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1.
Here we describe the well-preserved skull of a juvenile specimen of Sapeornis, STM 16-18. Only the tail and hindlimb plumage of this specimen have been previously described. It preserves what we consider to be the complete dentition of Sapeornis with four premaxillary teeth, three maxillary teeth and two tiny dentary teeth on each side, the latter feature being previously unknown for this taxon. Based on a study of 71 specimens of Sapeornis preserving dentition, we infer the absence of dentary teeth in previously described specimens of Sapeornis is taphonomic, and consider the true dental formula of Sapeornis to be 4-3-2 (premaxillary teeth number – maxillary teeth number – dentary teeth number). Rostral to the dentary teeth, STM 16-18 preserves three shallow, empty aveoli. We hypothesize that this morphology captures an early stage in dental reduction and indicates that in at least some avian lineages, the loss of teeth was gradual. 相似文献
2.
Ornithuromorph birds (the clade which includes modern avian radiation) first appeared in the Early Cretaceous in Asia and achieved a great diversity during the latest ages of the Late Cretaceous (Campanian and Maastrichtian). The evolutionary history of orithuromorphs during the first 17 MYAs of the Late Cretaceous (Cenomanian to Santonian ages) remains very poorly known, as the fossil record for this time interval is largely restricted to several isolated finds of the classic avian genus Ichthyornis in North America. Here we describe an isolated distal tibiotarsus of an evolutionary advanced bird, morphologically similar to Ichthyornis, from the middle Cenomanian of Saratov Province, European Russia. This is the first documentation of an Ichthyornis-like bird in the Old World. The find further constitutes only the second pre-Campanian record of the Late Cretaceous Ornithuromorpha in Eurasia, the second record of Cenomanian birds in Russia. This discovery shows that Ichthyornis-like birds enjoyed a wide geographical distribution as early as the beginning of the Late Cretaceous. Given that the earliest and the most primitive ornithuromorph birds are known from Asia, the new find supports a Eurasian origin for Ichthyornithidae. 相似文献
3.
Anchiornis huxleyi, which is a member of the Middle–Late Jurassic Yanliao Biota, is the smallest feathered dinosaur ever known. It has been described as a critical link between feathered dinosaurs and birds. Recent studies, including those of Anchiornis, Xiaotingia, Eosinopteryx and Aurornis, challenged Archaeopteryx as the most basal bird. The new Anchiornis huxleyi specimens that are described in this paper show some minor different characters compared to previously reported Anchiornis specimens, which has revised the character list of Anchiornis and indicates a different phylogenetic point from former opinions. 相似文献
4.
Evgeny N. Kurochkin 《Cretaceous Research》1985,6(3):271-278
A partial, associated skeleton with feather impressions of a bird from early Cretaceous (Neocomian) deposits in Mongolia constitutes a new family and order (Ambiortidae, Ambiortiformes). The specimen presents a mosaic of archaic and specialised characters within the Class Aves and shows that advanced carinate birds existed some 10 to 12 million years after Archaeopteryx, lending tentative support to the idea that Archaeopteryx may not be representative of the state of avian evolution in the late Jurassic. The new specimen and numerous feather impressions from other early Cretaceous localities in Mongolia and the Soviet Union, indicate that birds were probably common in early Cretaceous biotas. 相似文献
5.
We evaluated the distribution of waterfowl in relation to a seagrass (Ruppia maritima) patch, to infauna, and on its relationship with substrate characteristics. An experiment performed in the Mar Chiquita coastal lagoon (37°46′S, 57°27′W; Argentina) was used to evaluate the effect of herbivory on widgeon grass,R. maritima. Control plots of equal size, located between bird exclosures, were exposed to herbivory. The experiment ran for 31 d, starting on December 1, 1994. Censuses showed that black-necked swan ( $\bar x = 50$ birds ha?1, SD = 37, n = 10) and coots ( $\bar x = 42$ birds ha?1, SD = 28, n = 10) were the most important (always present) of the waterfowl seen feeding onR. maritima. The results of the experiment showed greater leaf lengths, lower belowground (rhizomes and roots) biomass, greater aboveground (leaves and shoots) biomass, and greater abundance of the polychaeteHeteromastus similis in exclosure plots. There were no exclosure effects on total biomass (belowground plus aboveground), reproductive parts (fruits and pre- and postpollination flowers), or abundance of most benthic infauna. Topographic surveys showed that sediment surface was higher within theR. maritima patches, but there were no significant differences in granulometric composition. Surveys also showed that bird distribution was strongly associated with the presence ofR. maritima. 相似文献
6.
