The phylogenetic studies of clam shrimps (Branchiopoda, Crustacea) demonstrated that the significance of several morphological characters for classification of branchiopod shells should be critically re-evaluated. Such a venture is partic-ularly important for integrating the taxonomy of fossil and extant branchiopods. One of the shell characters widely used in the branchiopod classification is the carapace ornamentation pattern. This character might, however, be significantly influenced by intraspecific variability and in particular the sexual dimorphism. In this study we investigate the pattern of ornamentation in extant branchiopods—including differences resulting from sexual dimorphism—in order to assess its value for branchiopod taxonomy. We examined 184 individuals representing 10 living species belonging to 7 genera, 5 families, and 2 suborders from China, and compared with the results of previous studies. Although some differences in ornamentation were related to reproductive modes, the basic ornamentation patterns or combinations were stable within each extant species. We found out that some taxa indeed display sexually dimorphic ornamentations, but their basic ornamentation patterns or combinations are stable within each species so they do not significantly influence the taxonomic identification. Integration of data on fossil and extant taxa indicates that similar ornamentation patterns can be observed on familial level of fossil spinicaudatan branchiopods and indicates therefore that characteristic ornamentation patterns can help to identify these taxa in the fossil record. In light of the new molecular phylogeny, we re-evaluated the phylogenetic relationship between fossil and extant spinicaudatan taxa. The resulting tree suggests: (i) paraphyly of the traditional Eosestherioidea, (ii) an affinity between Ozestheria and Triglypta , and (iii) an affinity between Cyzicus and Diestheria or Aquilonoglypta .
{"title":"Sexually dimorphic ornamentation in modern spinicaudatans and the taxonomic implications for fossil clam shrimps","authors":"Xiaoyan Sun, Jin-hui Cheng","doi":"10.4202/app.00892.2021","DOIUrl":"https://doi.org/10.4202/app.00892.2021","url":null,"abstract":"The phylogenetic studies of clam shrimps (Branchiopoda, Crustacea) demonstrated that the significance of several morphological characters for classification of branchiopod shells should be critically re-evaluated. Such a venture is partic-ularly important for integrating the taxonomy of fossil and extant branchiopods. One of the shell characters widely used in the branchiopod classification is the carapace ornamentation pattern. This character might, however, be significantly influenced by intraspecific variability and in particular the sexual dimorphism. In this study we investigate the pattern of ornamentation in extant branchiopods—including differences resulting from sexual dimorphism—in order to assess its value for branchiopod taxonomy. We examined 184 individuals representing 10 living species belonging to 7 genera, 5 families, and 2 suborders from China, and compared with the results of previous studies. Although some differences in ornamentation were related to reproductive modes, the basic ornamentation patterns or combinations were stable within each extant species. We found out that some taxa indeed display sexually dimorphic ornamentations, but their basic ornamentation patterns or combinations are stable within each species so they do not significantly influence the taxonomic identification. Integration of data on fossil and extant taxa indicates that similar ornamentation patterns can be observed on familial level of fossil spinicaudatan branchiopods and indicates therefore that characteristic ornamentation patterns can help to identify these taxa in the fossil record. In light of the new molecular phylogeny, we re-evaluated the phylogenetic relationship between fossil and extant spinicaudatan taxa. The resulting tree suggests: (i) paraphyly of the traditional Eosestherioidea, (ii) an affinity between Ozestheria and Triglypta , and (iii) an affinity between Cyzicus and Diestheria or Aquilonoglypta .","PeriodicalId":50887,"journal":{"name":"Acta Palaeontologica Polonica","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70478765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Roberts, Victoria Sjøholt Engelschiøn, J. Hurum
