Cretaceous Research最新文献_第10页

A carcharodontosaurid tooth from “Boca de Forno” Ravine of the Itapecuru Formation, Parnaíba Basin, Maranhão, Brazil 巴西maranh<e:1> Parnaíba盆地Itapecuru组“Boca de Forno”峡谷中的一颗齿龙

IF 1.9 3区地球科学 Q1 GEOLOGY

Cretaceous Research

Pub Date : 2025-05-13 DOI: 10.1016/j.cretres.2025.106163

Tainá Constância de França , Natan Santos Brilhante , Rafael Delcourt , João Lucas da Silva , Christophe Hendrickx , Manuel Alfredo Medeiros , Fabiana Rodrigues Costa

Carcharodontosauridae forms a clade of medium-to very large-sized (6–14 m long) allosauroid theropods mostly restricted to the Early and mid-Cretaceous with an almost global distribution, and characterized by deep and narrow ornamented skulls and strongly compressed ziphodont teeth. In Brazil, the carcharodontosaurid fossil record is limited to shed teeth and isolated postcranial elements from the Aptian-Cenomanian deposits of the eastern part of the country. Here we describe and identify a shed tooth from a little-known outcrop of the Early Cretaceous (Aptian-Albian) Itapecuru Formation of the Maranhão State, northeastern Brazil. Although some teeth have already been reported from the Aptian-Albian deposits of this unit, this specimen represents the first isolated dental material from the Parnaíba Basin that can be confidently assigned to a carcharodontosaurid through cladistic and morphometric techniques, but also based on a systematic study. The results of the herein conducted study suggest that the specimen belongs to a carcharodontosaurine closely related to the Patagonian taxa Giganotosaurus and Mapusaurus, which are younger in age. Although the specimen is closely related to the abovementioned Patagonian taxa, the faunal composition of the Parnaíba Basin seems to be more similar to that of North Africa. Nevertheless, further collecting efforts are needed in these localities to find skeletal carcharodontosaurid remains and to broaden the comparative base for the identification of theropod dentition.

Carcharodontosauridae是中等到非常大的异特龙类兽脚亚目的一个分支，长6-14 m，主要分布于早白垩世和中白垩世，其特征是深而窄的装饰头骨和强烈压缩的ziphodon牙齿。在巴西，carcharodontosaurus的化石记录仅限于脱落的牙齿和该国东部Aptian-Cenomanian沉积物中分离的颅后元素。在这里，我们描述并鉴定了来自巴西东北部maranh州早白垩世（Aptian-Albian） Itapecuru组一个鲜为人知的露头的脱落牙齿。虽然在该单元的Aptian-Albian沉积物中已经报道了一些牙齿，但该标本代表了Parnaíba盆地中第一个可以通过分支学和形态计量学技术自信地分配给carcharodontosaurd的牙齿材料，但也基于系统的研究。本文的研究结果表明，该标本属于一种与巴塔哥尼亚类群Giganotosaurus和Mapusaurus有密切关系的carcharodontosaurus，它们的年龄更小。虽然该标本与上述巴塔哥尼亚分类群密切相关，但Parnaíba盆地的动物组成似乎更类似于北非。然而，需要在这些地区进行进一步的收集工作，以发现骨齿龙遗骸，并扩大兽脚亚目牙齿鉴定的比较基础。

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引用次数: 0

Evidence of piscivorous diet in an enantiornithine bird from the Lower Cretaceous of Brazil 巴西下白垩纪一种反鸟目鸟类的食鱼证据

IF 1.9 3区地球科学 Q1 GEOLOGY

Cretaceous Research

Pub Date : 2025-05-13 DOI: 10.1016/j.cretres.2025.106161

Fernando Luiz Kilesse Salgado , Luis M. Chiappe , Reiner Neumann , Ismar de Souza Carvalho

Cratoavis cearensis, described from a single specimen unearthed from the Crato Formation of the Araripe Basin in Brazil, represents one of the earliest known fossil avians from South America (ca. 117 My). We report on the presence of disarticulated fish elements associated with the skeleton and interpret them as contained within the digestive tract of this enantiornithine bird. These bony elements are similar to ribs of Dastilbe crandalli, a fish belonging to Gonorynchiforms. Dastilbe crandalli is abundant in the same Crato deposits that have yielded Cratoavis cearensis. The identified bony elements provide direct evidence of a piscivorous diet for this Brazilian enantiornithine, thus contributing to the meager evidence available for understanding the trophic specializations of this major clade of Mesozoic birds.

