Among ray‐finned fishes (Actinopterygii), the crushing, durophagous feeding strategy first evolved in the early Carboniferous period, with the †Eurynotiformes possessing dentitions with single layers of partially to fully fused blunt teeth. In the †‘Platysomidae’ (Permian), a new form of crushing dentition evolved (phyllodonty), in which multiple layers of superimposed crushing teeth developed intraosseously, within the jaw. The phyllodont durophagous dentition is also recovered from later‐occurring taxa originating mainly in the Mesozoic, such as the †Bobastraniiformes, the neopterygians †Pycnodontiformes and Ginglymodi, and in the teleost group †Phyllodonta. By comparison, †Kazanichthys viatkensis, an actinopterygian from the middle Permian of European Russia, is characterized by a third, putatively durophagous dentition, with anterior conical teeth and closely packed molariform teeth on the buccal dental plates (a potential similarity with eurynotiforms). Whereas the conical teeth are similar to those of basal actinopterygians, the molariform teeth superficially resemble teeth of some teleosts (Characiformes, Tetraodontiformes), but are unique among known fossil and living Actinopterygii in being crowned by anastomosing, sharp apical ridges. Teeth are ankylosed to the jaw and acrodont in implantation. There is neither evidence of plicidentine, nor cavities corresponding to intraosseous crypts. Most replacement teeth formed extraosseously, differing from the phyllodont dentition, but similar to several more phylogenetically basal actinopterygians. The dental system morphologically resembles recent Sparidae (Teleostei; Perciformes), possibly indicating a similar trophic adaptation. Based on these comparisons and patterns of wear, we propose that †K. viatkensis was a generalist durophagous feeder, with the ability to switch prey types with its unique and complex dentition.
{"title":"The dental system of †Kazanichthys viatkensis (Actinopterygii, Acrolepididae) from the middle Permian of European Russia: palaeobiological and palaeoecological inferences","authors":"A. Bakaev, Z. Johanson, A. Leblanc","doi":"10.1002/spp2.1512","DOIUrl":"https://doi.org/10.1002/spp2.1512","url":null,"abstract":"Among ray‐finned fishes (Actinopterygii), the crushing, durophagous feeding strategy first evolved in the early Carboniferous period, with the †Eurynotiformes possessing dentitions with single layers of partially to fully fused blunt teeth. In the †‘Platysomidae’ (Permian), a new form of crushing dentition evolved (phyllodonty), in which multiple layers of superimposed crushing teeth developed intraosseously, within the jaw. The phyllodont durophagous dentition is also recovered from later‐occurring taxa originating mainly in the Mesozoic, such as the †Bobastraniiformes, the neopterygians †Pycnodontiformes and Ginglymodi, and in the teleost group †Phyllodonta. By comparison, †Kazanichthys viatkensis, an actinopterygian from the middle Permian of European Russia, is characterized by a third, putatively durophagous dentition, with anterior conical teeth and closely packed molariform teeth on the buccal dental plates (a potential similarity with eurynotiforms). Whereas the conical teeth are similar to those of basal actinopterygians, the molariform teeth superficially resemble teeth of some teleosts (Characiformes, Tetraodontiformes), but are unique among known fossil and living Actinopterygii in being crowned by anastomosing, sharp apical ridges. Teeth are ankylosed to the jaw and acrodont in implantation. There is neither evidence of plicidentine, nor cavities corresponding to intraosseous crypts. Most replacement teeth formed extraosseously, differing from the phyllodont dentition, but similar to several more phylogenetically basal actinopterygians. The dental system morphologically resembles recent Sparidae (Teleostei; Perciformes), possibly indicating a similar trophic adaptation. Based on these comparisons and patterns of wear, we propose that †K. viatkensis was a generalist durophagous feeder, with the ability to switch prey types with its unique and complex dentition.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":"12 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85108027","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}
The Branchiosauridae form a clade of tiny newt‐like, extinct amphibians of overall larval appearance. Although their status as neotenic (perennibranchiate) forms had long been universally accepted, adult specimens are known from only one taxon that was hitherto referred to as Melanerpeton (Apateon) gracile. Here we study this life cycle in depth, which includes the only well‐documented metamorphosis‐like transformation in an early tetrapod outside Lissamphibia. Based on various newly recognized features, Melanerpeton gracile is attributed to a new genus, Xerodromeus. Xerodromeus gracilis is characterized by a short postorbital skull table, wide supratemporal, quadrate condyles well posterior to the occipital ones, ossified endocranial elements, carpals, coracoid and pelvis as well as wedge‐shaped intercentra and cylindrical pleurocentra, of which the latter are identified for the first time in branchiosaurids. The studied size classes are referred to four phases: (A) integration of jaw and cheek, longer snout; (B) stronger teeth, robust limbs, incipient ossification of exoccipital, coracoid and pelvis, change in dermal ornament; (C) larger gape, wider skull, polygonal ornament; and (D) quadrate, coracoid, carpals and vertebral centra ossified, during which a probably terrestrial adult morph developed. Adult X. gracilis is more massively built than amphibamids, and its non‐pedicellate dentition indicates that it was probably feeding on different prey.
