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1.
A recently discovered articulated partial skeleton of Ornithomimus from the Upper Cretaceous Dinosaur Park Formation of Alberta, Canada is remarkable in the extent and quality of preservation of integumentary structures including feathers. It is the first ornithomimid to preserve a tail bearing extensive plumaceous feathers that are slightly more elongate in comparison to those present on the remainder of the body. However, the underside of the tail and the hind limb distal to the middle of the femur appear devoid of plumage. Overall, the plumage pattern in Ornithomimus is similar to that of Struthio camelus (ostrich) and other large palaeognaths, indicating a probable function in thermoregulation. The specimen also preserves the body outline around the legs, including a skin contour anterior to the femur, analogous to skin webs in extant birds. Whereas the knee web of birds bridges the knee to the abdomen, in Ornithomimus it spans from the mid-femoral shaft to the abdomen, and is herein referred to as an anterior femoral web. This is the first report of such soft tissue structures in non-avian theropods. It may indicate that the resting position of the femur was positioned more anteroventrally in ornithomimids than in most theropods, and in that sense may have been transitional to the situation in modern birds. 相似文献
2.
An isolated titanosaur femur recovered from the Javelina Formation (Maastrichtian) of Big Bend National Park, Texas is the most complete example yet reported from North America. The specimen is likely referable to Alamosaurus sanjuanensis, the only titanosaur thus far known from Upper Cretaceous strata in North America, but cannot be attributed with certainty to that taxon. Compared to femora from other titanosaurs, the specimen has a relatively reduced abductor crest, a less elevated femoral head, and a distal joint surface that is orthogonal to the long axis of the shaft. These differences suggest that the Big Bend femur pertains to a species where hindlimb stance was closer to vertical, and with a comparatively narrower gait than other titanosaurids. 相似文献
3.
Two natural casts of two-toed (didactyl) tracks from the Cretaceous (Albian) Plainview Sandstone (Plainview Member) of the South Platte Formation (Dakota Group) at Dinosaur Ridge, Colorado are attributed to deinonychosaurian theropod dinosaurs and placed in the ichnogenus Dromaeosauripus. This is both the first report of tracks from this unit in the Dinosaur Ridge area and the first report of deinonychosaurian tracks from Colorado. It is also only the third report of this track type from North America. The rarity of tracks from the Albian-aged, Plainview Sandstone (Dakota Group Sequence 2) contrasts with their abundance in the upper (Cenomanian) part of the overlying South Platte Formation (Dakota Group Sequence 3), which has yielded more than 120 sites mostly in Colorado, giving rise to the “Dinosaur Freeway” concept. As no deinonychosaurid tracks are known from the sequence 3 part of the South Platte Formation, despite the large vertebrate and invertebrate ichnological database available, it is evident that the sparse vertebrate ichnofauna from the Plainview Member (Sequence 2) is inherently different. This striking difference in both track abundance and track type reflects differences in both age and depositional environment. Based on the Albian age, and track type, the Plainview tracks invite comparison with the ichnofaunas of the Cedar Mountain Formation and not with those well-known from the upper part of the South Platte Formation known as the Dinosaur Freeway. 相似文献
4.
Speculation regarding Tyrannosaurus in West Texas has been largely based upon a sub-adult tyrannosaurid maxilla from the Javelina Formation (Late Cretaceous–Maastrichtian) of Big Bend National Park. However, a very large anterior caudal vertebra, recently collected from the Javelina Formation, exhibits a morphology that can confidently be assigned to Tyrannosauridae and, because of its size, likely pertains to an adult Tyrannosaurus. The stratigraphic position of the specimen is closely bracketed by titanosaurid remains and further supports coexistence of these taxa. The stratigraphic position of the specimen possibly records one of the earliest occurrences of Tyrannosaurus. If so, Tyrannosaurus likely existed during roughly equivalent temporal intervals in disparate paleobiomes in both northern and southern late Maastrichtian faunal realms of North America. 相似文献
5.