从巴西Araripe盆地的Crato组出土的单一标本中描述的Cratoavis cearensis是南美洲已知最早的鸟类化石之一（约117万年）。我们报告了与骨骼相关的分离鱼元素的存在，并将其解释为包含在这种反鸟鸟的消化道内。这些骨元素类似于大鲵（Dastilbe crandalli）的肋骨，大鲵是一种淋病鱼。在产生克拉托维斯火山的同一克拉托矿床中，有丰富的达斯蒂贝。已鉴定的骨骼元素为这种巴西反鸟鸟的食鱼性饮食提供了直接证据，从而为了解这一中生代鸟类主要分支的营养特化提供了微薄的证据。

引用次数: 0

Tides of rebirth: A stratigraphic perspective on the Lazarus effect in freshwater bivalves in the Aptian-Albian Romualdo Formation, Araripe Basin, Brazil 再生潮汐：巴西Araripe盆地Aptian-Albian Romualdo组淡水双壳类动物Lazarus效应的地层学视角

IF 1.9 3区地球科学 Q1 GEOLOGY

Cretaceous Research

Pub Date : 2025-05-10 DOI: 10.1016/j.cretres.2025.106165

Marcello G. Simões , Vitor B. Guerrini , Victor R. Silva , Filipe G. Varejão , Suzana A. Matos , Mariza G. Rodrigues , Lucas V. Warren , Mario L. Assine , Franz T. Fürsich

The Aptian-Albian Romualdo Formation was deposited in a confined aquatic setting marked by at least three distinct marine ingression events. Most paleontological knowledge of this unit derives from the shale-dominated interval in its middle part, while fossil data from the sandstone-dominated facies in the uppermost part of the formation remain scarce. This paucity of data arises because the overlying deposits were either eroded or are currently obscured by Cenozoic gravity-flow deposits. Nonetheless, the uppermost Romualdo Formation preserves a tide-dominated delta succession, documenting the basin gradual return to continental conditions. In the Sobradinho section, a new mollusk-dominated assemblage is identified in an intraclast-supported conglomerate located ∼10 m above the upper shell bed interval. The assemblage includes bone fragments, plant remains, and marine/brackish-water mollusks. Additionally, freshwater bivalves, previously known only from the underlying Crato Formation, are also recorded. All macroinvertebrates exhibit a consistent preservational pattern, with infill composed of the rock matrix. Therefore, the freshwater bivalves are not reworked fossils from older sediments within the conglomerate. Their presence suggests that, for much of the Romualdo Formation depositional history, these freshwater bivalves thrived in riverine and/or low-salinity transitional or coastal environments. Without this new record, their known vertical distribution would remain largely confined to the bivalve-rich mudstones of the basal third of the Crato Formation and to a siltstone bed within a confined bay succession ∼100 m below the newly reported assemblage. This discovery significantly expands their stratigraphic range as facies-controlled Lazarus taxa.

Aptian-Albian Romualdo组沉积在一个封闭的水生环境中，标志着至少三次不同的海洋入侵事件。该单元的大部分古生物知识来自于中部以页岩为主的层段，而地层上部以砂岩为主的相的化石资料仍然很少。这种数据的缺乏是因为上覆的沉积物要么被侵蚀，要么目前被新生代重力流沉积物掩盖。尽管如此，最上层的罗穆阿尔多组保留了潮汐主导的三角洲演替，记录了盆地逐渐回归大陆条件。在Sobradinho剖面中，在上部壳层段上方约10 m的层内支撑砾岩中发现了一种新的软体动物为主的组合。该组合包括骨碎片，植物遗骸和海洋/咸水软体动物。此外，淡水双壳类，以前只知道从克拉托组，也记录。所有大型无脊椎动物都表现出一致的保存模式，填充物由岩石基质组成。因此，淡水双壳类不是砾岩中较老沉积物的再加工化石。它们的存在表明，在罗穆阿尔多组沉积史的大部分时间里，这些淡水双壳类动物在河流和/或低盐度过渡或沿海环境中繁盛。如果没有这一新的记录，它们已知的垂直分布将主要局限于克拉托组基底三分之一富含双壳类的泥岩，以及在新报道的组合下方约100米的封闭海湾序列内的粉砂岩层。这一发现极大地扩展了它们作为相控拉撒路类群的地层范围。

