Cretaceous Fossil Research Articles

Cretabaltoraea volsella gen. et sp. nov. (Coleoptera: Nitidulidae) from Cretaceous Kachin amber and its relationship with Eocene Baltoraea (Coleoptera: Nitidulidae)

Here we describe Cretabaltoraea volsella Peris, Jelínek & Audisio gen. et sp. nov. of the family Nitidulidae (Coleoptera). As implied by its generic name, the new species is described after a fossil specimen preserved in the Upper Cretaceous Kachin amber from northern Myanmar. This new species is rather similar to the two fossil nitidulid species of Baltoraea Kurochkin & Kirejtshuk, 2010, previously described from the Eocene Baltic amber. The comparison between this group of fossils and the study of Baltoraea simillima Kurochkin & Kirejtshuk, 2010 using CT-scanning suggest that Cretabaltoraea volsella gen. et sp. nov. and the two Baltoraea species should be placed in the extinct Apophisandrinae, a basal subfamily of Nitidulidae which until now only includes a group of Cretaceous fossils from the Kachin amber, described as ancient pollinators of both gymnosperms and basal angiosperms.

Systematic of a Massively Constructed Specimen of Iguanodon galvensis (Ornithopoda, Iguanodontidae) from the Early Barremian (Early Cretaceous) of Eastern Spain

Styracosternan ornithopods are plenty abundant in the Lower Cretaceous fossil record of Europe. In particular, Iguanodon, the second genus of dinosaurs described worldwide, has been found in UK, Belgium, France, Germany, and Spain, evidencing a wide geographical distribution. Currently, the genus Iguanodon comprises two species, the type species I. bernissartensis from the late Barremian–Aptian of Europe and I. galvensis from the early Barremian of Teruel, Spain. The latter species is well known mainly from perinate and juvenile specimens. Here, axial and appendicular fossils of an adult, large and massively constructed ornithopod from the lower Barremian (Lower Cretaceous) Camarillas Formation of Galve (province of Teruel, Spain) are described. Fossil dimensions and some osteological evidence reveal that the specimen was a large (roughly 10 m long) ornithopod. An autapomorphic feature in the ischium and other characters allow us to ascribe this specimen to I. galvensis. In addition, postcranial co-ossification and fusion of the neurocentral suture indicate that the specimen was skeletally mature. Part of the material studied here was unknown in adults of I. galvensis, providing a better knowledge of the axial and appendicular region of this species.

The Cretaceous Diatom Database: A tool for investigating early diatom evolution.

The Cretaceous period is the time of the first appearance of the diatoms in the fossil record. These fossils give us direct evidence of the age and early evolution of the diatom lineage. The fossil record, however, is incomplete and therefore often extrapolated through time-calibrated phylogenies. These two approaches offer different perspectives on the early evolution of diatoms, which is still poorly understood. We compiled the first comprehensive Cretaceous Diatom Database, a tool to investigate the taxonomy, diversity, and occurrence of the earliest known diatom lineages. To further aid the integration and use of the oldest diatom fossils in molecular clock analyses, we present a set of well-documented Cretaceous fossils that can be placed onto molecular phylogenetic trees of extant and extinct species, making them ideal candidates for the calibration of molecular clocks. The analysis of the fossil record and the Cretaceous Diatom Database revealed Cretaceous diversity is substantially greater than previously thought, yet considerable taxonomic work is still needed. The Cretaceous Diatom Database and the list of Cretaceous fossils for calibrating molecular clocks represent valuable resources for future evolutionary and taxonomic studies of modern and fossil diatoms.

Bio-molecular analyses enable new insights into the taphonomy of feathers.