A large theropod ilium was recently collected from the Upper Cretaceous Honglishan Formation in the Sangequan area of the northern Junggar Basin, Xinjiang, China, which represents the first officially reported dinosaur fossil from this formation. Several morphological features, including robust supracetabular ridge, reduced supracetabular crest, concave anterior margin of the pubic peduncle, ventral flange on the pubic peduncle, converging dorsal surface of the iliac blades, laterally visible cuppedicus shelf, and ventral flange on the posterior surface of pubic peduncle, suggest that this specimen can be referred to Tyrannosaurinae, and furthermore, a few differences between this specimen and other tyrannosaurines in particular the contemporary Asian tyrannosaurine Tarbosaurus suggest that IVPP V22757 may represent a new tyrannosaurine species. However, in the absence of extensive data that would make it possible to properly evaluate these differences, we refrain from naming a new taxon based on this specimen. Some insect borings are also identified in this specimen, and are referable to the ichnogenus Cubiculum, which is interpreted as the insect pupichnia. This new fossil documents the presence of a gigantic theropod in the Upper Cretaceous of Junggar Basin, adding new information on its poorly studied ecosystems. 相似文献
6.
A new dinosaur sauropod from the Golmayo Formation (upper Hauterivian-lower Barremian) in Soria province (Spain) is described as Soriatitan golmayensis gen. et sp. nov. The new material consists of one tooth, three dorsal vertebrae with ribs, a partial sacrum, five caudal centra, two caudal vertebral spines, one chevron, a humerus, an ulna, a radius, two partial ilia, two ischia, a fragment of pubis, and a partial femur. Cladistic analysis identified the material as belonging to Brachiosaruidae within Titanosauriformes. Sauropod material from the Golmayo Formation shares a diagnostic feature with Abydosaurus, Cedarosaurus, Tastavinsaurus and Venenosaurus including anteriorly deflected anterior–middle caudal neural spines and with Cedarosaurus a proximodistally straight lateral margin between the proximal head and the shaft of the humerus. Eight characters are potential autapomorphies in the sauropod from Spain, including the presence of a large rectangular ventral ridge below the preacetabular process of the ilium, the same length of the pubic and ischiadic blades in the ischium, and two lateral ridges in the lateral area of the deltopectoral crest of the humerus. The presence of Early Cretaceous brachiosarids in both, North America and Europe, give support to the hypothesis of a connection between the tectonic plates of these continents at some point during the Early Cretaceous. 相似文献
7.
The John Martin Reservoir tracksites from the Dakota Group of Bent County, in southeastern Colorado form part of the mid Cretaceous Dinosaur Freeway characterized by abundant ornithopod footprints (Caririchnium). Over 350 tracks (331 Caririchnium, 1 Magnoavipes, 22 crocodiles, and a few pterosaurs) were discovered at 10 new tracksites. All tracks were found as natural casts, including Caririchnium trackways that were still in-situ, parallel and regularly spaced, suggesting gregarious behavior. Most crocodile tracks are swimming tracks that consist of three or four scratch marks also with parallel orientations in many cases. A few pterosaur tracks consist of pes footprints and scratch marks suggesting swimming or floating activity in shallow water. This is the first pterosaur evidence from the Dakota Group. The Caririchnium size structure from John Martin Reservoir is consistent with the size structure tendency of the whole Dinosaur Freeway, which shows larger track size in the north. This tendency could be interpreted as evidence for more than one ornithopod species spread out across the Dinosaur Freeway. The alternative, that there was one ornithopod species that migrated north and south seasonally is less likely. The John Martin paleoecosystem is interpreted from the track evidence as a well-vegetated coastal plain environment with many ornithopods and a few theropods on land, crocodiles in the water, and pterosaurs in the skies and on the water. 相似文献
8.
