Manja Hethke, K. Hartmann, Matthias Alberti, Theresa Kutzner, M. Schwentner
Fossil spinicaudatan taxonomy heavily relies on carapace features (size, shape, ornamentation) and palaeontologists have greatly refined methods to study and describe carapace variability. Whether carapace features alone are sufficient for distinguishing between species of a single genus has remained untested. In our study, we tested common palaeontological methods on 481 individuals of the extant Australian genus Ozestheria that have been previously assigned to ten species based on genetic analysis. All species are morphologically distinct based on geometric morphometrics (p ≤ 0.001), but they occupy overlapping regions in Ozestheria morphospace. Linear discriminant analysis of Fourier shape coefficients reaches a mean model performance of 93.8% correctly classified individuals over all possible 45 pairwise species comparisons. This can be further increased by combining the size and shape datasets. Nine of the ten examined species are clearly sexually dimorphic but male and female morphologies strongly overlap within species with little influence on model performance. Ornamentation is commonly species‐diagnostic; seven ornamentation types are distinguished of which six are species‐specific while one is shared by four species. A transformation of main ornamental features (e.g. from punctate to smooth) can occur among closely related species suggesting short evolutionary timescales. Our overall results support the taxonomic value of carapace features, which should also receive greater attention in the taxonomy of extant species. The extensive variation in carapace shape and ornamentation is noteworthy and several species would probably have been assigned to different genera or families if these had been fossils, bearing implications for the systematics of fossil Spinicaudata.
{"title":"Testing the success of palaeontological methods in the delimitation of clam shrimp (Crustacea, Branchiopoda) on extant species","authors":"Manja Hethke, K. Hartmann, Matthias Alberti, Theresa Kutzner, M. Schwentner","doi":"10.1111/pala.12634","DOIUrl":"https://doi.org/10.1111/pala.12634","url":null,"abstract":"Fossil spinicaudatan taxonomy heavily relies on carapace features (size, shape, ornamentation) and palaeontologists have greatly refined methods to study and describe carapace variability. Whether carapace features alone are sufficient for distinguishing between species of a single genus has remained untested. In our study, we tested common palaeontological methods on 481 individuals of the extant Australian genus Ozestheria that have been previously assigned to ten species based on genetic analysis. All species are morphologically distinct based on geometric morphometrics (p ≤ 0.001), but they occupy overlapping regions in Ozestheria morphospace. Linear discriminant analysis of Fourier shape coefficients reaches a mean model performance of 93.8% correctly classified individuals over all possible 45 pairwise species comparisons. This can be further increased by combining the size and shape datasets. Nine of the ten examined species are clearly sexually dimorphic but male and female morphologies strongly overlap within species with little influence on model performance. Ornamentation is commonly species‐diagnostic; seven ornamentation types are distinguished of which six are species‐specific while one is shared by four species. A transformation of main ornamental features (e.g. from punctate to smooth) can occur among closely related species suggesting short evolutionary timescales. Our overall results support the taxonomic value of carapace features, which should also receive greater attention in the taxonomy of extant species. The extensive variation in carapace shape and ornamentation is noteworthy and several species would probably have been assigned to different genera or families if these had been fossils, bearing implications for the systematics of fossil Spinicaudata.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"66 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63562178","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}
Yang Zhao, L. Parry, J. Vinther, F. Dunn, Yu-jing Li, Fan Wei, X. Hou, Pei-yun Cong
Cnidarians form a disparate phylum of animals and their diploblastic body plan represents a key step in animal evolution. Cnidarians are split into two main classes; anthozoans (sea anemones, corals) are benthic polyps, while medusozoans (hydroids, jellyfishes) generally have alternating life cycle stages of polyps and medusae. A sessile polyp is present in both groups and is widely regarded as the ancestral form of their last common ancestor. However, the nature and anatomy of the ancestral polyp, particularly of medusozoans, is controversial, owing to the divergent body plans of the extant lineages and the scarcity of medusozoan soft tissues in the fossil record. Here, we redescribe Conicula striata Luo & Hu from the early Cambrian Chengjiang biota, south China, which has previously been interpreted as a polyp, lophophorate or deuterostome. Through re‐examination of the holotype and 51 exceptionally preserved specimens, we show that C. striata possessed features of both anthozoans and medusozoan polyps. A conical, annulated organic skeleton (periderm) fully encasing a polyp is found in fossil and living medusozoans, while a tubular pharynx extending from the mouth into a gut partitioned by c. 28 mesenteries, resembling the actinopharynx of anthozoans. Our phylogenetic analyses recover C. striata as a stem‐group medusozoan, implying that the wealth of medusozoan diversity derived, ultimately, from an anemone‐like ancestor.