Exceptionally preserved feathers from the Mesozoic era have provided valuable insights into the early evolution of feathers and enabled color reconstruction of extinct dinosaurs, including early birds. Mounting chemical evidence for the two key components of feathers-keratins and melanins-in fossil feathers has demonstrated that exceptional preservation can be traced down to the molecular level. However, the chemical changes that keratin and eumelanin undergo during fossilization are still not fully understood, introducing uncertainty in the identification of these two molecules in fossil feathers. To address this issue, we need to examine their taphonomic process. In this study, we analyzed the structural and chemical composition of fossil feathers from the Jehol Biota and compared them with the structural and chemical changes observed in modern feathers during the process of biodegradation and thermal degradation, as well as the structural and chemical characteristics of a Cenozoic fossil feather. Our results suggest that the taphonomic process of feathers from the Cretaceous Jehol Biota is mainly controlled by the process of thermal degradation. The Cretaceous fossil feathers studied exhibited minimal keratin preservation but retained strong melanin signals, attributed to melanin's higher thermal stability. Low-maturity carbonaceous fossils can indeed preserve biosignals, especially signals from molecules with high resistance to thermal degradation. These findings provide clues about the preservation potential of keratin and melanin, and serve as a reference for searching for those two biomolecules in different geological periods and environments.

Lower Cretaceous iguanodontian dinosaurs from the southwestern margin of Gondwana

The early evolutionary and biogeographical history of Gondwanan iguanodontian dinosaurs is poorly understood due to their scarce Lower Cretaceous fossil record. In South America, the Lower Cretaceous iguanodontian osteological record is very fragmentary and most published reports cannot be used to discard or confirm hadrosauroid affinities. The single exception is Tietasaura from Brazil, whose incomplete femur shows a combination of traits found only in non-hadrosauroid iguandontians. Furthermore, no skeletal remains whatsoever of Lower Cretaceous iguanodontians have been reported from the western margin of South America. Here, we describe an isolated ornithopod caudal centrum (SGO.PV.22900) from the Lower Cretaceous Quebrada Monardes Formation in the Atacama Desert, northern Chile. Although incomplete, SGO.PV.22900 presents iguanodontian traits, such as the sub-hexagonal contour of the articular faces, the rectangular profile in lateral view and the absence of transverse processes below the neurocentral suture. We were also able to use quantitative measurements to explore taxonomic affinities, by carrying out a Linear Discriminant Analysis (LDA) and a Principal Components Analysis (PCA) using measurements of caudal centra of several iguanodontian species. The results of both analyses are consistent with those of our comparisons and suggest that SGO.PV.22900 belongs to a non-hadrosauroid iguanodontian ornithopod. This specimen represents one of the most compelling and best documented pieces of osteological evidence of Lower Cretaceous non-hadrosauroid iguanodontian dinosaurs in South America and provides further support for the presence of iguanodontians in the southwestern margin of Gondwana since at least the Early Cretaceous, as previously suggested based on footprints.

Fossil-informed biogeographic analysis suggests Eurasian regionalization in crown Squamata during the early Jurassic.

Squamata (lizards, snakes, and amphisbaenians) is a Triassic lineage with an extensive and complex biogeographic history, yet no large-scale study has reconstructed the ancestral range of early squamate lineages. The fossil record indicates a broadly Pangaean distribution by the end- Cretaceous, though many lineages (e.g., Paramacellodidae, Mosasauria, Polyglyphanodontia) subsequently went extinct. Thus, the origin and occupancy of extant radiations is unclear and may have been localized within Pangaea to specific plates, with potential regionalization to distinct Laurasian and Gondwanan landmasses during the Mesozoic in some groups. We used recent tectonic models to code extant and fossil squamate distributions occurring on nine discrete plates for 9,755 species, with Jurassic and Cretaceous fossil constraints from three extinct lineages. We modeled ancestral ranges for crown Squamata from an extant-only molecular phylogeny using a suite of biogeographic models accommodating different evolutionary processes and fossil-based node constraints from known Jurassic and Cretaceous localities. We hypothesized that the best-fit models would not support a full Pangaean distribution (i.e., including all areas) for the origin of crown Squamata, but would instead show regionalization to specific areas within the fragmenting supercontinent, likely in the Northern Hemisphere where most early squamate fossils have been found. Incorporating fossil data reconstructs a localized origin within Pangaea, with early regionalization of extant lineages to Eurasia and Laurasia, while Gondwanan regionalization did not occur until the middle Cretaceous for Alethinophidia, Scolecophidia, and some crown Gekkotan lineages. While the Mesozoic history of extant squamate biogeography can be summarized as a Eurasian origin with dispersal out of Laurasia into Gondwana, their Cenozoic history is complex with multiple events (including secondary and tertiary recolonizations) in several directions. As noted by previous authors, squamates have likely utilized over-land range expansion, land-bridge colonization, and trans-oceanic dispersal. Tropical Gondwana and Eurasia hold more ancient lineages than the Holarctic (Rhineuridae being a major exception), and some asymmetries in colonization (e.g., to North America from Eurasia during the Cenozoic through Beringia) deserve additional study. Future studies that incorporate fossil branches, rather than as node constraints, into the reconstruction can be used to explore this history further.