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引用次数: 0

Palaeoceanographic changes during the late Albian-early Turonian in the Sergipe-Alagoas Basin (Northeast Brazil) and their link with global events 巴西东北部Sergipe-Alagoas盆地albian晚期- Turonian早期古海洋学变化及其与全球事件的联系

IF 1.9 3区地球科学 Q1 GEOLOGY

Cretaceous Research

Pub Date : 2025-05-08 DOI: 10.1016/j.cretres.2025.106162

Valentina Cesari , Martino Giorgioni , Igor Carrasqueira , Aristóteles de Moraes Rios-Netto , Roberto Silva Jr , Luigi Jovane

The mid-Cretaceous was characterized by extreme greenhouse conditions, long-term sea level rise, and tectonic processes that influenced the dynamics of oceanic systems. The global carbon cycle was affected by major perturbations during Oceanic Anoxic Events (OAEs). We present new integrated geochemical, magnetic, and mineralogical data from a core drilled through late Albian to early Turonian sediments in the Sergipe-Alagoas Basin, off northeastern Brazil, which includes one of the few records of the OAE2 from the South Atlantic Ocean. The obtained results show a major change in sedimentation in the middle Cenomanian when mixed carbonate and siliciclastic deposits were replaced by chalk. This transition reflects a major change in palaeoceanographic conditions toward a more stable circulation mode, with better connection between the different oceanic basins, persistent currents, and bottom ventilation. Cyclicity in the ln(K/Al) record indicates insolation-driven fluctuations in aridity and humidity. A new age model, based on the stable 405 kyr-long eccentricity cycles, places the onset of the OAE2 carbon isotope excursion at ∼94.74 Ma. Sedimentation during the OAE2 seemed to be mainly controlled by long-term processes and local effects rather than global perturbations. Variations in ln(Sr/Ca) indicate increased primary productivity persisting for two long eccentricity cycles, while transient reducing conditions, inferred from loss in magnetic susceptibility compared to Fe, persisted across the earliest long eccentricity maximum phase, at least.

白垩纪中期以极端温室条件、长期海平面上升和影响海洋系统动力学的构造过程为特征。在海洋缺氧事件（oae）期间，全球碳循环受到重大扰动的影响。在巴西东北部的Sergipe-Alagoas盆地，我们提供了新的综合地球化学、磁场和矿物学数据，这些数据来自于钻取的一个岩心，该岩心穿过了晚Albian至早Turonian的沉积物，其中包括来自南大西洋的少数OAE2记录之一。结果表明，中塞诺曼期碳酸盐和硅质混合沉积被白垩取代，沉积发生了重大变化。这种转变反映了古海洋学条件向更稳定的环流模式转变，不同海洋盆地、持续流和海底通风之间的联系更好。ln（K/Al）记录的循环性表明由日照驱动的干湿波动。基于稳定的405 kyr-长偏心率周期，一个新的年龄模型认为OAE2碳同位素偏移开始于~ 94.74 Ma。OAE2期间的沉积似乎主要受长期过程和局部效应控制，而不是全球扰动。ln（Sr/Ca）的变化表明初级生产力的增加持续了两个长偏心周期，而与Fe相比，从磁化率损失推断的瞬态降低条件至少持续了最早的长偏心最大阶段。

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引用次数: 0

New species of ostracods from the non-marine upper Barremian (Lower Cretaceous) of Vadillos-1 (Cuenca, Spain) 西班牙昆卡vadilos -1非海相上巴雷米亚（下白垩世）介形类新种

IF 1.9 3区地球科学 Q1 GEOLOGY

Cretaceous Research

Pub Date : 2025-05-02 DOI: 10.1016/j.cretres.2025.106158

Marta Díez-Somolinos , Fernando Barroso-Barcenilla , Mélani Berrocal-Casero , Julio Rodríguez-Lázaro , Paloma Sevilla García , Benjamin Sames