刺胞动物形成了一个完全不同的动物门，它们的双胞体计划代表了动物进化的关键一步。刺胞动物分为两大类;珊瑚虫(海葵、珊瑚)是底栖珊瑚虫，而水母动物(水螅、水母)通常是珊瑚虫和水母交替的生命周期阶段。在这两个群体中都有一种无根息肉，并被广泛认为是它们最后共同祖先的祖先形式。然而，由于现存谱系的身体结构不同，并且化石记录中缺乏水母动物的软组织，因此，关于祖先水螅的性质和解剖结构，特别是水母动物的水螅，是有争议的。本文对中国南方早寒武世成江生物群中的Conicula striata Luo & Hu进行了重新描述，该生物以前被解释为水螅、磷藻或后口动物。通过对完整型和51个特殊保存标本的重新检查，我们发现纹状体同时具有珊瑚虫和水母的特征。在化石和活体水母动物中发现了一个圆锥形的、环状的有机骨架(表皮)，完全包裹着息肉，而管状咽从口腔延伸到由约28个肠系膜隔开的肠道，类似于珊瑚虫的放射线咽。我们的系统发育分析恢复了纹海葵作为茎群水母动物的特征，这意味着丰富的水母动物多样性最终来源于类似海葵的祖先。
{"title":"An early Cambrian polyp reveals a potential anemone‐like ancestor for medusozoan cnidarians","authors":"Yang Zhao, L. Parry, J. Vinther, F. Dunn, Yu-jing Li, Fan Wei, X. Hou, Pei-yun Cong","doi":"10.1111/pala.12637","DOIUrl":"https://doi.org/10.1111/pala.12637","url":null,"abstract":"Cnidarians form a disparate phylum of animals and their diploblastic body plan represents a key step in animal evolution. Cnidarians are split into two main classes; anthozoans (sea anemones, corals) are benthic polyps, while medusozoans (hydroids, jellyfishes) generally have alternating life cycle stages of polyps and medusae. A sessile polyp is present in both groups and is widely regarded as the ancestral form of their last common ancestor. However, the nature and anatomy of the ancestral polyp, particularly of medusozoans, is controversial, owing to the divergent body plans of the extant lineages and the scarcity of medusozoan soft tissues in the fossil record. Here, we redescribe Conicula striata Luo & Hu from the early Cambrian Chengjiang biota, south China, which has previously been interpreted as a polyp, lophophorate or deuterostome. Through re‐examination of the holotype and 51 exceptionally preserved specimens, we show that C. striata possessed features of both anthozoans and medusozoan polyps. A conical, annulated organic skeleton (periderm) fully encasing a polyp is found in fossil and living medusozoans, while a tubular pharynx extending from the mouth into a gut partitioned by c. 28 mesenteries, resembling the actinopharynx of anthozoans. Our phylogenetic analyses recover C. striata as a stem‐group medusozoan, implying that the wealth of medusozoan diversity derived, ultimately, from an anemone‐like ancestor.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47172937","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}
Although the clade Crocodylomorpha is represented by few extant species (Crocodylia), it has a rich fossil record. Hundreds of species, adapted to terrestrial, semi‐aquatic and marine environments, have existed over more than 200 million years. Numerous studies have attempted to characterize the factors driving the diversification and extinction events of Crocodylomorpha, resulting in ambiguous and even contradictory conclusions, which points to the need for phylogenetically and temporally smaller‐scaled studies. Here, we focus on differential survival at the Cretaceous–Palaeogene (K–Pg) crisis of Notosuchia, a diverse clade of mostly terrestrial Crocodylomorpha that achieved great diversity during the Cretaceous. More precisely, we tested the effect of body size and palaeotemperatures on notosuchian survival probability during the K–Pg crisis as well as the effect of diet on the evolution of their body size. We find that Notosuchia showed an evolutionary trend towards larger body sizes through time, associated with a shift from an omnivorous to a carnivorous diet. This may explain why sebecids were the only notosuchians to survive the K–Pg crisis. We also corroborate the conclusions of previous studies that detected a Lagerstätten effect occurring in the Adamantina Formation (Upper Cretaceous, Brazil, Bauru Group). This work confirms the value of more finely‐scaled macroevolutionary studies for understanding the history of a rich and complex group such as Crocodylomorpha.