{"title":"First three-dimensional skull of the Middle Triassic ichthyosaur Phalarodon fraasi (Mixosauridae) from Svalbard, Norway.","authors":"A. Roberts, Victoria Sjøholt Engelschiøn, J. Hurum","doi":"10.4202/app.00915.2021","DOIUrl":"https://doi.org/10.4202/app.00915.2021","url":null,"abstract":"","PeriodicalId":50887,"journal":{"name":"Acta Palaeontologica Polonica","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70479210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Brian M Davis, K. Jager, G. Rougier, K. Trujillo, K. Chamberlain
A morganucodontan mammaliaform from Morrison We describe two skull fragments of a new morganucodontan from the Cisco Mammal Quarry (Upper Jurassic Morrison Formation), preserving portions of the palate and snout in excellent 3D detail as well as the complete upper postcanine dentition. Morganucodontans are best known by isolated elements and relatively complete skulls of several species of Morganucodon from the Lower Jurassic of Wales and China; this group is fundamental to our understanding of the early evolution of mammals. Cifellilestes ciscoensis gen. et sp. nov. possesses derived features of the snout paired with plesiomorphic construction of the molars; the distal premolars are complex and there is an unusually low count (two) of strongly imbricated molars. This character combination expands craniodental variation for the group. We sampled mudstone from the Cisco Mammal Quarry for ash-fall zircon analysis and obtained a date of 151.50 ± 0.28 Ma. This dates the locality to the earliest Tithonian and slightly younger than other major dated mammal-bearing localities in the Morrison Formation. Cifellilestes represents one of the youngest members of this group and extends the record of morganucodontans in North America by more than 30 Ma. Morganucodontans are a rare component of Late Jurassic faunas but display surprising dental diversity through variations in a tooth count and cusp morphology of a deeply conserved, generalized mammalian tooth pattern, which was fully established in brasilodontid (non-mammalian) ancestors at least 80 my prior. Morganucodonta, dentition, Jurassic, Morrison Formation.
我们描述了来自Cisco哺乳动物采石场(上侏罗纪莫里森组)的一个新的morganucodontan的两个头骨碎片，以极好的3D细节保存了部分上颚和鼻子以及完整的上犬齿。Morganucodontans最为人所知的是来自威尔士和中国下侏罗纪的几个morganucodondon物种的孤立元素和相对完整的头骨;这个群体是我们理解哺乳动物早期进化的基础。ciscoensis . et sp. 11 .具有衍生的鼻部特征与臼齿的半形结构配对;远端前磨牙是复杂的，有一个非常低的计数(两个)的强烈叠瓦磨牙。这一特征组合扩大了这一群体的颅齿变异。我们从思科哺乳动物采石场采集泥岩样本进行灰落锆石分析，得到了151.50±0.28 Ma的年代。这将该地区的年代确定为最早的泰桑期，比莫里森组中其他主要哺乳动物生长的地区略年轻。Cifellilestes代表了这个群体中最年轻的成员之一，并将北美morganucodontans的记录延长了30多万年。Morganucodontans是晚侏罗世动物群中罕见的组成部分，但通过牙齿数量和齿尖形态的变化显示出令人惊讶的牙齿多样性，这是一种深度保守的、广泛的哺乳动物牙齿模式，这在至少80年前的巴西齿类(非哺乳动物)祖先中完全建立起来的。mororganucodonta，齿列，侏罗纪，Morrison组。
{"title":"A morganucodontan (Mammaliaformes) from the Upper Jurassic Morrison Formation, Utah, USA","authors":"Brian M Davis, K. Jager, G. Rougier, K. Trujillo, K. Chamberlain","doi":"10.4202/app.00955.2021","DOIUrl":"https://doi.org/10.4202/app.00955.2021","url":null,"abstract":"A morganucodontan mammaliaform from Morrison We describe two skull fragments of a new morganucodontan from the Cisco Mammal Quarry (Upper Jurassic Morrison Formation), preserving portions of the palate and snout in excellent 3D detail as well as the complete upper postcanine dentition. Morganucodontans are best known by isolated elements and relatively complete skulls of several species of Morganucodon from the Lower Jurassic of Wales and China; this group is fundamental to our understanding of the early evolution of mammals. Cifellilestes ciscoensis gen. et sp. nov. possesses derived features of the snout paired with plesiomorphic construction of the molars; the distal premolars are complex and there is an unusually low count (two) of strongly imbricated molars. This character combination expands craniodental variation for the group. We sampled mudstone from the Cisco Mammal Quarry for ash-fall zircon analysis and obtained a date of 151.50 ± 0.28 Ma. This dates the locality to the earliest Tithonian and slightly younger than other major dated mammal-bearing localities in the Morrison Formation. Cifellilestes represents one of the youngest members of this group and extends the record of morganucodontans in North America by more than 30 Ma. Morganucodontans are a rare component of Late Jurassic faunas but display surprising dental diversity through variations in a tooth count and cusp morphology of a deeply conserved, generalized