The upper Barremian (Lower Cretaceous) palaeontological site of Vadillos-1 is located in the northern part of the province of Cuenca, Spain. It comprises a sedimentary sequence in Wealden-type facies, rich in non-marine ostracods. In these materials, species of Cypridea have been identified, in particular Cypridea isasae, characterized by its rounded cyathus, and Cypridea ventriosa, being distinguished by the subcircular outline and a large rostrum separated by a very marked alveolar notch. Additionally, numerous specimens of Cypridea vatra nov. sp., defined by its well-marked anterior cardinal angle, and Cypridea marihoni nov. sp., well defined by its ornamented carapace, have been described. Other specimens have been assigned to the genus Cyclocypris, specifically to Cyclocypris bamba nov. sp., characterized by its inflated carapace and piriform outline. These taxa are reported for the first time in the study area and are characteristic of alluvial and palustrine palaeoenvironments. This analysis provides the basis for future studies that will allow a more precise interpretation of non-marine Barremian palaeoenvironments.

vadillo1的上巴雷米亚（下白垩纪）古生物遗址位于西班牙昆卡省北部。它是一个富非海相介形类的wealden型沉积层序。在这些资料中，已经确定了塞浦路斯的物种，特别是塞浦路斯的isasae，其特征是圆形的cyathus，和塞浦路斯的ventriosa，其特征是近圆形的轮廓和一个由非常明显的肺泡缺口分开的大喙。此外，还描述了许多塞浦路亚vatra 11 . sp.的标本，以其明显的前基角为特征，以及塞浦路亚marihoni 11 . sp.的标本，以其装饰的甲壳为特征。其他标本被归为环蝇属，特别是bamba十一月sp.环蝇属，其特征是其膨胀的甲壳和梨状的轮廓。这些分类群为研究区首次报道，具有冲积-滩相古环境特征。这一分析为未来的研究提供了基础，将允许对非海相巴雷米亚古环境进行更精确的解释。

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引用次数: 0

New records of frogs (Anura, Lissamphibia) from the Late Cretaceous Bauru Group of Brazil and its paleobiogeographic implications 巴西晚白垩世Bauru群蛙类（无尾目，lissamphiia）新记录及其古地理意义

IF 1.9 3区地球科学 Q1 GEOLOGY

Cretaceous Research

Pub Date : 2025-04-30 DOI: 10.1016/j.cretres.2025.106150

Fellipe Muniz , Ariovaldo Giaretta , Thiago S. Fachini , Thiago da Silva Marinho , Pedro Buck , Sabrina Rodrigues , Agustín G. Martinelli

South America hosts one of the largest diversities of living frogs in the world, but our knowledge of the group during the Mesozoic Era is still limited. The Upper Cretaceous Bauru Group, in the south-central region of Brazil, has yielded a variety of vertebrate groups. Frog records are rare and restricted to a few well-preserved skeletons and fragmentary material. Nevertheless, they have offered important clues about the early diversification and distribution of frogs, especially among the speciose clade Neobatrachia. Here, we report new records of frogs from the Adamantina and Serra da Galga formations. The described specimens expand the geographical range of frogs in the Bauru Group and corroborate the hypothesis of a widespread distribution of neobatrachians in Gondwana landmasses by the Late Cretaceous. The discovery of the first putative Calyptocephalella-like form from a northern region in South America sheds light on the proposed biogeographic provincialism of frog faunas in South America by the Late Cretaceous.

南美洲是世界上现存青蛙种类最多的地区之一，但我们对中生代这一群体的了解仍然有限。在巴西中南部地区的上白垩纪Bauru群，已经产生了各种各样的脊椎动物群。青蛙的记录是罕见的，仅限于一些保存完好的骨架和碎片材料。尽管如此，它们还是为青蛙的早期多样化和分布提供了重要的线索，尤其是在新蛙科的物种分支中。在这里，我们报告了来自Adamantina和Serra da Galga地层的青蛙的新记录。所描述的标本扩大了bauuru组青蛙的地理范围，并证实了晚白垩纪在冈瓦纳大陆广泛分布的新蛙类的假设。在南美洲北部地区发现的第一个推测的类萼头蛙形式，为提出的白垩纪晚期南美洲青蛙动物群的生物地理地方性提供了线索。

