Papers in Palaeontology最新文献

{"title":"The primitive giant panda Kretzoiarctos beatrix (Carnivora, Ursidae) from the hominid locality of Hammerschmiede: dietary implications","authors":"Nikolaos Kargopoulos, Juan Abella, Alexander Daasch, Thomas Kaiser, Panagiotis Kampouridis, Thomas Lechner, Madelaine Böhme","doi":"10.1002/spp2.1588","DOIUrl":"https://doi.org/10.1002/spp2.1588","url":null,"abstract":"Extant giant pandas are among the most herbivorous forms of the order Carnivora, feeding mainly on hard plant material. The first steps of their evolutionary lineage are of particular interest for our understanding of the factors that led to this specialized niche. The present work deals with newly discovered dental material of the primitive ailuropodine bear <jats:italic>Kretzoiarctos beatrix</jats:italic> from the Late Miocene locality of Hammerschmiede (Germany). This is the first report of the genus <jats:italic>Kretzoiarctos</jats:italic> outside the Iberian Peninsula, expanding its spatial range to Central Europe. All of the currently known localities with <jats:italic>K. beatrix</jats:italic>, from both Spain and Germany, are very similar in age (<jats:italic>c</jats:italic>. 11.9–11.4 Ma). The present material has distinct features that enable its taxonomic discrimination from other Miocene ursids of Europe, such as <jats:italic>Ballusia</jats:italic>, <jats:italic>Ursavus</jats:italic>, <jats:italic>Miomaci</jats:italic>, <jats:italic>Agriarctos</jats:italic> and <jats:italic>Indarctos</jats:italic>. A thorough comparison is conducted of all of these forms. The new specimens were used in a dental microwear texture analysis in combination with ecomorphological comparisons, to investigate the dietary habits of this primitive ailuropodine. The results suggest that <jats:italic>Kretzoiarctos</jats:italic> was not an eater of tough plant material like the extant giant panda but was more similar to the extant <jats:italic>Tremarctos</jats:italic>, exhibiting opportunistic behaviour with occasional consumption of meat.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Macroalgae from the early Cambrian Chengjiang biota","authors":"Gaorong Li, Fan Wei, Jin Guo, Peiyun Cong","doi":"10.1002/spp2.1585","DOIUrl":"https://doi.org/10.1002/spp2.1585","url":null,"abstract":"The Chengjiang biota, a Burgess Shale‐type Lagerstätte in eastern Yunnan, South China (Cambrian Series 2, Stage 3), provides valuable information regarding the origin and early evolution of metazoans, and complex marine ecosystems. Although the major animal phyla in the Chengjiang biota have been extensively studied, macroalgae have received comparatively little attention. Here, we establish new taxa <jats:italic>Yunnanospirellus typica</jats:italic> and <jats:italic>Y</jats:italic>. <jats:italic>elegans</jats:italic>, describe five genera and six species (<jats:italic>Tawuia</jats:italic> sp., <jats:italic>Morania fragmenta</jats:italic>, <jats:italic>Liulingjitaenia alloplecta</jats:italic>, <jats:italic>Longfengshania stipitata</jats:italic>, <jats:italic>Lo</jats:italic>. <jats:italic>spheria</jats:italic> and <jats:italic>Paralongfengshania sicyoides</jats:italic>) not previously reported in the Chengjiang biota, and elucidate the pith structure of <jats:italic>Enteromophites intestinalis</jats:italic>. With 13 genera and 17 species now recorded, macroalgae rank fourth in species‐level biodiversity in the Chengjiang biota (behind Euarthropoda, Porifera and Priapulida). Macroalgae account for 71.57% of total abundance, far more than all other animal phyla in the Chengjiang biota. <jats:italic>Fuxianospira</jats:italic> is the most dominant genus, accounting for 52.01% of all macroalgae specimens. Unattached (floating, planktonic or drifting) forms dominate (eight attached; nine unattached species). The high diversity of attached macroalgae indicates that the macroalgal communities adapted to the Proterozoic firm substrate (probably covered by microbial mats) persisted from the Ediacaran to the early Cambrian, providing compelling evidence for the existence of firm substrate during this time. Meanwhile, the blooming of unattached macroalgae in the Chengjiang biota suggests that other niches were also rich in macroalgae. Unattached macroalgae might have provided oxygen and energy to metazoans, eventually leading to ecological expansion in the upper and middle water column of the early Cambrian seas.