A New Hadrosauroid Dinosaur from the Early Late Cretaceous of Shanxi Province,China

Background

The origin of hadrosaurid dinosaurs is far from clear, mainly due to the paucity of their early Late Cretaceous close relatives. Compared to numerous Early Cretaceous basal hadrosauroids, which are mainly from Eastern Asia, only six early Late Cretaceous (pre-Campanian) basal hadrosauroids have been found: three from Asia and three from North America.

Methodology/Principal Findings

Here we describe a new hadrosauroid dinosaur, Yunganglong datongensis gen. et sp. nov., from the early Late Cretaceous Zhumapu Formation of Shanxi Province in northern China. The new taxon is represented by an associated but disarticulated partial adult skeleton including the caudodorsal part of the skull. Cladistic analysis and comparative studies show that Yunganglong represents one of the most basal Late Cretaceous hadrosauroids and is diagnosed by a unique combination of features in its skull and femur.

Conclusions/Significance

The discovery of Yunganglong adds another record of basal Hadrosauroidea in the early Late Cretaceous, and helps to elucidate the origin and evolution of Hadrosauridae.     

A Ceratopsian Dinosaur from the Lower Cretaceous of Western North America,and the Biogeography of Neoceratopsia

The fossil record for neoceratopsian (horned) dinosaurs in the Lower Cretaceous of North America primarily comprises isolated teeth and postcrania of limited taxonomic resolution, hampering previous efforts to reconstruct the early evolution of this group in North America. An associated cranium and lower jaw from the Cloverly Formation (?middle–late Albian, between 104 and 109 million years old) of southern Montana is designated as the holotype for Aquilops americanus gen. et sp. nov. Aquilops americanus is distinguished by several autapomorphies, including a strongly hooked rostral bone with a midline boss and an elongate and sharply pointed antorbital fossa. The skull in the only known specimen is comparatively small, measuring 84 mm between the tips of the rostral and jugal. The taxon is interpreted as a basal neoceratopsian closely related to Early Cretaceous Asian taxa, such as Liaoceratops and Auroraceratops. Biogeographically, A. americanus probably originated via a dispersal from Asia into North America; the exact route of this dispersal is ambiguous, although a Beringian rather than European route seems more likely in light of the absence of ceratopsians in the Early Cretaceous of Europe. Other amniote clades show similar biogeographic patterns, supporting an intercontinental migratory event between Asia and North America during the late Early Cretaceous. The temporal and geographic distribution of Upper Cretaceous neoceratopsians (leptoceratopsids and ceratopsoids) suggests at least intermittent connections between North America and Asia through the early Late Cretaceous, likely followed by an interval of isolation and finally reconnection during the latest Cretaceous.     

The Phytogeography of the extinct angiosperm Nordenskioeldia (Trochodendraceae) and its response to climate changes

Elucidating the spatio-temporal distributions of terrestrial plants is a key for interpreting the origin of distribution patterns and the tempo of intercontinental disjunction. Nordenskioeldia was distributed in eastern Asia and North America from the Late Cretaceous to the Miocene. Its fossil record provides important information on former patterns of disjunction and dispersal in the Northern Hemisphere. New specimens from the Paleocene of China allow us to further extend the history of the group and provide the impetus to review its distribution in space and time. The comparative morphological survey on fossil Nordenskioeldia found in the Paleocene sediments in both eastern Asia and North America confirms that they belonged to the same morpho-species, which indicates a close floristic continuity between both continents due to land connection available during that time. The spatio-temporal distributions of Nordenskioeldia indicate that the taxon probably expanded eastward from eastern Asia into North America by the end of Early/Middle Maastrichtian, subsequently colonized Greenland, northeastern North America and Spitsbergen in the Early Paleocene, and finally became extinct in the Miocene. The fluctuations in its northern limits took place in response to climate changes: warming from the Paleocene to the Eocene, cooling during the Eocene–Oligocene and amelioration during the Late Oligocene–Mid-Miocene.     