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引用次数: 0

Isolated theropod teeth from the Upper Jurassic to Lower Cretaceous Khorat Group: Implications for theropod diversity in Thailand 上侏罗统至下白垩统Khorat群的分离兽脚亚目牙齿：对泰国兽脚亚目多样性的启示

IF 1.9 3区地球科学 Q1 GEOLOGY

Cretaceous Research

Pub Date : 2025-04-29 DOI: 10.1016/j.cretres.2025.106147

Wongwech Chowchuvech , Sita Manitkoon , Phornphen Chanthasit , Duangsuda Chokchaloemwong , Wachirawit Kosulawatha , Chatchalerm Ketwetsuriya

Isolated theropod teeth are notably abundant of vertebrate remains within the Upper Jurassic to Lower Cretaceous Khorat Group of Thailand. However, despite the discovery of numerous dental materials, only a limited number of studies have focused on the morphology and taxonomy of these isolated teeth. This study investigated 112 isolated theropod teeth were retrieved from 19 localities on the Khorat Plateau in Northeastern Thailand. These teeth were divided into five morphotypes based on dental characteristics. They were identified based on cladistic and discriminant analyses that recovered four clades of theropod dinosaurs: Metriacanthosauridae, Tyrannosauroidea, Spinosauridae, and Allosauria. This dental evidence provide significant insights into the theropod diversity in Thailand during the Late Jurassic to Early Cretaceous. Specifically, the Late Jurassic to Early Cretaceous Phu Kradung Formation revealed an extended presence of metriacanthosaurids and basal tyrannosauroids, while the Sao Khua and Khok Kruat Formations indicated a shift towards allosaurian and spinosaurid dominance during the Early Cretaceous. The absence of metriacanthosaurids and basal tyrannosauroids in later formations suggests a faunal turnover, with allosaurians and spinosaurids becoming more prevalent, aligning with the changes in theropod faunal composition across Eurasia. Furthermore, this contribution suggested the faunal turnover pattern in the Eurasian theropods during the Jurassic-Cretaceous boundary interval, which might have been related to the change in herbivorous dinosaurs during this crucial timeframe of dinosaur evolution.

在泰国上侏罗统至下白垩统的Khorat群中，发现了大量的脊椎动物遗骸。然而，尽管发现了许多牙齿材料，但只有有限数量的研究集中在这些孤立牙齿的形态和分类上。本研究对泰国东北部呼叻高原19个地点采集的112颗兽脚亚目分离牙齿进行了调查。根据牙齿特征将这些牙齿分为五种形态。他们是根据对兽脚亚目恐龙的四个分支的分类和鉴别分析来确定的：长棘龙科、暴龙科、棘龙科和异特龙。这些牙齿证据为了解泰国晚侏罗世到早白垩纪的兽脚亚目动物多样性提供了重要的见解。具体而言，晚侏罗世至早白垩世Phu Kradung组显示了长棘龙类和基暴龙类的广泛存在，而Sao Khua组和Khok Kruat组显示了早白垩世异特龙类和棘龙类的优势转变。在后来的地层中，巨棘龙类和基底暴龙类的缺失表明了一种动物更替，异特龙类和棘龙类变得更加普遍，这与欧亚大陆兽脚亚目动物组成的变化相一致。此外，这一贡献还揭示了侏罗纪-白垩纪交界期欧亚兽脚亚目动物的更替模式，这可能与恐龙进化关键时期食草恐龙的变化有关。

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引用次数: 0

New sharks in a chondrichthyan fauna from the Upper Cretaceous Aguja Formation (lower Campanian) of West Texas support biogeographic segregation among chondrichthyans in the Western Interior 来自西德克萨斯州上白垩世Aguja组（下坎帕尼亚）的软骨鱼动物群中的新鲨鱼支持西部内陆软骨鱼动物之间的生物地理隔离