mammalian tooth pattern, which was fully established in brasilodontid (non-mammalian) ancestors at least 80 my prior. Morganucodonta, dentition, Jurassic, Morrison Formation.","PeriodicalId":50887,"journal":{"name":"Acta Palaeontologica Polonica","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70480079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cladistic analyses will be inaccurate if based on inaccurate data. Most blastozoan taxa were defined before cladistics was proposed. Redescription of precladistic taxa should be a priority. Cladistics recognizes similarities between taxa, not differences. Differences always exist, so the two approaches are asymmetrical. Any suggested similarity or homology needs testing, including output of computer-based analyses. New interpretations of plate homology between glyptocystitoid and hemicosmitoid rhombiferans had already rendered input data obsolete before the pan-dichoporite paper was published. Universal Elemental Homology (UEH) is not a scientific hypothesis. It makes no testable predictions; no system of naming plates can.
{"title":"Reply to Bauer et al 2022","authors":"Christopher Paul","doi":"10.4202/app.00995.2022","DOIUrl":"https://doi.org/10.4202/app.00995.2022","url":null,"abstract":"Cladistic analyses will be inaccurate if based on inaccurate data. Most blastozoan taxa were defined before cladistics was proposed. Redescription of precladistic taxa should be a priority. Cladistics recognizes similarities between taxa, not differences. Differences always exist, so the two approaches are asymmetrical. Any suggested similarity or homology needs testing, including output of computer-based analyses. New interpretations of plate homology between glyptocystitoid and hemicosmitoid rhombiferans had already rendered input data obsolete before the pan-dichoporite paper was published. Universal Elemental Homology (UEH) is not a scientific hypothesis. It makes no testable predictions; no system of naming plates can.","PeriodicalId":50887,"journal":{"name":"Acta Palaeontologica Polonica","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70480319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. Dimorphism in tetragonitid ammonoid Tetragonites minimus from the Upper Cretaceous in Hokkaido, Northern Japan. Acta
． 日本北海道上白垩统四龙石氨样四龙岩的二态性。学报
{"title":"Dimorphism in tetragonitid ammonoid Tetragonites minimus from the Upper Cretaceous in Hokkaido, Northern Japan","authors":"D. Aiba","doi":"10.4202/app.01000.2022","DOIUrl":"https://doi.org/10.4202/app.01000.2022","url":null,"abstract":". Dimorphism in tetragonitid ammonoid Tetragonites minimus from the Upper Cretaceous in Hokkaido, Northern Japan. Acta","PeriodicalId":50887,"journal":{"name":"Acta Palaeontologica Polonica","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70480375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Middle and Late Jurassic tube-dwelling polychaetes from the Polish Basin: diversity, palaeoecology and comparisons with other assemblages","authors":"J. Słowiński, O. Vinn, M. Jaeger, M. Zatoń","doi":"10.4202/app.01006.2022","DOIUrl":"https://doi.org/10.4202/app.01006.2022","url":null,"abstract":".","PeriodicalId":50887,"journal":{"name":"Acta Palaeontologica Polonica","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70480435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marta Wrześniewska-Pietrzak, Karolina Ruta-Korytowska
The article presents an analysis of the names and logotypes of companies, associations and other organiza-tions operating for the benefit of the d/Deaf in Poland. The analysis concerns the relationship between the name (its meaning) and the way of identifying the community of d/Deaf people. The description covers both the names and graphic elements, and their symbolism, which are present in the logotypes. The findings of cognitive methodology are used to read the correlation between the name, its logotype and the values identi-fied with the d/Deaf. The analysis covers 50 social chrematonims and logotypes of institutions from Poland who promote their activities on the Facebook social network or on Polish websites. The material collected allows one to notice that the most common way of identification with the d/Deaf community is the use of meanings and symbols of Polish Sign Language (PJM), which is one of the most important values creating the image of the Deaf as a linguistic and cultural minority.
