Cretaceous Vertebrate Research Articles

The non-avian theropod track Jialingpus from the Cretaceous of the Ordos Basin, China, with a revision of the type material: Implications for ichnotaxonomy and trackmaker morphology

Deposits from the Ordos Basin of mid-western China are rich in body fossils and ichnofossils of Early Cretaceous vertebrates. Thousands of Early Cretaceous sauropod, theropod and bird tracks described since 1958 have been found at several localities in the basin. We report two new sites (Dijiaping and Bawangzhuang) in the Luohe Formation of the Ordos Basin, Shaanxi Province, which contain small theropod footprints that are here referred to the ichnogenus Jialingpus. The assignment is based on pad configurations including (1) the large metatarsophalangeal area positioned in line with the axis of digit III, (2) the subdivision of this part into a small pad behind digit II, which in some specimens is close to the general position of the hallux (digit I), and a large metatarsophalangeal pad behind digit IV, and (3) a distinct inter-pad space between metatarsophalangeal pads and proximal phalangeal pads of digits II and III. We re-describe the type material of the type ichnospecies Jialingpus yuechiensis from the Upper Jurassic Penglaizhen Formation of Sichuan Province, proposing a largely amended diagnosis for this ichnotaxon. The presence of a digit I trace in the holotype, indicating a relatively long hallux, and the large metatarsophalangeal area positioned in line with digit III distinguishes Jialingpus from the ichnogenus Grallator and similar tracks that all lack these features. The only difference between Jialingpus specimens from the Cretaceous of the Ordos Basin and those of the Jurassic Penglaizhen Formation is the larger digit divarication in the Cretaceous taxon. This is the fourth record of Jialingpus in China and the second in Cretaceous strata, with the first being those from the Huangyangquan locality in Xinjiang, China.

Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans

The Late Cretaceous (∼95–66 million years ago) western North American landmass of Laramidia displayed heightened non-marine vertebrate diversity and intracontinental regionalism relative to other latest Cretaceous Laurasian ecosystems. Processes generating these patterns during this interval remain poorly understood despite their presumed role in the diversification of many clades. Tyrannosauridae, a clade of large-bodied theropod dinosaurs restricted to the Late Cretaceous of Laramidia and Asia, represents an ideal group for investigating Laramidian patterns of evolution. We use new tyrannosaurid discoveries from Utah—including a new taxon which represents the geologically oldest member of the clade—to investigate the evolution and biogeography of Tyrannosauridae. These data suggest a Laramidian origin for Tyrannosauridae, and implicate sea-level related controls in the isolation, diversification, and dispersal of this and many other Late Cretaceous vertebrate clades.

A new Late Cretaceous vertebrate fauna from the Cauvery Basin, South India: implications for Gondwanan paleobiogeography

ABSTRACT Late Cretaceous vertebrate faunas of India are known predominantly from intertrappean deposits in the Deccan volcanic province of the central and western parts of the country. A thick and nearly continuous sequence of Early Cretaceous–Early Paleocene fossiliferous sediments exposed in the Cauvery Basin of South India has been comparatively poorly explored. Here, we present a preliminary description of a new fauna consisting of vertebrate fossils discovered from the continental Upper Cretaceous (late Maastrichtian) Kallamedu Formation. The Kallamedu Fauna includes ganoid fishes, amphibians, turtles, crocodiles, and dinosaurs, with many taxa suggesting Late Cretaceous biotic links between India and other Gondwanan landmasses. Teeth of abelisaurid dinosaurs, known previously from the Middle Jurassic of South America and the Late Cretaceous of Africa, Madagascar, and central and western India, support a pan-Gondwanan distribution for this group of theropod dinosaurs. Of greatest significance, however, is the first discovery of a Simosuchus-like notosuchian crocodile outside of Madagascar. This report of the first Indian Simosuchus-like notosuchian crocodile further strengthens earlier evidence from other vertebrate groups for close biotic links between India and Madagascar in the Late Cretaceous, most likely through dispersal via the Seychelles block, Amirante Ridge, and Providence Bank.