{"title":"Phylogenetic structure of the extinction and biotic factors explaining differential survival of terrestrial notosuchians at the Cretaceous–Palaeogene crisis","authors":"P. Aubier, S. Jouve, J. Schnyder, J. Cubo","doi":"10.1111/pala.12638","DOIUrl":"https://doi.org/10.1111/pala.12638","url":null,"abstract":"Although the clade Crocodylomorpha is represented by few extant species (Crocodylia), it has a rich fossil record. Hundreds of species, adapted to terrestrial, semi‐aquatic and marine environments, have existed over more than 200 million years. Numerous studies have attempted to characterize the factors driving the diversification and extinction events of Crocodylomorpha, resulting in ambiguous and even contradictory conclusions, which points to the need for phylogenetically and temporally smaller‐scaled studies. Here, we focus on differential survival at the Cretaceous–Palaeogene (K–Pg) crisis of Notosuchia, a diverse clade of mostly terrestrial Crocodylomorpha that achieved great diversity during the Cretaceous. More precisely, we tested the effect of body size and palaeotemperatures on notosuchian survival probability during the K–Pg crisis as well as the effect of diet on the evolution of their body size. We find that Notosuchia showed an evolutionary trend towards larger body sizes through time, associated with a shift from an omnivorous to a carnivorous diet. This may explain why sebecids were the only notosuchians to survive the K–Pg crisis. We also corroborate the conclusions of previous studies that detected a Lagerstätten effect occurring in the Adamantina Formation (Upper Cretaceous, Brazil, Bauru Group). This work confirms the value of more finely‐scaled macroevolutionary studies for understanding the history of a rich and complex group such as Crocodylomorpha.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49003508","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}
Mário G. F. Esperança Júnior, G. B. Cybis, R. Iannuzzi
Glossopteris‐type leaves are the most abundant floristic element from the Gondwanan continent and are recorded throughout the Permian, which was a period of extreme icehouse‐to‐hothouse climatic global change. Fossil leaf traits can be useful for the reconstruction of palaeoenvironments and identification of climatic changes throughout geological time, but the conservative morphology of Glossopteris leaves has thus far made them difficult to use for this purpose. If the characters of Glossopteris can be better quantified then it should make them useful for tracking environmental changes over a wide geographical area and over a long time interval. Venation density is a highly variable leaf trait that might be useful for this purpose. This trait can be calculated, usually as vein length per centimetre squared, but this can be a time‐consuming procedure. In this paper we propose a new rapid method to estimate venation density in a conical sector of Glossopteris leaf lamina using an accurate linear model whose predictors are three linear venation densities, measured as veins per centimetre. In addition to substantially reducing the data collection time, it is less biased and more reproducible than methods applied previously with this leaf type. Using this more robust method, preliminary results significantly distinguish the venation densities of leaves produced in wet and drier ecosystems, matching a pattern similar to modern plants. This is the first survey using a large sample size to reveal that environmental stress controlled the vein architecture of Palaeozoic plants, in a manner similar to plants in modern ecosystems.