IF 1.9 3区地球科学 Q1 GEOLOGY

Cretaceous Research

Pub Date : 2025-04-28 DOI: 10.1016/j.cretres.2025.106151

Steven L. Wick , Thomas M. Lehman

A new, oral tooth-based chondrichthyan fauna consisting of 16 species is reported, two of which, Lonchidion conrugis sp. nov. and Restesia corricki sp. nov. are described for the first time. The present work compliments previous descriptions of other vertebrate groups from the early Campanian, Lowerverse microfossil locality in the Abajo Shale Member of the Aguja Formation of West Texas. This local fauna accumulated in a brackish water intertidal depositional setting, and differs significantly from the paracontemporaneous Ten Bits chondrichthyan assemblage found in overlying nearshore marine deposits of the Aguja Formation. The Lowerverse fauna exhibits a comparatively greater diversity and greater relative abundance of hybodont and orectolobiform sharks, but comparatively lower diversity and lower abundance of lamniform sharks compared to the Ten Bits fauna. The most abundant sharks in the Ten Bits fauna (Scapanorhynchus, Squalicorax, and Serratolamna) are rare or absent in the Lowerverse fauna. Rays and sawfishes are also more diverse and more abundant in the Ten Bits fauna, but the most common taxa in the Lowerverse fauna (Cristomylus, Texatrygon) are absent or very rare at Ten Bits. The Lowerverse assemblage is unique among paracontemporaneous Santonian–early Campanian chondrichthyan faunas in the Western Interior of North America in the presence of Restesia. Several taxa (Scapanorhynchus, Rhombodus) are found only in the southernmost of these faunas, and others (Cantioscyllium, Columbusia, Cristomylus, Ptychotrygon, and Texatrygon) are found only as far north as Utah. The Lowerverse chondrichthyan fauna supports regional segregation of some chondrichthyan species in the Western Interior during this time.

本文报道了一种以口腔牙齿为基础的新软骨鱼类区系，共包括16种，其中Lonchidion conrugis sp. 11和Restesia corricki sp. 11为首次报道。目前的工作补充了之前对其他脊椎动物群体的描述，这些群体来自西德克萨斯州Aguja组的Abajo页岩成员的早期坎帕尼亚，Lowerverse微化石地区。该动物群聚集在咸淡水潮间带沉积环境中，与上覆阿古加组近岸海相沉积物中发现的准同生10位软骨鱼组合有明显不同。与十比特区系相比，Lowerverse区系的鱼齿鲨和鳍甲双形鲨的多样性和丰度相对较高，而板形鲨的多样性和丰度相对较低。在10位区系中数量最多的鲨鱼（Scapanorhynchus、Squalicorax和Serratolamna）在Lowerverse区系中很少或没有。在Ten Bits区系中，鳐和锯鳐的种类也更丰富，但在Lowerverse区系中最常见的分类群（Cristomylus, Texatrygon）在Ten Bits区系中没有或非常罕见。Lowerverse组合在北美西部内陆存在Restesia的副同世圣东纪-早坎帕纪软骨鱼动物群中是独一无二的。一些分类群（Scapanorhynchus, Rhombodus）只在这些动物群的最南端被发现，而其他分类群（Cantioscyllium, Columbusia, Cristomylus， Ptychotrygon和Texatrygon）只在北部的犹他州被发现。在这段时间里，下游软骨鱼动物群支持西部内陆一些软骨鱼物种的区域分离。

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引用次数: 0

New discoveries of lepidosteoid scales from the Upper Cretaceous in Songliao Basin, China 松辽盆地上白垩统鳞片新发现

IF 1.9 3区地球科学 Q1 GEOLOGY

Cretaceous Research

Pub Date : 2025-04-28 DOI: 10.1016/j.cretres.2025.106149

Zhaoqing Liu , Wenhao Wu , Xiaobo Li , Li Yang

This study explores the morphological and histological characteristics of isolated rhomboid scales recovered from the Late Cretaceous Nenjiang Formation in Northeast China. Six distinct scale morphotypes were identified and compared with scales of various Holostei taxa. Macroscopic observations reveal that most scale exhibit small or completely absent peg-and-socket articulations and lack of tubercles and denticles. Histologically, these scales display lepidosteoid-type ganoid scale characteristics: a multi-layered enameloid layer forms the ganoine covering, which overlies the isopedine layer. The isopedine layer is densely penetrated by numerous Williamson’s canals and contains abundant well-developed osteocyte lacunae. Although these isolated scale fossils resemble primitive Holostei scales, they cannot be confidently assigned to any known neopterygian taxa. The detailed morphological and histological analyses of these isolated Cretaceous scale fossils provide more precise data, advancing our understanding of Mesozoic fish diversity and evolutionary trends in the Songliao Basin.