{"title":"Adult branchiosaurid temnospondyls: the life cycle of Xerodromeus gracilis","authors":"R. Schoch, R. Werneburg","doi":"10.1002/spp2.1513","DOIUrl":"https://doi.org/10.1002/spp2.1513","url":null,"abstract":"The Branchiosauridae form a clade of tiny newt‐like, extinct amphibians of overall larval appearance. Although their status as neotenic (perennibranchiate) forms had long been universally accepted, adult specimens are known from only one taxon that was hitherto referred to as Melanerpeton (Apateon) gracile. Here we study this life cycle in depth, which includes the only well‐documented metamorphosis‐like transformation in an early tetrapod outside Lissamphibia. Based on various newly recognized features, Melanerpeton gracile is attributed to a new genus, Xerodromeus. Xerodromeus gracilis is characterized by a short postorbital skull table, wide supratemporal, quadrate condyles well posterior to the occipital ones, ossified endocranial elements, carpals, coracoid and pelvis as well as wedge‐shaped intercentra and cylindrical pleurocentra, of which the latter are identified for the first time in branchiosaurids. The studied size classes are referred to four phases: (A) integration of jaw and cheek, longer snout; (B) stronger teeth, robust limbs, incipient ossification of exoccipital, coracoid and pelvis, change in dermal ornament; (C) larger gape, wider skull, polygonal ornament; and (D) quadrate, coracoid, carpals and vertebral centra ossified, during which a probably terrestrial adult morph developed. Adult X. gracilis is more massively built than amphibamids, and its non‐pedicellate dentition indicates that it was probably feeding on different prey.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":"304 2","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72431901","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}
Carlos Neto de Carvalho, A. Baucon, D. Badano, P. Proença Cunha, Cristiana Ferreira, S. Figueiredo, Fernando Muñiz, J. Belo, F. Bernardini, M. Cachão
The c. 100 myr extensive fossil record of bee brood nests and cells (calichnia) in siliciclastic sedimentary deposits, or palaeosols, is virtually devoid of the presence of their producers. The absence of a more specific assignment to a producer of the different ichnogenera of the ichnofamily Celliformidae precludes their use in phylogenetic and palaeobiogeographic studies. Omission surfaces developed in incipient carbonate palaeosols during the late Holocene (middle Neoglacial), c. 2975 yr cal BP, on the southwest coast of mainland Portugal show insect calichnia in dense ichnofabrics dominated by shallow discrete cells (Palmiraichnus castellanosi) and cells at the terminus of vertical shafts. At Carreira Brava, one of the studied sites, bees ready to abandon their cells were found in an exceptional state of preservation inside the sealed brood chambers. The chambers also preserve the inner cell hydrophobic polymerized membrane and remains of the monospecific Brassicaceae‐type pollen provision. Although the cause of mass mortality remains a mystery, oxygen depletion due to sudden flooding of the nesting substrate and consequent or overnight temperature drop, just before emergence, are plausible causes. The anaerobic conditions and later rapid carbonate diagenetic lithification are the likely causes of the preservation of the bees and the inner cell organic membrane. The favourable climate conditions for the development of successive, dense ichnofabrics from an omission suite dominated by bee brood cells may be the result of slightly colder and higher‐precipitation winters during the Neoglacial interval.
