Cretaceous Research最新文献

{"title":"The microsporangiate cone Classostrobus amealensis sp. nov. with in situ pollen from the Lower Cretaceous (lower Hauterivian) of Portugal: pollen ultrastructure and implications for frenelopsid species diversity","authors":"Maria Tekleva ,&nbsp;Mário Miguel Mendes ,&nbsp;Jiří Kvaček ,&nbsp;Johanna H.A. Van Konijnenburg-van Cittert ,&nbsp;Pedro Miguel Callapez ,&nbsp;Zuzana Heřmanová","doi":"10.1016/j.cretres.2026.106315","DOIUrl":"10.1016/j.cretres.2026.106315","url":null,"abstract":"<div><div>A new cheirolepidiaceous conifer pollen cone, <em>Classostrobus amealensis</em> sp. nov., is described from the Lower Cretaceous of Lusitanian Basin, in the Estremadura region of western Portugal. The new microsporangiate cone was collected in the Vale Cortiço open cast clay pit complex, near the small village of Ameal, from sedimentary deposits belonging to Santa Susana Formation and considered to be early Hauterivian in age. The new species is based on a single well-preserved, coalified microsporangiate cone, ca. 27 mm long and 14 mm wide, ovoid in shape, bearing ca. 20 helically arranged, imbricate microsporophylls. The microsporophyll bears four pollen sacs abaxially and it is smooth or finely papillate showing an acute apex fringed with short trichomes. The new microsporangiate cone is morphologically different from all <em>Classostrobus</em> species previously described, and we compare it with all other frenelopsid microsporangiate cones known to date. Pollen grains <em>in situ</em> show close similarity to dispersed pollen of the species <em>Classopollis martinottii</em> Reyre, 1970. Pollen details were studied using LM as well as scanning electron (SEM) and transmission electron microscopy (TEM). Pollen grains are spheroidal, ca. 26.1 μm in LM and 23.8 μm in SEM, characterized by an equatorial band with six to eight striations, a distal cryptopore, and a proximal tetrad scar. The exine sculpture is distinctly microechinate. The new microsporangiate cone is associated with fragments of vegetative shoots of <em>Frenelopsis teixeirae</em> Alvin et Pais 1978 and <em>Pseudofrenelopsis dinisii</em> M.M.Mendes et J.Kvaček et al., 2023.</div></div>","PeriodicalId":55207,"journal":{"name":"Cretaceous Research","volume":"181 ","pages":"Article 106315"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a large supradetachment basin and its tectonic implication: The Early Cretaceous Hetao Basin, NW China","authors":"Jin Zhang","doi":"10.1016/j.cretres.2025.106275","DOIUrl":"10.1016/j.cretres.2025.106275","url":null,"abstract":"<div><div>The eastern Asia experienced a regional tectonic-thermal event during the Early Cretaceous. The Hetao Basin is one of the larger Cretaceous basins developed in the northern North China Craton (NCC). Geological mapping and seismic profiles indicate that the formation of the western Hetao Basin in the Early Cretaceous was controlled by a low angle detachment fault with a dip angle of ca. 30° and was a supradetachment basin but not a foreland basin. The apatite fission track ages and the ⁴⁰Ar/³⁹Ar ages indicate that the western margin of the Hetao Basin experienced rapid exhumation (ca. 0.8mm/a) at ca. 130 Ma. The tectonic-thermal event of the Early Cretaceous were also widespread in the entire Alxa region to the west of Hetao Basin. Combined with the data from the eastern Hetao Basin, the whole Hetao Basin is the largest supradetachment basin in eastern Asia. The unified paleostress field and northwest-southeast extensional direction across the entire eastern Asia continent indicate that the simultaneous extension and basin formation was controlled firstly by a regional tectonic factor. The rollback of the Paleo-Pacific Plate to the eastern margin of the Asian continent in the Early Cretaceous maybe the only possibility, while locally the broken-off of oceanic slab of the Mongol-Okhotsk Ocean and the subsequent upwelling of the asthenosphere beneath the northern North China Craton were also important factors resulting in the development of Hetao Basin.