{"title":"An efficient method for estimating vein density of Glossopteris and its application","authors":"Mário G. F. Esperança Júnior, G. B. Cybis, R. Iannuzzi","doi":"10.1111/pala.12640","DOIUrl":"https://doi.org/10.1111/pala.12640","url":null,"abstract":"Glossopteris‐type leaves are the most abundant floristic element from the Gondwanan continent and are recorded throughout the Permian, which was a period of extreme icehouse‐to‐hothouse climatic global change. Fossil leaf traits can be useful for the reconstruction of palaeoenvironments and identification of climatic changes throughout geological time, but the conservative morphology of Glossopteris leaves has thus far made them difficult to use for this purpose. If the characters of Glossopteris can be better quantified then it should make them useful for tracking environmental changes over a wide geographical area and over a long time interval. Venation density is a highly variable leaf trait that might be useful for this purpose. This trait can be calculated, usually as vein length per centimetre squared, but this can be a time‐consuming procedure. In this paper we propose a new rapid method to estimate venation density in a conical sector of Glossopteris leaf lamina using an accurate linear model whose predictors are three linear venation densities, measured as veins per centimetre. In addition to substantially reducing the data collection time, it is less biased and more reproducible than methods applied previously with this leaf type. Using this more robust method, preliminary results significantly distinguish the venation densities of leaves produced in wet and drier ecosystems, matching a pattern similar to modern plants. This is the first survey using a large sample size to reveal that environmental stress controlled the vein architecture of Palaeozoic plants, in a manner similar to plants in modern ecosystems.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43901902","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}
Cnidarians are phylogenetically located near the base of the ‘tree of animals’, and their early evolution had a profound impact on the rise of bilaterians. However, the early diversity and phylogeny of this ‘lowly’ metazoan clade has hitherto been enigmatic. Fortunately, cnidarian fossils from the early Cambrian could provide key insights into their evolutionary history. Here, based on a scrutiny of the purported hyolith Burithes yunnanensis Hou et al. from the early Cambrian Chengjiang biota in South China, we reveal that this species shows characters distinct from those typical of hyoliths, not least a funnel‐shaped gastrovascular system with a single opening, a whorl of tentacles surrounding the mouth, and the lack of an operculum. These characters suggest a great deviation from the original definition of the genus Burithes, and a closer affinity with cnidarians. We therefore reassign the material to a new genus: Palaeoconotuba. Bayesian inference of phylogeny based on new anatomical traits identifies a new clade, including Palaeoconotuba and Cambrorhytium, as a stem group of sessile medusozoan cnidarians that are united by the synapomorphies of developing an organic conical theca and a funnel‐like gastrovascular system. This study unveils a stem lineage of medusozoans that evolved a lifelong conical theca in the early Cambrian.
