Pub Date : 2022-11-03DOI: 10.1080/14772019.2022.2128913
R. Müller, M. S. Garcia, André O Fonseca
Characterized by an elongated snout, proterochampsids are carnivorous non-archosaur archosauriforms. The clade is endemic to South America and its fossil record extends from the early Carnian to the late Carnian/early Norian. Nesting close to Archosauria, it is a key clade for understanding the origin and evolution of archosaurian traits. Unfortunately, hind limb elements are usually poorly preserved for the group. Therefore, the hind limb anatomy of proterochampsids still lacks detailed descriptions. In the present study, we partially fill this gap with the description of a new proterochampsid represented by a complete and well-preserved hind limb. Stenoscelida aurantiacus gen. et sp. nov. was excavated from the late Carnian/early Norian (Late Triassic) beds of southern Brazil. A phylogenetic investigation recovers the new taxon as a non-rhadinosuchine proterochampsid. The species bears an unusual set of traits for the group, which provides clues on the evolutionary origins of some muscle attachment structures. For instance, the femur of Stenoscelida aurantiacus gen. et sp. nov. possesses an anterior trochanter and an anterolateral scar. So far, these features have not been reported in other non-archosaurian archosauriforms. Therefore, the new specimen indicates that some typical archosaurian features evolved earlier than previously thought. The taxon also carries additional uncommon features for proterochampsids, such as an iliofibularis tubercle on the anterior margin of the fibula and a vestigial phalanx in digit V. In sum, Stenoscelida aurantiacus has one of the best-preserved hind limbs within Proterochampsidae and sheds light on the polarization of important traits regarding the evolutionary context of Archosauria. http://zoobank.org/urn:lsid:zoobank.org:pub:C78B7CE3-AB9B-4543-833E-B2A3FEA957D9
{"title":"A new proterochampsid (Archosauriformes: Proterochampsia) from the Late Triassic of southern Brazil and the emergence of archosaurian hind limb traits","authors":"R. Müller, M. S. Garcia, André O Fonseca","doi":"10.1080/14772019.2022.2128913","DOIUrl":"https://doi.org/10.1080/14772019.2022.2128913","url":null,"abstract":"Characterized by an elongated snout, proterochampsids are carnivorous non-archosaur archosauriforms. The clade is endemic to South America and its fossil record extends from the early Carnian to the late Carnian/early Norian. Nesting close to Archosauria, it is a key clade for understanding the origin and evolution of archosaurian traits. Unfortunately, hind limb elements are usually poorly preserved for the group. Therefore, the hind limb anatomy of proterochampsids still lacks detailed descriptions. In the present study, we partially fill this gap with the description of a new proterochampsid represented by a complete and well-preserved hind limb. Stenoscelida aurantiacus gen. et sp. nov. was excavated from the late Carnian/early Norian (Late Triassic) beds of southern Brazil. A phylogenetic investigation recovers the new taxon as a non-rhadinosuchine proterochampsid. The species bears an unusual set of traits for the group, which provides clues on the evolutionary origins of some muscle attachment structures. For instance, the femur of Stenoscelida aurantiacus gen. et sp. nov. possesses an anterior trochanter and an anterolateral scar. So far, these features have not been reported in other non-archosaurian archosauriforms. Therefore, the new specimen indicates that some typical archosaurian features evolved earlier than previously thought. The taxon also carries additional uncommon features for proterochampsids, such as an iliofibularis tubercle on the anterior margin of the fibula and a vestigial phalanx in digit V. In sum, Stenoscelida aurantiacus has one of the best-preserved hind limbs within Proterochampsidae and sheds light on the polarization of important traits regarding the evolutionary context of Archosauria. http://zoobank.org/urn:lsid:zoobank.org:pub:C78B7CE3-AB9B-4543-833E-B2A3FEA957D9","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"20 1","pages":"1 - 19"},"PeriodicalIF":2.6,"publicationDate":"2022-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45706780","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}
Pub Date : 2022-10-10DOI: 10.1080/14772019.2022.2109216
M. Pulsipher, Evan P. Anderson, Lauren S. Wright, J. Kluessendorf, D. Mikulic, J. Schiffbauer