</div></div>","PeriodicalId":55207,"journal":{"name":"Cretaceous Research","volume":"181 ","pages":"Article 106275"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A sauropod Tengrisaurus starkovi from the Lower Cretaceous of Transbaikalia, Russia, and Asiatic origin of Titanosauria","authors":"Alexander O. Averianov ,&nbsp;Alexander V. Sizov ,&nbsp;Dmitry V. Grigoriev ,&nbsp;Veniamin V. Kolchanov ,&nbsp;Pavel P. Skutschas","doi":"10.1016/j.cretres.2025.106271","DOIUrl":"10.1016/j.cretres.2025.106271","url":null,"abstract":"<div><div>Titanosauria is the final and most diverse radiation of sauropod dinosaurs, which is predominantly distributed throughout the Late Cretaceous of Gondwana. Previous hypotheses have suggested that Gondwana might have served as the origin for Titanosauria. However, the presence of a significant number of titanosaurs with procoelous caudal vertebrae in the Early Cretaceous of Asia indicates that the titanosaurian bauplan may have been established on the northern continents as early as the earliest Cretaceous. In contrast, the titanosaurs with procoelous both anterior and middle caudal vertebrae appeared in South America only during the Albian. The most recent research has identified the <em>Tengrisaurus starkovi</em> Averianov et Skutschas, 2017 from the Lower Cretaceous (Valanginian) Murtoi Formation at the Mogoito locality in Buryatia, Transbaikalia, Russia, as the earliest documented sauropod to display the titanosaurian bauplan, as evidenced by its procoelous anterior and middle caudal vertebrae. The present study reports on a recently discovered sauropod posterior cervical vertebra from the Mogoito locality, which is attributed to <em>T. starkovi</em>. A novel phylogenetic analysis, incorporating data from the cervical and caudal vertebrae, confirms the position of <em>Tengrisaurus</em> as a basal member of the titanosaurian clade Colossosauria. Consequently, the Valanginian <em>Tengrisaurus</em> is recognized as the earliest member of both Colossosauria and Titanosauria, which substantially supports a potential Asiatic origin of these clades.</div></div>","PeriodicalId":55207,"journal":{"name":"Cretaceous Research","volume":"181 ","pages":"Article 106271"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impact of transgression on the development model of lacustrine source rocks: Insights from the Upper Cretaceous Qingshankou Formation source rocks in the Songliao Basin","authors":"Cheng Wu ,&nbsp;Lin Chen ,&nbsp;Zongsheng Lu ,&nbsp;Jiaxin Yan ,&nbsp;Kening Lu","doi":"10.1016/j.cretres.2025.106302","DOIUrl":"10.1016/j.cretres.2025.106302","url":null,"abstract":"<div><div>The extensive deposition of black shales during the Cretaceous Period formed significant petroleum resources. Sea-level rise and tectonic activity often led to seawater incursions into terrestrial lacustrine basins, a process linked to the formation of high-quality hydrocarbon source rocks. However, the precise influence of these marine transgression events on source rock deposition remains poorly constrained. This study investigates the Qingshankou Formation in the Songliao Basin by integrating paleontological, inorganic, and organic geochemical data. Four discrete marine incursion events were identified, allowing for the reconstruction of paleoclimatic conditions, depositional environments, organic matter provenance, and primary productivity levels. Based on these results, three depositional models are proposed: ‘Burst’, ‘Destroy’, and ‘Slow’. The ‘Burst’ model enhances the formation of high-quality source rocks by increasing primary productivity via marine algae and nutrient influx, which fosters an anoxic environment favorable for organic matter preservation. In contrast, the ‘Destroy’ model inhibits source rock formation, as excessive terrestrial detrital input dilutes organic matter and disrupts anoxic preservation conditions. Finally, the ‘Slow’ model has an indirect influence and typically follows the ‘Destroy’ phase. During this subsequent stage, the lacustrine environment becomes relatively stable, inheriting the abundant nutrient load from preceding phase while developing the persistent anoxia through internal biogeochemical regulation within the lake system, which is required for effective organic matter preservation. Ultimately, the interplay between high productivity and favorable preservation conditions represents the key control on source rock formation in marine-influenced lacustrine systems.