A New Basal Hadrosauroid Dinosaur from the Lower Cretaceous Khok Kruat Formation in Nakhon Ratchasima Province,Northeastern Thailand

A new basal hadrosauroid dinosaur from the Lower Cretaceous Khok Kruat Formation of Thailand, Sirindhorna khoratensis gen. et sp. nov is described. The new taxon is based on composite skull and mandible including premaxilla, maxilla, jugal, quadrate, braincases, predentary, dentaries, surangular, and maxillary and dentary teeth. It is diagnostic by such characters as, sagittal crest extending along entire dorsal surface of the parietal and reaching the frontoparietal suture (autapomorphy), transversely straight frontoparietal suture, caudodorsally faced supraoccipital, no participation of the supraoccipital in the foramen magnum, mesiodistally wide leaf-shaped dentary tooth with primary and secondary ridges on the lingual surface of the crown, perpendicularly-erected and large coronoid process of dentary, and nonvisible antorbital fossa of the maxilla in lateral view. Phylogenetic analysis revealed S. khoratensis as among the most basal hadrosauroids. Sirindhorna khoratensis is the best-preserved iguanodontian ornithopod in Southeast Asia and sheds new light to resolve the evolution of basal hadrosauriforms.     

A new hadrosaurid dentary from the latest Maastrichtian of the Pyrenees (north Spain) and the high diversity of the duck-billed dinosaurs of the Ibero-Armorican Realm at the very end of the Cretaceous

In the latest Maastrichtian, the European hadrosauroid fauna was more diverse than those of North America and Asia. The European record of hadrosaurid dentaries is an example of this diversity, and most of the sites with mandibular remains are located in the Ibero-Armorican Realm. Within the Iberian Peninsula, most of the remains are located in the Tremp Basin (South Central Pyrenees). Two of the three valid hadrosaurid taxa defined in this basin are from the Blasi sites (Arén, Huesca province): Arenysaurus ardevoli (Blasi-3) and Blasisaurus canudoi (Blasi-1). A new locality in Blasi (Blasi 3.4) has provided a new dentary from an indeterminate euhadrosaurid. This dentary presents some characters intermediate between Arenysaurus and Blasisaurus, some characters similar to Pararhabdodon isonensis (from the nearby province of Lleida), and some characters of its own. Nevertheless, due to its fragmentary character, without dentition or its edentulous anterior part, it cannot be determined above the level of Euhadrosauria. It thus represents a fourth Iberian euhadrosaurian taxon in the Ibero-Armorican Realm, different from Arenysaurus, Blasisaurus and Pararhabdodon, increasing the diversity of hadrosauroids in this realm at the very end of the Cretaceous.     

Global historical biogeography of hadrosaurid dinosaurs

Hadrosaurids were the most derived ornithopods and amongst the most diverse herbivore dinosaurs during the Late Cretaceous of Europe, Asia, and the two Americas. Here, their biogeographical history is reconstructed using dispersal‐vicariance analysis (DIVA). The results showed that Hadrosauridae originated in North America and soon after dispersed to Asia no later than the Late Santonian. The most recent common ancestor of Saurolophidae (= Saurolophinae + Lambeosaurinae) is inferred to have been widespread in North America and Asia. The split between saurolophines and lambeosaurines occurred in response to vicariance no later than the Late Santonian: the former clade originated in North America, whereas the latter did so in Asia. Saurolophine biogeographical history included a minimum of five dispersal events followed by vicariance. Four of these dispersals were inferred to have occurred from North America to Asia during the Campanian and Early Maastrichtian, whereas a fifth event represented a southward dispersal from North to South America no later than the Late Campanian. The historical biogeography of lambeosaurines was characterized by an early evolution in Asia, with a Campanian dispersal to the European archipelago followed by vicariance. Reconstruction of the ancestral areas for the deepest nodes uniting the more derived lambeosaurines clades (‘hypacrosaurs’, ‘corythosaurs’, and ‘parasaurolophs’) is ambiguous. The split between North American and Asian clades of ‘hypacrosaurs’ and ‘parasaurolophs’ occurred in response to vicariance during the Campanian. The evolutionary history of North American ‘hypacrosaurs’ and ‘parasaurolophs’ was characterized by duplication events. The latter also characterized the Late Campanian ‘corythosaurs’, which remained restricted to North America. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 503–525.     

