Cretaceous Research最新文献

The Upper Cretaceous sauropod fossil record from Romania is abundant, mostly originated from the Maastrichtian deposits of the western-southwestern margin of the Transylvanian Basin, and in the Hațeg and Rusca Montană basins. Most specimens were found in isolation or in low degree of association and only few partial skeletons have been reported. The presence of at least four taxa was recently considered, including three defined forms: Magyarosaurus dacus, Paludititan nalatzensis and “Magyarosaurus” hungaricus. However, the phylogenetic affinities of these taxa within Lithostrotia are still under debate. A large sample of appendicular remains, predominantly composed by unpublished specimens, is described here in detail to provide new data about the diversity of the sauropods of the Hațeg Island during the Maastrichtian. All specimens show affinities or are compatible with lithostrotian sauropods, even if the availability of characters of some of them does not allow its attribution to this clade. Five morphotypes for the femora, three to four for the humeri, three for the fibulae, and two for the radii, ulnae, manus, pubes, ischia, tibiae, and pedes are established, supporting the presence of four or five taxa in this domain. A unique partial manus morphology characterized by its extreme gracile metacarpals is reported, only surpassed by an unpublished manus found in the Spanish Lo Hueco fossil-site (late Campanian-early Maastrichtian), suggesting that a titanosaurian lineage with extremely elongated manus inhabited the European realm, in both Hațeg and Ibero-Armorican islands, at the end of the Mesozoic.

Two ice-rafted dropstones were discovered in the Yaojia Formation (early Santonian) of wells Ao14 and F247 in the Songliao Basin, northeastern China. The dropstone from well Ao14 was further studied using computed tomography (CT) scanning, sporopollen, carbon and oxygen isotope, and zircon U–Pb isotope analyses. The results show that the dropstone is composed of quartz monzonite and has an age of 178.0 ± 3.3 Ma. Based on the bedrock age analysis around the Songliao Basin, it is suggested that the dropstone in well Ao14 may have originated from the Zhangguangcai Range. The palynoflora assemblage indicates a mixed survival of cold and warm palynomorphs. The carbon and oxygen isotope compositions of the synsedimentary calcareous clasts surrounding the dropstone exhibit obvious negative biases, suggesting that glacier meltwater flowed into the paleo-lake, probably due to the significant topographic height difference between the Songliao Basin and adjacent areas during the early Santonian. Additionally, it can be inferred that coastal mountains formed in the Zhangguangcai Range area, which is located southeast of the Songliao Basin, and the dropstones derived from this region. During the cold season, the dropstones may be transported to the edge of Songliao Lake by avalanche and mixed with carbonate debris. As the seasons changed, the lake ice broke into pieces and carrying the dropstones and carbonate debris into the deep lake area. The present research provides direct evidence of a brief global cold event and the presence of high mountains in the southeastern Songliao Basin during the early Santonian in the Cretaceous greenhouse world.

A turtle carapace, identified as Algorachelus cf. peregrina (Pleurodira, Pelomedusoides, Bothremydidae), is reported here from the shallow marine deposits of the Boundary Marls Unit (Utrillas Group), in Estercuel (Teruel Province, northeastern Spain). These levels are identified as deposited during the Lower to Upper Cretaceous transition (late Albian to earliest Cenomanian). This is the oldest record of a bothremydid turtle in Laurasia, documenting that the first dispersal of pelomedusoid turtles from Gondwana to Laurasia occurred earlier than previously identified, most probably in the Early Cretaceous. Pleurodiran turtles always require warm climatic conditions and are mainly freshwater forms. This dispersal was favored by climate change (global warming) that began in the Albian, as well as by the habitat change of the Algorachelus lineage from freshwater to coastal marine environments.