</div></div>","PeriodicalId":55207,"journal":{"name":"Cretaceous Research","volume":"181 ","pages":"Article 106302"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Successional stages of a Maastrichtian plesiosaur fall community from Antarctica","authors":"Marianella Talevi ,&nbsp;Soledad Brezina ,&nbsp;Darío G. Lazo","doi":"10.1016/j.cretres.2025.106306","DOIUrl":"10.1016/j.cretres.2025.106306","url":null,"abstract":"<div><div>Research on ecological successions in recent skeletal remains, such as those of whales, has revealed specific colonization patterns and four distinct succession phases. These succession patterns can also be inferred in the fossil record from evidence such as bioerosion traces, bone encrustation, and associated body fossils. The study of ecological successions in fossil bones of Mesozoic marine reptiles not only helps to understand the phases of degradation and entombing in the past but also contributes to our knowledge of the communities associated with these carcasses during that time. In this work, the presence of sclerobionts (represented by micro and macroborings) in bone remains of a plesiosaur from the upper Maastrichtian of Antarctica was identified and described, interpreting the phases of ecological succession in a high-latitude marine environment. Macroborings were assigned to <em>Trypanites</em> and <em>Osedacoides</em>. The microborings, similar to Wedl tunnels, were attributed to cyanobacteria and fungi, indicating that the bones were exposed for a long time. Furthermore, framboid pyrite in the bones shows anaerobic stages associated with bacterial activity. The four known stages of ecological succession were documented: the mobile scavenger stage, identified by bite marks; the opportunistic enrichment stage by <em>Osedacoides;</em> the sulfophilic stage, marked by modified vascular channels filled with pyrite; and the reef stage, by <em>Trypanites</em> traces, which indicate colonization by organisms before final burial. These findings enhance our understanding of the interactions between microorganisms and mineralization in ancient marine vertebrates, and aid in reconstructing paleocommunities associated with marine reptile falls, offering valuable insights into past ecosystem dynamics.</div></div>","PeriodicalId":55207,"journal":{"name":"Cretaceous Research","volume":"181 ","pages":"Article 106306"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Latest Maastrichtian climate changes: Insights from high-resolution palynological data from the XHY2008 borehole, Jiayin, NE China","authors":"Jiahui Yu ,&nbsp;Yuewu Sun ,&nbsp;Eugenia V. Bugdaeva ,&nbsp;Valentina S. Markevich","doi":"10.1016/j.cretres.2025.106270","DOIUrl":"10.1016/j.cretres.2025.106270","url":null,"abstract":"<div><div>The latest Maastrichtian was an important interval in Earth's history, characterized by global climatic fluctuations and significant biotic transitions. Understanding the climate and vegetation changes during this time is important for reconstructing the climatic perturbations during the pre-end-Maastrichtian mass extinction and elucidating the cause of the extinction. However, detailed reconstructions of terrestrial climate and vegetation changes remain limited due to the uneven preservation of palynomorphs and the scarcity of high-resolution palynological records. In this study, based on high-resolution palynological data from the Furao Formation in the XHY2008 borehole, Jiayin, Heilongjiang Province, Northeast China, three latest Maastrichtian palynological assemblages were identified, in ascending stratigraphic order: (1) the <em>Gabonisporis</em>–<em>Pinuspollenites</em>–<em>Aquilapollenites</em> assemblage; (2) the <em>Laevigatosporites</em>–<em>Monocolpopollenites</em>–<em>Ulmoideipites</em> assemblage; and (3) the <em>Osmundacidites</em>–<em>Pseudointegricorpus</em>–<em>Wodehouseia</em> assemblage. These assemblages provide key insights into the composition of latest Maastrichtian palynoflora and associated climatic changes. The data indicate that the latest Maastrichtian climate was warm and humid (i.e., subtropical) in the mid-latitudes of the Northern Hemisphere, which was typical of the Cretaceous greenhouse climate. However, two cooling and drying events were recognized based on quantitative analyses of the palynomorphs using principal component analysis and ecological affinity statistics. These two transient events involved changes from a subtropical<strong>–</strong>humid to temperate<strong>–</strong>subhumid climate in the last 34 kyr of the Cretaceous. These short-term climatic changes might record abrupt climatic perturbations during latest Maastrichtian cooling and enhance our knowledge on the frequency of climatic change.