Oldest known avian footprints from Australia: Eumeralla Formation (Albian), Dinosaur Cove, Victoria

AbstractTwo thin‐toed tridactyl tracks in a fluvial sandstone bed of the Eumeralla Formation (Albian) at Dinosaur Cove (Victoria, Australia) were likely made by avian trackmakers, making these the oldest known fossil bird tracks in Australia and the only Early Cretaceous ones from Gondwana. These tracks, which co‐occur on the same surface with a slightly larger nonavian theropod track, are distinguishable by their anisodactyl form, hallux impressions and wide digit II–IV divarication angles. A lengthy hallux impression and other deformational structures associated with one track indicate foot movement consistent with an abrupt stop, suggesting its tracemaker landed after either flight or a hop. The single nonavian theropod track is similar to other tracks described from the Eumeralla Formation at another locality. The avian footprints are larger than most Early Cretaceous avian tracks recorded worldwide, indicating sizeable enantiornithine or ornithurine species in formerly polar environments of Australia. The avian tracks further supplement scant body fossil evidence of Early Cretaceous birds in southern Australia, which includes a furcula from the Wonthaggi Formation. Because of this discovery, Dinosaur Cove, previously known for its vertebrate body fossils, is added to a growing list of Early Cretaceous vertebrate tracksites in southern Australia.

Tafonomía de Vertebrados Del Cretácico Superior de la Formación Loncoche en Calmu-Co (Mendoza, Argentina): Implicancias Paleoambientales y Paleogeográficas

VERTEBRATE TAPHONOMY OF UPPER CRETACEOUS VERTEBRATES FROM THE LONCOCHE FORMATION IN CALMU-CO (MENDOZA, ARGENTINA): PALEOENVIRONMENTAL AND PALEOGEOGRAPHICAL IMPLICATIONS. This paper presents a taphonomic study of vertebrate fossils from the Loncoche Formation (late Campanian—early Maastrichtian) found in the Calmu-Co area in Mendoza, Argentina. Four environmental stages were recognized in this site, (1) saline lacustrine systems; (2) fluvial systems; (3) deltaic systems; (4) shallow fluvial and lacustrine systems. The vertebrates found in the deltaic environment comprise disarticulated parautochthonous—allochthonous concentrations (taphofacies 1) of fishes (Chondrichthyes, Teleostei, Lepisosteidae and Ceratodontidae), turtles (Chelidae), dinosaurs (Titanosauria) and plesiosaurs (Plesiosauria). The disarticulated and fragmentary feature of these mixed concentrations (terrestrial, freshwater, marine) suggest a mixture of remains from littoral environments and fluvial systems. The above interpretation is based on the taphonomic attributes of these concentrations, which showed a high degree of weathering, abrasion and time-averaging. On the other hand, disarticulated parautochthonous concentrations (taphofacies 2) of dinosaurs were registered in the fluvial environment. These remains showed processes of fragmentation and abrasion due to hydraulic transport. Fossil-diagenetic processes include events of permineralization and cementation of vascular canals and fractures, phenomena of deformation and lithostatic compression. These evidences indicate that the Atlantic marine ingression (Maastrichtian—Paleocene) which covered northern Patagonia, spread until Calmu-Co, in the western Neuquén Basin.

