved prior to their coossification. The general morphology of the wrist and ankle of these juveniles highlights once again the striking similarity between nonavian theropods and early birds.
... Yatenavis can be referred to Enantiornithes on the basis of a transversely expanded and craniocaudally compressed distal end of the humerus (width being three times maximum craniocaudal depth), weakly developed distal condyles, a ventral condyle almost transverse to the humeral shaft, and a very wide olecranal fossa (Sereno, 2000;Chiappe and Walker, 2002;Lawver et al., 2011). Yatenavis shares with select Late Cretaceous enantiornithines (e.g., Alexornis, Kizylkumavis, Martinavis, and the indeterminate enantiornithine from Chubut Province, Argentina e MPEF-PV 2359-, and Madagascar; Brodkorb, 1976;Nessov, 1984;Walker et al., 2007;Walker and Dyke, 2009;O'Connor and Forster, 2010;Lawver et al., 2011) the following features: 1) presence of a small but welldefined dorsal supracondylar process, and 2) presence of a caudal ridge on the ventral condyle distally (Lawver et al., 2011;Fig. ...
Enantiornithes were the dominant avialan clade in the Mesozoic. However, their record for the Upper Cretaceous is scarce. In this study, we present and describe Yatenavis ieujensis gen. et sp. nov., one of the youngest occurrence of an enantiornithine bird. The specimen, the distal half of a right humerus, was found in Chorrillo Formation, southern Santa Cruz Province of Argentina, making it also the australmost enantiornithine specimen recorded to date. Yatenavis is unique among enantiornithines for its combination of characters, including a crest on the medial side of the shaft which bears a muscular scar cranially; the presence of a dorsal supracondylar process proximal to the dorsal epicondyle; equally distally projected dorsal and ventral condyles; and a rod-like caudal extension of the ventral condyle bearing a distal sulcus scapulotricipitalis. Several of these features are shared with an unnamed enantiornithine recovered from Upper Cretaceous beds in another fossil site in Patagonia.
... In the pectoral girdle, the scapula has a large acromion and the coracoid shows the usual enantiornithine morphology of the proximal articular head, with the straight acrocoracoid proximodistally in line with the glenoid and flat scapular cotyla (Fig. 4). The weakly sigmoid humerus has a saddle-shaped proximal margin with concave cranial and convex caudal surfaces (Fig. 4); as in other Late Cretaceous enantiornithines, the epicondyles are round and bulbous (Sereno, 2000;Chiappe & Walker, 2002). The minor metacarpal projects distally farther than the major metacarpal. ...
A new enantiornithine bird is described on the basis of a well preserved partial skeleton from the Upper Cretaceous Qiupa Formation of Henan Province (central China). It provides new evidence about the osteology of Late Cretaceous enantiornithines, which are mainly known from isolated bones; in contrast, Early Cretaceous forms are often represented by complete skeletons. While the postcranial skeleton shows the usual distinctive characters of enantiornithines, the skull displays several features, including confluence of the antorbital fenestra and the orbit and loss of the postorbital, evolved convergently with modern birds. Although some enantiornithines retained primitive cranial morphologies into the latest Cretaceous Period, at least one lineage evolved cranial modifications that parallel those in modern birds.
... If these teeth belong to theropod dinosaurs other than carcharodontosaurid carcharodontosaurians, this means that the palaeobiodiversity of the theropods of the Early Cretaceous of Spain could be greater than previously thought (Gasca et al. 2014), including spinosaurids, diverse non-spinosaurid basal tetanurans such as carcharodontosaurids (Ortega et al. 2010;Gasca et al. 2014) and other clades (Canudo et al. 2006), ceratosaurs (Sánchez-Hernández andBenton 2014) and different coelurosaurs such as ornithomimosaurs (Pérez-Moreno et al. 1994), maniraptorans and birds (Sanz et al. 1988;Lacasa-Ruiz 1989;Sanz and Buscalioni 1992;Sanz et al. 1996;Sereno 2000). Nevertheless, further work is required to find more diagnostic skeletal remains in order to clarify this question. ...
Introduction
The relationship between dinosaur carcasses and isolated theropod teeth is well known in the fossil record. The usual explanation is that theropod dinosaurs fed on the herbivore carcass. Other evidence is provided by theropod tooth marks on the surface of herbivore skeletal remains. In this work we study isolated theropod teeth and the tooth marks in evidence on the bones of the sauropod from El Oterillo II (Salas de los Infantes, Spain, Lower Cretaceous). Theropod and crocodylomorph teeth have been found in relationship with the sauropod carcass. The fossils lie on channel lag deposits composed of sandstones with quartzite gravel.
Materials and methods
Thirty theropod teeth have been studied using qualitative features, statistical and cladistics analysis in addition to the tooth marks present on the vertebrae.
Results
The morphology of the theropod teeth has revealed greater palaeobiodiversity in these faunas than previously known, including baryonychine spinosaurids, basal tetanurans, dromaeosaurids and a singular coelurosaurian. The presence of tooth marks and isolated theropod teeth in close relationship with the sauropod carcass could also provide new evidence of the scavenging of theropod dinosaurs on the sauropods of this age and location.
Conclusions
Six morphotypes of theropod teeth have been distinguished; the combination of basal and derived tetanurans is congruent with the known record from the Early Cretaceous of the Iberian Peninsula. The most probable explanation for the association of isolated theropod teeth and sauropod remains is the scavenging of the carcass by theropod dinosaurs.