Felipe Chinaglia Montefeltro Carolina Rettondini Laurini Max Cardoso Langer 《Cretaceous Research》2009,30(5):1279-1286
The six peculiar multicusped teeth described here were collected from sediments of the Upper Cretaceous of São José do Rio Preto Formation, near Ibirá (northeastern São Paulo, Brazil). Their bulbous crowns are slightly labio-lingual compressed, and bear a main plus two accessory cusps, which conceal a well developed cingulum. Wear facets are seen on the main and distal accessory cusps. Comparison to the known Crocodyliformes with multicusped teeth show that the new material is not referable to “protosuchians” or eusuchians, nor related to two unnamed forms from Morocco and “notosuchians” such as Uruguaysuchus, Chiamaerasuchus, and Simosuchus. On the other hand, possible affinities with Candidodon and Malawisuchus were maintained based on shared traits. This includes teeth with the main cusp and some accessory cusps arranged in more than one axis, a previously defined unambiguous apomorphy of the putative clade composed of Candidodon plus Malawisuchus. The term Candidodontidae can be applied to this group, and defined as all taxa closer to Candidodon itapecuruensis than to Notosuchus terrestris, Uruguaysuchus aznarezi, Comahuesuchus brachybuccalis, Sphagesaurus huenei, Baurusuchus pachecoi, and Crocodylus niloticus. 相似文献
9.
10.
A Corythosaurus skull (UALVP 13) was collected in 1920 from what is now Dinosaur Provincial Park in southern Alberta, Canada and was designated the holotype of Corythosaurus excavatus, a new hadrosaur species by Gilmore (1923). In 1992, a previously uncovered, weathered, headless skeleton was found. This was collected in 2012 by the University of Alberta as there was potential it could belong to the holotype skull. In addition, an isolated hadrosaur dentary had been found in 1992 close to the articulated postcranial skeleton and may be one of the missing jaws of Corythosaurus excavatus. The hypothesis that it may be the skeleton of the holotype of Corythosaurus excavatus is tested using anatomical information and statistical analyses. Statistical comparisons suggest it is possible that the skull and dentary belong to the same specimen. Furthermore, bivariate plots and percentage prediction errors also indicate that the postcranial material could belong to the UALVP 13 skull. Because many large vertebrate fossil specimens (even types) are not always collected in their entirety, this method may be used as a line of evidence to determine whether independently collected specimens potentially belong to the same individual. The problems described herein highlight the need to collect specimens in their entirety, and for good field documentation, including the spatial and stratigraphic context of all finds. 相似文献
11.
A large, isolated symphyseal region of fused dentaries of an oviraptorosaurian was found in the Upper Cretaceous Bayn Shire Formation at Tsagaan Teg in the Mongolian Gobi Desert. A phylogenetic analysis places this specimen within Caenagnathidae. This specimen is comparable in size and morphology to the gigantic caenagnathid Gigantoraptor erlianensis from the Iren Dabasu Formation in China and is likely closely related to it. The occurrence of the specimen with possible affinities to G. erlianensis in the Bayn Shire Formation is consistent with the hypothesized correlation between the Bayn Shire and Iren Dabasu formations based on the co-occurrences of vertebrate fossils, especially turtles. 相似文献
12.
There exists a major gap in the fossil record of tyrannosauroid theropod dinosaurs spanning the early part of the Late Cretaceous. We report on skeletal remains referable to Tyrannosauroidea indet. from the Turonian Bissekty Formation at Dzharakuduk in the central Kyzylkum Desert of Uzbekistan. Phylogenetic analysis of the hypodigm places the Bissekty tyrannosauroid as a non-tyrannosaurid tyrannosauroid more basal than the Campanian tyrannosauroids Appalachiosaurus and Bistahieversor from North America. 相似文献
13.
《Proceedings of the Geologists' Association. Geologists' Association》2022,133(3):212-217
The cirripede Calantica? saskatchewanensis Russell, 1967, from the Maastrichtian Bearpaw Formation of Saskatchewan (Canada), is redescribed on the basis of new material and transferred to the genus Pachyscalpellum Buckeridge, 1991. This considerably extends the known range of the genus from the eastern Tethys (Australasia, Tunisia) to the northern part of the Western Interior Seaway of North America. Species of the genus achieved an exceptionally large size for stalked barnacles, with a projected possible height (capitulum and peduncle) of 150–200 mm. 相似文献
14.