The Silurian Waukesha Lagerstätte of Wisconsin, USA, hosts a fauna of distinctive soft-bodied organisms, including a range of graptolites, worms, trilobites and uncommon arthropods, but otherwise lacks most of the shelly fauna typical of contemporaneous deposits. While several species have been described, much of the Waukesha biota remains understudied. Here, we examine numerous specimens of a previously unnamed and undescribed vermiform arthropod that bears a cephalic carapace, a suite of specialized head appendages, a long, segmented trunk, and a battery of small swimming appendages. The taxonomic and phylogenetic evaluations presented herein establish this taxon as a novel genus and species, Acheronauta stimulapis gen. et sp. nov., plausibly positioned within the basal mandibulates. Our phylogenetic analyses suggest that a new arthropod clade may be warranted, comprising Acheronauta gen. nov., Captopodus, and the thylacocephalans. https://zoobank.org/urn:lsid:zoobank.org:pub:B572831B-1A8A-4E4E-9258-34D91AA22A74nk
{"title":"Description of Acheronauta gen. nov., a possible mandibulate from the Silurian Waukesha Lagerstätte, Wisconsin, USA","authors":"M. Pulsipher, Evan P. Anderson, Lauren S. Wright, J. Kluessendorf, D. Mikulic, J. Schiffbauer","doi":"10.1080/14772019.2022.2109216","DOIUrl":"https://doi.org/10.1080/14772019.2022.2109216","url":null,"abstract":"The Silurian Waukesha Lagerstätte of Wisconsin, USA, hosts a fauna of distinctive soft-bodied organisms, including a range of graptolites, worms, trilobites and uncommon arthropods, but otherwise lacks most of the shelly fauna typical of contemporaneous deposits. While several species have been described, much of the Waukesha biota remains understudied. Here, we examine numerous specimens of a previously unnamed and undescribed vermiform arthropod that bears a cephalic carapace, a suite of specialized head appendages, a long, segmented trunk, and a battery of small swimming appendages. The taxonomic and phylogenetic evaluations presented herein establish this taxon as a novel genus and species, Acheronauta stimulapis gen. et sp. nov., plausibly positioned within the basal mandibulates. Our phylogenetic analyses suggest that a new arthropod clade may be warranted, comprising Acheronauta gen. nov., Captopodus, and the thylacocephalans. https://zoobank.org/urn:lsid:zoobank.org:pub:B572831B-1A8A-4E4E-9258-34D91AA22A74nk","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"20 1","pages":"1 - 24"},"PeriodicalIF":2.6,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45996007","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}
Pub Date : 2022-10-05DOI: 10.1080/14772019.2022.2113831
R. Schoch
The Amphibamiformes, small temnospondyls from late Palaeozoic rocks, have been increasingly considered as the stem-group of some or all extant amphibians (Lissamphibia). Their relationships have become intensely studied after the discovery of new taxa and the revision of poorly known ones, but understanding is hampered by the fact that amphibamiforms fall into two very distinct groups: (a) terrestrial taxa known by adults only (Amphibamidae, Micropholidae) and (b) aquatic taxa known by larvae and neotenic adults (Branchiosauridae). The Branchiosauridae were recognized as a clade supported by a suite of larval synapomorphies, but the unknown larval morphology of the terrestrial clades leaves the question open to whether some branchiosaurid apomorphies might have been more widely distributed. Recently, some branchiosaurid specimens from Nýřany (Czech Republic) were proposed to be larvae of olsoniforms and amphibamids, and together with a revision of ancient branchiosaurid-like taxa from the United States and France prompt a re-analysis of this issue. In a phylogenetic analysis of 48 taxa and 113 characters, the Branchiosauridae were found to be monophyletic and nest in an unresolved trichotomy with Amphibamidae and the putative relatives of Lissamphibia. The present analysis finds the hypothesized olsoniform larvae from Nýřany to be adults of Branchiosaurus salamandroides, whereas some of the larvae from Mazon Creek (Illinois, USA) are not branchiosaurids, but immature specimens of the amphibamid Amphibamus grandiceps. Within branchiosaurids, four clades have been identified: (a) the Carboniferous Anthracobamus clade (Anthracobamus, Montceaubatrachus), (b) the mostly Carboniferous Branchiosaurinae (Branchiosaurus, Milnererpeton) and two largely Permian clades, the newly defined Apateoninae (genus Apateon) and Leptorophinae (Melanerpeton, Leptorophus, Schoenfelderpeton) clade. Branchiosaurid evolution involved a trend towards an enhanced paedomorphosis, a modification of branchial teeth, and successive reduction of bone in the scales and pectoral girdle.