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Illuminating the richness of the ascidian fossil record: a new exceptionally diverse assemblage of ascidian spicules from the Middle Miocene of Bosnia and Herzegovina","authors":"Magdalena Łukowiak, Oleg Mandic, Anna Omalecka, Mădălina‐Elena Kallanxhi, Stjepan Ćorić, Patrick Grunert","doi":"10.1002/spp2.1586","DOIUrl":"https://doi.org/10.1002/spp2.1586","url":null,"abstract":"Ascidians, or sea squirts, are sac‐like sessile tunicates commonly found in modern seas. Although the oldest ascidians, or at least ascidian‐like tunicates, are mid‐Cambrian in age, the quality of the ascidian fossil record is extraordinarily poor. It mostly consists of isolated finds or low‐diversity assemblages, often represented by mineral spicules. Our study reports the world's most diverse assemblage of ascidian spicules, originating from the Middle Miocene Bogutovo Selo near Ugljevik, Bosnia and Herzegovina. This material includes 31 spicule types, with four assignable to species (<jats:italic>Lissoclinum</jats:italic> cf. <jats:italic>perforatum</jats:italic>, <jats:italic>Polysyncraton</jats:italic> cf. <jats:italic>bilobatum</jats:italic>, <jats:italic>Didemnum</jats:italic> cf. <jats:italic>vexillum</jats:italic> and <jats:italic>D</jats:italic>. cf. <jats:italic>leopardi</jats:italic>) and 10 to genera, all belonging to aplousobranchiate ascidians. Comparing our findings with those of two other studies that use modern biological nomenclature, our assemblage shows a closer resemblance to the distant Eocene Australian assemblage than to the Miocene ascidians from Eastern Paratethys. This suggests the persistence of a once‐homogeneous and widely distributed Eocene fauna into the Miocene, while the Eastern Paratethyan basin developed an endemic fauna after the isolation of Eastern Paratethys from the open sea. Some taxa of our assemblage currently inhabit the Mediterranean Sea. The discovery of one species in distant South African waters suggests that tectonic and environmental changes during the Late Miocene, including the closure of the Gibraltar Strait and prior disconnection from the Indian Ocean, may have limited its survival to remote refugia. The study underscores the importance of including spicules in reconstructing ascidian faunas in the geological past, an area that has been surprisingly understudied.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 possible archaic precursor of the octocoral structural plan from the Ordovician of Estonia","authors":"Sergey V. Rozhnov","doi":"10.1002/spp2.1593","DOIUrl":"https://doi.org/10.1002/spp2.1593","url":null,"abstract":"A new species and genus of colonial coral, <jats:italic>Lindaphylon solovjevi</jats:italic>, from the Upper Ordovician of Estonia is described in detail. The colony has a zonation similar to the zonation structure of the mesogleal skeleton of octocorals, since it consists of a narrow axis and a surrounding wide cortex of small calcite sclerites and a system of large solenia. Corallites present 12 sclerosepta in a wide shallow cup. A new family Lindaphylonidae and an order Lyndaphylonaceae are based on these features, and a new order placed in the subphylum Anthozoa as <jats:italic>incertae sedis.</jats:italic> A comparative study of skeleton formation and mesenteric apparatus symmetry in different groups of coral polyps is considered in detail.