A new weevil, Oxycorynoides bucklowae sp. nov. is described from the lower Barremian Upper Weald Clay Formation of south Surrey, UK. The new species differs from other species of the nominative subgenus in the large body size; large, elongate eyes; and distinctly curved rostrum. It approaches but is also distinguished from the Berriasian-Hauterivian Oxycorynoides mongolicus Zherikhin, 1986 and O. gurvanensis Legalov, 2010 from Mongolia by the long metaventrite from the former species, and by the short rostrum from the latter. 相似文献
15.
Grzegorz Nied?wiedzki Tomasz SingerGerard D. Gierliński Martin G. Lockley 《Cretaceous Research》2012,33(1):7-10
The Djadokhta Formation of the Gobi Desert is known for the number and diversity of dinosaur and other vertebrate bones and skeletons found there, but only theropod, hadrosaur and supposed ankylosaurid footprints have been reported from this stratum. Dinosaur footprints are also noted from the Nemegt Formation, and occur as typical dinosaur track accumulations (tracksites). An articulated protoceratopsid skeleton - specimen ZPAL Mg D-II/3 - was collected by the Polish-Mongolian Expedition of 1965 from the Djadokhta Formation of Flaming Cliffs in Mongolia. Recently, the natural cast of a tetradactyl digitigrade footprint was found underneath the pelvic girdle while the skeleton and matrix were being prepared. This is possibly the first find of a dinosaur track in close association with an articulated skeleton. Although Protoceratops is an extremely common dinosaur in Mongolia, its footprints have never previously been reported from the Late Cretaceous of the Gobi Desert. 相似文献
16.
Upper Cretaceous sediments of the Kanguk Formation exposed in Eidsbotn and Viks Fiord grabens on Devon Island, Nunavut, Canadian High Arctic, yielded 91 fossil marine diatom species and varieties (including indeterminate taxa), representing 41 genera. Excellent preservation of the assemblages was aided by shallow burial, protection in downfaulted linear grabens, and the presence of abundant volcanic material. Planktonic species and resting spores comprise nearly 70% of the diatom assemblage, and provided abundant food resources for the Late Cretaceous Arctic ecosystem. Deposition of the approximately 225 m-thick stratigraphic sequence was predominantly in a shallow marine neritic setting, with an upward progression to interbedded terrestrial deposits of the Expedition Fiord Formation, reflecting a regression and eventual persistence of terrestrial facies into the Early Cenozoic. The Kanguk Formation is widespread across the Canadian Arctic, and diatom biostratigraphy indicates a Santonian–Campanian age for the sequences reported herein, based on the presence of Gladius antiquus in the lowermost strata and occurrence of Costopyxis antiqua throughout the succession. However, Amblypyrgus sp. A and Archepyrgus sp. aff. A. melosiroides, encountered in the lower part of the succession, are known exclusively from the Lower Cretaceous. This may suggest a slightly older age. New information on shallow shelf diatom assemblages from this study is compared to reports on two other Late Cretacous Arctic diatom assemblages. These three sites represent an environmental transect from shallow to distal shelf settings and into the oceanic realm. 相似文献
17.
Upper Cretaceous deposits in Mongolia, Chinese Inner Mongolia, and, more recently, southern China, have yielded individually rich and taxonomically diverser lizard assemblages. Here we describe the remains of a new terrestrial lizard, Asprosaurus bibongriensis gen. et sp. nov., from the Upper Cretaceous of South Korea. It represents the first record of a Mesozoic lizard from the Korean Peninsula and, although incomplete, is exceptional in its very large size. Characters of the mandible support attribution to crown-group Anguimorpha, with the closest similarities being to monstersaurs, the group represented today by the venomous North American Beaded lizard and Gila monster, genus Heloderma. This group is well-represented in the Upper Cretaceous fossil record in of eastern Asia, and the remains of large monstersaurs have been recovered from several dinosaur egg localities, suggesting dietary preferences similar to those of the living genus. The new Korean lizard, recovered from the Boseong Bibong-ri Dinosaur Egg Site, fits the same pattern. 相似文献
18.