... If these teeth belong to theropod dinosaurs other than carcharodontosaurid carcharodontosaurians, this means that the palaeobiodiversity of the theropods of the Early Cretaceous of Spain could be greater than previously thought (Gasca et al. 2014), including spinosaurids, diverse non-spinosaurid basal tetanurans such as carcharodontosaurids (Ortega et al. 2010;Gasca et al. 2014) and other clades (Canudo et al. 2006), ceratosaurs (Sánchez-Hernández andBenton 2014) and different coelurosaurs such as ornithomimosaurs (Pérez-Moreno et al. 1994), maniraptorans and birds (Sanz et al. 1988;Lacasa-Ruiz 1989;Sanz and Buscalioni 1992;Sanz et al. 1996;Sereno 2000). Nevertheless, further work is required to find more diagnostic skeletal remains in order to clarify this question. ...
... It is characterized by a unique character combination, including strong coracoids, a furcula with a marked hypocleideum, a fused pelvis, sharply curved foot claws, and no evidence of metatarsal fusion Padian, 2004). Iberomesornis was first placed in an intermediate position between Archaeopteryx and modern birds, but new phylogenetic analyses shows that it is a basal enantiornithine (Sereno, 2000;Chiappe, 2001;. ...
... enantiornithines that pur− portedly reside outside Euenantiornithes are known from the Early Cretaceous of Spain: Iberomesornis romerali (Sanz and Bonaparte 1992) and Noguerornis gonzalezi (Lacasa− Ruiz 1989). In Iberomesornis, both the proximal and distal tarsals have been described as free, and the metatarsals ap− pear to be unfused (Sanz and Bonaparte 1992;Sanz et al. 2002; but see Sereno 2000). Conversely, in CAGS−IG−04− CM−007, the proximal tarsals are fused to the distal tibia, and the distal tarsals to the proximal surfaces of the metatarsals. ...
Although recent discoveries from Lower Cretaceous sediments in northeastern China have greatly improved our understanding of the initial stages of avian diversification in eastern Asia, the early evolution of Aves elsewhere on the continent remains poorly understood. In 2004, a collaborative field effort directed by personnel from the Chinese Academy of Geological Sciences and Carnegie Museum of Natural History recovered multiple partial to nearly complete avian skeletons from outcrops of the Lower Cretaceous Xiagou Formation exposed in the Changma Basin of northwestern Gansu Province, China. Here we describe a thrush-sized partial skeleton comprised of a fragmentary pelvic girdle and largely complete hind limbs. A phylogenetic analysis of 20 avian ingroup taxa and 169 anatomical characters places the specimen in Enantiomithes, and within that clade, in Enenantiomithes. When coupled with additional recent discoveries from the Changma Basin, the new skeleton improves our understanding of early avian evolution and diversification in central Asia.
... It is characterized by a unique character combination, including strong coracoids, a furcula with a marked hypocleideum, a fused pelvis, sharply curved foot claws, and no evidence of metatarsal fusion Padian, 2004). Iberomesornis was first placed in an intermediate position between Archaeopteryx and modern birds, but new phylogenetic analyses shows that it is a basal enantiornithine (Sereno, 2000;Chiappe, 2001;. ...
... Inclusion of UFRJ-DG 031 Av within data matrix offered by O'Connor and Zhou 31 results in a polytomy of most enantiornithine genera. However, UFRJ-DG 031 Av exhibits some general similarities with Iberomesornis, Pengornis, Eopengornis and Eoenantiornis, such as a humeral head globose and projected further proximally, a capital groove poorly defined on proximal humerus, and dorsal vertebral centra craniocaudally short 7,20,32,33 . However, the differences noted in the diagnosis and description preclude considering UFRJ-DG 031 Av as nearly related to any of these taxa until more evidence becomes available. ...
The fossil record of birds in the Mesozoic of Gondwana is mostly based on isolated and often poorly preserved specimens, none of which has preserved details on feather anatomy. We provide the description of a fossil bird represented by a skeleton with feathers from the Early Cretaceous of Gondwana (NE Brazil). The specimen sheds light on the homology and 3D structure of the rachis-dominated feathers, previously known from two-dimensional slabs. The rectrices exhibit a row of rounded spots, probably corresponding to some original colour pattern. The specimen supports the identification of the feather scapus as the rachis, which is notably robust and elliptical in cross-section. In spite of its juvenile nature, the tail plumage resembles the feathering of adult individuals of modern birds. Documentation of rachis-dominated tail in South American enantiornithines broadens the paleobiogeographic distribution of basal birds with this tail feather morphotype, up to now only reported from China.
... We believe the difference is due to overlap of the cranialmost sacral by other bones (e.g., pelvis) in the holotype of P. houi. The presence of eight sacrals is typical for Enantiornithes, as exemplified by Sinornis (Sereno et al., 2002), Iberomesornis (Sereno, 2000), Longipteryx , Vescornis and Rapaxavis . The synsacrum in V 18632 is longer than the ilia (Table 1). ...
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
... Free distal tarsals are still relatively rare among Mesozoic birds, having only recently been definitively reported for five taxa: Archaeopteryx (Wellnhofer, 1992), Rahonavis (Forster et al., 1998), the juvenile enantiornithine GMV-2158 (Chiappe et al., 2007b), Shenqiornis (Wang et al., 2010), and Rapaxavis (O' Connor et al., 2011). Their existence in Iberomesornis is still controversial (Sanz and Bonaparte, 1992;Sereno, 2000). The tarsal cap covers metatarsals III and IV. ...