Biogeographical and geological evidence for a smaller, completely-enclosed Pacific Basin in the Late Cretaceous

Aim To use biogeographical, palaeomagnetic, palaeosedimentary, and plate circuit data from Late Cretaceous regions in and around the Pacific to test the plate tectonic hypothesis of a pre‐Pacific superocean. Location East Asia, Australia, Antarctica, the western Americas, and the Pacific. Methods Literature surveys of the distributions of Cretaceous, circum‐Pacific taxa were compared with palaeomagnetic and palaeosedimentary data. Uncontroversial plate motions based on seafloor spreading data were also used to test the results of the biogeographical and palaeomagnetic analyses. Results The distributions of Cretaceous terrestrial taxa, mostly dinosaurs, imply direct, continental connections between Australia and East Asia, East Asia and North America, North America and South America, South America and Antarctica, and Antarctica and Australia. Palaeomagnetic, palaeosedimentary, and basic plate circuit analyses require little to no latitudinal motion of the Pacific plate with respect to the surrounding continents. Specifically, the data implies that western North America, East Asia, and the Pacific plate all increased in latitude by roughly the same amount (c. 11 ± 5°) since the Campanian – and that the Pacific Ocean Basin has increased in length north‐to‐south. Main conclusions Each of the analyses provides independent corroboration for the same conclusion: the Late Cretaceous Pacific plate was completely enclosed by the surrounding continents and has not experienced significant latitudinal motion with respect to North America, East Asia, or the Bering land bridge. This contrasts significantly with the plate tectonic history of the Pacific, implying instead that the Pacific plate formed in situ, pushing the continents apart as the plate and basin expanded. These results also substantiate recent biogeographical analyses that have concluded that a narrower Pacific Ocean Basin in the Mesozoic and early Tertiary provides the most reasonable explanation for the great number of trans‐Pacific disjunctions of poor dispersing taxa.     

A new primitive hadrosauroid dinosaur from the Early Cretaceous of Inner Mongolia (P.R. China)

The right dentary of a new hadrosauroid dinosaur, Penelopognathus weishampeli, has been discovered in the Bayan Gobi Formation (Albian, Lower Cretaceous) of Inner Mongolia (P.R. China). This new taxon is characterised by its elongated, straight dental ramus, whose lateral side is pierced by about 20 irregularly distributed foramina. Its dentary teeth appear more primitive than those of Probactrosaurus, but more advanced than those of Altirhinus, both also from the Lower Cretaceous of the Gobi area. Non-hadrosaurid Hadrosauroidea were already well diversified in eastern Asia by Early Cretaceous time, suggesting an Asian origin for the hadrosauroid clade. To cite this article: P. Godefroit et al., C. R. Palevol 4 (2005).     

Biogeographic history of the butterfly subtribe Euptychiina (Lepidoptera,Nymphalidae, Satyrinae)

Peña, C., Nylin, S., Freitas, A. V. L. & Wahlberg, N. (2010). Biogeographic history of the butterfly subtribe Euptychiina (Lepidoptera, Nymphalidae, Satyrinae).—Zoologica Scripta, 39, 243–258. The diverse butterfly subtribe Euptychiina was thought to be restricted to the Americas. However, there is mounting evidence for the Oriental Palaeonympha opalina being part of Euptychiina and thus a disjunct distribution between it (in eastern Asia) and its sister taxon (in eastern North America). Such a disjunct distribution in both eastern Asia and eastern North America has never been reported for any butterfly taxon. We used 4447 bp of DNA sequences from one mitochondrial gene and four nuclear genes for 102 Euptychiina taxa to obtain a phylogenetic hypothesis of the subtribe, estimate dates of origin and diversification for major clades and perform a biogeographic analysis. Euptychiina originated 31 Ma in South America. Early Euptychiina dispersed from North to South America via the temporary connection known as GAARlandia during Eocene–Oligocene times. The current disjunct distribution of the Oriental Palaeonympha opalina is the result of a northbound dispersal of a lineage from South America into eastern Asia via North America. The common ancestor of Palaeonympha and its sister taxon Megisto inhabited the continuous forest belt across North Asia and North America, which was connected by Beringia. The closure of this connection caused the split between Palaeonympha and Megisto around 13 Ma and the severe extinctions in western North America because of the climatic changes of the Late Miocene (from 13.5 Ma onwards) resulted in the classic ‘eastern Asia and eastern North America’ disjunct distribution.     

