A theropod–sauropod track assemblage from the ?Middle–Upper Jurassic Shedian Formation at Shuangbai,Yunnan Province,China, reflecting different sizes of trackmakers: Review and new observations

A dinosaur tracksite at Hemenkou (Shuangbai County, Yunnan Province) in the ?Middle–Upper Jurassic Shedian Formation that consists mainly of gray-purple feldspathic quartz sandstones was previously reported incorrectly as being in the Lower Cretaceous Puchanghe Formation. The previous assignment is also inconsistent with two regional geological maps. Although mostly yielding poorly preserved tracks, the site nevertheless indicates a diversity of theropod and sauropod trackmakers partly consistent with the Late Jurassic body fossils from the region. Purported ornithopod are re-evaluated here as those of theropods. The theropod tracks and trackways show distinct similarities to those of the Grallator–Eubrontes plexus and can be subdivided into three morphotypes that may reflect different pes anatomy and/or substrate conditions. Two sizes of tracks (small, large) indicate the presence of different size classes or species in this area in the Late Jurassic. Similarly, the sauropod trackways document three differently sized trackmakers (small–medium–large) showing a typical wide-gauge (Brontopodus) pattern. The track record is the first evidence of theropods in the ?Middle–Late Jurassic of central Yunnan, whereas the sauropod tracks suggest a relation to the coeval basal eusauropods known from this region by skeletal remains.     

Large sauropod and theropod tracks from the Middle Jurassic Chuanjie Formation of Lufeng County,Yunnan Province and palaeobiogeography of the Middle Jurassic sauropod tracks from southwestern China

Tracks of large theropods and a single sauropod footprint are reported from red beds at Beikeshan locality in the Middle Jurassic Chuanjie Formation, of Lufeng County, near the large World Dinosaur Valley Park complex. The Chuanjie theropod tracks are assigned to the ichnogenus Eubrontes and the large sauropod track is given the provisional label Brontopodus. All occur as isolated tracks, i.e., trackways are not preserved. Saurischian dominated ichnofaunas are relatively common in the Jurassic of China. The producers of the Chuanjie tracks may have been similar to the basal tetanuran theropod Shidaisaurus and to mamenchisaurid sauropods, which were widely distributed throughout China, during the Jurassic, and are known from skeletal remains found in the same unit. Other potential sauropod trackmakers include titanosauriforms or as-yet-unknown basal eusauropods. The ichno- and skeletal records from the Jurassic of the Lufeng Basin are largely consistent, and both document the presence of middle-large sized theropods and sauropods.     

A tyrannosauroid dinosaur from the Upper Jurassic of Portugal

Fragmentary theropod remains from the Upper Jurassic (Kimmeridgian) of Guimarota, Portugal, represent a new taxon of theropod dinosaurs, Aviatyrannis jurassica gen. et sp. nov. Together with Stokesosaurus from the Morrison Formation of North America, Aviatyrannis represents the oldest known tyrannosauroid, indicating that tyrannosauroid origins may be found in the Middle–Late Jurassic of Europe/North America. Furthermore, current evidence suggests that early tyrannosaurs were rather small animals, which is in general accordance with their origin amongst the generally rather small coelurosaurs.     

Late Triassic dinosaur teeth from southern Belgium

Isolated Dinosaur teeth have been discovered in the Upper Triassic locality of Habay-la-Vieille, in southern Belgium. Ornithischia are represented by three dental morphotypes; two of them closely resemble isolated teeth from the Middle or Upper Jurassic of Portugal and England. The presence of sauropods in the Upper Triassic of Europe is confirmed. Sauropods already had a wide geographical distribution during the Latest Triassic, as fossils have been discovered in South Africa, Thailand and western Europe. At Habay-la-Vieille, sauropods and prosauropods co-existed at the end of the Triassic. Two dental morphotypes may tentatively be referred to as theropod dinosaurs. The study of isolated teeth indicates that dinosaurs were already well diversified in the Latest Triassic of western Europe. To cite this article: P. Godefroit, F. Knoll, C. R. Palevol 2 (2003) 3–11.     