Taphonomy of a Baurusuchus (Crocodyliformes, Baurusuchidae) from the Adamantina Formation (Upper Cretaceous, Bauru Basin), Brazil: Implications for preservational modes, time resolution and paleoecology

Upper Cretaceous vertebrate accumulations from the Adamantina Formation are known due to their high taxonomic diversity. On the other hand, taphonomic analyses still are rare, limiting the understanding of processes related to the biostratinomic and fossildiagenetic histories of this lithostratigraphic unit. In 2005, fossils were collected from an outcrop located at Jales municipality, state of São Paulo, southeastern Brazil. From this outcrop, a well-preserved Baurusuchus was recovered, which displays a peculiar set of taphonomic signatures. This paper identifies and interprets taphonomic features of a specimen of Baurusuchus (Crocodyliformes, Baurusuchidae; UFRJ DG 418-R) from the Adamantina Formation (Upper Cretaceous of the Bauru Basin), in Jales municipality, state of São Paulo. Brief taphonomic comparisons with other specimens previously studied (crocodiles and dinosaurs) and a lithofaciological analysis of the outcrop were undertaken in order to enhance the knowledge of the stratigraphy and paleoenvironment and improve the time resolution for the Adamantina Formation in the region of Jales. Furthermore, paleoecological data were interpreted based on the taphonomic analysis.The fossil is composed of an articulated segment of vertebral column, ribs, part of the pelvic girdle and gastralia. There is no hydraulic equivalence between both the specimen of Baurusuchus and the size of quartz grain predominant in the fossiliferous layer, suggesting death in situ or short transport as a “water carcass”. Teeth marks identified on the pubes were assigned to a small/juvenile baurusuchid crocodyliform or a theropod dinosaur. The repositioning of some elements (ribs and dorsal osteoderms) is suggestive of mummification. Desiccation marks were observed and attributed to the stage 1 of weathering. These features suggest subaerial exposure of the carcass prior to burial, however, probably after the mummification. On the other hand, the subaerial exposure was short, because the individual was not fully disarticulated. Furthermore, the degrees of articulation and preservation of the specimen nullify the hypothesis of reworking.Lithofaciological and taphonomic analyses suggest a well-drained floodplain as the burial environment and an arid or semi-arid climate in the region of Jales outcrop. In addition, the taphonomic signatures seem to indicate a time resolution about 100–104 years for the layer where the crocodyliforms were collected, but it seems to have, within this time limit, temporal-mixing among terrestrial crocodiles and dinosaurs collected from the same layer, suggesting time-averaging in this outcrop.

Albanerpetontid amphibians from the Late Cretaceous (Santonian) of Iharkút, Hungary, with remarks on regional differences in Late Cretaceous Laurasian amphibian assemblages

Since its discovery in 2000, the Iharkút fossil locality in the Upper Cretaceous (Santonian) Csehbánya Formation of western Hungary has yielded a taxonomically diverse assemblage of terrestrial and freshwater vertebrates that continue to provide insights into the diversity, paleobiogeography, and paleoecology of Late Cretaceous vertebrates in Europe. Albanerpetontidae, an extinct group of superficially salamander-like amphibians that were widespread across Laurasia during the latter part of the Mesozoic, are represented at Iharkút by 16 fragmentary jaws. Here we describe and figure these specimens as Albanerpetontidae genus and species indeterminate. Based on the age of the Iharkút locality, several premaxillary features, the known distribution (late Early Cretaceous – late Pliocene) of the type genus Albanerpeton, and an unusually large dentary specimen, we suggest that the Iharkút albanerpetontid may pertain to a previously unrecognized species of Albanerpeton, but verification of that must await the recovery of more diagnostically informative specimens, such as frontals and more nearly complete premaxillae. The Iharkút lissamphibian assemblage contains a mixture of taxa with Laurasian (the albanerpetontid and a discoglossid anuran) and Gondwanan (a neobatrachian anuran) affinities. Intriguing higher level differences are evident among Late Cretaceous Laurasian assemblages; for example, urodeles are scarce or absent (as at Iharkút) in Europe, whereas albanerpetontids are scarce in Middle Asia.