Cretafrica orapensis: a new genus and species of Mycetoporinae (Coleoptera: Staphylinidae) from lacustrine deposits at Orapa Diamond Mine, Botswana

Abstract A new genus and species of staphylinid beetle, Cretafrica orapensis gen. nov. et sp. nov. is described using a single well-preserved impression fossil from an Upper Cretaceous fossil insect deposit, the Orapa Diamond Mine in Botswana. Cretafrica is placed in the extant subfamily Mycetoporinae based on its general habitus, typical sublimuloid medium-to-large body form, elongated head, visible ridge on ventral side of head under eyes, antennomeres increasing in length and width apically, scutellum with basal carina that is distinctly divided medially, elevated area along suture of the elytra, and presumably large metacoxae, and tapering abdomen. It differs from other Mycetoporinae by its triangular head and elytra with broadly rounded apico-lateral margins. A possible preservation distortion illustrates brush-like or fork-like mouthparts. The fossil insect may have been found in forest litter or fresh and rotting mushrooms at Orapa. It confirms the widespread distribution of mycetoporines with phytophagous or mycophagous lifestyles during the mid-Cretaceous. Moreover, like other described fossil staphylinids, the fossil portrays morphological stasis dating back to the Cretaceous. It further confirms the proposed punctuated equilibrium pattern of evolution.

Cretaceous fossil birds from China

Abstract The explosive radiation of early birds has been well documented by the extraordinary discoveries of the Early Cretaceous fossil birds in China in the past three decades. They have greatly expanded the diversity, disparity and temporal distribution of Mesozoic birds, refining our knowledge of the evolutionary path leading to the characteristic avian body plan, including feathers and powered flight, locomotion and habitat differentiation, diet and digestion, reproduction and development, feather colours and display. In addition, studies on the geological background of the Jehol Biota that produced the majority of the Chinese Cretaceous birds have provided important clues to our understanding of the taphonomy as well as the interaction between deep geological process and biological evolution in northeastern China and East Asia during the Early Cretaceous. Future multidisciplinary studies are expected to advance our knowledge of the palaeogeography of Early Cretaceous birds, what impacted the changes in the diversity of early birds in China, and the roles that early birds played in the Early Cretaceous terrestrial ecosystem.

Mississippi, USA's local landscapes: geoheritage value and educational benefits within college palaeontology classrooms

Abstract In Mississippi, USA, exposures of fossiliferous Cretaceous and Paleogene strata contributed to geological investigations for more than 200 years. Since 2012, four Mississippi fossiliferous field sites were regularly integrated within university palaeontology classrooms, with community engaged learning (CEL) introduced in 2018. Through CEL projects, the students assisted local organizations with optimizing and/or protecting local fossiliferous sites. Analysis of student surveys demonstrated that students were overwhelmingly positive toward local field sites and CEL inclusion in the palaeontology courses. Students acknowledged ‘real-world’ interdisciplinary CEL experiences moved them beyond the palaeontology content and made them stakeholders in modern issues. While these four sites contain landscapes that qualify as local geoheritage sites because of their educational and potential geotourism value, only one site, W.M. Browning Cretaceous Fossil Park, is preserved for future generations. The other sites (Blue Springs, Osborn Prairie, Smith County) face challenges in their long-term sustainability.