</div></div>","PeriodicalId":55207,"journal":{"name":"Cretaceous Research","volume":"181 ","pages":"Article 106270"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Orbit shape evolution in abelisauridae: Macroevolutionary trends and functional implications","authors":"Enzo Emanuel Seculi Pereyra","doi":"10.1016/j.cretres.2025.106272","DOIUrl":"10.1016/j.cretres.2025.106272","url":null,"abstract":"<div><div>Large carnivorous theropods evolved diverse orbital morphologies, including eight-shaped, keyhole-shaped, and elliptical orbits, which have been linked to feeding performance and biomechanical adaptations. In Abelisauridae, the most abundant and best-known clades of Gondwanan theropods, the orbit underwent significant morphological changes, with Cretaceous taxa exhibiting keyhole-shaped and eight-shaped orbits. However, a rigorous phylogenetic comparative approach and multivariate quantification of orbit shape are necessary to further investigate macroevolutionary trends in Abelisauridae orbital evolution. To address this, I applied 2D geometric morphometrics and phylogenetic comparative methods to analyze macroevolutionary trends of orbit shape in Abelisauridae. The results indicate that the abelisaurid orbit shape evolved as an integrated morphological module undergoing accelerated evolution in Cretaceous taxa, likely driven by intensified ecological and functional pressures on orbital shape design. Additionally, phylogenetic signal was not detected, supporting the hypothesis that orbit evolution was primarily driven by selective pressures rather than phylogenetic constraints. Disparity through time analysis revealed a decline in morphological variation during the Late Cretaceous, coinciding with the canalization of specialized orbit morphologies. The results are consistent with previous studies on abelisaurid feeding strategies and suggest that specialized predation may have influenced orbit evolution since at least the Early Cretaceous. These findings provide new insights into the evolutionary history of Abelisauridae, emphasizing the role of ecological and functional factors in shaping the dinosaurs orbital diversity.</div></div>","PeriodicalId":55207,"journal":{"name":"Cretaceous Research","volume":"181 ","pages":"Article 106272"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Marine incursion in the lower Cretaceous Sanfranciscana Basin evidenced by ichnological data","authors":"Daniel Sedorko","doi":"10.1016/j.cretres.2026.106312","DOIUrl":"10.1016/j.cretres.2026.106312","url":null,"abstract":"<div><div>The Lower Cretaceous deposits of the Sanfranciscana Basin (Brazil) were predominantly shaped by continental processes. Despite this, thin chert layers bearing marine microfossils indicate brief marine incursions. Various hypotheses have been proposed to explain these fossils, ranging from storm-induced remobilization to episodic incursions controlled by faulting. The short-lived nature of these events has been suggested by the absence of sedimentological and ichnological evidence of sustained marine influence in the basin's interior. To explore whether these incursions left additional evidence beyond microfossil assemblages, this study integrates ichnological and sedimentological analyses in the southern Sanfranciscana Basin. Fieldwork focused on the transitional interval between the Quiricó and Três Barras formations. Notably, three sections within the basal Três Barras Formation preserve a marine ichnoassemblage, consisting of whitish, fine-grained stratified sandstones, with horizontally concentric-filled (<em>Asterosoma</em>), plug-shaped (<em>Bergaueria</em>), and spreiten-bearing (<em>Teichichnus</em>) burrows. The low-diversity ichnoassemblage suggests impacted salinity conditions, corresponding to a polyhaline-brackish setting. The studied successions show dominance of low angle stratified sandstone interbedded with trough cross-bedded sandstones and wave ripples, suggesting high energetic settings, locally reworked by waves. However, restricted exposition area and thickness, as well as low diverse marine signatures allow to identify a marine connection to the sea, precluding definition of an architectural element or depositional scenario. This record suggests that the marine incursions were long enough to allow benthic colonization of the substrate, as evidenced by at least 12 bioturbated beds. This data argues against episodic, short-lived colonization driven by storm events, at least for the here studied sections.