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction to ‘A Middle Triassic Cassian‐type fauna (Pelsa‐Vazzoler Lagerstätte) and the adaptive radiation of the Modern evolutionary fauna’","authors":"","doi":"10.1002/spp2.1594","DOIUrl":"https://doi.org/10.1002/spp2.1594","url":null,"abstract":"","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 new neoceratopsian (Ornithischia, Ceratopsia) from the Lower Cretaceous Ohyamashimo Formation (Albian), southwestern Japan","authors":"Tomonori Tanaka, Kentaro Chiba, Tadahiro Ikeda, Michael J. Ryan","doi":"10.1002/spp2.1587","DOIUrl":"https://doi.org/10.1002/spp2.1587","url":null,"abstract":"The herbivorous dinosaur clade Ceratopsia flourished in the northern hemisphere during the Late Jurassic to Late Cretaceous. Previous palaeobiogeographic studies have suggested that their initial diversification occurred in Asia, with early‐branching neoceratopsians extending their geographical range to North America sometime during the Barremian to Albian. However, the specific timing and mode of their dispersal from Asia to North America remains unknown. Here we describe a new, early‐branching neoceratopsian, <jats:italic>Sasayamagnomus saegusai</jats:italic> gen. et sp. nov., from the Albian Ohyamashimo Formation in southwestern Japan, representing the easternmost fossil record of ceratopsians in Asia. <jats:italic>Sasayamagnomus</jats:italic> exhibits three diagnostic features in the jugal, squamosal and coracoid, respectively, and also has a unique combination of characters in the lacrimal. Our phylogenetic analysis indicates that <jats:italic>Sasayamagnomus</jats:italic> forms a clade with <jats:italic>Aquilops americanus</jats:italic>, one of the earliest neoceratopsians from North America, followed by the sister taxon <jats:italic>Auroraceratops rugosus</jats:italic> from China. The present time‐calibrated phylogenetic tree indicates that the immigration of neoceratopsians from Asia to North America occurred during the latest Aptian or early Albian, refining the previously suggested timeframe. This aligns with fragmentary neoceratopsian fossil records from the Lower Cretaceous of North America and the initial formation of the Bering land bridge. Furthermore, the simultaneous occurrence of global warming (which enabled the development of extensive forests in the Arctic region) and the emergence of the Bering land bridge during the Aptian–Albian, probably played a crucial role in facilitating the immigration of neoceratopsians from Asia to North America.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exceptionally preserved radiodont arthropods from the lower Cambrian (Stage 3) Qingjiang Lagerstätte of Hubei, South China and the biogeographic and diversification patterns of radiodonts","authors":"Yu Wu, Stephen Pates, Mingjing Zhang, Weiliang Lin, Jiaxin Ma, Cong Liu, Yuheng Wu, Xingliang Zhang, Dongjing Fu","doi":"10.1002/spp2.1583","DOIUrl":"https://doi.org/10.1002/spp2.1583","url":null,"abstract":"The Cambrian (Series 2, Stage 3) Qingjiang Lagerstätte of South China is one of the most diverse Burgess Shale‐type deposits around the world, yielding abundant non‐biomineralized fossils. Radiodonta, a taxonomically and ecologically diverse stem‐euarthropod group, has been generally thought to represent the largest consumers in early Palaeozoic marine ecosystems. Here we describe several new radiodont specimens from the Qingjiang Lagerstätte assigned to various groups, including <jats:italic>Stanleycaris qingjiangensis</jats:italic> sp. nov., a new type of hurdiid head carapace, one possible <jats:italic>Hurdia</jats:italic> carapace, and two partial appendages with uncertain affinities. These specimens not only extend the geographic and stratigraphic range of these taxa, they also illuminate the diversity of radiodonts (in particular hurdiids) in their early evolutionary history. Radiodont palaeobiogeographic patterns are visualized using network analysis. Laurentia and South China share many members at the genus level, <jats:italic>Anomalocaris</jats:italic> is the most cosmopolitan taxon, but most genera are endemic. Radiodonts show a high initial diversity that declines through the early Palaeozoic, enabling three diversification phases of radiodonts to be recognized: the thriving phase (Cambrian Series 2), declining phase (Cambrian Miaolingian) and terminal phase (Cambrian Furongian to Ordovician