The evolutionary history of Coleoptera (Insecta) in the late Palaeozoic and the Mesozoic

AbstractRecent progress in beetle palaeontology has incited us to re‐address the evolutionary history of the group. The Permian †Tshekardocoleidae had elytra that covered the posterior body in a loose tent‐like manner. The formation of elytral epipleura and a tight fit of elytra and abdomen were important evolutionary transformations in the Middle Permian, resulting in a tightly enclosed subelytral space. Permian families were likely associated with dead wood of gymnospermous trees. The end‐Permian extinction event resulted in a turnover in the composition of beetle faunas, especially a decline of large‐bodied wood‐associated forms. Adephaga and Myxophaga underwent a first wave of diversification in the Triassic. Polyphaga are very rare in this period. The first wave of diversification of this suborder occurs in the Jurassic, with fossils of Elateriformia, Staphyliniformia and Cucujiformia. The Cretaceous fossil record has been tremendously enriched by the discovery of amber inclusions. Numerous fossils represent all major polyphagan lineages and also the remaining suborders. Improved analytical methods for documenting and placing extinct taxa are discussed. Different factors have played a role in the diversification of beetles. The enormous number of species associated with flowering plants, and timing and patterns of diversification in phytophagous lineages indicate that the angiosperm radiation played a major role in beetle macroevolution. Moreover, the evolution of intimate partnerships with symbionts and the acquisition of novel genes—obtained from fungi and bacteria via horizontal gene transfers—facilitated the use of plant material as a food source and were key innovations in the diversification of plant‐feeding beetles.

A new enantiornithine specimen from the Lower Cretaceous of Las Hoyas: avifaunal diversity and life-history of a wetland Mesozoic bird

The Lower Cretaceous fossil site of Las Hoyas (Cuenca, Spain) has yielded the richest Cretaceous avifauna of the European continent. We describe a new fossil (MUPA-LH-33333) of an enantiornithine bird from this locality. This specimen consists of a partially articulated skeleton preserving portions of the vertebral column, both girdles and limbs, ribs and sternum; it also preserves patches of soft tissues including remigial feathers and integumentary structures belonging to the postpatagium. MUPA-LH-33333 shares dimensions and some anatomical features with the holotype of Concornis lacustris, a species previously described from Las Hoyas. However, the new specimen shows differences especially in the coracoid and the sternum, suggesting the presence of a different morphotype closely related to C. lacustris. Nevertheless, the poor preservation prevents asserting that it represents a new species. Histological evidence from its long bones indicates that is subadult or adult and that early fast rates followed by slower and protracted cyclical phases took place during its growth, a previously unnoticed pattern in Lower Cretaceous enantiornithines. This new finding supports the hypothesis that enantiornithines regularly inhabited the Las Hoyas wetland, making this site a hotspot for enhancing our understanding of the evolution and life history of these Cretaceous birds.

Integrating Cretaceous Fossils into the Phylogeny of Living Angiosperms: Fossil Magnoliales and Their Evolutionary Implications

Integrating Cretaceous Fossils into the Phylogeny of Living Angiosperms: Fossil Magnoliales and Their Evolutionary Implications

A unique Late Cretaceous fossil wood assemblage from Chilean Patagonia provides clues to a high‐latitude continental environment

AbstractFossil plants, including large trunks, stems, some branches, and twigs, were collected from the Maastrichtian (68.9 Ma), upper Dorotea Formation in the Magallanes–Austral Basin, 16 km north of the Cerro Guido–Las Chinas complex in the southern Chilean Magallanes region. These fossil trunks range from 0.2 to 2.2 m in length. Petrographic slides were made in three sections (transverse, radial and tangential) and analysed under a light microscope to study the permineralized fossils. The woods and stems belong to Austroginkgoxylon gen. et sp. nov., Agathoxylon antarcticum, Podocarpoxylon paradoxi sp. nov., Podocarpoxylon mazzonii, Palmoxylon subantarcticae and Notomalvaceoxylon magallanense gen. et sp. nov. The growth rings of gymnosperms and anatomical characters of angiosperms were analysed to obtain palaeoecological data. Interactions between gymnosperm roots growing into the secondary xylem of an angiosperm (nurse logs) are recorded. The data obtained from the fossil woods suggest warm and humid conditions in this southern South American locality during the Late Cretaceous, providing a unique opportunity to study continental environments at high southern latitudes, which are poorly represented on a global scale.