Dientes de Theropoda (Dinosauria: Saurischia) de la Formación Bajo Barreal, Cretácico Superior, Provincia del Chubut, Argentina

Theropod teeth from the Bajo Barreal Formation (Upper Cretaceous: Cenomanian-Turonian) at the “estancia Ocho Hermanos”, Chubut Province are described. Most of them show features of Abelisauroidea, a clade already represented in the Bajo Barreal Formation by Xenotarsosaurus bonapartei and other isolated remains including a left maxilla. Dromaeosauridae and Carcharodontosauridae represent the first record of these taxa for the Bajo Barreal Formation. Besides this, at least three theropod clades (Abelisauroidea, Carcharodontosauridae, and Dromaeosauridae) coexisted in central Patagonia during the Cenomanian-Turonian along with other theropods as Aniksosaurus darwini and Megaraptor sp.     

Parallel evolution of theropod dinosaurs and birds

The hypothesis of the direct origin of birds from theropod dinosaurs has recently become widespread. Direct sisterly relationships between theropods and birds were assumed in the basis of random and formal synapomorphies, such as the number of caudal vertebrae, relative length of the humerus, and flattening of the dorsal margin of the pubis. In essence, this hypothesis is supported by the characters of theropods and birds, such as the presence of feathering, furcula, uncinate processes of ribs, pygostyle, double-condyled dorsal joint of the quadrate, and posteriorly turned pubis, which are recognized as homologies. Until recently, these characters have been regarded as avian apomorphies; however, they are presently known in various coelurosaurian groups. At the same time, they occur in various combinations in the Dromaeosauridae, Troodontidae, Oviraptoridae, Therizinosauridae, and Tyrannosauridae. None of the theropod groups possesses the entire set of these characters. This suggests that theropods and birds acquired them in parallel. Theropod dinosaurs and Sauriurae (Archaeornithes and Enantiornithes) show a number of important system synapomorphies, which indicate that they are closely related. Ornithurine birds lack such synapomorphies; however, their monophyly is supported by a large number of diagnostic characters. The hypothesis of independent origin of Sauriurae and Ornithurae is substantiated; the former are considered to have evolved from theropods in the Jurassic, while the latter deviated from a basal archosauromorph group in the Late Triassic. The hypothesis that birds existed in the Early Mesozoic is supported by the findings of small avian footprints in the Upper Triassic and Lower Jurassic of different continents.     

Multituberculaten-Zähne aus dem Ober-Jura von Porto das Barcas (Portugal)

An isolated m₁ from the Upper Jurassic of Porto das Barcas, Portugal, is described asKuehneodon barcasensis n. sp. It is similar toK. uniradiculatus G. Hahn 1978 from the Guimarota Coal Pit, Portugal, especially in subdivision of the first and third buccal cusps into two cuspules. But it differs fromK. uniradiculatus in the breadth of the cusp-rows: The buccal row is nearly twice as broad as the lingual cusps row, whereas inK. uniradiculatus both rows are nearly of the same breadth. Moreover, the m₁ ofK. barcasensis is only 1 mm long, whereas the m₁ ofK. uniradiculatus are 1.6-1.9 mm in length. A second tooth, a p₃, is tentatively grouped withK. barcasensis. It is of the same small dimensions as the m₁ (1 mm long). It bears four serrations, and two basal cuspules. The exact stratigraphical age of these teeth is unknown, but their close affinities to the taxa of the Guimarota Coal Pit make an Oxfordian to Kimmeridgian age probable.     

Additional non-avian theropod and bird remains from the early Late Cretaceous (Santonian) of Hungary and a review of the European abelisauroid record

Hitherto unpublished remains of non-avian and avian theropods from the Late Cretaceous (Formation Csehbánya, Santonian) Iharkút locality (western Hungary) are described. Non-avian theropod remains include an abelisaurid femur, which confirms the presence of this theropod family at Iharkút, and a metacarpal and a tibiotarsus from a paravian which may belong to Pneumatoraptor fodori, previously described from Iharkút. Birds are represented by two femora which clearly belong to enantiornithines, possibly to Bauxitornis, previously described from Iharkút. The abelisauroid record from the Cretaceous of Europe is reviewed.     