ABSTRACT A new Late Cretaceous avian taxon, Parvavis chuxiongensis, gen. et sp. nov., is reported here based on an incomplete skeleton from Upper Cretaceous lake deposits in Yunnan Province, southern China. A phylogenetic analysis of 32 taxa and 242 morphological characters resulted in three most parsimonious trees, the strict consensus tree of which places Parvavis chuxiongensis within Enantiornithes. Histological study shows that the bones of Parvavis were composed of parallel-fibered bone tissue without lines of arrested growth, and indicated that growth rate had slowed but had not stopped at any stage prior to death. The bones also lack the rough surface texture seen in juvenile birds. Therefore, the new bird was probably close to adult body size at the time of death. However, the specimen is surprisingly small, highlighting the wide range of body sizes in Upper Cretaceous enantiornithines. The new specimen also represents both the first known bird from the Upper Cretaceous of China and the first Mesozoic bird from the south of China, and thus extends the temporal and geographic range of Mesozoic birds in China. SUPPLEMENTAL DATA?Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
... We identify Intiornis as a member of Enantiornithes on the basis of the following traits: tibiotarsus with a bulbous and inflated medial condyle (much larger than the lateral one) with its cranial surface nearly flat, a condition that is mirrored by an enlarged medial cotyle of the tarsometatarsus; distal articular surface of metatarsal II expanded, being larger than that of the metatarsal III, and ungual of digit I very large, with enlarged proximal surface for articulation with the first phalanx (Kurochkin, 1995;Martin, 1995;Sereno, 2000;Walker, 1981). In addition, Intiornis lacks several traits diagnostic of the more derived Ornithuromorpha, including metatarsal III not displaced plantarly with respect to metatarsals II and IV, absence of a proximal vascular foramen, and trochlea of metatarsal III poorly developed (Kurochkin, 2000). ...
A new enantiornithine bird, Intiornis inexpectatus gen. et sp. nov, is described here. It is based on a partial hind limb found in beds of the Upper Cretaceous Las Curtiembres Formation (Campanian), North-West Argentina. The new taxon is referred to the family Avisauridae on the basis of its cranially convex third metatarsal. Several features suggest close relationships between Intiornis and the avisaurid Soroavisaurus, from the Lecho Formation (Maastrichtian; North-West Argentina). Intiornis was the size of a sparrow, thus representing the smallest Enantiornithes known from South America. The new species shows adaptations for a perching mode of life. Moreover, the hypothesis suggesting that the flying pterosaur reptiles decrease in taxonomic diversity due to competitive interaction with birds is discussed. The new species shows adaptations for a perching mode of life. Moreover, the hypothesis suggesting that the flying pterosaur reptiles decrease in taxonomic diversity due to competitive interaction with birds is discussed.
... The acute angle subtended by the long axes of the humeral distal condyles in CM-023 renders it more similar to Cathayornis yandica (Zhou and Hou 2002), Eocathayornis (Zhou 2002), and Vescornis hebeiensis (Zhang et al. 2004) than to to many other enantiornitheans, such as those from the Lecho Formation, in which the condylar long axes are close to parallel (Chiappe and Walker 2002). The ulna:radius width ratio of CM-023 (1.7) is similar to that of Longipteryx chaoyangensis (Zhang et al. 2001), smaller than the typical, approximately 2.0 ratio reported for most other enantiornitheans, including Eoenantiornis buhleri and the possibly basal ( Elzanowski 1981; Gong et al. 2004; Hou et al. 2004; Sanz et al. 1995 Sanz et al. , 1996 Sanz et al. , 2002 Sereno 2000; Sereno et al. 2002; Zhang and Zhou 2000; Zhou and Hou 2002; Zhou et al. 2005), but is greater than the subequal dimensions reported for Noguerornis gonzalezi (Chiappe and Lacasa-Ruiz 2002), the ratio of roughly 1.3 reported for Eocathayornis (Zhou 2002), and the ratio of about 1.5 in Cathayornis (Zhou and Hou 2002). There is no pit on the olecranon process of CM-023 like the one reported in Alexornis antecedens (Brodkorb 1976). ...
A new specimen of an enantiornithean bird from the Lower Cretaceous Xiagou Formation of Gansu Province, northwestern China, consists of an articulated distal left humerus, ulna, radius, carpus, and manus. The specimen may represent a primitive enantiornithean because it lacks a longitudinal sulcus on the radius, has incompletely fused alular and major metacarpals, and possibly retains a remnant of a second phalanx on the minor digit. It differs from all other known enantiornitheans, and exhibits possible autapomorphies, including peculiar, flat humeral epicondyles, a pair of eminences on the distal minor metacarpal, and an enormous flexor tuberculum on the alular ungual. The specimen probably pertains to the same taxon as a previously described enantiornithean arm from Changma; the incompleteness of the taxon precludes erecting a new name, but it provides new information concerning enantiornithean diversity in the Early Cretaceous of central Asia.
... However, CPP 482 differs from Confuciusornis and resembles enantiornithine birds in lacking a medial crest above the distal articular surface and in lacking a transverse ridge delimiting the proximal end of the extensor pit (Chiappe et al. 1999). Moreover, the medial distal ring of the articular trochlea of CPP 482 extends farther distally than the lateral ring, a condition considered as synapomorphic of Enantiornithes (Sereno 2000). Although proximally incomplete, the preserved portion of shaft of CPP 482 differs from the derived Avisauridae in having a flat, rather than convex, dorsal surface of metatarsal III (Chiappe 1993). ...
We report on the first occurrence of Maastrichtian bird material from the Peirópolis locality (Uberaba district), Minas Gerais State (Brazil). The specimens consist of an indeterminate pedal ungual phalanx (CPP 481), a pedal phalanx 1 of left digit II (CPP 470) and an incomplete metatarsal III (CPP 482). The material can be assigned to Aves gen. et sp. indet. (CPP 470 and CPP 481) and to cf. Enantiornithes gen. et sp. indet. (CPP 482). Despite the isolated and incompleteness nature of these specimens, they add to the otherwise poor record of Cretaceous birds from Brazil.