An adult male of †Burmecaelinus armis Uchida, Husemann and Kotthoff, 2023, and a newly identified genus and species †Moban zhengzhemini gen. et sp. nov., are reported based on two well preserved adult specimens from mid-Cretaceous Burmese amber. †M. zhengzhemini gen. et sp. nov. can be distinguished by following characters: body with irregular small dark spots; pronotum is in uniform width, with dispersed shallow dents and two distinct transverse sulci, posterior angle is protruding forward; posterior thoracic process is shark-tooth shaped; pronotal disc without four longitudinal carinae; tip of apical spurs on metatibia not curved. The morphological diagnosis of the family †Burmecaelidae was emended, and the posterior thoracic process of adult †Burmecaelidae species is possibly specialized scutellum. We proposed a hypothesis that this extinct family was a sister group of Tridactyloidea and species of †Burmecaelidae lived in humid environment near water and had affinity for wet and semi-aquatic habitats.

Abundant and diverse pterosaur records have been reported from the Jehol Biota since the end of the last century, including an early reported member, Haopterus gracilis, from the Yixian Formation. The referral of Haopterus gracilis has been a subject of debate since its discovery. Various phylogenetic analyses have suggested different positions for Haopterus gracilis, including the sister taxon of the Ornithocheiroidea or placed differently in the Pteranodontoidea. Recent research has proposed that Haopterus gracilis is the sister-taxon of the Lebanese istiodactyliform Mimodactylus libanensis. Here we redescribe the holotype and only specimen of Haopterus gracilis, a relatively complete skeleton of a juvenile individual in detail using Micro-CL scanning. Haopterus possesses several pteranodontoid features including a stout scapula shorter than the coracoid, a sternum with a constriction posterior to the sternocoracoid articulations, and humeri with trapezoidal deltopectoral crests and constricted mid-shafts. A close affinity between Haopterus and istiodactylids has been suggested by several researchers, whereas some features of Haopterus revealed here distinguish Haopterus from istiodactylids, including the low skull with a long rostrum occupying more than half the skull length anterior to the jaw articulation, and a long tooth row with different tooth morphologies. The phylogenetic position of Haopterus was reevaluated by utilizing a more comprehensive character matrix derived from three previous matrices. The new analysis revealed Haopterus in the Pteranodontoidea and, within this clade, it was an istiodactyliform. The study of Haopterus holds potential significance in enhancing our understanding of the morphology and taxonomy of short-toothed pteranodontoids.

Dryolestoid mammals are classical members of the Jurassic faunas of Laurasia but mostly absent during the Cretaceous. The reverse is true in Gondwana in general and South America in particular, where meridiolestid dryolestoids are dominant in the Late Cretaceous. We describe here 21 new mammalian specimens from the Upper Cretaceous locality Cerro Tortuga (Allen Formation, Patagonia, Argentina) collected via screenwashing, which we identify as meridiolestid dryolestoids. We recognize a new species of meridiolestid and reassign a previously described specimen to the new taxon. The morphology of these new remains represents a new morphotype in the spectrum of meridiolestid diversity, recording a broadening of trophic adaptations from the ancestral insectivory to the more derived herbivory observed among the later and more derived members of the group. The novel dental morphology helps bridge the anatomy of the plesiomorphic sharp-toothed meridiolestidans with that of the more derived and bunodont mesungulatoids. The new taxon suggests that development of both broad cingulids and complex crown morphology precede the development of the wide compressed roots, bunodonty, and thickened enamel characteristic of derived mesungulatids. Other specimens from the collection are referable to taxa previously known from the same locality. These provide new information about tooth positioning, dental formula, and overall dental morphology. The new material suggests that Groebertherium, previously regarded as a dryolestid taxon, is in fact a likely member of Meridiolestida.

Acanthopteris is a fossil fern genus that was established by H.C. Sze in 1931 based on leaf remains from the Lower Cretaceous of the Fuxin Basin in Liaoning Province, China. Traditionally, Acanthopteris is considered to belong to the tree fern family Dicksoniaceae and has been mainly found in the Lower Cretaceous of Fuxin Basin, Huolinhe Basin, and other coeval basins in Northeast China. Since this genus was founded, five fossil species have been described, including A. gothani Sze, A. acutata (Samylina) Zhang, A. alata (Fontaine) Zhang, A. onychioides (Vassilevskaja et Kara-Mursa) Zhang, and A. szei Cao. Based on the investigations on the newly collected fossil specimens and the examinations of other specimens, a reassessment of the systematics and fossil record of Acanthopteris is performed by using both morphological and cluster analysis approaches. The emendation of generic diagnosis of Acanthopteris is provided herein. Geographically, Acanthopteris shows limited distribution in North and NE China, Siberia, Russia and the Inner Zone of Japan. Temporally, Acanthopteris is restricted to the Aptian-Albian period, representing a climate index fossil for a warm and humid climate condition of tropical to subtropical zones during the Early Cretaceous.