A review of theropod dinosaurs from the Late Jurassic to mid-Cretaceous of Southeast Asia

Several non-avian theropod dinosaurs, as well as some Mesozoic birds, have been reported from Southeast Asia. The fossils are dominantly found in northeastern Thailand, however, one bizarre theropod has been described from Laos, one theropod has been reported from Malaysia, and some avian and non-avian theropods have been recently reported from Myanmar. The temporal distribution of Southeast Asian theropods ranges from the Late Jurassic to the mid-Cretaceous. All non-avian theropod faunas from Southeast Asia consist of non-maniraptoran tetanurans. They show similarity to Chinese plus Japanese theropods during the Early Cretaceous in broad systematic terms. During this time, megaraptorans can be found only in Japan, Australia, Brazil, and possibly Thailand, whereas tyrannosauroids can be found in China, Europe, possibly Brazil and Australia. Spinosaurids, carcharodontosaurians, and some coelurosaurs such as ornithomimosaurs were almost cosmopolitan. Metriacanthosaurids, on the other hand, were endemic to Europe and Asia including China and Thailand during the Middle to Late Jurassic.     

A new troodontid theropod dinosaur from the lower Cretaceous of Utah

Background

The theropod dinosaur family Troodontidae is known from the Upper Jurassic, Lower Cretaceous, and Upper Cretaceous of Asia and from the Upper Jurassic and Upper Cretaceous of North America. Before now no undisputed troodontids from North America have been reported from the Early Cretaceous.

Methodology/Principal Findings

Herein we describe a theropod maxilla from the Lower Cretaceous Cedar Mountain Formation of Utah and perform a phylogenetic analysis to determine its phylogenetic position. The specimen is distinctive enough to assign to a new genus and species, Geminiraptor suarezarum. Phylogenetic analysis places G. suarezarum within Troodontidae in an unresolved polytomy with Mei, Byronosaurus, Sinornithoides, Sinusonasus, and Troodon + (Saurornithoides + Zanabazar). Geminiraptor suarezarum uniquely exhibits extreme pneumatic inflation of the maxilla internal to the antorbital fossa such that the anterior maxilla has a triangular cross-section. Unlike troodontids more closely related to Troodon, G. suarezarum exhibits bony septa between the dental alveoli and a promaxillary foramen that is visible in lateral view.

Conclusions/Significance

This is the first report of a North American troodontid from the Lower Cretaceous. It therefore contributes to a fuller understanding of troodontid biogeography through time. It also adds to the known dinosaurian fauna of the Cedar Mountain Formation.     

Isolated theropod teeth from the Kem Kem Beds (Early Cenomanian) near Taouz, Morocco

Thirty-seven well-preserved, isolated theropod teeth from the Early Cenomanian Kem Kem beds, Morocco, are identified by using morphometric data and direct comparison with teeth previously described in the literature. Direct comparison reveals that four different morphotypes (MT 1–4) are present in the sample. The teeth of MT 1 are characterised by unserrated carinae and belong to spinosaurid dinosaurs. The teeth of MT 2–4 have serrated carinae, and our data analysis indicates they are of carcharodontosaurid, dromaeosaurid, and abelisaurid origin. Three types of crown enamel ornamentation are present among the teeth of MT 1, which implies that, apart from Spinosaurus aegyptiacus STROMER 1915, more than one species of spinosaurine theropods may be present in the Early Cenomanian of Northern Africa. Our results also confirm the occurrence of abelisaurids, dromaeosaurids, and carcharodontosaurids in Morocco.     