... The Late Cretaceous long−tailed Rahonavis preserves a single distal tarsal over the fourth metatarsal (Forster et al. 1998). A tarsal cap fused to the proximal ends of the metatarsals was reported in Ibero− mesornis (Sereno 2000), although Sanz and Bonaparte (1992) considered the tarsals in this subadult specimen to be separate, as they are interpreted here. A juvenile enantio− rnithine from Liaoning, GMV 2158, preserves a single small, free distal tarsal located between the proximal ends of meta− tarsals II and III (Chiappe et al. 2007). ...
The exquisitely preserved longipterygid enantiornithine Rapaxavis pani is redescribed here after more extensive preparation. A complete review of its morphology is presented based on information gathered before and after preparation. Among other features, Rapaxavis pani is characterized by having an elongate rostrum (close to 60% of the skull length), rostrally restricted dentition, and schizorhinal external nares. Yet, the most puzzling feature of this bird is the presence of a pair of pectoral bones (here termed paracoracoidal ossifications) that, with the exception of the enantiornithine Concornis lacustris, are unknown within Aves. Particularly notable is the presence of a distal tarsal cap, formed by the fusion of distal tarsal elements, a feature that is controversial in non-ornithuromorph birds. The holotype and only known specimen of Rapaxavis pani thus reveals important information for better understanding the anatomy and phylogenetic relationships of longipterygids, in particular, as well as basal birds as a whole.
... , 1995b), y un diente de teropodo indeterminado (Buscalioni et a!., 1988) (Sanz et aI. , 1994, Sereno, 2000, y un «pellet» (pelota de regurgitacion) con restos postcraneales de cuatro aves enantiornitas juveniles, pertenecientes a tres especies distintas a), En el Valanginiense-Hauteriviense de Masegosa, Sanz ( 1985) describe una vertebra caudal de ornitopodo que asigna a Iguanodon bernissartensis tomando como base su gran tamafio. Como Ruiz-Omefiaca et aL (1998c) ponen de manifiesto, el tamafio no es un can'tcter diagnostico en las especies de Iguanodon , por 10 que es mas correcto asignar la vertebra a Iguanodon sp. ...
... Most paleontological workers are most comfortable with the traditional Owenian terminology as evidenced by its continued dominance in, or mixture with, standardized terminology in recent papers. Oddly, even in situations where the NAA should apply, such as descriptions of basal, and even some derived, fossil avians, this continues to be true (Sereno, 2000;Zhang et al., 2001;Chatterjee, 2002). In scope, however, the switch is no different than either the original change in the late 1800s-early 1900s from numerous regional anatomical nomenclatural systems to a single in-ternational one (ICVGAN, 1994). ...
At present, three different systems of anatomical nomenclature are available to researchers describing new tetrapod taxa: a nonstandardized traditional system erected in part by Sir Richard Owen and subsequently elaborated by Alfred Romer; a standardized system created for avians, the Nomina Anatomica Avium (NAA); and a standardized system for extant (crown-group) mammals, the Nomina Anatomica Veterinaria (NAV). Conserved homologous structures widely distributed within the Tetrapoda are often granted different names in each system. The recent shift toward a phylogenetic system based on homology requires a concomitant shift toward a single nomenclatural system also based on both evolutionary and functional morphological homology. Standardized terms employed in the NAA and NAV should be perpetuated as far as possible basally in their respective phylogenies. Thus, NAA terms apply to nonavian archosaurs (or even all diapsids) and NAV terms apply to noncrown-group mammals and more basal synapsids. Taxa equally distant from both avians and crown-group mammals may maintain the traditional nonstandardized terminology until a universal anatomical nomenclature for all tetrapods is constructed.
An unabated surge of new and important discoveries continues to transform knowledge of pen-naraptoran biology and evolution amassed over the last 150+ years. This chapter summarizes progress made thus far in sampling the pennaraptoran fossil record of the Mesozoic and Paleocene and proposes priority areas of attention moving forward. Oviraptorosaurians are bizarre, nonparavian pennaraptorans first discovered in North America and Mongolia within Late Cretaceous rocks in the early 20th century. We now know that oviraptorosaurians also occupied the Early Cretaceous and their unquestionable fossil record is currently limited to Laurasia. Early Cretaceous material from China preserves feathers and other soft tissues and ingested remains including gastroliths and other stomach contents, while brooding specimens and age-structured, single-species accumulations from China and Mongolia provide spectacular behavioral insights. Less specialized early oviraptorosaurians like Incisivosaurus and Microvenator remain rare, and ancestral forms expected in the Late Jurassic are yet to be discovered, although some authors have suggested Epidexipteryx and possibly other scansoriopterygids may represent early-diverging oviraptorosaurians. Long-armed scansoriopterygids from the Middle-Late Jurassic of Laurasia are either early-diverging oviraptorosaurians or paravians, and some have considered them to be early-diverging avialans. Known from five (or possibly six) feathered specimens from China, only two mature individuals exist, representing these taxa. These taxa, Yi and Ambopteryx, preserve stylopod-supported wing membranes that are the only known alternative to the feathered, muscular wings that had been exclusively associated with dinosaurian flight. Thus, scansoriopterygid specimens-particularly those preserving soft tissue-remain a key priority for future specimen collection. Dromaeosaurids and troodontids were first discovered in North America and Mongolia in Late Cretaceous rocks. More recent discoveries show that these animals originated in the Late Jurassic, were strikingly feathered, lived across diverse climes and environments, and at least in the case of dromaeosaurids, attained a global distribution and the potential for aerial locomotion at small size.