{"title":"Nazwy i logotypy stowarzyszeń i innych organizacji działających na rzecz g/Głuchych","authors":"Marta Wrześniewska-Pietrzak, Karolina Ruta-Korytowska","doi":"10.17651/polon.42.4","DOIUrl":"https://doi.org/10.17651/polon.42.4","url":null,"abstract":"The article presents an analysis of the names and logotypes of companies, associations and other organiza-tions operating for the benefit of the d/Deaf in Poland. The analysis concerns the relationship between the name (its meaning) and the way of identifying the community of d/Deaf people. The description covers both the names and graphic elements, and their symbolism, which are present in the logotypes. The findings of cognitive methodology are used to read the correlation between the name, its logotype and the values identi-fied with the d/Deaf. The analysis covers 50 social chrematonims and logotypes of institutions from Poland who promote their activities on the Facebook social network or on Polish websites. The material collected allows one to notice that the most common way of identification with the d/Deaf community is the use of meanings and symbols of Polish Sign Language (PJM), which is one of the most important values creating the image of the Deaf as a linguistic and cultural minority.","PeriodicalId":50887,"journal":{"name":"Acta Palaeontologica Polonica","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83300039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The petrosal and neighboring bones of the early Eocene palaeoryctid mammal Eoryctes melanus are described in tympanic and endocranial views based on CT scan data of the holotype. A second cranium of E. melanus has fragments of an osseous bulla, which have been interpreted as possibly formed by an independent entotympanic. The CT scans of the holotype reveal that the medial bullar wall is formed by an expanded rostral tympanic process of the petrosal, but the element(s) in the bullar floor remain unknown. The CT scans also allow for a comprehensive reconstruction of the cranial arterial and venous system. The arterial pattern differs from that in early eutherians by the absence of the arteria diploëtica magna and the bifurcation of the end branches of the stapedial artery dorsal to the tympanic roof. The venous pattern includes a large frontal diploic vein arising from the dorsal sagittal sinus on the midline and running through the frontal bone in a canal. Comparisons are made with other palaeoryctids, various Paleogene mammals (pantolestids, leptictids, apternodontids, apatemyids, and cimolestids) and the extant lipotyphlan Solenodon paradoxus. For the last taxon, the structure of the piriform fenestra and associated arteries is detailed. Cranial features support the monophyly of palaeoryctids and suggest possible lipotyphlan affinities.