Theropod dinosaurs from the Albian–Cenomanian Wayan Formation of eastern Idaho

The record of terrestrial vertebrates in the upper Albian to Cenomanian Wayan Formation of Idaho is sparse, with most fossils recovered belonging to the small orodromine neornithischian Oryctodromeus cubicularis and the maniraptoran ootaxon Macroelongatoolithus carlylei. Here we report on a diversity of theropod forms now recognised from various isolated teeth, vertebrae, eggs and eggshell. Theropods recognised from isolated teeth include a large possible tyrannosauroid, a small tyrannosauroid, dromaeosaurids, and indeterminate theropods. A possible neovenatorid and indeterminate theropods are recognised from isolated vertebrae. A giant oviraptorosaur is indicated by the presence of rare eggs and common eggshell accumulations referred to Macroelongatoolithus. While these remains are admittedly meager, their presence indicates that a substantial diversity of theropods existed in the Albian to Cenomanian environments of southeastern Idaho. The Wayan theropod assemblage is among the most diverse reported for this time period in North America, and represents a transitional assemblage resembling that of the later Late Cretaceous.     

Small Theropod Teeth from the Late Cretaceous of the San Juan Basin,Northwestern New Mexico and Their Implications for Understanding Latest Cretaceous Dinosaur Evolution

Studying the evolution and biogeographic distribution of dinosaurs during the latest Cretaceous is critical for better understanding the end-Cretaceous extinction event that killed off all non-avian dinosaurs. Western North America contains among the best records of Late Cretaceous terrestrial vertebrates in the world, but is biased against small-bodied dinosaurs. Isolated teeth are the primary evidence for understanding the diversity and evolution of small-bodied theropod dinosaurs during the Late Cretaceous, but few such specimens have been well documented from outside of the northern Rockies, making it difficult to assess Late Cretaceous dinosaur diversity and biogeographic patterns. We describe small theropod teeth from the San Juan Basin of northwestern New Mexico. These specimens were collected from strata spanning Santonian – Maastrichtian. We grouped isolated theropod teeth into several morphotypes, which we assigned to higher-level theropod clades based on possession of phylogenetic synapomorphies. We then used principal components analysis and discriminant function analyses to gauge whether the San Juan Basin teeth overlap with, or are quantitatively distinct from, similar tooth morphotypes from other geographic areas. The San Juan Basin contains a diverse record of small theropods. Late Campanian assemblages differ from approximately co-eval assemblages of the northern Rockies in being less diverse with only rare representatives of troodontids and a Dromaeosaurus-like taxon. We also provide evidence that erect and recurved morphs of a Richardoestesia-like taxon represent a single heterodont species. A late Maastrichtian assemblage is dominated by a distinct troodontid. The differences between northern and southern faunas based on isolated theropod teeth provide evidence for provinciality in the late Campanian and the late Maastrichtian of North America. However, there is no indication that major components of small-bodied theropod diversity were lost during the Maastrichtian in New Mexico. The same pattern seen in northern faunas, which may provide evidence for an abrupt dinosaur extinction.     

The skull ofvelociraptor mongoliensis,a small cretaceous theropod dinosaur from Mongolia

The skull of the small theropod dinosaurVelociraptor mongoliensis is described in detail, using the holotype from the Djadokhta Formation (Campanian) of Mongolia. A reconstruction of the skull is attempted.Velociraptor is closely related toDeinonychus andDromaeosaurus; however, it is distinguished from all other dromaeosaurids described by its relatively long, low skull and a depressed muzzle. The affinities ofVelociraptor are discussed and the taxonomic status of all other previously described East Asian dromaeosaurids is examined.     

Late Jurassic footprints reveal walking kinematics of theropod dinosaurs

Avanzini, M., Piñuela, L. & García‐Ramos, J.C. 2011: Late Jurassic footprints reveal walking kinematics of theropod dinosaurs. Lethaia, Vol. 45, pp. 238–252. This study describes a set of theropod footprints collected from the Late Jurassic Lastres Formation (Asturias, N Spain). The footprints are natural casts (tracks and undertracks) grouped into three morphotypes, which are characterized by different size frequency, L/W relationship and divarication angles: ‘Grallatorid’ morphotype, ‘Kayentapus–Magnoavipes’ morphotype, ‘Hispanosauropus’ morphotype. The tracks were produced in firm, stiff and soft sediments. The infills of deep tracks, which are typically formed in soft mud, lack fine anatomical details, but they can reveal the walk kinematics of the trackmaker through the morphology of internal track fills and sinking traces. In all footprints, a horizontal outwardly directed translation movement and rotation are recognizable. The amount and geometry of digit penetration in the ground also show a pronounced difference. It can be inferred from the described sample that different theropoda‐related ichnogenera share common kinematics. □Asturias, dinosaur footprint, late jurassic, theropods, walking kinematics.     