《Cretaceous Research》2012,33(6):781-785
The terrestrial lizard fossil record of Gondwana is very scarce. Few lizards, from mostly fragmentary fossils, have been identified in Madagascar, Tanzania, Morocco, South Africa, India and South America. Among the South American specimens there are basal Squamata forms (Olindalacerta and Tijubina) and a possible iguanid (Pristiguana) form Brazil. In Argentina gondwanian terrestrial lizards are represented by a putative iguanid and a small, poorly preserved dentary. This last specimen, recovered from the Anacleto Formation (Neuquén Group, Río Colorado Subgroup) in vicinity of the locality of Cinco Saltos (Río Negro Province), is here described formally. Comparisons with extant lizards indicate more affinity of the fossil with the Scincomorpha (non Scincophidia) than with any other group of lizards. This finding suggests that lizards were probably better represented and more diverse in the Mesozoic of South America than previously thought, although the fossil record is, at the moment, much poorer than in Laurasia. 相似文献
7.
本文描述了产于中国辽宁凌源早白垩世九佛堂组地层的一件鸟类化石标本。该标本中等大小,具有许多原始今鸟型鸟类的共同衍征;同时该标本也具有一个区别与其他已知原始今鸟型鸟类的长吻:吻长超过整个头骨长的70%;前颌骨前端尖而下钩,向前超出下颌前端,下颌齿骨前端直,仅上颌骨和齿骨上具有牙齿,代表了原始今鸟型鸟类一个新的属种和一个新的生态类型,因此建立了一个今鸟型鸟类新属种——张氏觉华鸟(Juehuaornis zhangi gen.et sp.nov)。 相似文献
8.
Stephen K. Donovan Mart J.M. Deckers John W.M. Jagt A.J. de Winter 《Proceedings of the Geologists' Association. Geologists' Association》2021,132(1):66-69
In the Netherlands, Late Palaeozoic pelmatozoans – that is, stalked echinoderms – are known from building stones and cobbles in rivers, but there are no in-situ carbonate rocks from which they might be collected. Unsurprisingly, most recognisable specimens are columnals and pluricolumnals. Two small thecae, collected in the mid-1970s from silexite cobbles in the bedload of the River Maas in the Venlo-Tegelen area (province of Limburg, south-east Netherlands) are exceptional finds. One specimen, the diplobathrid camerate crinoid Rhodocrinites sp., has an unsculptured theca and some minor differences of form, yet otherwise satisfies the diagnosis of this genus. The other, the pentremitid blastoid Doryblastus? sp. is rather poorly preserved, yet is the first blastoid to be recorded from the Netherlands. Either or both of these specimens may be juveniles, particularly the blastoid. They are unlikely to be coeval, coming from separate cobbles and being of slightly different preservation. Their provenance from silexite cobbles suggest they originated from Lower Carboniferous (Tournaisian-Visean = Mississippian) carbonates in the southern Ardennes (south-central Belgium). 相似文献
9.
WANG Xuri Jingmai K. O’Connor ZHAO Bo Luis M. Chiappe Gao Chunling Cheng Xiaodong 《《地质学报》英文版》2010,84(2):247-256
<正>We report on a new species of enantiornithine bird from the Lower Cretaceous Qiaotou Formation of northern Hebei,China.The new taxon,Shenqiornis mengi gen.et sp.nov.,possesses several enantiornithine synapomorphies but is unique from other known species.The specimen has a well-preserved skull that reveals new information about enantiornithine cranial morphology.The new taxon possesses a large postorbital with a long tapering jugal process indicating that some enantiornithines may have had a fully diapsid skull,as in Confuciusornis.The tooth morphology of the specimen is unique and likely represents a previously unknown trophic specialization within Enantiornithes. 相似文献
10.
V. L. De Pietri C. Mourer-Chauviré U. Menkveld-Gfeller C. A. Meyer L. Costeur 《Swiss Journal of Geoscience》2013,106(2):187-197
The fossil skeletal record of birds from the Cenozoic of Switzerland is rather poor, despite the fact that avian tracks have been described from twenty tracksites. We review the Swiss fossil skeletal avifauna with emphasis put on new material discovered in the collection of the Natural History Museum Basel. This material includes two new owls (Strigiformes), one from a Late Eocene fissure filling from the Gösgen canal, and another from the Late Oligocene of Mümliswil. The Eocene owl specimen consists of a partial, distal tarsometatarsus, and is therefore too incompletely preserved to allow for reliable hypotheses concerning its taxonomic affinities. It does, however, display features resembling members of the extinct family Palaeoglaucidae. The Oligocene specimen is tentatively attributed to the genus Oligostrix, and it is the youngest representative of the extinct family Protostrigidae. Based on the first complete tarsometatarsus for this family, we erect a new species, ?Oligostrix bergeri. These two specimens represent the first record of fossil owls from Switzerland. 相似文献
11.