A new lizard skull from the Purbeck Limestone Group (Lower Cretaceous) of England

Abstract The Purbeck Limestone Group of England has yielded a rich assemblage of Late Jurassic to Early Cretaceous (Berriasian) vertebrate fossils, including one of the most diverse Early Cretaceous lizard assemblages on record. Here we describe the first articulated lizard skull from Purbeck. The specimen was rediscovered in the collections of the British Geological Survey, having been excavated at least a century ago. Although originally assigned to the Purbeck genus Paramacellodus, with which it shares maxillary and some dental characters, the new Purbeck skull differs from other Purbeck genera, including Paramacellodus, in frontal, pterygoid and maxillary morphology. It is here assigned to a new genus and species. Cladistic analysis groups it with Lacertoidea, unlike Paramacellodus, Becklesius and Parasaurillus which group with scincids and cordyliforms.

A New Lower Cretaceous Vertebrate Bonebed Near Ariño (Teruel, Aragón, Spain); Found and Managed in a Joint Collaboration Between a Mining Company and a Palaeontological Park

Systematic prospecting in the Oliete Geological Sub-basin (Aragonese Branch of the Iberian Range), specifically at an open-pit mine in the Escucha Formation (Lower Cretaceous) in Arino (Teruel, Spain), has revealed a fossiliferous layer with abundant vertebrate and other early Albian fossils. The fossiliferous stratigraphic level coincides with the floor of the mining operations, i.e. the bonebed is just below the lowest layer of coal mined for industrial purposes. Coal mining in this area of Teruel province has occurred for over a century and intense mining activity is at the present time a major economic force in the region. The new discoveries at this Mesozoic vertebrate locality presented in this paper document the most important Albian dinosaur site identified in Europe. This important discovery is a direct result of mining activity, without which these important data would have remained buried hundreds of metres underground. These discoveries below the coal seams at Arino fill out the Lower Cretaceous terrestrial record of Europe and expand upon the palaeogeographic context by which Europe may be compared against correlative dinosaur faunas in North America, Asia and North Africa.

Galvechelone lopezmartinezae gen. et sp. nov., a new cryptodiran turtle in the Lower Cretaceous of Europe

Abstract: The Spanish town of Galve (Teruel) is notable because of the abundance of Upper Jurassic and, especially, Lower Cretaceous vertebrates recorded there. Although most groups have been studied in detail, information on turtles is very limited even though the material is relatively abundant. So far, no turtle taxa have been identified at the generic level. The only Lower Cretaceous articulated specimen from Galve is analysed here. It is identified as a representative of Cryptodira, Galvechelone lopezmartinezae gen. et sp. nov. Galvechelone lopezmartinezae is determined as a taxon belonging to the node that groups the turtles traditionally assigned to ‘Macrobaenidae’ and ‘Sinemydidae’, and other taxa such as the members of Panchelonioidea. This node, very abundant in the Lower Cretaceous of Asia, and with a broad subsequent distribution, has recently been recognized in the Lower Cretaceous of Europe. The diversity of basal members of Eucryptodira in the European Late Jurassic (represented by Thalassemydidae, Plesiochelyidae and Eurysternidae) was high. Owing to a relative scarcity of well‐preserved early Cretaceous turtles from Europe, the knowledge of this group of reptiles is limited. The study of the new turtle from Galve, together with the recently described Hoyasemys jimenezi, and the recently completed review of the enigmatic Chitracephalus dumonii demonstrate that members of the cryptodiran node grouping ‘Macrobaenidae’, ‘Sinemydidae’ and Panchelonioidea were also very diverse in this period.

The “Continental Intercalaire” of southern Tunisia: Stratigraphy, paleontology, and paleoecology