A new scolebythid-like chrysidoid genus and species (Hymenoptera: Chrysidoidea) with striking metasomal structure from the mid-Cretaceous Kachin amber

The Cretaceous fossil record of the aculeate superfamily Chrysidoidea has been greatly enriched in the past few years, thanks especially to the abundance of available material in the late Albian-early Cenomanian amber from the Kachin state (Myanmar). We here document the discovery of a new genus and species, Thagyaminobythus martini gen. et sp. nov., from Kachin amber, emphasizing the extraordinary diversity of chrysidoid wasps in this deposit. The genus is left as incertae sedis within the superfamily because it exhibits a combination of Scolebythidae, Bethylidae and Chrysididae features. We discuss the possibility that Thagyaminobythus martini gen. et sp. nov. could retract its posterior metasomal segments and the co-occurrence of such a structure in several chrysidoid families.

Independent wing reductions and losses among stick and leaf insects (Phasmatodea), supported by new Cretaceous fossils in amber

BackgroundPhasmatodea (stick and leaf insects) play a central role on the debate regarding wing reduction and loss, and its wings are putative reacquisition from secondarily wingless ancestors based solely on extant species. A pivotal taxon in this respect is the species-poor Timematodea, consisting of approximately 21 wingless extant species, which form the sister group of all remaining winged or wingless stick and leaf insects, the Euphasmatodea.ResultsHerein, the new fossils of Timematodea from mid-Cretaceous Kachin amber are reported, with winged and wingless species co-occurring. The palaeogeographic distributions of all fossils of Holophasmatodea are summarized, showing their wide paleo-distributions. The phylogenetic analysis based on morphological characters confirms the earliest-diverging lineage of winged Breviala cretacea gen. et sp. nov. in Timematodea, and the possible relationships among all families of Holophasmatodea. These are critical for the reconstruction of patterns of wing evolution in early Phasmatodea.ConclusionsThe new fossils suggest that Timematodea once had wings, at least during the mid-Cretaceous. The palaeogeographic occurrences imply that Timematodea probably have been widely distributed since at least the Jurassic. The phylogenetic analysis with the ancestral-state reconstruction of wings indicates that the common ancestors of Holophasmatodea were winged, the reductions and losses of wings among Timematodea and Euphasmatodea have occurred independently since at least the Cretaceous, and the reduction or loss of the forewing earlier than the hind wings.

The “Judith River−Belly River problem” revisited (Montana-Alberta-Saskatchewan): New perspectives on the correlation of Campanian dinosaur-bearing strata based on a revised stratigraphic model updated with CA-ID-TIMS U-Pb geochronology

Terrestrial strata of the Judith River−Belly River wedge, widely exposed in the plains of north-central Montana, southern Alberta, and southwestern Saskatchewan, were pivotal in early stratigraphic investigations of the Western Interior of North America and are renowned to this day for their spectacular preservation of Late Cretaceous fossils, most notably dinosaurs. Correlation of the Judith River Formation in Montana with the Foremost, Oldman, and Dinosaur Park Formations (= Belly River Group) in Canada has been challenging for a variety of reasons, including lithostratigraphic complexities, legacy bentonite ages of limited comparability, and distinctly different stratigraphic models on opposite sides of the international border. An updated model calibrated with U-Pb zircon ages provides an improved framework for stratigraphic analysis. New geochronology indicates that the Oldman−Dinosaur Park discontinuity in Dinosaur Provincial Park correlates in age with the mid-Judith discontinuity in the Judith River Formation in Montana, which is interpreted as an expansion surface linked to a major pulse of accommodation and onset of the Bearpaw transgression at ca. 76.3 Ma. The regionally expressed shift in alluvial facies marking the mid-Judith discontinuity can be traced in well logs from Montana to southern Canada, where it loses distinction and transitions to a subsurface signature typical of the Oldman−Dinosaur Park discontinuity, which in turn can be traced north to Dinosaur Provincial Park and beyond. Across this expanse, both discontinuities parallel the Eagle/Milk River shoulder at approximately the same stratigraphic height, confirming their chronostratigraphic significance. These findings have clear implications for regional correlation and the evolution of alluvial depositional systems in a foreland basin setting, and they afford an opportunity to evaluate existing interpretations and advance understanding of the stratigraphy and paleontology of the Judith River−Belly River wedge. The term “Judith River−Belly River discontinuity” should be used henceforth to refer to the chronostratigraphically significant stratal discontinuity that subdivides the Judith River−Belly River wedge throughout the plains of north-central Montana, southern Alberta, and southwestern Saskatchewan.