Floian).","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 critical interval in blastoid evolution: the respiratory transition and palaeogeographic dispersion of the spiraculate blastoids in the Devonian","authors":"Jan Bohatý, D. Bradford Macurda, Johnny A. Waters","doi":"10.1002/spp2.1584","DOIUrl":"https://doi.org/10.1002/spp2.1584","url":null,"abstract":"Blastoids underwent a revolution in respiration in the Devonian. Emsian blastoid faunas were dominated by fissiculates such as <jats:italic>Pentremitidea</jats:italic>, giving rise to a transitional spiraculate, <jats:italic>Conuloblastus</jats:italic>. <jats:italic>Hyperoblastus</jats:italic> and a mosaic of spiraculates followed; they featured a more advanced respiratory system and were dominant until the Permian. This diversification occurred just prior to or during the Stony Point and Kačák Events, major ecological disruptions of marine ecosystems. Most new spiraculate blastoids were endemic and short lived, but <jats:italic>Hyperoblastus</jats:italic> survived the major extinction events, lasting into the Famennian. Material from Germany, Spain and North America enables us to trace the diversification of the spiraculates during the Devonian. We erect the new family Conuloblastidae, including <jats:italic>Hreggoblastus differentialis</jats:italic> gen. et sp. nov.; also <jats:italic>Altusoblastus</jats:italic> (type species <jats:italic>Pentatrematites eifeliensis</jats:italic>) with new species <jats:italic>A</jats:italic>. <jats:italic>eremitus</jats:italic>, <jats:italic>A</jats:italic>. <jats:italic>palliolatus</jats:italic>, <jats:italic>A</jats:italic>. sp. 1 and <jats:italic>A</jats:italic>. sp. 2 in the Hyperoblastidae. <jats:italic>Pentremitidea roemeri</jats:italic> and <jats:italic>Hyperoblastus schultzei</jats:italic> are assigned to <jats:italic>Altusoblastus</jats:italic>. <jats:italic>Hyperoblastus batheri</jats:italic> is declared the type species of <jats:italic>Absensoblastus</jats:italic> gen. nov.; <jats:italic>H</jats:italic>. <jats:italic>ludwigi</jats:italic> sp. nov. is assigned to <jats:italic>Hyperoblastus</jats:italic>. <jats:italic>Pentahedronoblastus</jats:italic> gen. nov. (type species <jats:italic>P</jats:italic>. <jats:italic>giesdorfensis</jats:italic> sp. nov.) is described. The fissiculate nymphaeoblastid genus <jats:italic>Pentremitella</jats:italic> (including <jats:italic>P. osoleae</jats:italic> and ?<jats:italic>P</jats:italic>. sp. 1) is redescibed. We recognize the eleutherozoic <jats:italic>Freisoblastus</jats:italic> gen. nov. (type species <jats:italic>F</jats:italic>. <jats:italic>hemisphaericus</jats:italic> sp. nov.), <jats:italic>Dissimiloblastus</jats:italic> gen. nov. (type species <jats:italic>D</jats:italic>. <jats:italic>inequalis</jats:italic> sp. nov.) and non‐eleutherozoic <jats:italic>Lotusoblastus</jats:italic> gen. nov. (type species <jats:italic>Pentremitidea medusa</jats:italic>) (order and family <jats:italic>incertae sedis</jats:italic>). We recognize 13 American species of <jats:italic>Hyperoblastus</jats:italic>.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 Middle Triassic Cassian‐type fauna (Pelsa‐Vazzoler Lagerstätte) and the adaptive radiation of the Modern evolutionary fauna","authors":"Stefano Dominici, Silvia Danise, Andrea Tintori","doi":"10.1002/spp2.1579","DOIUrl":"https://doi.org/10.1002/spp2.1579","url":null,"abstract":"We describe a high‐diversity silicified assemblage of marine molluscs (Pelsa‐Vazzoler Lagerstätte) from the upper Ladinian of the Agordo Dolomites (northeastern Italy). New data on the Triassic rebound, after the end‐Permian mass extinction, constrain it to an interval of relatively stable climatic conditions. This Lagerstätte, in the Sciliar Formation, yields a structure comparable to the famous lower Carnian San Cassiano Lagerstätte and suggests that the radiation of benthic molluscs may have occurred as early as the late Middle Triassic. We classified more than 4800 Cassian‐type molluscs, measuring abundance distributions of 109 species, including one new family (Rhaetidiidae), three new