{"title":"Petrosal and cranial vascular system of the early Eocene palaeoryctid Eoryctes melanus from northwestern Wyoming, USA","authors":"Jean M. Wible","doi":"10.4202/app.00916.2021","DOIUrl":"https://doi.org/10.4202/app.00916.2021","url":null,"abstract":"The petrosal and neighboring bones of the early Eocene palaeoryctid mammal Eoryctes melanus are described in tympanic and endocranial views based on CT scan data of the holotype. A second cranium of E. melanus has fragments of an osseous bulla, which have been interpreted as possibly formed by an independent entotympanic. The CT scans of the holotype reveal that the medial bullar wall is formed by an expanded rostral tympanic process of the petrosal, but the element(s) in the bullar floor remain unknown. The CT scans also allow for a comprehensive reconstruction of the cranial arterial and venous system. The arterial pattern differs from that in early eutherians by the absence of the arteria diploëtica magna and the bifurcation of the end branches of the stapedial artery dorsal to the tympanic roof. The venous pattern includes a large frontal diploic vein arising from the dorsal sagittal sinus on the midline and running through the frontal bone in a canal. Comparisons are made with other palaeoryctids, various Paleogene mammals (pantolestids, leptictids, apternodontids, apatemyids, and cimolestids) and the extant lipotyphlan Solenodon paradoxus. For the last taxon, the structure of the piriform fenestra and associated arteries is detailed. Cranial features support the monophyly of palaeoryctids and suggest possible lipotyphlan affinities.","PeriodicalId":50887,"journal":{"name":"Acta Palaeontologica Polonica","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70479248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Frederickson, J. Cohen, M. Engel, Tyler C. Hunt, Greg A. Wilbert, O. Castañeda, N. Czaplewski
The Optima Local Fauna represents an important glimpse into the ecological transition between savannah and grassland during the late Miocene (Hemphillian) of what is now the southcentral Great Plains of North America. Though dominated by horses, herbivores from the Optima are morphologically diverse, bearing adaptations for both browsing and grazing lifestyles. Likewise, the carnivorans show similar ranges of size and presumed dietary behavior. In this study, we used carbonate isotope, mesowear, and tooth breakage and wear analyses to investigate the dietary complexity of mammals from a single site collected by the Oklahoma Museum of Natural History. Seventeen taxa were analyzed, including five perissodactyls ( Teleoceras hicksi, Dinohippus interpolatus, Neohipparion eurystyle, Nannippus ingenuus, and Astrohippus ansae ), four artiodactyls ( Texoceros guymonensis, Pediomeryx hemphillensis, Megatylopus matthewi, and Platygonus sp . ), a single proboscidean ( Mammut sp.), two rodents ( Dipoides indet. and Umbogaulus monodon ), and five carnivorans ( Agriotherium schneideri, Amphimachairodus coloradensis, Borophagus secundus, Eucyon davisi, Pliotaxidea cf. nevadensis ). Both stable isotope analysis and dental mesowear indicate a broad dietary partitioning occurred among the Optima herbivores, where the artiodactyls were identified as mixed feeders and the perissodactyls were recovered as grazers. In the carnivorans, the large felid Amphimachairodus coloradensis was a hypercarnivore with limited tooth breakage and an enriched δ 13 C signature, indicating low carcass utilization and a prey preference for horses. The canids had a more generalized diet, with B. secundus showing a greater proportional consumption of carcasses through a higher tooth breakage rate. The large ursid Agriotherium schneideri is here interpreted as an omnivore based on depleted δ 13 C values. Overall, we found evidence for a diversity of dietary niches in both carnivores and herbivores during the late Hemphillian in Oklahoma, likely driven by the expansion of grasslands in the region.
{"title":"The paleoecology of the Late Miocene mammals \u0000from the Optima Local Fauna of Oklahoma, USA","authors":"J. Frederickson, J. Cohen, M. Engel, Tyler C. Hunt, Greg A. Wilbert, O. Castañeda, N. Czaplewski","doi":"10.4202/app.00941.2021","DOIUrl":"https://doi.org/10.4202/app.00941.2021","url":null,"abstract":"The Optima Local Fauna represents an important glimpse into the ecological transition between savannah and grassland during the late Miocene (Hemphillian) of what is now the southcentral Great Plains of North America. Though dominated by horses, herbivores from the Optima are morphologically diverse, bearing adaptations for both browsing and grazing lifestyles. Likewise, the carnivorans show similar ranges of size and presumed dietary behavior. In this study, we used carbonate isotope, mesowear, and tooth breakage and wear analyses to investigate the dietary complexity of mammals from a single site collected by the Oklahoma Museum of Natural History. Seventeen taxa were analyzed, including five perissodactyls ( Teleoceras hicksi, Dinohippus interpolatus, Neohipparion eurystyle, Nannippus ingenuus, and Astrohippus ansae ), four artiodactyls ( Texoceros guymonensis, Pediomeryx hemphillensis, Megatylopus matthewi, and