{"title":"Phylogeny of the amphibamiform temnospondyls: the relationship of taxa known by adults, larvae and neotenes","authors":"R. Schoch","doi":"10.1080/14772019.2022.2113831","DOIUrl":"https://doi.org/10.1080/14772019.2022.2113831","url":null,"abstract":"The Amphibamiformes, small temnospondyls from late Palaeozoic rocks, have been increasingly considered as the stem-group of some or all extant amphibians (Lissamphibia). Their relationships have become intensely studied after the discovery of new taxa and the revision of poorly known ones, but understanding is hampered by the fact that amphibamiforms fall into two very distinct groups: (a) terrestrial taxa known by adults only (Amphibamidae, Micropholidae) and (b) aquatic taxa known by larvae and neotenic adults (Branchiosauridae). The Branchiosauridae were recognized as a clade supported by a suite of larval synapomorphies, but the unknown larval morphology of the terrestrial clades leaves the question open to whether some branchiosaurid apomorphies might have been more widely distributed. Recently, some branchiosaurid specimens from Nýřany (Czech Republic) were proposed to be larvae of olsoniforms and amphibamids, and together with a revision of ancient branchiosaurid-like taxa from the United States and France prompt a re-analysis of this issue. In a phylogenetic analysis of 48 taxa and 113 characters, the Branchiosauridae were found to be monophyletic and nest in an unresolved trichotomy with Amphibamidae and the putative relatives of Lissamphibia. The present analysis finds the hypothesized olsoniform larvae from Nýřany to be adults of Branchiosaurus salamandroides, whereas some of the larvae from Mazon Creek (Illinois, USA) are not branchiosaurids, but immature specimens of the amphibamid Amphibamus grandiceps. Within branchiosaurids, four clades have been identified: (a) the Carboniferous Anthracobamus clade (Anthracobamus, Montceaubatrachus), (b) the mostly Carboniferous Branchiosaurinae (Branchiosaurus, Milnererpeton) and two largely Permian clades, the newly defined Apateoninae (genus Apateon) and Leptorophinae (Melanerpeton, Leptorophus, Schoenfelderpeton) clade. Branchiosaurid evolution involved a trend towards an enhanced paedomorphosis, a modification of branchial teeth, and successive reduction of bone in the scales and pectoral girdle.","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"20 1","pages":"1 - 30"},"PeriodicalIF":2.6,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46847616","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}
Pub Date : 2022-10-05DOI: 10.1080/14772019.2022.2109217
Nicolas Bekkouche, L. Gąsiorowski
The Cambrian fossil Amiskwia sagittiformis has puzzled palaeontologists for more than a century, but recent re-investigation of its morphology suggested a close relationship with the bilaterian clade Gnathifera, comprising Rotifera, Gnathostomulida and Micrognathozoa. Since Amiskwia has already been considered closely related to Chaetognatha, this new interpretation of its morphology supports recent molecular and developmental studies finding a close phylogenetic relationship between Chaetognatha and Gnathifera. The recent re-description of the jaw apparatus of Amiskwia with the first phylogenetic analysis by Vinther & Parry (2019) found a rather surprising topology with Amiskwia and Chaetognatha being sister groups and nested inside Gnathifera. Furthermore, a subsequent paper from Caron & Cheung (2019) re-described the jaws of Amiskwia as very similar to the configuration found in Gnathostomulida, but did not include any phylogenetic analysis. Here we test the topology of Vinther & Parry with various parsimony and Bayesian analyses, taking into account the new description of Caron & Cheung with careful re-amendment of the matrix of Vinther & Parry. According to our results and the recent findings on the molecular phylogeny of their extant members, we suggest a new systematization of these taxa. We recovered Amiskwia as a stem-group chaetognath within a clade Cucullophora nov., rejecting the Caron & Cheung hypothesis of its close affinity to Gnathostomulida, and found a more consensual topology with monophyletic Gnathifera sister group to Cucullophora, all together forming the clade Chaetognathifera. Furthermore, Rotifera + Micrognathozoa form a clade named Gynognathifera nov. We discuss the characters supporting each clade and the reasons that account for the topology found by Vinther & Parry. Finally, we hope that this carefully amended matrix focused on Gnathifera, Amiskwia and Chaetognatha, together with a formal classification and robust phylogeny, will be of use for future studies on the palaeontology and morphology of these clades.