Andrew T. McDonald 《Cretaceous Research》2012,33(1):1-6
Dollodon bampingi was recently named based upon a specimen from the Bernissart Quarry that had previously been referred to Mantellisaurus atherfieldensis. The initial diagnosis of Dollodon did not adequately distinguish it from Mantellisaurus or from other basal iguanodonts, necessitating a reassessment of the material. Firsthand examination of the holotypes of the two taxa and numerous other basal iguanodont specimens, as well as a principal components analysis of basal iguanodont dentaries, did not find any morphological features to justify the distinction of Dollodon from Mantellisaurus. D. bampingi is thus best considered a junior synonym of M. atherfieldensis. Furthermore, the recent referral of the species Iguanodon seelyi to the genus Dollodon is not supported; I. seelyi is indistinguishable from Iguanodon bernissartensis, and is considered a junior synonym of that species. Finally, the recently named taxon Proplanicoxa galtoni, also based upon a specimen formerly attributed to M. atherfieldensis, is considered a nomen dubium and probable junior synonym of M. atherfieldensis. Thus, only two species of large-bodied basal iguanodont should be recognized from the Barremian-Aptian of England and Belgium: M. atherfieldensis and I. bernissartensis. 相似文献
12.
Enantiornithine Bird with Diapsidian Skull and Its Dental Development in the Early Cretaceous in Liaoning, China 总被引：7，自引：5，他引：2
GONG Enpu HOU Lianhai WANG Lixia Department of Geology Northeastern University Shenyang Liaoning Institute of Vertebrate Paleontology Paleoanthropology Chinese Academy of Sciences Beijing Liaoning Department of Land Resources Shenyang Liaoning 《《地质学报》英文版》2004,78(1):1-7
A Iarge number of enantiornithine birds are discovered from the Early Cretaceous Jiufutang Formation in western Liaoning, China. They are all small-sized birds with a few small teeth. The enantiornithine bird from the Jiufutang Formation in the Shangheshou area, Chaoyang, Liaoning Province reported in this paper is the largest individual known in all enantiornithine birds of the Early Cretaceous. However, its teeth possess a feature of pseudoheterodont. Some different development stages of the new teeth substitute the earlier stages and the stages of development are preserved in this specimen. This development pattern is similar to that of Archaeopteryx and alligator but not dinosaur. A well-developed postorbital was also preserved in the skull, which was a diapsidian skull like that of Confuciusornis. Additionally, the distinctive preservation of its prefrontal distinguishes it from other enantiornithine birds of the Early Cretaceous. 相似文献
13.
14.
The burrowing crab,Chasmagnathus granulatus, is the dominant benthic macroinvertebrate of southwest Atlantic salt marshes and tidal flats, having strong ecosystem engineering
effects by direct and indirect effects on soil, vegetation, invertebrates, fishes, and birds. Vegetation structure is a main
component for bird habitat selection, since greater habitat complexity generates higher niche diversity. This environmental
complexity can be modified by species interactions or disturbance events (i.e., by crabs), in turn modifying the associated
community. The bird species of salt marshes of the southwest Atlantic are highly dependent on these ecosystems. We assessed
the effects of the burrowing crab on the structure of the cordgrass,Spartina densiflora, marshes, and how these changes affected the composition and diversity of birds. This study was conducted at the Mar Chiquita
Coastal Lagoon, Argentina (37°40′S, 57°23′W).S. densiflora marshes were classified within three categories: marshes without burrowing crabs, marshes with low burrow densities, and
marshes with high burrow densities. We made vegetation and bird surveys during spring beforeS. densiflora produce seeds and in summer when seeds are abundant. We also manipulated inflorescence (i.e., spike) density (a variable
affected by crabs) to assess the effect on bird habitat use. The highest inflorescence density ofS. densiflora and highest bird diversity were recorded at low burrow densities. Cover and height ofS. densiflora were negatively correlated with burrow density. The number of bird species and the number of red-capped wren-spinetail,Spartonoica maluroides, were negatively related with cover and height ofS. densiflora. Experiments confirmed that granivorous species used areas with higher spike densities, a variable related to crab burrow
density. Burrowing crabs directly and indirectly affect the cover, height, spike density, and morphologic characteristic of
seeds ofS. densiflora marshes. These effects indirectly affect the bird community that uses these marshes, being negatively related toS. maluroides and total bird abundance, and positively related to bird diversity. 相似文献
15.
A new species of Macrocnemus is described on the basis of two incomplete specimens from the Lower Ladinian Prosanto Formation of southeastern Switzerland. The new form can be distinguished by its gracile limb elements and having a noticeably longer tibia than either Macrocnemus bassanii or Macrocnemus fuyuanensis. One of the new specimens exhibits soft part preservation in the region of the pelvic girdle. The hind part of this individual is preserved fully articulated and allows a complete count of the caudal vertebrae to be made for the first time with 52 caudals. It is postulated that this specimen was predated upon and that the anterior part of the animal was consumed by a large predator such as a nothosaurid reptile or the actinopterygian fish Saurichthys. 相似文献
16.