Transfer of the Cretaceous fossil vertebrate collection from Columbus State University to the Smithsonian's National Museum of Natural History

Transfer of the Cretaceous fossil vertebrate collection from Columbus State University to the Smithsonian's National Museum of Natural History

Transfer of the Cretaceous fossil vertebrate collection from Columbus State University to the Smithsonian's National Museum of Natural History

Transfer of the Cretaceous fossil vertebrate collection from Columbus State University to the Smithsonian's National Museum of Natural History

The Las Hoyas Lagerstätte: a palaeontological view of an Early Cretaceous wetland

Las Hoyas (Cuenca, Spain) represents a unique Early Cretaceous (Barremian) fossil biota of a wetland. The site has yielded a particularly diverse assemblage of >20 000 plant and animal fossils, many of which present unprecedented soft tissue preservation, including microstructural details. Among the most significant discoveries are the oldest angiosperms, the smallest species of chondrichtians and squamates, new theropod dinosaurs, including several enantiornithine birds, the first European tapejarid pterosaur and the most complete eutriconodont mammal. Such discoveries have produced data on important aspects related to plant and animal evolution, such as the first steps in flower development by plants, insights into unknown anatomical and diet specializations in theropod dinosaurs, the development of flight manoeuvrability in early birds, the unexpected global distribution of tapejarid dinosaurs and ground-breaking data on early mammalian hair development. There are many more discoveries to unveil and new research is now linking the immense wealth of palaeobiological information with mathematical procedures to study the ecological structure of the wetland. Supplementary material: Taxonomic structure of the Las Hoyas diversity and systematic list of unearthed taxa are available at https://doi.org/10.6084/m9.figshare.c.6336914

New Cretaceous crickets of the subfamilies Nemobiinae and Podoscirtinae (Orthoptera, Grylloidea: Trigonidiidae, Oecanthidae) attest the antiquity of these clades

AbstractFossils are more and more used in phylogenetic evolutionary studies either for clade calibration, or as terminals in a dataset including morphological characters. The strength of these methodological advances relies however on the quality and completeness of the fossil record. For crickets (Insecta, Orthoptera, Gryllidea), few ancient (pre-Cenozoic) well-preserved fossils are known, except for isolated wings often classified in purely fossil groups and a few fossils found in Cretaceous amber. Here, we present two remarkable fossils from mid-Cretaceous amber of France, that were imaged using X-ray synchrotron microtomography and exhibit an exquisite preservation allowing description with a precision similar to that of extant taxa.Palaeonemobius occidentalisLaurent and Desutter-Grandcolas,gen. nov., sp. nov.andPicogryllus carentonensisJosse and Desutter-Grandcolas,gen. nov., sp. nov.are the oldest representatives of the Nemobiinae and Podoscirtinae subfamilies of the Trigonidiidae and Oecanthidae families respectively.P. carentonensisJosse and Desutter-Grandcolas,gen. nov., sp. nov.is also the smallest adult male with a full stridulatory apparatus ever documented in crickets (body length 3.3 mm), and the first taxon of the cricket clade for which male genitalia can be partly described. We discuss the significance of Cretaceous fossils of crickets for future evolutionary studies of this clade.