{"title":"Eucera bees (Hymenoptera, Apidae, Eucerini) preserved in their brood cells from late Holocene (middle Neoglacial) palaeosols of southwest Portugal","authors":"Carlos Neto de Carvalho, A. Baucon, D. Badano, P. Proença Cunha, Cristiana Ferreira, S. Figueiredo, Fernando Muñiz, J. Belo, F. Bernardini, M. Cachão","doi":"10.1002/spp2.1518","DOIUrl":"https://doi.org/10.1002/spp2.1518","url":null,"abstract":"The c. 100 myr extensive fossil record of bee brood nests and cells (calichnia) in siliciclastic sedimentary deposits, or palaeosols, is virtually devoid of the presence of their producers. The absence of a more specific assignment to a producer of the different ichnogenera of the ichnofamily Celliformidae precludes their use in phylogenetic and palaeobiogeographic studies. Omission surfaces developed in incipient carbonate palaeosols during the late Holocene (middle Neoglacial), c. 2975 yr cal BP, on the southwest coast of mainland Portugal show insect calichnia in dense ichnofabrics dominated by shallow discrete cells (Palmiraichnus castellanosi) and cells at the terminus of vertical shafts. At Carreira Brava, one of the studied sites, bees ready to abandon their cells were found in an exceptional state of preservation inside the sealed brood chambers. The chambers also preserve the inner cell hydrophobic polymerized membrane and remains of the monospecific Brassicaceae‐type pollen provision. Although the cause of mass mortality remains a mystery, oxygen depletion due to sudden flooding of the nesting substrate and consequent or overnight temperature drop, just before emergence, are plausible causes. The anaerobic conditions and later rapid carbonate diagenetic lithification are the likely causes of the preservation of the bees and the inner cell organic membrane. The favourable climate conditions for the development of successive, dense ichnofabrics from an omission suite dominated by bee brood cells may be the result of slightly colder and higher‐precipitation winters during the Neoglacial interval.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":"6 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91031120","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}
Romain Sabroux, G. Edgecombe, D. Pisani, R. Garwood
Three species of sea spider (Arthropoda, Pycnogonida) have been described from the Middle Jurassic (Callovian) Konservat‐Lagerstätte of La Voulte‐sur‐Rhône: Palaeopycnogonides gracilis, Colossopantopodus boissinensis and Palaeoendeis elmii. These fossils were initially attributed to three extant families or superfamilies, justifying their use as calibration points in a recent tree‐dating analysis. However, their taxonomic affinities are still debated. Our knowledge of the morphology of these Jurassic sea spiders is limited by prior investigation with only light microscopy and radiographs, such that further morphological details such as cephalic appendages (chelifores, palps, ovigers) remain poorly documented. Here, we reinvestigate the La Voulte‐sur‐Rhône fossils using x‐ray microtomography and reflectance transformation imaging. A new specimen, tentatively attributed to P. gracilis, was found using x‐ray microtomography, while another fossil initially interpreted as Palaeoendeis elmii may also be related to this species. We attribute all fossils to Pantopoda, crown‐group Pycnogonida. Palaeopycnogonides gracilis had ovigers in at least one sex and had chelifores and palps that were either reduced or absent. Together, the cephalic appendage set and the structure of the ovigers are unique among Pantopoda, and this species is reassigned to the new family Palaeopycnogonididae. Colossopantopodus boissinensis lacked chelifores but had palps and ovigers, the latter with the typical structure shown by extant Colossendeinae, to which we attribute the fossil. The absence of chelifores and palps in Palaeoendeis elmii and the structure of its ovigers indicate affinities with Endeidae. The impact of these new taxonomic assignments on the way Jurassic sea spiders can be used as fossil calibrations is discussed.