The “Continental Intercalaire” deposits of southern Tunisia preserve one of the most diverse Early Cretaceous vertebrate fauna from Africa, consisting of elasmobranchs, actinopterygians, sarcopterygians, turtles, crocodyliforms, pterosaurs, and non-avian dinosaurs. Vertebrate remains representative of both marine and fluvial environments have been historically referred to a specific bonebed within the Chenini Member, which crops out extensively in the Tataouine region. A stratigraphic revision of the mainly siliciclastic deposits of the Douiret and the Aïn El Guettar formations in the area based on new sedimentological and paleontological data is presented. Data collected indicate the presence of multiple fossil-bearing strata encompassing the stratigraphic interval from the Berriasian to the Albian and document faunal variation through time as well as major environmental and climatic changes. Detailed sedimentological analysis combined with biostratigraphic correlation performed at a basin scale indicate lateral facies variability within each formation as a result of tectonically and climatically driven zonations within the Tataouine Basin in the Early Cretaceous. Furthermore, proposed stratigraphic correlations indicate that vertebrate remains previously referred to the fluvial Chenini Member (and in particular theropod and sauropod dinosaurs) are instead representative of a transgressive deposit which mark the base of the overlying Oum ed Diab Member.

New cranial remains of titanosaurian sauropod dinosaurs from the Late Cretaceous of Fox-Amphoux-Métisson (Var, SE France)

The Fox-Amphoux Syncline of the Aix Basin (SE France) has yielded a diverse Late Cretaceous vertebrate assemblage, including several taxa of dinosaurs. Here, we report on cranial material of titanosaurian sauropods, which consist of a partial braincase, two fragmentary skull roofs, and nine teeth, from the Métisson locality (Var Department). The braincase differs from those found previously in Europe (i.e., Ampelosaurus atacis, Lirainosaurus astibiae, and an unnamed juvenile skull from Romania) as well as from other titanosaurian braincases in having a groove that extends along the ventral surface of the occipital condyle neck (this feature may be autapomorphic). One of the fragmentary skull roofs may belong to the same taxon, whereas the other suggests the presence of a second titanosaur at Métisson very close to Ampelosaurus. Two dental morphologies are present in the sample; one of them includes teeth of different sizes. We suggest that this could be accounted for by age differences within a single taxon, or be due to different positions in the tooth row. The presence of a new, still unnamed titanosaurian taxon in the Ibero-Armorican Island supports previous works indicating a high titanosaurian diversity during the Campanian-Maastrichtian in southern Europe.

First Evidence of Reproductive Adaptation to “Island Effect” of a Dwarf Cretaceous Romanian Titanosaur, with Embryonic Integument In Ovo

BackgroundThe Cretaceous vertebrate assemblages of Romania are famous for geographically endemic dwarfed dinosaur taxa. We report the first complete egg clutches of a dwarf lithostrotian titanosaur, from Toteşti, Romania, and its reproductive adaptation to the “island effect”.Methodology/FindingsThe egg clutches were discovered in sequential sedimentary layers of the Maastrichtian Sânpetru Formation, Toteşti. The occurrence of 11 homogenous clutches in successive strata suggests philopatry by the same dinosaur species, which laid clutches averaging four ∼12 cm diameters eggs. The eggs and eggshells display numerous characters shared with the positively identified material from egg-bearing level 4 of the Auca Mahuevo (Patagonia, Argentina) nemegtosaurid lithostrotian nesting site. Microscopic embryonic integument with bacterial evidences was recovered in one egg. The millimeter-size embryonic integument displays micron size dermal papillae implying an early embryological stage at the time of death, likely corresponding to early organogenesis before the skeleton formation.Conclusions/SignificanceThe shared oological characters between the Haţeg specimens and their mainland relatives suggest a highly conservative reproductive template, while the nest decrease in egg numbers per clutch may reflect an adaptive trait to a smaller body size due to the “island effect”. The combined presence of the lithostrotian egg and its embryo in the Early Cretaceous Gobi coupled with the oological similarities between the Haţeg and Auca Mahuevo oological material evidence that several titanosaur species migrated from Gondwana through the Haţeg Island before or during the Aptian/Albian. It also suggests that this island might have had episodic land bridges with the rest of the European archipelago and Asia deep into the Cretaceous.