The origin and early evolution of metatherian mammals: the Cretaceous record

Metatherians, which comprise marsupials and their closest fossil relatives, were one of the most dominant clades of mammals during the Cretaceous and are the most diverse clade of living mammals after Placentalia. Our understanding of this group has increased greatly over the past 20 years, with the discovery of new specimens and the application of new analytical tools. Here we provide a review of the phylogenetic relationships of metatherians with respect to other mammals, discuss the taxonomic definition and diagnosis of Metatheria, outline the Cretaceous history of major metatherian clades, describe the paleobiology, biogeography, and macroevolution of Cretaceous metatherians, and provide a physical and climatic background of Cretaceous metatherian faunas. Metatherians are a clade of boreosphendian mammals that must have originated by the Late Jurassic, but the first unequivocal metatherian fossil is from the Early Cretaceous of Asia. Metatherians have the distinctive tightly interlocking occlusal molar pattern of tribosphenic mammals, but differ from Eutheria in their dental formula and tooth replacement pattern, which may be related to the metatherian reproductive process which includes an extended period of lactation followed by birth of extremely altricial young. Metatherians were widespread over Laurasia during the Cretaceous, with members present in Asia, Europe, and North America by the early Late Cretaceous. In particular, they were taxonomically and morphologically diverse and relatively abundant in the Late Cretaceous of western North America, where they have been used to examine patterns of biogeography, macroevolution, diversification, and extinction through the Late Cretaceous and across the Cretaceous-Paleogene (K-Pg) boundary. Metatherian diversification patterns suggest that they were not strongly affected by a Cretaceous Terrestrial Revolution, but they clearly underwent a severe extinction across the K-Pg boundary.     

New Dinosaur Footprints from the Upper Cretaceous of Poland in the Light of Paleogeographic Context

The Late Cretaceous track assemblage of southeastern Poland includes intriguing ichnotaxa with Asian or North American affinities. New finds of the ceratopsian-like ichnite and small hadrosauroid track refer directly to this problem, whereas the re-evaluation of foraminifer taxa estimates the stratigraphic positions of the track-bearing horizon and allowed to understand paleogeographic context of the studied and adjacent areas. The results demonstrate that during the Late Cretaceous times, migration of dinosaurs was possible from Asia through the East European Land to Kukeritz Island and the islands at peri-Tethys area.     

The morphology,taxonomy, and occurrence of the genus <Emphasis Type="Italic">Pseudoprotophyllum</Emphasis> Hollick (Platanaceae) in Late Cretaceous floras of Northern Asia

An extended generic diagnosis of Pseudoprotophyllum is given on the basis of new data from Late Cretaceous floras of Northern Asia. Both peltate and apeltate morphological types are included in the genus. The morphological diversity is described in the type species P. boreale (Dawson) Hollick from the Cenomanian-Turonian of North America and four North Asiatic species: P. minimum I. Lebed. , P. sibiricum I. Lebed., P. hatangaense Abramova, and P. giganteum Sveshn. et Budants. The geographical and stratigraphic analyses show that Pseudoprotophyllum evolved in Northern Asia since the Cenomanian until Campanian and was restricted to the Siberian-Canadian floristic region with a warm-temperate humid climate.     

Mesofossils with platanaceous affinity from the Dakota Formation (Cretaceous) in Kansas, USA

The Platanaceae holds a basal position in the phylogeny of eudicots and therefore is of great interest to angiosperm systematists. The fossil record of the family is found in strata ranging from the Cretaceous to Recent in America, Europe and Asia. The research on the Platanaceae in the Dakota Formation can be traced back to 19th century; however, mesofossils of reproductive organs of the Platanaceae were never reported in the Midwest of North America before. This paper reports several specimens of Friisicarpus (Platanaceae) from the Dakota Formation in Kansas, USA. It complements the existing fossil records, and provides more information on reproductive biology of the family. The comparison with similar fossils from eastern North America and Europe provides some hints on biostratigraphy of the Cretaceous.     

The oldest higher true crabs (Crustacea: Decapoda: Brachyura): insights from the Early Cretaceous of the Americas

Despite the extensive fossil record of higher crabs (Eubrachyura) from Late Cretaceous and Cenozoic rocks worldwide, their Early Cretaceous occurrences are scarce and fragmentary, obscuring our understanding of their early evolution. Until now, representatives of only two families of eubrachyuran‐like crabs were known from the Early Cretaceous: Componocancridae and Tepexicarcinidae fam. nov., both monospecific lineages from the Albian (~110–100 Ma) of North and Central America, respectively. The discovery of Telamonocarcinus antiquus sp. nov. (Telamonocarcinidae) from the early Albian of Colombia, South America (~110 Ma), increases to three the number of known Early Cretaceous eubrachyuran‐like families. The ages and geographical distributions of the oldest eubrachyuran‐like taxa (i.e. Componocancridae, Telamonocarcinidae and Tepexicarcinidae fam. nov.) suggest that the oldest higher true crabs might have originated in the Americas; that they were already morphologically diverse by the late Early Cretaceous; and that their most recent common ancestor must be rooted in the Early Cretaceous, or even the Late Jurassic.     