Pterosaur and dinosaur remains from the Middle Jurassic Balabansai Svita in the northern Fergana Depression, Kyrgyzstan (Central Asia)

Abstract: Isolated pterosaur and dinosaur teeth and a sauropod metatarsal I and manual phalanx V-1 from the Middle Jurassic (Callovian) Balabansai Svita in the northern Fergana Valley, Kyrgyzstan, are described and attributed to the pterosaur taxon Rhamphorhynchinae indet., a theropod Tetanurae indet., a sauropod Neosauropoda indet., and a new pachycephalosaurid Ferganocephale adenticulatum gen. et sp. nov. The Balabansai theropod is possibly a stem-lineage representative of Dromaeosauridae. The new pachycephalosaurid is the oldest representative of the group and extends its known history by 10–20 myr. The Balabansai vertebrate assemblage is most similar to the Callovian assemblages from the Qigu and Upper Shaximiao formations in China, and intermediate in the evolutionary level of the taxa present between the Bathonian assemblages from Wucaiwan and the Lower Shaximiao formations (China) and the Late Jurassic Shar Teg fauna from Mongolia.     

Integument structure in ornithischian dinosaurs (Hypsilophodontia,Ornithopoda) from the Late Jurassic of Transbaikalia

Integumentary structures of ornithischain dinosaurs of the taxon Hypsilophodontia (Ornithopoda) from the Ukureiskaya Formation (Upper Jurassic) of the Kulinda locality (Transbaikal Region, Russia) are described in detail. It is shown that members of this group had so-called bristle scales, integumentary appendages previously unknown in ornithischian dinosaurs. These are relatively small horn plates embedded in the skin, the distal margin of which has several long, flat, and probably constantly growing bristles. The monobristle variant of bristle scale is probably homologous to the protofeather of theropods; if this is the case, it is possible to reconstruct the protofeather as an elongated and constantly growing scale.     

When did theropods become feathered?--evidence for pre-Archaeopteryx feathery appendages

Filamentous impressions associated with locomotive theropod tracks in the Lower Jurassic Turners Falls Formation of western Massachusetts, U.S.A. represent the oldest evidence of feathered dinosaurs. Feather impressions are preserved with sitting traces which bear integumentary structures along the outlines of the pre-pubic and ischiadic impressions. Extant palaeognathous down feathers provide a valuable comparative model for these filamentous integumental structures and for similar structures described in Chinese theropods from younger deposits. The described morphologies are congruent with Stage II of Prum ('99) and support that plumulaceous morphologies evolved before the origin of the rhachis and the planar vane. Appearance of feathery appendages in theropods may be linked to evolution of higher metabolic rates, improved locomotory abilities, and/or distinct behavior(s) and visual communication. Development of feathery integument might have also played a crucial role in the competitiveness and successful radiation of maniraptoriform theropods and their actively flying descendants in the Jurassic.     

Fabrosauridae,the basal family of ornithischian dinosaurs (Reptilia: Ornithopoda)

In fabrosaurids the upper jaw is flat and the lower jaw is slender so the ’cheek’ teeth are marginal and not inset as is the case in all other ornithischian dinosaurs. The ’cheek’ teeth of fabrosaurids have anteroposteriorly expanded crowns but lack wear surfaces formed by tooth to tooth contact. Two genera are recognized from the Triassic-Jurassic boundary of Lesotho with good material previously referred toFabrosaurus as a new genus that represents the most conservative ornithopod described to date. The anatomy ofNanosaurus (Upper Jurassic, U.S.A.) andEchinodon (Jurassic-Cretaceous boundary, England) is redescribed; in both genera the tooth bearing bone of the lower jaw is deepened posteriorly and inEchinodon there is a true canine tooth in the upper jaw.