{"title":"Careful amendment of morphological data sets improves phylogenetic frameworks: re-evaluating placement of the fossil Amiskwia sagittiformis","authors":"Nicolas Bekkouche, L. Gąsiorowski","doi":"10.1080/14772019.2022.2109217","DOIUrl":"https://doi.org/10.1080/14772019.2022.2109217","url":null,"abstract":"The Cambrian fossil Amiskwia sagittiformis has puzzled palaeontologists for more than a century, but recent re-investigation of its morphology suggested a close relationship with the bilaterian clade Gnathifera, comprising Rotifera, Gnathostomulida and Micrognathozoa. Since Amiskwia has already been considered closely related to Chaetognatha, this new interpretation of its morphology supports recent molecular and developmental studies finding a close phylogenetic relationship between Chaetognatha and Gnathifera. The recent re-description of the jaw apparatus of Amiskwia with the first phylogenetic analysis by Vinther & Parry (2019) found a rather surprising topology with Amiskwia and Chaetognatha being sister groups and nested inside Gnathifera. Furthermore, a subsequent paper from Caron & Cheung (2019) re-described the jaws of Amiskwia as very similar to the configuration found in Gnathostomulida, but did not include any phylogenetic analysis. Here we test the topology of Vinther & Parry with various parsimony and Bayesian analyses, taking into account the new description of Caron & Cheung with careful re-amendment of the matrix of Vinther & Parry. According to our results and the recent findings on the molecular phylogeny of their extant members, we suggest a new systematization of these taxa. We recovered Amiskwia as a stem-group chaetognath within a clade Cucullophora nov., rejecting the Caron & Cheung hypothesis of its close affinity to Gnathostomulida, and found a more consensual topology with monophyletic Gnathifera sister group to Cucullophora, all together forming the clade Chaetognathifera. Furthermore, Rotifera + Micrognathozoa form a clade named Gynognathifera nov. We discuss the characters supporting each clade and the reasons that account for the topology found by Vinther & Parry. Finally, we hope that this carefully amended matrix focused on Gnathifera, Amiskwia and Chaetognatha, together with a formal classification and robust phylogeny, will be of use for future studies on the palaeontology and morphology of these clades.","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"20 1","pages":"1 - 14"},"PeriodicalIF":2.6,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47802911","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}
Pub Date : 2022-09-30DOI: 10.1080/14772019.2022.2113832
Alison M. Murray
†Protosyngnathus sumatrensis is known from six specimens from Eocene lacustrine deposits of the Sangkarawang Formation of Sumatra, Indonesia. The fish was named almost 150 years ago, but has never been well described or figured. Probably because of this, it has not been included in phylogenies of extant pipefishes and seahorses (Syngnathiformes). A detailed description is provided, along with a new phylogenetic analysis of morphological characters that allows the Eocene fish to be confidently placed with the extant families Syngnathidae (pipefishes and seahorses) and Solenostomidae (ghost seahorses) along with the Paleocene marine fossil †Eekaulostomus cuevasae from Mexico. The vast majority of these fishes are marine inhabitants, with a few syngnathids entering brackish or freshwater habitats. †Protosyngnathus documents the occurrence of syngnathiform fishes in a lacustrine environment, indicating that this lineage invaded and became adapted to the freshwater environment early in the evolution of this group.
{"title":"Re-description and phylogenetic relationships of †Protosyngnathus sumatrensis (Teleostei: Syngnathoidei), a freshwater pipefish from the Eocene of Sumatra, Indonesia","authors":"Alison M. Murray","doi":"10.1080/14772019.2022.2113832","DOIUrl":"https://doi.org/10.1080/14772019.2022.2113832","url":null,"abstract":"†Protosyngnathus sumatrensis is known from six specimens from Eocene lacustrine deposits of the Sangkarawang Formation of Sumatra, Indonesia. The fish was named almost 150 years ago, but has never been well described or figured. Probably because of this, it has not been included in phylogenies of extant pipefishes and seahorses (Syngnathiformes). A detailed description is provided, along with a new phylogenetic analysis of morphological characters that allows the Eocene fish to be confidently placed with the extant families Syngnathidae (pipefishes and seahorses) and Solenostomidae (ghost seahorses) along with the Paleocene marine fossil †Eekaulostomus cuevasae from Mexico. The vast majority of these fishes are marine inhabitants, with a few syngnathids entering brackish or freshwater habitats. †Protosyngnathus documents the occurrence of syngnathiform fishes in a lacustrine environment, indicating that this lineage invaded and became adapted to the freshwater environment early in the evolution of this group.","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"20 1","pages":"1 - 16"},"PeriodicalIF":2.6,"publicationDate":"2022-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46856239","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}
Pub Date : 2022-09-22DOI: 10.1080/14772019.2022.2111232
J. Calede, Y. T. Tse, K. D. Cairns