An unabated surge of new and important discoveries continues to transform knowledge of pen-naraptoran biology and evolution amassed over the last 150+ years. This chapter summarizes progress made thus far in sampling the pennaraptoran fossil record of the Mesozoic and Paleocene and proposes priority areas of attention moving forward. Oviraptorosaurians are bizarre, nonparavian pennaraptorans first discovered in North America and Mongolia within Late Cretaceous rocks in the early 20th century. We now know that oviraptorosaurians also occupied the Early Cretaceous and their unquestionable fossil record is currently limited to Laurasia. Early Cretaceous material from China preserves feathers and other soft tissues and ingested remains including gastroliths and other stomach contents, while brooding specimens and age-structured, single-species accumulations from China and Mongolia provide spectacular behavioral insights. Less specialized early oviraptorosaurians like Incisivosaurus and Microvenator remain rare, and ancestral forms expected in the Late Jurassic are yet to be discovered, although some authors have suggested Epidexipteryx and possibly other scansoriopterygids may represent early-diverging oviraptorosaurians. Long-armed scansoriopterygids from the Middle-Late Jurassic of Laurasia are either early-diverging oviraptorosaurians or paravians, and some have considered them to be early-diverging avialans. Known from five (or possibly six) feathered specimens from China, only two mature individuals exist, representing these taxa. These taxa, Yi and Ambopteryx, preserve stylopod-supported wing membranes that are the only known alternative to the feathered, muscular wings that had been exclusively associated with dinosaurian flight. Thus, scansoriopterygid specimens-particularly those preserving soft tissue-remain a key priority for future specimen collection. Dromaeosaurids and troodontids were first discovered in North America and Mongolia in Late Cretaceous rocks. More recent discoveries show that these animals originated in the Late Jurassic, were strikingly feathered, lived across diverse climes and environments, and at least in the case of dromaeosaurids, attained a global distribution and the potential for aerial locomotion at small size.
The Sihedang locality of the Lower Cretaceous Yixian Formation is the only recognized ornithuromorph-dominated locality in the Jehol Group of north-eastern China. Here we report on the first enantiornithine from this locality and erect a new taxon Monoenantiornis sihedangia gen. et sp. nov. The holotype and only specimen preserves a rare ontogenetic stage in which the intermedium is ossified but free from the other proximal tarsals and the tibia, consistent with the pattern of ossification that occurs in neornithines. In order to explore the pattern of skeletal development in the enantiornithines, we select several published specimens inferred to represent different ontogenetic stages and document their degree of fusion in five key compound bones and the sterna. This provides a preliminary hypothesis for the sequence in which compound bones form in Early Cretaceous enantiornithines. From this hypothesis, most known specimens can be categorized into four major ontogenetic stages: all the compound bones unfused; synsacrum and pygostyle fused; tarsals fused; tibiotarsus and carpometacarpus formed.
http://zoobank.org/urn:lsid:zoobank.org:pub:347485CA-87E6-4834-BEB5-687B6798644E
This work serves as a compendium of anatomical resources upon which a companion phylogenetic analysis of Aves and related Theropoda (Avialae) was based (Livezey and Zusi 2006). Following a brief historical overview of avian anatomy and avian systematics, the rich published literature pertinent to these topics is classified chronologically and geographically. The former also was organized with respect to eras of predominant methodologies in avian systematics, with an emphasis on recent paleontological finds bearing importantly on the origins of modern birds (Neornithes). This was followed by an exposition on the theoretical and abstract underpinnings of morphological characterization for purposes of phylogenetic reconstructions (to be published separately), with aspects of analysis for phylogenetic inference (e.g., tactics for employment of currently available software, ordering, criteria for optimization of trees) considered elsewhere. The principal contribution of this exposition is a listing of characters and states manifesting what was inferred to hold promise with respect to phylogenetic or historical signal. In total, 2,954 anatomical characters were defined—2,451 osteological, 256 myological, and 247 miscellaneous—of which 981 (approximately one-third) were multiple-state (i.e., comprised three or more states), the latter including 537 characters treated as ordered. Bibliographic provenance for characters was provided, where possible, but exact equivalence of characters and states among workers was seldom feasible. In many cases, previously published characters were listed on the grounds that these pertained most closely to the structure or complex at hand in the present study, and that such listings provided at least a historical grasp of the magnitude of prior usages of a given character. We also summarized, to the extent feasible, previously published characters for which inclusion in the present work was judged to be unreliable or lacking sufficient clarity. In addition to the descriptions of characters, a limited series of figures are provided, in no small part to ameliorate the challenges posed by new terms and formal anatomical nomenclature. We are adherents to nomenclatural formalism (Livezey and Zusi 2001) in anatomical contexts sensu the ICAAN (International Committee on Avian Anatomical Nomenclature; Baumel 1993). I.e., we consider that characters and states—implicitly proposals of homology—warrant clarity with respect to surrounding text in the same sense that binomial taxa—i.e., as hypotheses of historical lineages—are subject to formal conventions. Finally, literature cited herein is listed, as a work of this kind is impossible without access to the wealth of information and insight provided by such a resource. As this literature is integrated by citation with the descriptions of characters, it is hoped that the bibliography will lessen the challenges posed by a deep, multilingual, and variably technical literature for systematists using these descriptions. The dimension of the character matrix also led us to enclose a CD of the data set in the present work to assist those seeking to improve, append, or refine our efforts. A phylogenetic (cladistic) analysis of these data will appear separately (Livezey and Zusi 2006). Soon thereafter a collaboration with an unparalleled compilation of molecular data (i.e., DNA sequences) and confirmatory paleontological data is planned to conclude with the publication of a total-evidence analysis of avian phylogeny under the auspices of the NSF “Tree of Life” program, one to encompass extant birds (Neornithes), avian relatives from the Mesozoic (outgroups), and nonavialian fossil taxa from the Mesozoic (“deep” outgroups).