近2～3年来,陕西省考古研究院科研人员再次对蓝田县的新街遗址进行了抢救性发掘,经过清理整理,发现于新街遗址灰坑、探沟和探方中的全新世鸟类骨骼共70件.鸟类化石均为分散保存骨骼,但此次发现的鸟类骨骼保存不仅数量多,而且形态也较完好,是国内全新世鸟类化石发现记录所罕见的.本文记述了对这批鸟类化石开展形态解剖学的鉴定,并系统完成分类学研究的成果,新街遗址中总计鸟类所属8目、8科、8属,共9种,其中以水生鸟类居多.此外,根据鸟类的生存习性及鸟类骨骼上残存的人工痕迹,还针对新街遗址全新世时期的环境和古人类的生活行为进行了全方位多角度的分析和推理,为新街遗址在传统考古学研究的基础上提供了全新的科学信息和有益的补充. 相似文献
17.
Feathers are rare in the fossil record because they have a low fossilization potential. Despite their palaeobiological significance, they also provide important palaeoecological and taphonomic information. Here, we report a new occurrence of three isolated feathers from the shales of the Oligocene Tremembé Formation (Taubaté Basin, SE Brazil). Their possible taxonomic affinities and taphonomic features are also discussed. Analyses identified the specimens as representatives of two pennaceous morphotypes (i.e., a contour and a rectrice feather). Both are preserved as carbonized traces, although, due taphonomic processes, they show different degrees of preservation. Since the Tremembé Formation is responsible for the most diverse record of Cenozoic birds, and because water-adapted birds (e.g., anseriformes and phoenicopteriformes) occur in this unit, it is highly possible that these feathers belonged to these aquatic taxa. Further investigations should concentrate on geochemical and microscopic techniques in order to reveal additional taxonomic and paleoecological features currently unknown in Paleogene birds of Brazil. 相似文献
18.
The terrestrial lizard fossil record of Gondwana is very scarce. Few lizards, from mostly fragmentary fossils, have been identified in Madagascar, Tanzania, Morocco, South Africa, India and South America. Among the South American specimens there are basal Squamata forms (Olindalacerta and Tijubina) and a possible iguanid (Pristiguana) form Brazil. In Argentina gondwanian terrestrial lizards are represented by a putative iguanid and a small, poorly preserved dentary. This last specimen, recovered from the Anacleto Formation (Neuquén Group, Río Colorado Subgroup) in vicinity of the locality of Cinco Saltos (Río Negro Province), is here described formally. Comparisons with extant lizards indicate more affinity of the fossil with the Scincomorpha (non Scincophidia) than with any other group of lizards. This finding suggests that lizards were probably better represented and more diverse in the Mesozoic of South America than previously thought, although the fossil record is, at the moment, much poorer than in Laurasia. 相似文献
19.
We review the previously described Late Cretaceous (Santonian) bird remains from the Csehbánya Formation in the Bakony Mountains of Hungary, augmenting initial work by Ősi ( 2008 ), and add a number of newly collected fossils. All together, the eight fossil specimens so far collected from this site are important to our understanding of avian evolution because they document a large range of taxon body sizes from at least one major lineage (Enantiornithes) and come from a critically undersampled time period in the Cretaceous. Globally, very little fossil bird material has been collected from the middle stages of the Late Cretaceous, the Coniacian and Santonian; most known taxa are either Early Cretaceous (ca. 120 Ma) in age or are from the terminal Campanian and Maastrichtian (ca. 70–65 Ma). Indeed, one of the Csehbánya Formation fossil birds is recognized as a new taxon of large enantiornithine, an avisaurid apparently similar in its largely unfused foot morphology to the Argentine Soroavisaurus and to the North American Avisaurus. The Central European records reviewed in this paper highlight the wide distribution of some Late Cretaceous fossil birds, particularly avisaurid enantiornithines, and lead us to a brief discussion of avian biogeography at the end of the Mesozoic. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
20.
A. Lacasa-Ruiz 《地学学报》1989,1(1):45-46
From among fossil fauna and flora specimens discovered in the famous outcrop of lithographic limestone of Montsec Mountain (Lleida, Spain), from the Early Cretaceous, there is one specimen of a small incomplete bird skeleton. Only the bones of the left wing, the wish-bone (furcula), feathers and some other fragmentary bones are preserved. It lacks the skull, backbone, pectoral region, pelvic girdle and hind legs. 相似文献