{"title":"New insights into the sea spider fauna (Arthropoda, Pycnogonida) of La Voulte‐sur‐Rhône, France (Jurassic, Callovian)","authors":"Romain Sabroux, G. Edgecombe, D. Pisani, R. Garwood","doi":"10.1002/spp2.1515","DOIUrl":"https://doi.org/10.1002/spp2.1515","url":null,"abstract":"Three species of sea spider (Arthropoda, Pycnogonida) have been described from the Middle Jurassic (Callovian) Konservat‐Lagerstätte of La Voulte‐sur‐Rhône: Palaeopycnogonides gracilis, Colossopantopodus boissinensis and Palaeoendeis elmii. These fossils were initially attributed to three extant families or superfamilies, justifying their use as calibration points in a recent tree‐dating analysis. However, their taxonomic affinities are still debated. Our knowledge of the morphology of these Jurassic sea spiders is limited by prior investigation with only light microscopy and radiographs, such that further morphological details such as cephalic appendages (chelifores, palps, ovigers) remain poorly documented. Here, we reinvestigate the La Voulte‐sur‐Rhône fossils using x‐ray microtomography and reflectance transformation imaging. A new specimen, tentatively attributed to P. gracilis, was found using x‐ray microtomography, while another fossil initially interpreted as Palaeoendeis elmii may also be related to this species. We attribute all fossils to Pantopoda, crown‐group Pycnogonida. Palaeopycnogonides gracilis had ovigers in at least one sex and had chelifores and palps that were either reduced or absent. Together, the cephalic appendage set and the structure of the ovigers are unique among Pantopoda, and this species is reassigned to the new family Palaeopycnogonididae. Colossopantopodus boissinensis lacked chelifores but had palps and ovigers, the latter with the typical structure shown by extant Colossendeinae, to which we attribute the fossil. The absence of chelifores and palps in Palaeoendeis elmii and the structure of its ovigers indicate affinities with Endeidae. The impact of these new taxonomic assignments on the way Jurassic sea spiders can be used as fossil calibrations is discussed.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":"45 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87555049","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}
Nidia Álvarez‐Armada, J. Bauer, J. Waters, I. Rahman
Brooding of young is a reproductive strategy observed in many extant echinoderms, but the evolutionary history of this behaviour is largely unknown due to the scarcity of examples preserved in the fossil record. Here, synchrotron x‐ray tomography is used to describe an exceptionally preserved specimen of the Devonian blastoid echinoderm Hyperoblastus reimanni. The coelomic cavity appears completely preserved in a coiled arrangement partially enclosing organs associated with the digestive, haemal and axial systems. The vault region of the coelom surrounds four structures interpreted as three internally brooded larvae and a gonad. The presence of putative larvae brooded internally in this specimen sheds new light on the reproductive strategies used by blastoids, suggesting they were sexually dimorphic and that internal brooding was acquired early in the group's history. The acquisition of brooding may have been linked to high clastic sediment influx associated with the Appalachian Orogeny, which would have been detrimental to the survival of larvae living at the soupy sediment–water interface.
{"title":"The oldest evidence of brooding in a Devonian blastoid reveals the evolution of new reproductive strategies in early echinoderms","authors":"Nidia Álvarez‐Armada, J. Bauer, J. Waters, I. Rahman","doi":"10.1002/spp2.1493","DOIUrl":"https://doi.org/10.1002/spp2.1493","url":null,"abstract":"Brooding of young is a reproductive strategy observed in many extant echinoderms, but the evolutionary history of this behaviour is largely unknown due to the scarcity of examples preserved in the fossil record. Here, synchrotron x‐ray tomography is used to describe an exceptionally preserved specimen of the Devonian blastoid echinoderm Hyperoblastus reimanni. The coelomic cavity appears completely preserved in a coiled arrangement partially enclosing organs associated with the digestive, haemal and axial systems. The vault region of the coelom surrounds four structures interpreted as three internally brooded larvae and a gonad. The presence of putative larvae brooded internally in this specimen sheds new light on the reproductive strategies used by blastoids, suggesting they were sexually dimorphic and that internal brooding was acquired early in the group's history. The acquisition of brooding may have been linked to high clastic sediment influx associated with the Appalachian Orogeny, which would have been detrimental to the survival of larvae living at the soupy sediment–water interface.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":"39 1 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80905765","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}
R. Matamales‐Andreu, E. Mujal, À. Galobart, J. Fortuny
Moradisaurine captorhinid eureptiles are one of the best‐known groups of Permian herbivorous tetrapods. Moradisaurines, with several rows of teeth on the maxillae and jaws, first appeared in the Cisuralian and went extinct at the end of the Lopingian; they were especially abundant in the equatorial latitudes of Pangaea. However, the postcranial skeleton of this clade is relatively poorly known, given that most of the species described have been based on skulls. This fact has precluded a detailed correlation with coeval tracks. The present work describes a new moradisaurine genus and species, Tramuntanasaurus tiai, based on an almost complete, semi‐articulated skeleton from the Port des Canonge Formation of Mallorca (Balearic Islands, western Mediterranean), identifying it as the trackmaker of the co‐occurring small‐sized traces of the ichnogenus Hyloidichnus. Apart from documenting the new moradisaurine species, the results presented herein strongly support the hypothesis that Hyloidichnus was produced by both non‐moradisaurine captorhinids and moradisaurines; those of small to medium size, at least, had a very conserved autopodial morphology and gait. Therefore, this study provides new data to infer the trackmakers of Hyloidichnus where bone remains are missing, and thus contributes to our understanding of Permian tetrapod ichnofaunas and tetrapod communities.