An isolated coracoid represents the first described occurrence of an enantiornithine bird from the Kaiparowits Formation (Upper Cretaceous) of southern Utah, USA. The specimen is identified as enantiornithine by the convex scapular facet, approximate alignment of this facet with the humeral articular facet and acrocoracoid process, and the presence of an acrocoracoidal tubercle. This coracoid came from a comparatively large individual, consistent with previous reports of other large enantiornithines from strata of Campanian strata in North America, South America, and Europe. The occurrence of enantiornithines in the Kaiparowits Formation and their apparent absence in the well-sampled Dinosaur Park Formation of similar age in Alberta represents yet another faunal difference between the two areas, although this may be a result of environmental differences rather than the endemism proposed for non-avian dinosaurs.
A tibiotarsus of an archaic bird from the Upper Cretaceous of Fox-Amphoux (Var, southern France) is described and referred to the Enantiornithes. Taken together with other recent discoveries of Late Cretaceous birds from France, this find suggests that at the end of the Cretaceous, the European avifauna was dominated by archaic forms.
Recent field efforts in the Mahajanga Basin of northwestern Madagascar have recovered a diverse Late Cretaceous terrestrial and freshwater vertebrate fauna, including a growing diversity of avialans. Previous work on associated bird skeletons resulted in the description of two named avialans (Rahonavis, Vorona). Other materials, including two synsacra and numerous appendicular elements, represent at least five additional taxa of basal (non-neornithine) birds. Among the materials described herein are two humeri tentatively referred to Rahonavis and numerous elements (e.g., humeri, ulnae, tibiotarsi, tarsometatarsi) assigned to Vorona. A near-complete carpometacarpus exhibits a minor metacarpal that exceeds the major metacarpal in length, documenting an enantiornithine in the fauna. Moreover, two additional, small humeri, an ulna, a femur, and a tarsometatarsus also compare favorably with enantiornithines. Finally, two other isolated humeri and a synsacrum are referable to Ornithurae. The latter specimen is notable in the presence of distinct, transversely oriented lumbosacral canals along the inner surface of the bony neural canal. This reveals for the first time a hard-tissue correlate of an anatomical specialization related to increased sensorimotor integration, one likely related to the unique form of avialan bipedal locomotion. Bird fossils recovered from the Maevarano Formation document one of the most size- and phylogenetically diverse Cretaceous-age Gondwanan avifaunas, including representative (1) basal pygostylian, (2) enantiornithine, (3) nonenantiornithine, ornithothoracine, and (4) ornithurine taxa. This Maastrichtian avifauna is notable in that it demonstrates the co-existence of multiple clades of basal (non-neornithine) birds until at least the end of the Mesozoic.
In recent years, the Lower Cretaceous (Aptian) Xiagou Formation has yielded approximately 100 avian partial skeletons, many with soft-tissue traces, from sites in the Changma Basin of Gansu Province, north-western China. The most abundant taxon amongst these is the ornithuromorph Gansus yumenensis, but enantiornithines have also been identified in the sample. Here we describe two incomplete, semi-articulated appendicular skeletons, the first consisting of a partial left pelvic girdle and complete pelvic limb, and the second comprised of a nearly complete right pelvic limb. Both specimens bear characteristics diagnostic of Enantiornithes, and are referred to a new taxon, Qiliania graffinigen. et sp. nov. The exceptional, three-dimensional preservation of these specimens (compared to the crushed, nearly two-dimensional condition of most other Early Cretaceous avian fossils) reveals new information regarding enantiornithine anatomy, evolution, and diversity.
© 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162, 201–219.
Review of Cunampaia simplex Rusconi 1946 (Crocodylomorpha, Mesoeucrocodylia; non Aves) from the Lower Tertiary of Mendoza, Argentina. In this paper we review and analyze the systematic position of Cunampaia simplex from the Eocene of the Mendoza Province, Argentina, a controversial taxon which was originally described as a bird. This taxon is here excluded from Aves and referred to Crocodylomorpha. ____________ La familia monotípica Cunampaiidae fue eri-gida por Rusconi (1946a) para incluir el género y especie Cunampaia simplex dentro de las aves fororracoideas (Ralliformes, Phororhacoidea). Posteriormente el mismo autor (1946b) descri-bió en detalle este taxón y remarcó numerosas peculiaridades únicas de Cunampaia entre las aves. El material tipo de esta especie lo compo-nen (según Rusconi, 1946a) una ulna, radio, meta-carpianos, tibia, fíbula y fémur incomple-tos, los cuales fueron hallados asociados, por lo que se interpretan como pertenecientes a un único ejemplar. El citado material procede de las cercanías de la ciudad de Mendoza (Argentina), Formación Divisadero Largo (Chiotti, 1946) de donde también se han colectado otros verte-brados fósiles como tortugas (Minoprio, 1947), cocodrilos (Rusconi 1946b; Gasparini, 1972) y mamíferos (Rusconi, 1946b; Minoprio, 1947; López, 2002). Entre los Crocodyliformes se en-cuentran: Ilchunaia parca (Rusconi, 1946a) y cf. Bretesuchus (Gasparini et al., 1993), ambos asig-nados a Sebecosuchia. Debido a la pérdida del holotipo de Cunam-paia simplex (Cerdeño, 2005), sumado a las par-ticularidades del material remarcadas por Rusconi (1946a), algunos autores han cuestio-nado la posición sistemática de la familia Cunampaiidae y consideraron al menos dudosa su pertenencia a Phororracoidea e inclusive a Ralliformes (Tonni, 1980; Olson, 1985; Tam-bussi & Noriega, 1996; Alvarenga & Höfling, 2003). A pesar de las relaciones inciertas dentro de la clase Aves, la familia Cunampaiidae ha sido utilizada como ejemplo de un linaje endémico de América del Sur, teniendo esto implicancias en el análisis de la dinámica de las avifaunas del Terciario sudamericano (Vuilleumier, 1984, 1985, 1987). Sin embargo, la pertenencia de Cunam-paia al grupo Aves nunca fue cuestionada. La lo-calización del holotipo sobre el cual Rusconi fun-dó la especie Cunampaia simplex permite revi-sar dicho material y precisar la posición taxo-nómica del citado taxón. En esta nota se adopta la terminología ana-tómica de Baumel y Witmer (1993), y la nomen-clatura sistemática empleada por Buckley & Brochu (1999).