</div></div>","PeriodicalId":55207,"journal":{"name":"Cretaceous Research","volume":"181 ","pages":"Article 106312"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soft-tissue preservation in an ichthyosaur from the lower Cretaceous (Barremian-Aptian) of Colombia","authors":"Manuel F. Martinez-Motta ,&nbsp;Dirley Cortés ,&nbsp;Erin E. Maxwell ,&nbsp;Leslie F. Noè ,&nbsp;Andrés Alfonso-Rojas ,&nbsp;Fredy H. Parra-Ruge ,&nbsp;Edwin-Alberto Cadena","doi":"10.1016/j.cretres.2025.106305","DOIUrl":"10.1016/j.cretres.2025.106305","url":null,"abstract":"<div><div>In recent years, global research on soft-tissue preservation in fossils has grown significantly, offering insights into the biology, taphonomy, and diagenesis of extinct organisms. However, studies from low-latitude regions, particularly northern South America, remain limited, and this gap, together with the Lower Cretaceous Gap, restricts our understanding of the processes that enable soft-tissue preservation in these regions. The Paja Formation is a Lower Cretaceous (Hauterivian to Aptian) marine sequence located in central Colombia, notable for its abundant and well-preserved fossils, including vertebrates, invertebrates, and plants. In this study, we analyzed a Barremian-Aptian ichthyosaur from the Paja Formation to investigate soft-tissue preservation. We applied various analytical techniques, including EDTA demineralization, thin-sectioning, transmitted and cross-polarized light microscopy, SEM-EDS, ATR-FTIR spectroscopy, and Raman microspectroscopy. Our findings reveal net-like structures interpreted as fragments of the stratum spinosum layer of the epidermis, composed of N-heterocyclic polymers. We identified laminar and flexible structures defined as the skin-like layer of preserved integumentary tissue, with original proteins transformed into geochemically stable components, including N-heterocyclic polymers and kerogen-like materials. This study reports the first known case of preserved integument in a marine reptile from northern South America. We propose a taphonomic and preservational model based on rapid burial in soft sediment, persistent dysoxic-anoxic regional conditions, microbial biofilm activity, and the formation of early diagenetic carbonate concretions that influenced soft-tissue preservation in this specimen.</div></div>","PeriodicalId":55207,"journal":{"name":"Cretaceous Research","volume":"181 ","pages":"Article 106305"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146188394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revaluation of the taxonomy and diversity of Lepisosteiformes from the Alcântara Formation (Cenomanian, Upper Cretaceous), Brazil","authors":"Erick Ribeiro-Souza ,&nbsp;Yuri Modesto Alves ,&nbsp;Cesar Leandro Schultz ,&nbsp;Manuel Alfredo Medeiros","doi":"10.1016/j.cretres.2025.106291","DOIUrl":"10.1016/j.cretres.2025.106291","url":null,"abstract":"<div><div>Lepisosteiformes, ginglymodian fishes with fusiform bodies and ganoid scales, are a common source of Mesozoic fossil remains. Despite their widespread historical distribution, their diversity in the Alcântara Formation (northeastern Brazil) remains poorly understood, with only one lepisosteid previously identified. In contrast, nearby groups, such as the Santana Group and the Kem Kem Group, host diverse lepisosteiform <em>taxa</em>. This study revises the taxonomy of ganoid scales from the Alcântara Formation using external morphology, microstructure, and ultrastructure analyses. The scales examined exhibit characteristic Lepisosteiformes features, including ganoine on the free field and articulation via ventral and vertical processes. Histological analysis revealed both palaeoniscoid and lepidosteoid scales. Lepidosteoid scales varied significantly in shape, size, and structure based on body position, with smooth ganoine scales dominating the sample, and representing a large, non-gar lepisosteiform (cf. <em>Adrianaichthys</em>). Smaller, ornamented scales were rare and indicative of a lepisosteid taxon. Palaeoniscoid scales, identified as <em>Obaichthys</em>, were the least abundant and showed a prominent median spine; they were of different developmental stages and allowed the inference of the existence of different <em>Obaichthys africanus</em> morphotypes. This study offer many insights regarding the different aspects of lepisosteiform squamation such as histological structure, external morphology, shape, size, and ornamentation. We identified at least three Lepisosteiformes <em>taxa</em> in the Alcântara Formation: a non-gar lepisosteiform (cf. <em>Adrianaichthys</em>), the obaichthyid <em>Obaichthys</em>, and a lepisosteid. These findings highlight similarities between Cenomanian faunal communities in northeastern Brazil and northwestern Africa, expanding our understanding of Lepisosteiformes diversity and extending the known vertical distribution of Obaichthyidae in South America to the Cenomanian. We also propose the existence of two distinct morphotypes of <em>O</em>. <em>africanus</em>.</div></div>","PeriodicalId":55207,"journal":{"name":"Cretaceous Research","volume":"181 ","pages":"Article 106291"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}