腕足类真爬行动物是二叠纪最著名的食草四足动物之一。上颌和下颚上有几排牙齿的moradiaurines，最早出现在顺苏拉纪，在罗平纪末期灭绝;它们在泛大陆的赤道纬度地区尤其丰富。然而，考虑到大多数物种的描述都是基于头骨，这个分支的颅后骨骼相对来说鲜为人知。这一事实排除了与同期轨迹的详细相关性。目前的工作描述了一个新的moradidisurine属和种，Tramuntanasaurus tiai，基于来自马略卡岛(地中海西部巴利亚利群岛)的Port des Canonge组的几乎完整的半关节骨架，并将其确定为同时出现的Hyloidichnus属小型痕迹的追踪者。本文的研究结果有力地支持了Hyloidichnus是由非非二氨基二磺酸的captorhinids和非二氨基二磺酸的captorhinids共同产生的假说;那些小到中等大小的，至少，有一个非常保守的自耳廓形态和步态。因此，本研究提供了新的数据，可以推断出遗失骨骸的Hyloidichnus的足迹，从而有助于我们对二叠纪四足动物和四足动物群落的认识。
{"title":"A new medium‐sized moradisaurine captorhinid eureptile from the Permian of Mallorca (Balearic Islands, western Mediterranean) and correlation with the co‐occurring ichnogenus Hyloidichnus","authors":"R. Matamales‐Andreu, E. Mujal, À. Galobart, J. Fortuny","doi":"10.1002/spp2.1498","DOIUrl":"https://doi.org/10.1002/spp2.1498","url":null,"abstract":"Moradisaurine captorhinid eureptiles are one of the best‐known groups of Permian herbivorous tetrapods. Moradisaurines, with several rows of teeth on the maxillae and jaws, first appeared in the Cisuralian and went extinct at the end of the Lopingian; they were especially abundant in the equatorial latitudes of Pangaea. However, the postcranial skeleton of this clade is relatively poorly known, given that most of the species described have been based on skulls. This fact has precluded a detailed correlation with coeval tracks. The present work describes a new moradisaurine genus and species, Tramuntanasaurus tiai, based on an almost complete, semi‐articulated skeleton from the Port des Canonge Formation of Mallorca (Balearic Islands, western Mediterranean), identifying it as the trackmaker of the co‐occurring small‐sized traces of the ichnogenus Hyloidichnus. Apart from documenting the new moradisaurine species, the results presented herein strongly support the hypothesis that Hyloidichnus was produced by both non‐moradisaurine captorhinids and moradisaurines; those of small to medium size, at least, had a very conserved autopodial morphology and gait. Therefore, this study provides new data to infer the trackmakers of Hyloidichnus where bone remains are missing, and thus contributes to our understanding of Permian tetrapod ichnofaunas and tetrapod communities.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":"26 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80316931","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}
Harry O. Berks, Morten Lunde Nielsen, Joseph T. Flannery‐Sutherland, Arne Thorshøj Nielsen, T. Park, J. Vinther
Artiopoda was a diverse group of Palaeozoic euarthropods that proliferated in the early Palaeozoic, epitomized by the ubiquitous trilobites. Their possible phylogenetic position outside mandibulates and chelicerates offers the potential for understanding the evolution of euarthropods in more detail. However, this opportunity remains unexploited given that identification of deep‐splitting artiopodans remains to be fully explored. Here, we describe a new non‐trilobite artiopodan from the lower Cambrian Sirius Passet Lagerstätte, North Greenland. Thulaspis tholops gen. et sp. nov. is a large species with a broad, domed head shield, followed by a trunk consisting of 15 thoracic tergites and a small pygidium, giving the body an ovoid appearance when viewed dorsally. Thulaspis is distinctive with its rounded genae and anterior thoracic pleural tips, as well as short pleural spines posteriorly. A heart‐shaped hypostome with an anterior lobe is present. Appendages, partly obscured by the tergal skeleton, have many moderate length gnathobasic spines, and large flap‐like exopods with a fringe of small setae. Cladistic analyses recover Thulaspis as the sister taxon to Squamacula, a genus found in the Chengjiang and Emu Bay Shale biotas, in either a polytomy with a number of artiopodan taxa or as a sister group to all other artiopodans, indicating an important role in understanding the roots of artiopodan anatomy and evolution.