The Eurasian fossil record is rich with the remains of sminthid rodents, a clade today represented by a single genus, Sicista. In contrast, the North American record of the family is sparse and exclusively composed of species of Plesiosminthus, an animal bearing a grooved incisor, during the Oligocene. This fossil record is the product of dispersal events from Eurasia. We here present the first occurrence of a smooth-incisor sminthid from North America. The new species, Heosminthus teredens from the Arikareean-aged Cabbage Patch beds of Montana, represents a rare occurrence of cranial material showing the clear association between incisors and cheek teeth, and the first postcranial remains for fossil sminthids. Our phylogenetic analysis, expanding on prior work, shows that Heosminthus teredens is most closely related to Heosminthus borrae, from Mongolia. In combination with published radioisotopic dating, our phylogenetic framework of sminthids provides evidence for an additional dispersal of sminthid rodents from Eurasia to North America 30 million years ago via Beringia. Our morphometric analysis of the tibia and metatarsal supports a terrestrial ecology for the new species; it is possible the animal had limited scansorial and/or saltatorial abilities. The large sample size of teeth available for the new taxon enables an analysis of morphological variation and indicates a high degree of polymorphism as well as a large size variation, even when controlling for stratigraphical and geographical range. https://zoobank.org/urn:lsid:zoobank.org:pub:B7D4245C-992F-4956-96AD-10D7CFA8E5C8
{"title":"The first evidence of Heosminthus from North America and the phylogenetics of Sminthidae (Mammalia, Rodentia, Dipodoidea): biogeographical implications","authors":"J. Calede, Y. T. Tse, K. D. Cairns","doi":"10.1080/14772019.2022.2111232","DOIUrl":"https://doi.org/10.1080/14772019.2022.2111232","url":null,"abstract":"The Eurasian fossil record is rich with the remains of sminthid rodents, a clade today represented by a single genus, Sicista. In contrast, the North American record of the family is sparse and exclusively composed of species of Plesiosminthus, an animal bearing a grooved incisor, during the Oligocene. This fossil record is the product of dispersal events from Eurasia. We here present the first occurrence of a smooth-incisor sminthid from North America. The new species, Heosminthus teredens from the Arikareean-aged Cabbage Patch beds of Montana, represents a rare occurrence of cranial material showing the clear association between incisors and cheek teeth, and the first postcranial remains for fossil sminthids. Our phylogenetic analysis, expanding on prior work, shows that Heosminthus teredens is most closely related to Heosminthus borrae, from Mongolia. In combination with published radioisotopic dating, our phylogenetic framework of sminthids provides evidence for an additional dispersal of sminthid rodents from Eurasia to North America 30 million years ago via Beringia. Our morphometric analysis of the tibia and metatarsal supports a terrestrial ecology for the new species; it is possible the animal had limited scansorial and/or saltatorial abilities. The large sample size of teeth available for the new taxon enables an analysis of morphological variation and indicates a high degree of polymorphism as well as a large size variation, even when controlling for stratigraphical and geographical range. https://zoobank.org/urn:lsid:zoobank.org:pub:B7D4245C-992F-4956-96AD-10D7CFA8E5C8","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"20 1","pages":"1 - 21"},"PeriodicalIF":2.6,"publicationDate":"2022-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41811530","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}
Pub Date : 2022-09-22DOI: 10.1080/14772019.2022.2093661
M. A. Cerroni, M. Baiano, J. Canale, F. Agnolín, A. Otero, F. Novas
Skorpiovenator bustingorryi is a derived abelisaurid theropod represented by a fairly complete skeleton from the Late Cretaceous sedimentary beds of north-western Patagonia. Although some features were described in the original paper, mainly related to the skull, the appendicular anatomy remains undescribed. The aim of the present contribution is to provide a detailed description and analysis of the available appendicular bones, including comparisons with other ceratosaurian theropods close to Skorpiovenator. In this way, new autapomorphies emerged to further distinguish Skorpiovenator from its relatives. Furthermore, a comprehensive phylogenetic analysis was performed and several characteristics of the hind limb, in particular some of the autopodium, resulted in the identification of new apomorphic traits for Ceratosauria and Abelisauridae. These features might prove to be useful for future phylogenetic analyses and may help to resolve the still confusing and debated internal relationships of abelisaurid theropods.