Cretaceous faunas and events, northern Eromanga Basin, Queensland

The stratigraphy, sedimentary history and paleontology of the northern Eromanga Basin are reviewed in the light of extensive field effort, searching for Cretaceous vertebrate fossils, in particular dinosaurs. Prolonged non-marine deposition throughout the Jurassic was followed by Lower Cretaceous marine incursions which extended to the late Albian. Whilst biostratigraphy is underpinned by microfloral assemblages there are three distinct marine faunas preserved from the late Aptian, early middle Albian and late Albian. Effective regression caused by sediment oversupply in the latest Albian heralded the final phase of non-marine deposition in the Eromanga Basin which continued into the Cenomanian. A distinct floral assemblage is accompanied by a modest fossil vertebrate assemblage.

Vertebrate fossils (Dinosauria) from the Bonnet Plume Formation, Yukon Territory, Canada

Dinosaurs and other terrestrial vertebrates are poorly documented in the Mesozoic of the Canadian polar region. Here, we provide a complete review of the Upper Cretaceous (Maastrichtian) vertebrate fauna of the Bonnet Plume Formation in the northeastern Yukon Territory, Canada, which includes the description of the first newly collected dinosaur bones from this unit in almost half a century. Previously reported fragmentary dinosaur remains collected in the early 1960’s pertain to an indeterminate hadrosaurid. New material includes a poorly preserved forelimb bone and a pedal phalanx. These new remains pertain to at least one species of non-hadrosaurid ornithischian dinosaur, and the humerus is tentatively referred to a small-bodied basal ornithopod. The new vertebrate fossils from the Bonnet Plume Formation provide further evidence of vertebrates from this unit. However, directed field surveys in 2008 and 2009 suggest that vertebrate fossils are not abundant. A review of the known localities of terrestrial Mesozoic vertebrates from the Canadian Arctic indicate that it had a relatively diverse community of terrestrial vertebrates, including dinosaurs, during the Late Cretaceous, but emphasizes our limited knowledge of the Mesozoic Arctic and considerable potential for future exploration and discovery.

Evaluation of Diagenetic Effect using Fourier Transform Infrared Spectroscopy: Possibility of Application to Enamel of Cretaceous Marine Reptiles

The isotopic composition of fossil animal substances has performed an important role as an indicator of ecological signature for Cenozoic mammals over the last few decades. Recently, isotopic analysis of Cretaceous vertebrates has been used to reconstruct paleoecology, but the effect of diagenesis on such old materials has not been well understood. An evaluation of the effect of diagenesis on enamel from Cretaceous vertebrates is necessary to determine the reliability of isotopic paleoecology. I evaluated the extent of diagenetic effect on enamel from Cretaceous mosasaurs by using Fourier Transform Infrared Spectroscopy (FT-IR). Clear diagenetic alteration was not found in the enamel, showing Cretaceous material may retain pristine isotopic information.

Marine vertebrates from the ‘middle’ Cretaceous (early Cenomanian) of South India

ABSTRACT Vertebrate fossils have been known from South India's Cauvery Basin since the 1840s, but records of marine vertebrates from the late Albian to Turonian Karai Formation have been limited to a single set of ichthyosaur remains. Recent surface collecting and sieving of lower Cenomanian glauconitic mudstones has yielded the first ichthyosaur material reported in India over the last 140 years, as well as a diverse and previously unrecorded shark assemblage. The ichthyosaur material, including several teeth and vertebrae, is assigned to the sole described Cretaceous genus Platypterygius and to the species P. indicus (Lydekker, 1879). Eight species of shark (one squaliformes, two hexanchiformes, and five lamniformes) are recorded. A new hexanchiform genus Gladioserratus is erected, and two new species (Gladioserratus magnus, gen. et sp. nov., and Dwardius sudindicus, sp. nov.) are named. Many of the shark genera within this largely species-level endemic fauna are known from high paleolatitudes elsewhere, with many showing an antitropical distribution, but are absent in Tethyan areas. This first description of the Karai Formation marine fauna documents the previously unappreciated diversity and unique character of India's Cretaceous marine vertebrates, and indicates a cool-water paleoenvironment for the marine vertebrate assemblage.

Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early Cretaceous climates

Early Cretaceous vertebrate assemblages from East Asia and particularly the Jehol Biota of northeastern China flourished during a period of highly debated climatic history. While the unique characters of these continental faunas have been the subject of various speculations about their biogeographic history, little attention has been paid to their possible climatic causes. Here we address this question using the oxygen isotope composition of apatite phosphate (δ ) from various reptile remains recovered from China, Thailand, and Japan. δ values indicate that cold terrestrial climates prevailed at least in this part of Asia during the Barremian-early Albian interval. Estimated mean air temperatures of about 10 ± 4 °C at midlatitudes (∼ 42 °N) correspond to present day cool temperate climatic conditions. Such low temperatures are in agreement with previous reports of cold marine temperatures during this part of the Early Cretaceous, as well as with the widespread occurrence of the temperate fossil wood genus Xenoxylon and the absence of thermophilic reptiles such as crocodilians in northeastern China. The unique character of the Jehol Biota is thus not only the result of its evolutionary and biogeographical history but is also due to rather cold local climatic conditions linked to the paleolatitudinal position of northeastern China and global icehouse climates that prevailed during this part of the Early Cretaceous.

Oxygen and carbon isotope compositions of middle Cretaceous vertebrates from North Africa and Brazil: Ecological and environmental significance

In order to investigate mid-Cretaceous terrestrial climates of low paleolatitudes, Moroccan, Tunisian and Brazilian vertebrate apatites have been analyzed for their oxygen and carbon isotope compositions of phosphates (δ 18O p) and carbonates (δ 18O c, δ 13C c). At each site, coexisting theropod dinosaurs, titanosaurid sauropods, pterosaurs, crocodilians, turtles and fish have distinct δ 18O p and δ 13C c values reflecting their ecologies, diets and foraging environments. Oxygen isotope compositions of surface waters (δ 18O w) estimated from turtle and crocodile δ 18O p values range from − 5.0 ± 1.0‰ to − 2.4 ± 1.0‰, which do not differ from mean annual rainwater values occurring today under inter-tropical sub-arid to arid climates. High water temperatures ranging from 21 ± 6 °C to 34 ± 2 °C deduced from fish δ 18O p values are in agreement with those published for mid-Cretaceous low latitudes. Temporary or seasonal droughts are inferred from high δ 18O p values of lungfish teeth, even though lower reptile δ 18O p values suggest the use of distinct and most likely larger or regularly renewed bodies of water. Environmental conditions of the studied low latitude regions during the Aptian–Cenomanian interval were somewhat similar to those experienced today under semi-arid to arid tropical or equatorial climates, but with higher mean surface temperatures than present-day ones.

An aberrant island-dwelling theropod dinosaur from the Late Cretaceous of Romania.

Islands are noted for the occurrence of aberrant, endemic, and dwarfed taxa (the "island effect"). Late Cretaceous vertebrate assemblages of Romania and elsewhere in Europe are classic examples of island faunas in the fossil record, and are characterized by dwarfed herbivorous dinosaurs and other endemic taxa that are noticeably primitive relative to their mainland contemporaries. Fossils of the predators inhabiting the European paleoislands, however, are exceptionally rare and fragmentary. We describe a new dromaeosaurid theropod, based on an articulated skeleton from the Maastrichtian of Romania, which represents the most complete predatory dinosaur from the middle to Late Cretaceous of Europe. This taxon is characterized by a peculiar body plan, most notably extensive fusion in the hand and distal hindlimb, a highly retroverted pelvis with enlarged femoral muscle attachments, and a pair of hyperextensive pedal claws. However, unlike the island-dwelling herbivorous dinosaurs, its closest relatives are contemporary similar-sized Laurasian taxa, indicating faunal connections between Asia and the European islands late into the Cretaceous. This theropod provides support for the aberrant nature of the Late Cretaceous European island-dwelling dinosaurs, but indicates that predators on these islands were not necessarily small, geographically endemic, or primitive.