Knowledge of continental faunas and floras from the Jurassic–Cretaceous transition in Gondwana, and especially in Africa, is limited. Here, we report the discovery of a rare assemblage of plants and aquatic reptiles from the Tithonian–Berriasian interval of the Anoual syncline in southeastern Morocco. Our preliminary field investigations led to the discovery of a disarticulated skeleton of a goniopholidid crocodylomorph, of a single fragment of a turtle plate, and of abundant plant remains, inviting further exploitation of the fossiliferous horizon. This assemblage indicates a freshwater habitat bordered by a lush moist conifer forest. Its taxonomic composition shows a strong similarity with better known contemporaneous Laurasian assemblages and stresses the paucity of coeval Gondwanan assemblages. Our discovery highlights that peri-Tethys continental assemblages may have shared common taxa and raises the question whether Laurasian and Gondwanan taxa from the Jurassic-Cretaceous transition were cosmopolitan, before they diverged later during the Cretaceous.

The Cretaceous/Paleogene boundary (K/Pg) event, associated with a meteorite impact at Chicxulub, Mexico, is globally recognized as one of the largest mass extinctions in natural history, marking the end of the Mesozoic Era. However, most of the outcrops with records and geochemical evidence of this boundary are distributed in the Northern Hemisphere and at mid-latitudes. Here, aiming to contribute to the knowledge of this event at high southern latitudes, we characterize a single iridium anomaly correlated with the K/Pg boundary, present within a carbonaceous mudstone level in a continental depositional environment in the Río de las Chinas Valley, Chilean Patagonia. High-resolution geochemical and palynofacies analyses were performed on a stratigraphic section from the top of the Dorotea Formation. Results showed that the iridium enrichment coincides with an anomaly of other platinum group elements. In addition, the palynofacies analysis showed a disturbance in the depositional environment, marked by an abrupt change from non-degraded phytoclasts (e.g., cuticles) to pseudoamorphous and degraded cuticles, and by an increase in the abundance of spores at the same level. The Río de las Chinas Valley locality provides new evidence for the comprehensive study of the end-Cretaceous event, from the poorly represented continental environments of high southern latitudes.

Acanthohoplites aschiltaensis, a late Aptian ammonite originally described from the Caucasus of Dagestan, is recognised from the British Isles for the first time. A study of the full ontogenetic development of this species is enabled owing to the preservation of a mature body-chamber, not previously known. Stratigraphically, it confirms the correlation of the Fullers' Earth deposits within the Parahoplites nutfieldiensis Zone at Baulking, Oxfordshire, with strata of the Parahoplites melchioris Zone at the type locality and elsewhere. Palaeobiogeographically, it underlines the strong relationship between the Boreal fauna of western Europe and that of the Mediterranean-Caucasian Subrealm of the Tethyan realm. Additionally, a small Hypacanthoplites spp. fauna is described from the H. rubricosus Subzone of the Hypcanthoplites jacobi Zone at the Aptian/Albian boundary interval exposed in the Shanklin area, Isle of Wight. From this locality, otherwise almost devoid of ammonite remains, we present fairly well-preserved specimens of ‘Hypacanthoplites’ elegans, H. plesiotypicus, H. pricei, H. tenuiformis, H. rubricosus, H. sigmoidalis and H. sp. 1 indet., only known thanks to some decades of intensive collecting. In addition to the other members of this genus previously described from the British Isles, the occurrence of ‘H.’ elegans and H. plesiotypicus further supports the existence of narrow sea connections eastwards onto the European continent.