偶足动物是古生代真节肢动物的一个多样化群体，在古生代早期大量繁殖，以无处不在的三叶虫为代表。它们可能在下颌骨和螯肢动物之外的系统发育位置，为更详细地了解真节肢动物的进化提供了可能。然而，由于深裂偶蹄足动物的鉴定仍有待充分探索，这一机会仍未被利用。在这里，我们描述了来自北格陵兰岛下寒武纪天狼星Passet Lagerstätte的一种新的非三叶虫兽足动物。Thulaspis tholops gen. et sp. 11 .是一个巨大的物种，有一个宽阔的圆顶头盾，接着是一个由15个胸椎体和一个小柱体组成的躯干，当从背面看时，身体呈卵形外观。其特点是其圆形的属和前胸胸膜尖端，以及后面的短胸膜棘。心脏形假设体，有前叶。附属物，部分被虎骨遮蔽，有许多中等长度的齿状棘，和大的瓣状外足，有小刚毛的边缘。分支分析发现，在与许多偶蹄动物类群的多聚关系中，Thulaspis是在澄江和鸸鹋湾页岩生物群中发现的Squamacula属的姐妹类群，或者是作为所有其他偶蹄动物的姐妹类群，这对了解偶蹄动物解剖和进化的根源具有重要作用。
{"title":"A possibly deep branching artiopodan arthropod from the lower Cambrian Sirius Passet Lagerstätte (North Greenland)","authors":"Harry O. Berks, Morten Lunde Nielsen, Joseph T. Flannery‐Sutherland, Arne Thorshøj Nielsen, T. Park, J. Vinther","doi":"10.1002/spp2.1495","DOIUrl":"https://doi.org/10.1002/spp2.1495","url":null,"abstract":"Artiopoda was a diverse group of Palaeozoic euarthropods that proliferated in the early Palaeozoic, epitomized by the ubiquitous trilobites. Their possible phylogenetic position outside mandibulates and chelicerates offers the potential for understanding the evolution of euarthropods in more detail. However, this opportunity remains unexploited given that identification of deep‐splitting artiopodans remains to be fully explored. Here, we describe a new non‐trilobite artiopodan from the lower Cambrian Sirius Passet Lagerstätte, North Greenland. Thulaspis tholops gen. et sp. nov. is a large species with a broad, domed head shield, followed by a trunk consisting of 15 thoracic tergites and a small pygidium, giving the body an ovoid appearance when viewed dorsally. Thulaspis is distinctive with its rounded genae and anterior thoracic pleural tips, as well as short pleural spines posteriorly. A heart‐shaped hypostome with an anterior lobe is present. Appendages, partly obscured by the tergal skeleton, have many moderate length gnathobasic spines, and large flap‐like exopods with a fringe of small setae. Cladistic analyses recover Thulaspis as the sister taxon to Squamacula, a genus found in the Chengjiang and Emu Bay Shale biotas, in either a polytomy with a number of artiopodan taxa or as a sister group to all other artiopodans, indicating an important role in understanding the roots of artiopodan anatomy and evolution.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":"75 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80506231","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}
F. Ferratges, J. Luque, J. L. Domínguez, À. Ossó, M. Aurell, S. Zamora
Eubrachyurans, or ‘higher’ true crabs, are the most speciose group of decapod crustaceans and have a rich fossil record extending into the Early Cretaceous. However, most extant families are first found in the fossil record in the Palaeogene, and particularly in the Eocene. Unfortunately, fossils of many early eubrachyuran groups are often fragmentary, and only a few studies have combined extinct and extant taxa in a phylogenetic context using different optimality criteria. Here, we report the dairoidid crab Phrynolambrus sagittalis sp. nov., an enigmatic eubrachyuran from the upper Eocene of Huesca (northern Spain), whose completeness and exquisite preservation permit examination of its anatomy in a phylogenetic context. Dairoidids have previously been considered among the oldest stone crabs (Eriphioidea) or elbow crabs (Parthenopoidea), two disparate and distantly related groups of true crabs living today. Mechanical preparation and computed tomography of the fossil material revealed several diagnostic features that allow a detailed comparison with families across the crab tree of life, and test hypotheses about its phylogenetic affinities. Phrynolambrus sagittalis is the first record of the genus in the Iberian Peninsula, and represents one of the oldest crown parthenopoidean crabs worldwide, expanding our knowledge of the biogeographical distribution of elbow crabs during the Palaeogene, as well as their early origins, anatomical diversity and systematic affinities. Understanding the disparity of Eocene eubrachyurans is pivotal to disentangling the systematic relationships among crown families, and interpreting the spatio‐temporal patterns leading to the evolution of modern faunas.