{"title":"Appendicular osteology of Skorpiovenator bustingorryi (Theropoda, Abelisauridae) with comments on phylogenetic features of abelisaurids","authors":"M. A. Cerroni, M. Baiano, J. Canale, F. Agnolín, A. Otero, F. Novas","doi":"10.1080/14772019.2022.2093661","DOIUrl":"https://doi.org/10.1080/14772019.2022.2093661","url":null,"abstract":"Skorpiovenator bustingorryi is a derived abelisaurid theropod represented by a fairly complete skeleton from the Late Cretaceous sedimentary beds of north-western Patagonia. Although some features were described in the original paper, mainly related to the skull, the appendicular anatomy remains undescribed. The aim of the present contribution is to provide a detailed description and analysis of the available appendicular bones, including comparisons with other ceratosaurian theropods close to Skorpiovenator. In this way, new autapomorphies emerged to further distinguish Skorpiovenator from its relatives. Furthermore, a comprehensive phylogenetic analysis was performed and several characteristics of the hind limb, in particular some of the autopodium, resulted in the identification of new apomorphic traits for Ceratosauria and Abelisauridae. These features might prove to be useful for future phylogenetic analyses and may help to resolve the still confusing and debated internal relationships of abelisaurid theropods.","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"20 1","pages":"1 - 32"},"PeriodicalIF":2.6,"publicationDate":"2022-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47879157","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}
Pub Date : 2022-09-15DOI: 10.1080/14772019.2022.2093139
D. Demar, Marc E. H. Jones, M. Carrano
We describe a new, small-bodied rhynchocephalian reptile, Opisthiamimus gregori gen. et sp. nov., from the Upper Jurassic Morrison Formation of Wyoming, USA. Whereas many fossil rhynchocephalians are based on isolated incomplete jaws, the holotype of O. gregori includes most of the skull and postcranium and therefore represents one of the most complete specimens of Rhynchocephalia known from North America. We used micro-computed tomography to examine its skeletal anatomy in detail and to develop a three-dimensional reconstruction of the skull. The skull of O. gregori is similar to that of several non-neosphenodontian rhynchocephalians such as Planocephalosaurus (e.g. large orbits) and Clevosaurus (e.g. parietal parasagittal crests) yet exhibits a suite of other features related to the proal shearing mechanism that becomes increasingly elaborated among more phylogenetically nested taxa such as Sphenodon (e.g. lateral palatine tooth row parallels maxillary tooth row along its entire length, pyramidal dentary teeth with mesial shearing crests). The postcranial skeleton of O. gregori exhibits characteristics typical of a terrestrial rhynchocephalian. Our phylogenetic analyses use a substantially updated data set of 118 characters and 46 taxa, and both maximum parsimony and Bayesian frameworks. Results place O. gregori inside Eusphenodontia but outside Neosphenodontia, and therefore in a key position for contributing to character polarity for more deeply nested clades such as Clevosauridae, Sphenodontidae and Pleurosauridae. We also erect Leptorhynchia taxon nov., composed primarily of aquatically adapted taxa (e.g. Pleurosaurus, Sapheosaurus), which is supported by both cranial and postcranial characters. Because O. gregori is not particularly closely related to the other named Morrison rhynchocephalians (e.g. Opisthias rarus), it increases both the alpha and beta taxonomic diversities within the formation. Similarly, major differences in body size and inferred diet of the Morrison taxa imply considerable concomitant palaeoecological diversity just prior to a major global decline in rhynchocephalian diversity around the close of the Jurassic. http://zoobank.org/urn:lsid:zoobank.org:pub:888E055B-8AC1-4BD0-A37C-8CB192F79673
我们描述了一种来自美国怀俄明州上侏罗统莫里森组的小型喙头类爬行动物，Opisthiamimus gregori gen. et sp. nov.。尽管许多舌头动物化石是基于孤立的不完整的颌骨，但o.g regori的完整型包括了大部分头骨和头盖骨，因此代表了北美已知的最完整的舌头动物标本之一。我们使用微型计算机断层扫描来详细检查其骨骼解剖结构，并开发了头骨的三维重建。O. gregori的头骨与一些非新颅齿目喙头类动物的头骨相似，如平头龙(如大轨道)和Clevosaurus(如顶骨副柱头嵴)，但也显示出一系列与原始剪切机制相关的其他特征，这些特征在更多的系统上嵌套的分类群中得到了越来越多的阐述，如蝶龙(如腭侧齿排沿着整个长度与上颌齿排平行)。金字塔形的无齿齿具中部的剪切冠)。O. gregori的颅后骨骼表现出陆生喙头类动物的典型特征。我们的系统发育分析使用了118个字符和46个分类群的更新数据集，以及最大简约和贝叶斯框架。结果表明，格里戈瑞氏在尤显亚内，但在新显亚外，因此对嵌套更深的Clevosauridae、Sphenodontidae和Pleurosauridae等分支的特征极性有重要影响。我们还建立了Leptorhynchia分类群nov.，该分类群主要由水适应分类群(如胸骨龙、嘴龙)组成，并得到了颅骨和后颅骨特征的支持。由于O. gregori与其他已命名的Morrison rhynchocephalis(如Opisthias rarus)并没有特别密切的关系，因此它增加了该地层内α和β的分类多样性。同样，莫里森类群在体型和推断饮食上的主要差异表明，在侏罗纪末期全球喙头类动物多样性大幅下降之前，它们的古生态多样性相当可观。http://zoobank.org/urn:lsid:zoobank.org:pub:888E055B-8AC1-4BD0-A37C-8CB192F79673
{"title":"A nearly complete skeleton of a new eusphenodontian from the Upper Jurassic Morrison Formation, Wyoming, USA, provides insight into the evolution and diversity of Rhynchocephalia (Reptilia: Lepidosauria)","authors":"D. Demar, Marc E. H. Jones, M. Carrano","doi":"10.1080/14772019.2022.2093139","DOIUrl":"https://doi.org/10.1080/14772019.2022.2093139","url":null,"abstract":"We describe a new, small-bodied rhynchocephalian reptile, Opisthiamimus gregori gen. et sp. nov., from the Upper Jurassic Morrison Formation of Wyoming, USA. Whereas many fossil rhynchocephalians are based on isolated incomplete jaws, the holotype of O. gregori includes most of the skull and postcranium and therefore represents one of the most complete specimens of Rhynchocephalia known from North America. We used micro-computed tomography to examine its skeletal anatomy in detail and to develop a three-dimensional reconstruction of the skull. The skull of O. gregori is similar to that of several non-neosphenodontian rhynchocephalians such as Planocephalosaurus (e.g. large orbits) and Clevosaurus (e.g. parietal parasagittal crests) yet exhibits a suite of other