The North American fossil record of dinosaur eggshells for the Cretaceous is primarily restricted to formations of the middle (Albian–Cenomanian) and uppermost (Campanian–Maastrichtian) stages, with a large gap in the record for intermediate stages. Here we describe a dinosaur eggshell assemblage from a formation that represents an intermediate and poorly fossiliferous stage of the Upper Cretaceous, the Santonian Milk River Formation of southern Alberta, Canada. The Milk River eggshell assemblage contains five eggshell taxa: Continuoolithus, Porituberoolithus, Prismatoolithus, Spheroolithus, and Triprismatoolithus. These ootaxa are most similar to those reported from younger Campanian–Maastrichtian formations of the northern Western Interior than they are to ootaxa reported from older middle Cretaceous formations (i.e., predominantly Macroelongatoolithus). Characteristics of the Milk River ootaxa indicate that they are ascribable to at least one ornithopod and four small theropod species. The taxonomic affinity of the eggshell assemblage is consistent with the dinosaur fauna known based on isolated teeth and fragmentary skeletal remains from the formation, although most ornithischians and large theropods are not represented by eggshell. Relative to the Milk River Formation eggshell, similar oospecies occurring in younger Cretaceous deposits tend to be somewhat thicker, which may reflect an increase in body size of various dinosaur lineages during the Late Cretaceous. 相似文献
19.
A new ornithopod dinosaur from Antarctica, Trinisaura santamartaensis n. gen. et n. sp. is diagnosed by a unique combination of characters that includes a scapula with a spike-like acromial process with a strong and sharp lateral crest and longer than other ornithopods, a humerus with a rudimentary deltopectoral crest represented as a thickening on the anterolateral margin of the humerus, and shaft strongly bowed laterally, and an ischium gently curved along its entire length. The holotype specimen comprises vertebral and appendicular elements. The presence of axially elongate distal caudal vertebrae, pubis with long prepubic and postpubic processes, as well as a femur with a distinct anterior trochanter, pendant 4th trochanter and shallow anterior intercondylar groove constitute a combination of characters present in the Late Cretaceous Patagonian Gasparinisaura, Anabisetia and Talenkahuen. The materials were found on the surface enclosed in a hard sandstone concretion collected near the Santa Marta Cove, James Ross Island, from the lower levels of the Snow Hill Island Formation (Campanian). This is the first ornithopod taxon identified from this unit, and the second ornithischian dinosaur, after the ankylosaur Antarctopelta oliveroi. However, other ornithopod reports from nearby localities of James Ross and Vega islands in outcrops of the overlying Lopez de Bertodano Formation suggest that this clade was widely represented in the Campanian and Maastrichtian of the James Ross Basin, Antarctic continent. 相似文献
20.
In this paper we describe previously unpublished trionychid turtle material, consisting of numerous shell fragments, from the Late Cretaceous (late Turonian) Bissekty Formation of the Dzharakuduk locality in Uzbekistan. This material is assigned to two shell-based taxa: Aspideretoides cf. riabinini and “Trionyx” cf. kansaiensis. The material which cannot be confidently attributed to these two taxa is identified as Trionychidae indet. In addition to these shell-based trionychid taxa, the Dzharakuduk turtle assemblage includes two skull-based taxa of trionychids (Khunnuchelys kizylkumensis and Trionychini indet.). The trionychids from the Bissekty Formation are most similar to trionychids from the younger (Santonian – early Campanian) Bostobe Formation of Kazakhstan, represented by three shell-based taxa (Aspideretoides riabinini, Paleotrionyx riabinini and “Trionyx” kansaiensis), and one skull-based taxon (Khunnuchelys sp.). We provide an improved understanding of the subtle similarities and differences between four closely related Cretaceous turtle assemblages of Middle Asia and Kazakhstan. 相似文献