{"title":"The oldest dairoidid crab (Decapoda, Brachyura, Parthenopoidea) from the Eocene of Spain","authors":"F. Ferratges, J. Luque, J. L. Domínguez, À. Ossó, M. Aurell, S. Zamora","doi":"10.1002/spp2.1494","DOIUrl":"https://doi.org/10.1002/spp2.1494","url":null,"abstract":"Eubrachyurans, or ‘higher’ true crabs, are the most speciose group of decapod crustaceans and have a rich fossil record extending into the Early Cretaceous. However, most extant families are first found in the fossil record in the Palaeogene, and particularly in the Eocene. Unfortunately, fossils of many early eubrachyuran groups are often fragmentary, and only a few studies have combined extinct and extant taxa in a phylogenetic context using different optimality criteria. Here, we report the dairoidid crab Phrynolambrus sagittalis sp. nov., an enigmatic eubrachyuran from the upper Eocene of Huesca (northern Spain), whose completeness and exquisite preservation permit examination of its anatomy in a phylogenetic context. Dairoidids have previously been considered among the oldest stone crabs (Eriphioidea) or elbow crabs (Parthenopoidea), two disparate and distantly related groups of true crabs living today. Mechanical preparation and computed tomography of the fossil material revealed several diagnostic features that allow a detailed comparison with families across the crab tree of life, and test hypotheses about its phylogenetic affinities. Phrynolambrus sagittalis is the first record of the genus in the Iberian Peninsula, and represents one of the oldest crown parthenopoidean crabs worldwide, expanding our knowledge of the biogeographical distribution of elbow crabs during the Palaeogene, as well as their early origins, anatomical diversity and systematic affinities. Understanding the disparity of Eocene eubrachyurans is pivotal to disentangling the systematic relationships among crown families, and interpreting the spatio‐temporal patterns leading to the evolution of modern faunas.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":"157 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87627358","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}
Y. Ezaki, Mei Kishida, Yusuke Takeda, Natsuko Adachi, Jianbo Liu, Yasuhiro Iba
The Cambrian cnidarian Cambroctoconus orientalis occurs in clusters exhibiting pendent growth in crypts within thrombolite frameworks. Here we successfully reconstruct its three‐dimensional (3D) in situ mode of life. The 3D reconstruction shows the initial individuals of colonies and attachment structures, budding sites and growth modes of coralla in response to the extent of sheltered spaces. The earliest individuals were attached to the framework by a suction‐cup‐like structure and were basically orthogonal to the walls, growing downward. Their calicular bases were pierced by a hole. Individuals were initially cylindrical and gradually formed an octagonal column during growth. Budding occurred everywhere, and toroidal budding traces are abundant upon the corallite surfaces. The attachment structures were secondarily reinforced by continuous secretion from the coenenchymal tissue. Offsets continued to grow only when sufficient growth space was available, while producing as many individuals as possible. Growth of individuals was commonly halted by the surrounding framework. Growth directions were in part modified by corallite curvature to avoid collisions between corallites and to make full use of the intricate void spaces. In deteriorating conditions, offset corallites appeared through regeneration rather than budding from the remaining soft tissues. Active exploitation of the sheltered spaces within thrombolites, which remained dominant during the Cambrian, was thus conducted by C. orientalis. Notably, the cryptobionts treated herein adopted subtle growth strategies that have not previously been fully understood and are not easily interpreted with reference to organisms living in open spaces.