Platygonus sp . ), a single proboscidean ( Mammut sp.), two rodents ( Dipoides indet. and Umbogaulus monodon ), and five carnivorans ( Agriotherium schneideri, Amphimachairodus coloradensis, Borophagus secundus, Eucyon davisi, Pliotaxidea cf. nevadensis ). Both stable isotope analysis and dental mesowear indicate a broad dietary partitioning occurred among the Optima herbivores, where the artiodactyls were identified as mixed feeders and the perissodactyls were recovered as grazers. In the carnivorans, the large felid Amphimachairodus coloradensis was a hypercarnivore with limited tooth breakage and an enriched δ 13 C signature, indicating low carcass utilization and a prey preference for horses. The canids had a more generalized diet, with B. secundus showing a greater proportional consumption of carcasses through a higher tooth breakage rate. The large ursid Agriotherium schneideri is here interpreted as an omnivore based on depleted δ 13 C values. Overall, we found evidence for a diversity of dietary niches in both carnivores and herbivores during the late Hemphillian in Oklahoma, likely driven by the expansion of grasslands in the region.","PeriodicalId":50887,"journal":{"name":"Acta Palaeontologica Polonica","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70479855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pablo A. Núñez Demarco, G. Piñeiro, Jorge Ferigolo
Isometry in Implications for growth patterns in early Mesosaurs were small amphibious tetrapods that lived in western Gondwana during the early Permian or even earlier, when temperate Carboniferous–Permian conditions initiated after the glaciations that affected the southern region of Pangea. In this contribution, we applied traditional linear regression morphometrics to analyse proportions of both the skull and limb bones in more than 100 mesosaur specimens. The analyses revealed that all mesosaur bones scale remarkably close to a model of geometrical similarity (isometry), and that this pattern is particularly strong in long bones and also in the skull. These results indicate that juvenile and adult mesosaurs do not display appreciable change in bone proportions, meaning that there are few or no noticeable differences between them during growth. The well-defined isometry, and particularly, the high interrelation between metatarsals and phalanges permit us to suggest that the mesosaur hind limb is subject to notable modularity. This evidence strongly argues that the differences previously described to support three mesosaur species in Western Gondwana, might instead reflect natural intraspecific variability, taphonomic features or even possible sexual dimorphism, as recently suggested. Our study also reinforces the general plesiomorphic structure of the mesosaur skeleton, which along with some cranial specializations for ecological fitness and the evidence of strong isometric growth as we demonstrate herein, may suggest new hypotheses of relationships for mesosaurs which thus would position them as more basal amniotes than previously thought.
{"title":"Isometry in mesosaurs: implications for growth patterns in early amniotes","authors":"Pablo A. Núñez Demarco, G. Piñeiro, Jorge Ferigolo","doi":"10.4202/app.00931.2021","DOIUrl":"https://doi.org/10.4202/app.00931.2021","url":null,"abstract":"Isometry in Implications for growth patterns in early Mesosaurs were small amphibious tetrapods that lived in western Gondwana during the early Permian or even earlier, when temperate Carboniferous–Permian conditions initiated after the glaciations that affected the southern region of Pangea. In this contribution, we applied traditional linear regression morphometrics to analyse proportions of both the skull and limb bones in more than 100 mesosaur specimens. The analyses revealed that all mesosaur bones scale remarkably close to a model of geometrical similarity (isometry), and that this pattern is particularly strong in long bones and also in the skull. These results indicate that juvenile and adult mesosaurs do not display appreciable change in bone proportions, meaning that there are few or no noticeable differences between them during growth. The well-defined isometry, and particularly, the high interrelation between metatarsals and phalanges permit us to suggest that the mesosaur hind limb is subject to notable modularity. This evidence strongly argues that the differences previously described to support three mesosaur species in Western Gondwana, might instead reflect natural intraspecific variability, taphonomic features or even possible sexual dimorphism, as recently suggested. Our study also reinforces the general plesiomorphic structure of the mesosaur skeleton, which along with some cranial specializations for ecological fitness and the evidence of strong isometric growth as we demonstrate herein, may suggest new hypotheses of relationships for mesosaurs which thus would position them as more basal amniotes than previously thought.","PeriodicalId":50887,"journal":{"name":"Acta Palaeontologica Polonica","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70479993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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