研究了中国东北晚白垩世嫩江组分离菱形鳞片的形态和组织学特征。鉴定出6种不同的鳞片形态，并与不同全骨虫分类群的鳞片进行了比较。宏观观察显示，大多数鳞片表现为小或完全缺失钉窝关节，缺乏结节和小齿。组织学上，这些鳞片表现出鳞片骨性类瘤鳞片的特征：多层的类瘤质层形成了盖在异哌啶层上的瘤氨酸覆盖物。异哌啶层被大量的威廉姆森管密集渗透，并含有大量发育良好的骨细胞腔隙。虽然这些孤立的鳞片化石类似于原始的全骨虫鳞片，但它们不能被自信地归属于任何已知的新翼龙分类群。这些白垩纪鳞片化石的详细形态和组织学分析为松辽盆地中生代鱼类多样性和进化趋势的认识提供了更精确的数据。

引用次数: 0

Ammonoids and inoceramid bivalves from the Upper Cretaceous shallow marine deposits of Taneichi Formation in Hirono Town, Iwate Prefecture, northeastern Japan: Implication for biostratigraphy 日本东北部岩手县广野镇上白垩统谷一组浅海沉积中的菊石类和双壳类：生物地层学意义

IF 1.9 3区地球科学 Q1 GEOLOGY

Cretaceous Research

Pub Date : 2025-04-25 DOI: 10.1016/j.cretres.2025.106148

Daisuke Aiba , Takafumi Mochizuki

We examined 47 specimens of ammonoid and inoceramid bivalves from the Cretaceous Taneichi Formation in Iwate Prefecture, northeastern Japan and assigned them to seven species of ammonoids and two species of inoceramids. Of these, five species of ammonoids, Protexanites (Anatexanites) fukazawai (Yabe and Shimizu, 1925); Eubostrychoceras valdelaxum Aiba, Yamato, Kurihara, and Karasawa, 2017; Hyphantoceras transitorium Matsumoto, 1977; Polyptychoceras yubarense (Shimizu, 1935); and Po. obatai (Matsumoto, 1977); and one species of inoceramid, Platyceramus japonicus (Nagao and Matumoto, 1940) are reported for the first time from this Formation. The inoceramid Pl. japonicus and a few biostratigraphically informative ammonoids indicate that the middle Member of the Taneichi Formation was deposited in Santonian–early Campanian (Late Cretaceous). Ammonoid species found in the Taneichi Formation were generally similar to those of the Santonian–lower Campanian in other regions of the northwestern Pacific. Heteromorph taxa were the most abundant ammonoids, accounting for approximately 70 % of the total. Additionally, it is notable that “Leiostraca” taxa, such as Tetragonitoidea and Desmoceratoidea, were not included in the examined specimens. These patterns of occurrence might suggest the palaeoecology of ammonoids, but determining whether they reflect the true distribution requires verification of taphonomic processes, such as post-mortem drifting.

摘要对日本东北部岩手县白垩纪谷一组的47个菊科双壳类和双壳类标本进行了研究，并将其归属于菊科7种和双壳类2种。其中，五种菊石，原石岩（Anatexanites） fukazawai (Yabe and Shimizu, 1925)；Eubostrychoceras valdelaxum Aiba, Yamato，栗原和Karasawa, 2017；Hyphantoceras transitorium Matsumoto, 1977；polytychoceras yubarense（清水，1935）；和阿宝。obatai（松本，1977）；该组中首次报道了一种鱼科植物Platyceramus japonicus （Nagao and Matumoto, 1940）。菊石Pl. japonicus和少量生物地层学资料表明，Taneichi组中段沉积于晚白垩世圣东—早坎帕尼亚期。在Taneichi组中发现的类氨物种与西北太平洋其他地区的圣东统-下坎帕尼亚统的类氨物种大致相似。异型类群中菊石种类最多，约占总数的70%。此外，值得注意的是，“Leiostraca”分类群，如Tetragonitoidea和Desmoceratoidea，没有包括在检查的标本中。这些发生模式可能暗示了菊石的古生态学，但要确定它们是否反映了真实的分布，需要对埋藏学过程进行验证，例如死后漂流。

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引用次数: 0