Abstract An incomplete caudal vertebral series (IVPP V11309) from the Yixian Formation of late Mesozoic, Jianshangou area of Beipiao, western Liaoning Province, may represent a new bird. The tail is composed of at least 12 free caudal vertebrae and the most distal 5 caudal vertebrae co-ossified into a pygostyle. The pygostyle is plate-like and slightly curved dorsally. The anterior free caudals are amphiplatyan. The anterior caudal surfaces of the last three free caudals are concave, but their posterior articular surfaces are convex. The pygostyle is regarded as the first appeared flight apparatus during the evolutionary process from Archaeopteryx to neornithes. The pygostyle appeared in most early fossil birds and almost all the modern birds. Although their morphologies are different, they are basically formed by at least four last caudal vertebrae. The specimen V11309 is regarded as a bird rather than a non-avian theropod dinosaur based on the following characters: short caudal vertebrae, numerous pits present on the surfaces of the centra and, a foramen present between the basal part of the fused neural spines, which is similar to that of Struthio camelus. The discoveries of pygostyles from the therizinosauroids and oviraptorosaurs may provide strong evidence for supporting the origin of birds from small theropod dinosaurs. The structure of the pygostyle in specimen V11309 is different from those of Beipiaosaurus (Therizinosauroid) and Nomingia (oviraptorosaur). The most parsimonious interpretation is that these pygostyle-like structures are independently acquired by Beipiaosaurus and Nomingia during their evolutionary process.
The origin of flight in birds and theropod dinosaurs is a many-sided and debatable problem. We develop a new approach to the
resolution of this problem, combining terrestrial and arboreal hypotheses of the origin of flight. The bipedalism was a key
adaptation for the development of flight in both birds and theropods. The bipedalism dismissed the forelimbs from the supporting
function and promoted transformation into wings. For the development of true flapping avian flight, a key role was played
by the initial universal anisodactylous foot of birds. This foot pattern provided a firm support on both land and trees. Theropod
dinosaurs, archaeopteryxes, and some other early feathered creatures had a pamprodactylous foot and, hence, they developed
only gliding descent. Early birds descended by flattering parachuting with the use of incipient wings; this gave rise to true
flight. Among terrestrial vertebrates, only bats, pterosaurians, and birds developed true flapping flight, although they followed
different morphofunctional pathways when solving this task. However, it remains uncertain what initiated the adaptation of
the three groups for the air locomotion. Nevertheless, the past decade has provided unexpectedly abundant paleontological
data, which facilitate the resolution of this question with reference to birds.
KeywordsAves–Enantiornithes–
Archaeopteryx
–Theropoda–Ornithurae–Mesozoic–origin of flight
Based on evolutionary morphological analysis of the fore and hind limbs of extinct and extant birds, a new compromise hypothesis
of the origin of flight in birds and theropod dinosaurs is proposed. The bipedalism and anisodactylous foot suitable for various
functions were key adaptations for the development of flight. The bipedalism freed forelimbs from the supporting function
and promoted transformation into wings, as animals moved from one tree branch to another and descended from trees. At the
initial stage, the strong hind limbs provided the opportunity to climb and leap onto trees, bushes, or eminence, while the
anisodactylous foot provided a firm support on both dry land and trees. The support provided by this foot allowed the reduction
of the tail, which was initially composed of a long row of vertebrae. Thus, a stage of gliding flight was not necessarily
passed by early birds. In the other lineages of feathered creatures, functional changes in forelimbs that resulted in the
formation of wings developed in parallel and followed almost the same scenario.
In the present paper we analyze the phylogenetic position of the derived Gondwanan theropod clade Unenlagiidae. Although this group has been frequently considered as deeply nested within Deinonychosauria and Dromaeosauridae, most of the features supporting this interpretation are conflictive, at least. Modification of integrative databases, such as that recently published by Hu et al. (2009), produces significant changes in the topological distribution of taxa within Deinonychosauria, depicting unenlagiids outside this clade. Our analysis retrieves, in contrast, a monophyletic Avialae formed by Unenlagiidae plus Aves.
Use of transgenic maize expressing phytase in seeds as feedstuff can greatly increase phosphate availability to livestock and poultry. Because phosphorus is an essential mineral for all living organisms, growing of phytase transgenic maize may affect the performance of the arthropod community in maize fields. We conducted a preliminary study to assess the potential effects of phytase transgenic maize (BVLA430101) on two herbivore species, Ostrinia furnacalis (Guenée) and Helicoverpa armigera (Hübner), both of which are directly exposed to high concentrations of phytase caused by ingestion of transgenic maize kernels. Our results showed that for both species, survival and duration of the first and second instars and fresh weight of the third instar were not affected when fed transgenic phytase maize kernels compared with those fed nontransformed near isoline kernels. Similarly, there was no statistical difference detected for the same life table parameters when the herbivores were fed artificial diet containing either transgenic phytase maize meal or nontransformed maize meal. In addition, the nutrition utilization of the two species was evaluated with the same diet treatments by comparing the following indices: relative food consumption rate (RCR), relative metabolic rate (RMR), efficiency of approximate digestibility (EAD), efficiency of conversation of ingested food (ECI), and efficiency of conversation of digested food (ECD). No statistical difference was detected for any index of either species between transgenic maize and nontransformed maize treatments. These results provide useful baseline information for further studies to assess the potential effects of phytase transgenic maize on other arthropods in maize fields.