{"title":"Three‐dimensional reconstruction of the in situ mode of life of the Cambrian coral Cambroctoconus: asexual reproduction and colony growth in immediate response to cryptic habitats","authors":"Y. Ezaki, Mei Kishida, Yusuke Takeda, Natsuko Adachi, Jianbo Liu, Yasuhiro Iba","doi":"10.1002/spp2.1497","DOIUrl":"https://doi.org/10.1002/spp2.1497","url":null,"abstract":"The Cambrian cnidarian Cambroctoconus orientalis occurs in clusters exhibiting pendent growth in crypts within thrombolite frameworks. Here we successfully reconstruct its three‐dimensional (3D) in situ mode of life. The 3D reconstruction shows the initial individuals of colonies and attachment structures, budding sites and growth modes of coralla in response to the extent of sheltered spaces. The earliest individuals were attached to the framework by a suction‐cup‐like structure and were basically orthogonal to the walls, growing downward. Their calicular bases were pierced by a hole. Individuals were initially cylindrical and gradually formed an octagonal column during growth. Budding occurred everywhere, and toroidal budding traces are abundant upon the corallite surfaces. The attachment structures were secondarily reinforced by continuous secretion from the coenenchymal tissue. Offsets continued to grow only when sufficient growth space was available, while producing as many individuals as possible. Growth of individuals was commonly halted by the surrounding framework. Growth directions were in part modified by corallite curvature to avoid collisions between corallites and to make full use of the intricate void spaces. In deteriorating conditions, offset corallites appeared through regeneration rather than budding from the remaining soft tissues. Active exploitation of the sheltered spaces within thrombolites, which remained dominant during the Cambrian, was thus conducted by C. orientalis. Notably, the cryptobionts treated herein adopted subtle growth strategies that have not previously been fully understood and are not easily interpreted with reference to organisms living in open spaces.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":"78 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75214678","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}
Eight coleoid genera have so far been described from the Callovian‐aged La Voulte‐sur‐Rhône Lagerstätte (c. 165 Ma; Ardèche, France), a locality noted for its unique three‐dimensional preservation of soft tissues. Here, we used high resolution x‐ray‐based imaging methods, in conjunction with reflectance transformation imaging, to study the soft tissues of a previously undescribed coleoid from the La Voulte‐sur‐Rhône locality. This analysis identified both an ink sac and internal light organs, a combination of defence mechanisms present in the Recent, although not previously described from the coleoid fossil record, as well as the presence of Octobrachia‐type arm musculature and Vampyroteuthis‐like sucker attachments. The morphology of the gladius could not be attributed to any known coleoids and therefore justified the assignment of this single specimen to a new taxon: Vampyrofugiens atramentum. The addition of this new vampyromorph species not only increases the coleoid diversity known from the site, but also broadens the morphological variation observed in the co‐occurring coleoid taxa. These findings suggest that there was a high diversity of cephalopods occupying differentiated communities during the Middle Jurassic.
{"title":"A new vampyromorph species from the Middle Jurassic La Voulte‐sur‐Rhône Lagerstätte","authors":"A. J. Rowe, I. Kruta, L. Villier, I. Rouget","doi":"10.1002/spp2.1511","DOIUrl":"https://doi.org/10.1002/spp2.1511","url":null,"abstract":"Eight coleoid genera have so far been described from the Callovian‐aged La Voulte‐sur‐Rhône Lagerstätte (c. 165 Ma; Ardèche, France), a locality noted for its unique three‐dimensional preservation of soft tissues. Here, we used high resolution x‐ray‐based imaging methods, in conjunction with reflectance transformation imaging, to study the soft tissues of a previously undescribed coleoid from the La Voulte‐sur‐Rhône locality. This analysis identified both an ink sac and internal light organs, a combination of defence mechanisms present in the Recent, although not previously described from the coleoid fossil record, as well as the presence of Octobrachia‐type arm musculature and Vampyroteuthis‐like sucker attachments. The morphology of the gladius could not be attributed to any known coleoids and therefore justified the assignment of this single specimen to a new taxon: Vampyrofugiens atramentum. The addition of this new vampyromorph species not only increases the coleoid diversity known from the site, but also broadens the morphological variation observed in the co‐occurring coleoid taxa. These findings suggest that there was a high diversity of cephalopods occupying differentiated communities during the Middle Jurassic.","PeriodicalId":48705,"journal":{"name":"Papers in Palaeontology","volume":"12 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80279028","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}
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