The oldest Cretaceous North American sauropod dinosaur

Sauropod dinosaurs have been found in sediments dating to most of the Cretaceous Period on all major Mesozoic landmasses, but this record is spatiotemporally uneven, even in relatively well-explored North American sediments. Within the 80 million-year-span of the Cretaceous, no definitive sauropod occurrences are known in North America from two ca. 20–25 million-year-long gaps, one from approximately the Berriasian–Barremian and the other from the mid-Cenomanian–late Campanian. Herein, we present an undescribed specimen that was collected in the middle part of the twentieth century that expands the known spatiotemporal distribution of Early Cretaceous North American sauropods, partially filling the earlier gap. The material is from the Berriasian–Valanginian-aged (ca. 139 Ma) Chilson Member of the Lakota Formation of South Dakota and appears to represent the only non-titanosauriform from the Cretaceous of North America or Asia. It closely resembles Camarasaurus and may represent a form closely related to that genus that persisted across the Jurassic–Cretaceous boundary.     

Mosasaur predation on a nautiloid from the Maastrichtian Pierre Shale,Central Colorado,Western Interior Basin,United States

Mosasaurs were common predators on the ammonites that inhabited the upper water column of the Late Cretaceous Western Interior epicontinental seaway of North America. Mosasaurs developed predictable behaviour patterns for feeding on ammonite prey. There are no previous reports of mosasaur predation on the much less common Cretaceous nautiloids, possibly because of the prey's predominantly deep, epibenthic habitat, as deduced from modern Nautilus life habits. A single specimen of the highly inflated nautiloid, Eutrephoceras dekayi (Conrad), prey to a small adult mosasaur, likely Platycarpus, Prognathodon or Mosasaurus, is reported herein from the Pierre Shale of Colorado in the Early Maastrichtian biozone of Baculitesgrandis transitional to the biozone of B. clinolobatus. The nautiloid was killed in the same manner as described previously for discoid ammonites (Placenticeras, Sphenodiscus) from coeval strata in the USA and Canada.     

A new evolutionary lineage of diving birds from the Late Cretaceous of North America and Asia

A new family, Brodavidae, with one new genus and four species, is described from the Late Cretaceous (Maastrichtian) of Asia and North America. These include the first freshwater occurrences and latest records of the order Hesperornithiformes, an extinct group of diving birds whose marine members had probably lost their powers of flight by the end of the Early Cretaceous. Minimal pachyostosis in the freshwater form suggests the possibility of volant abilities.     

A SPALACOLESTINE SPALACOTHERIID (MAMMALIA,TRECHNOTHERIA) FROM THE EARLY CRETACEOUS (BARREMIAN) OF SOUTHERN ENGLAND AND ITS BEARING ON SPALACOTHERIID EVOLUTION

Abstract: Bulk screening of Early Cretaceous (Barremian) Wealden Group strata of the Wessex Formation exposed on the south‐west and south‐east coasts of the Isle of Wight, southern England, has resulted in the recovery of fragmentary remains pertaining to a new spalacolestine spalacotheriid mammal, Yaverlestes gassoni gen. et sp. nov. These represent the first European record of the Spalacolestinae. The remains comprise a dentulous incomplete dentary and isolated upper and lower molariforms, the former representing the most substantial mammal remains yet recovered from the Wealden Group. Hitherto, six species of spalacotheriid mammal were known from the Lower Cretaceous of Europe. All are referred to the genus Spalacotherium but in the case of taxa diagnosed on the basis of isolated lower teeth and other specimens where the post‐canine dentition is incompletely known, it is now evident that these referrals should be treated with caution. Furthermore, the new Wessex Formation spalacotheriid and recently described spalacotheriids from the ?Barremian of Japan, and the Barremian and Aptian of China exhibit combinations of characters that suggest that spalacotheriids were more diverse and that their evolution was more complex than previously recognized. The systematic position of an isolated tooth from the basal Cretaceous Lourinhã Formation of Portugal is discussed and the tooth reassigned to the Spalacotheriidae. Together with the new Wessex Formation taxon, eight species are now known from the Lower Cretaceous of Europe. The discovery of a spalacolestine in the Barremian Wessex Formation supports the concept of faunal interchange between Europe, Asia and North America during the Early Cretaceous. It also supports derivation of North American spalacotheriids from a European or Eurasian ancestor.