features related to the proal shearing mechanism that becomes increasingly elaborated among more phylogenetically nested taxa such as Sphenodon (e.g. lateral palatine tooth row parallels maxillary tooth row along its entire length, pyramidal dentary teeth with mesial shearing crests). The postcranial skeleton of O. gregori exhibits characteristics typical of a terrestrial rhynchocephalian. Our phylogenetic analyses use a substantially updated data set of 118 characters and 46 taxa, and both maximum parsimony and Bayesian frameworks. Results place O. gregori inside Eusphenodontia but outside Neosphenodontia, and therefore in a key position for contributing to character polarity for more deeply nested clades such as Clevosauridae, Sphenodontidae and Pleurosauridae. We also erect Leptorhynchia taxon nov., composed primarily of aquatically adapted taxa (e.g. Pleurosaurus, Sapheosaurus), which is supported by both cranial and postcranial characters. Because O. gregori is not particularly closely related to the other named Morrison rhynchocephalians (e.g. Opisthias rarus), it increases both the alpha and beta taxonomic diversities within the formation. Similarly, major differences in body size and inferred diet of the Morrison taxa imply considerable concomitant palaeoecological diversity just prior to a major global decline in rhynchocephalian diversity around the close of the Jurassic. http://zoobank.org/urn:lsid:zoobank.org:pub:888E055B-8AC1-4BD0-A37C-8CB192F79673","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"20 1","pages":"1 - 64"},"PeriodicalIF":2.6,"publicationDate":"2022-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41879119","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}
Pub Date : 2022-09-07DOI: 10.1080/14772019.2022.2093662
E. Obraztsova, S. Krasnolutskii, V. Sukhanov, I. Danilov
This paper is devoted to the description of a new species of xinjiangchelyid turtle – Annemys variabilis sp. nov. – represented by thousands of isolated bones and several more complete specimens from the Middle Jurassic (Bathonian) Itat Formation of the Berezovsk coal mine, Krasnoyarsk Territory, western Siberia, Russia. The description is based on a sample of the best-preserved specimens. The new species differs from other Annemys spp. by a combination of cranial and shell characters. The basisphenoids (about 200 specimens) of A. variabilis demonstrate variation in 12 characters, some of which are reported in turtles for the first time. About 20 shell characters of A. variabilis are subject to ontogenetic or interindividual variation. Some of these characters are variable in other Annemys spp. and other xinjiangchelyids. The formula of the cervical vertebrae [(2(3()4()5()6()7()8) or (2(3()4()5()6()7()8(] with two opisthocoelous vertebrae (2 and 3), four or five amphicoelous vertebrae (4–7 or 4–8), and one procoelous vertebra is unique for this species among xinjiangchelyids, which were previously known to have only amphicoelous cervicals. Other characters of the non-shell postcranium correspond to those of other xinjiangchelyids. Of the three phylogenetic analyses performed in this study, Analysis 1 does not support the monophyly of either Xinjiangchelyidae or Annemys, Analysis 2 shows paraphyly of Xinjiangchelyidae and monophyly of the Annemys clade (A. latiens, A. levensis, A. variabilis and A. wusu), and Analysis 3 supports monophyly of the Annemys clade with A. latiens, A. levensis and A. variabilis, only in the majority rule consensus tree. The diversity of the turtle assemblage of the Itat Formation is re-assessed as containing 2–3 taxa (A. variabilis [=Testudines indet. 2], Testudines indet. 1 and 3), which is in agreement with similar diversities seen in some other Middle Jurassic Asian turtle assemblages. The known record of Annemys spp. is restricted to the northern part of Asia. https://zoobank.org/urn:lsid:zoobank.org:pub:E836F02F-21DD-4A36-ACBB-4170A6CD46AD
{"title":"Xinjiangchelyid turtles from the Middle Jurassic of the Berezovsk coal mine (Krasnoyarsk Territory, Russia): systematics, skeletal morphology, variation, relationships and palaeobiogeographic implications","authors":"E. Obraztsova, S. Krasnolutskii, V. Sukhanov, I. Danilov","doi":"10.1080/14772019.2022.2093662","DOIUrl":"https://doi.org/10.1080/14772019.2022.2093662","url":null,"abstract":"This paper is devoted to the description of a new species of xinjiangchelyid turtle – Annemys variabilis sp. nov. – represented by thousands of isolated bones and several more complete specimens from the Middle Jurassic (Bathonian) Itat Formation of the Berezovsk coal mine, Krasnoyarsk Territory, western Siberia, Russia. The description is based on a sample of the best-preserved specimens. The new species differs from other Annemys spp. by a combination of cranial and shell characters. The basisphenoids (about 200 specimens) of A. variabilis demonstrate variation in 12 characters, some of which are reported in turtles for the first time. About 20 shell characters of A. variabilis are subject to ontogenetic or interindividual variation. Some of these characters are variable in other Annemys spp. and other xinjiangchelyids. The formula of the cervical vertebrae [(2(3()4()5()6()7()8) or (2(3()4()5()6()7()8(] with two opisthocoelous vertebrae (2 and 3), four or five amphicoelous vertebrae (4–7 or 4–8), and one procoelous vertebra is unique for this species among xinjiangchelyids, which were previously known to have only amphicoelous cervicals. Other characters of the non-shell postcranium correspond to those of other xinjiangchelyids. Of the three phylogenetic analyses performed in this study, Analysis 1 does not support the monophyly of either Xinjiangchelyidae or Annemys, Analysis 2 shows paraphyly of Xinjiangchelyidae and monophyly of the Annemys clade (A. latiens, A. levensis, A. variabilis and A. wusu), and Analysis 3 supports monophyly of the Annemys clade with A. latiens, A. levensis and A. variabilis, only in the majority rule consensus tree. The diversity of the turtle assemblage of the Itat Formation is re-assessed as containing 2–3 taxa (A. variabilis [=Testudines indet. 2], Testudines indet. 1 and 3), which is in agreement with similar diversities seen in some other Middle Jurassic Asian turtle assemblages. The known record of Annemys spp. is restricted to the northern part of Asia. https://zoobank.org/urn:lsid:zoobank.org:pub:E836F02F-21DD-4A36-ACBB-4170A6CD46AD","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"20 1","pages":"1 - 61"},"PeriodicalIF":2.6,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44108735","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}
Pub Date : 2022-08-30DOI: 10.1080/14772019.2022.2100725
Atzcalli Ehécatl Hernández-Cisneros
The aetiocetids are a well-known extinct taxon of Oligocene toothed mysticetes in the North Pacific. They display a high degree of diversity contrasting with that of other tooth-bearing mysticetes such as mammalodontids, llanocetids and Coronodon spp. The disparate developmental patterns (heterochrony) and origin of the first kelp forests in the North Pacific during the Eocene–Oligocene transition might explain such diversity. Aetiocetidae have been the focus of debate regarding the origin of baleen and filter-feeding in Mysticeti. The current interpretation of aetiocetid feeding strategies is based on the presence of teeth, unfused mandibular symphysis and lateral palatal foramina. However, our understating of their feeding apparatus function is limited, leaving associated structures like the zygomatic arch unnoticed. The present study describes a new fossil of a small-sized mysticete (∼3 m long), Kaaucetus thesaurus gen. et sp. nov., which belongs to Aetiocetidae. The protruded squamosal prominence and distinctive zygomatic process present in this new fossil highlight disparity in feeding morphology amongst aetiocetids. Moreover, the zygomatic arch complex and masticatory muscle system reconstruction are crucial to interpreting the likely capability of mastication (shearing motion) in aetiocetids and other toothed mysticetes. Lastly, the record of several aetiocetid genera in Mexico extends the geographical range of the group into the subtropical region. https://zoobank.org/urn:lsid:zoobank.org:pub:urn:lsid:zoobank.org:pub:26167623-8F9C-4C03-8CA2-911D93519031
{"title":"A new aetiocetid (Cetacea, Mysticeti, Aetiocetidae) from the late Oligocene of Mexico","authors":"Atzcalli Ehécatl Hernández-Cisneros","doi":"10.1080/14772019.2022.2100725","DOIUrl":"https://doi.org/10.1080/14772019.2022.2100725","url":null,"abstract":"The aetiocetids are a well-known extinct taxon of Oligocene toothed mysticetes in the North Pacific. They display a high degree of diversity contrasting with that of other tooth-bearing mysticetes such as mammalodontids, llanocetids and Coronodon spp. The disparate developmental patterns (heterochrony) and origin of the first kelp forests in the North Pacific during the Eocene–Oligocene transition might explain such diversity. Aetiocetidae have been the focus of debate regarding the origin of baleen and filter-feeding in Mysticeti. The current interpretation of aetiocetid feeding strategies is based on the presence of teeth, unfused mandibular symphysis and lateral palatal foramina. However, our understating of their feeding apparatus function is limited, leaving associated structures like the zygomatic arch unnoticed. The present study describes a new fossil of a small-sized mysticete (∼3 m long), Kaaucetus thesaurus gen. et sp. nov., which belongs to Aetiocetidae. The protruded squamosal prominence and distinctive zygomatic process present in this new fossil highlight disparity in feeding morphology amongst aetiocetids. Moreover, the zygomatic arch complex and masticatory muscle system reconstruction are crucial to interpreting the likely capability of mastication (shearing motion) in aetiocetids and other toothed mysticetes. Lastly, the record of several aetiocetid genera in Mexico extends the geographical range of the group into the subtropical region. https://zoobank.org/urn:lsid:zoobank.org:pub:urn:lsid:zoobank.org:pub:26167623-8F9C-4C03-8CA2-911D93519031","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"20 1","pages":"1 - 15"},"PeriodicalIF":2.6,"publicationDate":"2022-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43854985","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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