Information on the first steps of the avian evolutionary history has dramatically increased during the last few years. The fossil record provides a general view of the morphological changes of the avian flight apparatus from nonvolant ancestors (non-avian theropod dinosaurs) to the first derived fliers of the Early Cretaceous. The Las Hoyas bird record includes three genera: Iberomesornis, Concornis and Eoalulavis. This fossil material has yielded information about the early avian evolutionary history. These Early Cretaceous birds (some 120 Myr old) had a wingbeat cycle and breathing devices similar to those of extant birds. The function of the rectricial fan was also similar. In the evolutionary transition from cursorial ancestors to derived fliers it is possible to verify a trend to increase lift. Primitive wing aspect ratio morphotypes were elliptical ones, other derived morphotypes appeared, for example, in the Neornithes (extant birds). Some primitive fliers, like the Las Hoyas genus Eoalulavis, had an alula (feathers attached to the first digit of the hand) similar to that of present day birds, indicating braking and manoeuvring skills similar to those of their extant relatives. Primitive avian life habits are poorly understood. Some evidence from the Las Hoyas bird record indicates that Early Cretaceous birds were present in the trophic chains.
The study of the origin and early evolution of birds has never produced as much excitement and public attention as in the past decade. Well preserved and abundant new fossils of birds and dinosaurs have provided unprecedented new evidence on the dinosaurian origin of birds, the arboreal origin of avian flight, and the origin of feathers prior to flapping flight. The Mesozoic avian assemblage mainly comprises two major lineages: the prevalent extinct group Enantiornithes, and the Ornithurae, which gave rise to all modern birds, as well as several more basal taxa. Cretaceous birds radiated into various paleoecological niches that included fish- and seed-eating. Significant size and morphological differences and variation in flight capabilities, ranging from gliding to powerful flight among early birds, highlight the diversification of birds in the Early Cretaceous. There is little evidence, however, to support a Mesozoic origin of modern avian groups. Controversy and debate, nevertheless, surround many of these findings, and more details are needed to give a better appreciation of the significance of these new discoveries.
The Neocomian Spanish outcrops of Montsec (province of Lérida) and the new one of Las Hoyas (province of Cuenca) have yielded several avian remains in the last few years. Several isolated feathers have been reported from Montsec, and a specimen of some feathered wing bones has recently been found. Las Hoyas has yielded an isolated feather and a nearly articulated small fossil bird that lacks the skull. This new specimen, reported here, presents a combination of derived (strut-like coracoids, pygostyle) and primitive (pelvic girdle, sacrum, hind limb) character states. If one considers Archaeopteryx, Ornithurae and the new Spanish fossil bird, it seems clear that the latter taxon is the sister group of Ornithurae (extant birds and all other fossil birds that are closer to recent forms than is Archaeopteryx).
More than half of the evolutionary history of birds is played out in the Mesozoic. A recent burst of fossil discoveries has documented a tremendous diversity of early avians. Clarification of the Phylogenetic structure of this diversity has provided clues for a better understanding of the evolution of functional, developmental and physiological characteristics of modern birds. Yet their long Mesozoic history is only beginning to be deciphered.
A feathered skeleton of a Lower Cretaceous enantiornithine bird from Spain indicates that the modified diapsid skull of modern
birds did not evolve until late in their evolution: Basal birds retained an essentially primitive diapsid design. The fossil
provides data clarifying long-standing debates on the cranial morphology of the basalmost bird, Archaeopteryx. It also reemphasizes the notion that the early morphological transformations of birds were focused on the flight apparatus.
This fossil was a nestling and suggests that early postnatal developments in the Cretaceous enantiornithine birds and those
in their extant counterparts are comparable.
A partial skeleton of a primitive bird, Rahona ostromi, gen. et sp. nov., has been discovered from the Late Cretaceous of Madagascar. This specimen, although exhibiting avian features such as a reversed hallux and ulnar papillae, retains characteristics that indicate a theropod ancestry, including a pubic foot and hyposphene-hypantra vertebral articulations. Rahona has a robust, hyperextendible second digit on the hind foot that terminates in a sicklelike claw, a unique characteristic of the theropod groups Troodontidae and Dromaeosauridae. A phylogenetic analysis places Rahona with Archaeopteryx, making Rahona one of the most primitive birds yet discovered.
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.
It is described in this paper for the frrst time the fossil bird skeleton found at the famous quarry of Iimestones of Montsec mountain dated from Early Cretaceous. Unfortunately it is only preserved a few part of this skeleton concerning to the fore arms mainly. The few characters preserved do not allow to assign any taxonomic position but they show some mixed signs between the Sauriurae and Ornithurae.
Se describe el primer esqueleto fósil perteneciente a un ave hallada en la célebre cantera de calizas litográficas del Montsec de edad Neocomiense. Desafortunadamente solamente se ha preservado una pequeña parte de dicho esqueleto relativa a los miembros anteriores principalmente. Los pocos caracteres conservados no permiten adscripción taxonómica aunque presentan rasgos mixtos entre la Saururas y Omithuras.
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.
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.
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'.
Fossil bird skeletons discovered in Lower Cretaceous lake deposits in China shed new light on the early evolution of avian
flight and perching. The 135 million-year-old sparrow-sized skeletons represent a new avian, Sinornis santensis, n. gen. n. sp., that preserves striking primitive features such as a flexible manus with unguals, a footed pubis, and stomach
ribs (gastralia). In contrast to Archaeoperyx, however, Sinornis exhibits advanced features such as a broad sternum, wing-folding mechanism, pygostyle, and large fully reversed hallux. Modern
avian flight function and perching capability, therefore, must have evolved in small-bodied birds in inland habitats not long
after Archaeopteryx.