genera (<jats:italic>Pelsia</jats:italic>, <jats:italic>Gaetania</jats:italic>, <jats:italic>Agordozyga</jats:italic>) and 21 new species: <jats:italic>Grammatodon egortinus</jats:italic>, <jats:italic>Modiolus friesenbichlerae</jats:italic>, <jats:italic>Myoconcha busattae</jats:italic>, <jats:italic>Schizogonium letiziae</jats:italic>, <jats:italic>Predazzella</jats:italic>? <jats:italic>monarii</jats:italic>, <jats:italic>Eucycloscala nitida</jats:italic>, <jats:italic>Tricolnaticopsis elongatus</jats:italic>, <jats:italic>Cortinella stricta</jats:italic>, <jats:italic>Triadoskenea alpicornu</jats:italic>, <jats:italic>Trachynerita tenuicostata</jats:italic>, <jats:italic>Coelostylina civettae</jats:italic>, <jats:italic>Gaetania coronata</jats:italic>, <jats:italic>Agordozyga caprina</jats:italic>, <jats:italic>Euthystylus dincae</jats:italic>, <jats:italic>Zygopleura elongata</jats:italic>, <jats:italic>Diatrypesis agordina</jats:italic>, <jats:italic>Cryptaulax pelsae</jats:italic>, <jats:italic>Pseudoscalites karapunari</jats:italic>, <jats:italic>Promathildia gracile</jats:italic>, <jats:italic>Camponaxis ladinica</jats:italic> and <jats:italic>Striactaeonina ingens</jats:italic>. In this fauna, associated with tropical carbonate platforms, epifaunal filter‐feeding bivalves adopted new antipredatory features and gastropods conquered new ecospace, including parasitism and microcarnivory on sponges and scleractinian corals. Small size was an advantage in an ecosystem of small, isolated patch reefs. This is how, where and when caenogastropod and heterobranch snails (groups that today dominate global marine diversity) began their rise in the marine benthos. The origins of some evolutionary innovations that are key to our understanding of the time and place of the Mesozoic Marine Revolution, are therefore pushed back to the Middle Triassic.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New early Cambrian sponges of the Siberian platform and the origins of spiculate crown‐group demosponges","authors":"Kirill A. Kolesnikov, Joseph P. Botting, Andrey Yu. Ivantsov, Andrey Yu. Zhuravlev","doi":"10.1002/spp2.1582","DOIUrl":"https://doi.org/10.1002/spp2.1582","url":null,"abstract":"Sponges are among the most common and diverse Cambrian fossils. However, the origin of the crown groups of the extant sponge classes constitutes the principal problem in the understanding of the evolution of these lower metazoans. New intact spiculate sponges from the lower Cambrian Stage 3–Stage 4 Sinsk Lagerstätte of the Siberian Platform enable a better understanding of the early evolution of crown‐group demosponges. The skeletons of <jats:italic>Neomenispongia plexa</jats:italic> and <jats:italic>N. diazoma</jats:italic> gen. et sp. nov. consist mostly of simple oxeas, which are organized in relatively regular tufts that are additionally strengthened by sigmoidal spicules. The C‐shaped elements of <jats:italic>N. diazoma</jats:italic> are megascleres in their size range but have sigmoidal shapes similar to sigma microscleres of extant demosponges; the sigmoidal spicules of <jats:italic>N. plexa</jats:italic> fully accord with microscleres and are the smallest spicules in known Cambrian demosponges. Together with an unnamed early Cambrian demosponge from the Sirius Passet biota (Greenland) and middle Cambrian <jats:italic>Ulospongiella</jats:italic> from the Burgess Shale (Canada), the new species represent the earliest heteroscleromorph demosponges and indicate an evolutionary origin of microscleres from megascleres. The thin, homogenous skeleton of <jats:italic>Keithospongos loricatus</jats:italic> gen. et sp. nov. is built of small, spirally arranged oxeas corresponding to the skeletal structure of the primitive Hazeliidae, which have been interpreted as the ancestral skeletal organization of demosponges. These new sponges therefore provide a link from extant spiculate demosponge groups to their more familiar Cambrian ancestors.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141932665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}