{"title":"Thecate stem medusozoans (Cnidaria) from the early Cambrian Chengjiang biota","authors":"Hanzhi Qu, Kexin Li, Q. Ou","doi":"10.1111/pala.12636","DOIUrl":"https://doi.org/10.1111/pala.12636","url":null,"abstract":"Cnidarians are phylogenetically located near the base of the ‘tree of animals’, and their early evolution had a profound impact on the rise of bilaterians. However, the early diversity and phylogeny of this ‘lowly’ metazoan clade has hitherto been enigmatic. Fortunately, cnidarian fossils from the early Cambrian could provide key insights into their evolutionary history. Here, based on a scrutiny of the purported hyolith Burithes yunnanensis Hou et al. from the early Cambrian Chengjiang biota in South China, we reveal that this species shows characters distinct from those typical of hyoliths, not least a funnel‐shaped gastrovascular system with a single opening, a whorl of tentacles surrounding the mouth, and the lack of an operculum. These characters suggest a great deviation from the original definition of the genus Burithes, and a closer affinity with cnidarians. We therefore reassign the material to a new genus: Palaeoconotuba. Bayesian inference of phylogeny based on new anatomical traits identifies a new clade, including Palaeoconotuba and Cambrorhytium, as a stem group of sessile medusozoan cnidarians that are united by the synapomorphies of developing an organic conical theca and a funnel‐like gastrovascular system. This study unveils a stem lineage of medusozoans that evolved a lifelong conical theca in the early Cambrian.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45922132","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}
D. Winkler, T. Kubo, Mugino O. Kubo, T. Kaiser, T. Tütken
Theropods were the dominating apex predators in most Jurassic and Cretaceous terrestrial ecosystems. Their feeding ecology has always been of great interest, and new computational methods have yielded more detailed reconstructions of differences in theropod feeding behaviour. Many approaches, however, rely on well‐preserved skulls. Dental microwear texture (DMT) analysis is potentially applicable to isolated teeth, and here employed for the first time to investigate dietary ecology of theropods. In particular, we test whether tyrannosaurids show DMT associated with more hard‐object feeding than compared to Allosaurus; this would be a sign for higher levels of osteophagy, as has often been suggested. We find no significant difference in complexity and roughness of enamel surfaces between Allosaurus and tyrannosaurids, which conflicts with inferences of more frequent osteophagic behaviour in Tyrannosaurus as compared to other theropods. Orientation of wear features reveals a more pronounced bi‐directional puncture‐and‐pull feeding mode in Allosaurus than in tyrannosaurids. Our results further indicate ontogenetic niche shift in theropods and crocodylians, based on significantly larger height parameters in juvenile theropods which might indicate frequent scavenging, resulting in more bone–tooth contact during feeding. Overall, DMT is found to be very similar between theropods and extant large, broad‐snouted crocodylians and shows great similarity in feeding ecology of theropod apex predators throughout the Jurassic and Cretaceous.
{"title":"First application of dental microwear texture analysis to infer theropod feeding ecology","authors":"D. Winkler, T. Kubo, Mugino O. Kubo, T. Kaiser, T. Tütken","doi":"10.1111/pala.12632","DOIUrl":"https://doi.org/10.1111/pala.12632","url":null,"abstract":"Theropods were the dominating apex predators in most Jurassic and Cretaceous terrestrial ecosystems. Their feeding ecology has always been of great interest, and new computational methods have yielded more detailed reconstructions of differences in theropod feeding behaviour. Many approaches, however, rely on well‐preserved skulls. Dental microwear texture (DMT) analysis is potentially applicable to isolated teeth, and here employed for the first time to investigate dietary ecology of theropods. In particular, we test whether tyrannosaurids show DMT associated with more hard‐object feeding than compared to Allosaurus; this would be a sign for higher levels of osteophagy, as has often been suggested. We find no significant difference in complexity and roughness of enamel surfaces between Allosaurus and tyrannosaurids, which conflicts with inferences of more frequent osteophagic behaviour in Tyrannosaurus as compared to other theropods. Orientation of wear features reveals a more pronounced bi‐directional puncture‐and‐pull feeding mode in Allosaurus than in tyrannosaurids. Our results further indicate ontogenetic niche shift in theropods and crocodylians, based on significantly larger height parameters in juvenile theropods which might indicate frequent scavenging, resulting in more bone–tooth contact during feeding. Overall, DMT is found to be very similar between theropods and extant large, broad‐snouted crocodylians and shows great similarity in feeding ecology of theropod apex predators throughout the Jurassic and Cretaceous.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44192589","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}
Aodhán Ó Gogáin, G. O’Sullivan, Thomas Clements, Brendan C. Hoare, J. Murray, P. N. Wyse Jackson
The Jarrow assemblage is a Lagerstätte of Pennsylvanian tetrapods and fish preserved in the Leinster Coalfield, Ireland. Fossils from this site have an interesting taphonomy that is not observed in other Pennsylvanian coal swamp assemblages. Jarrow tetrapod bone material has undergone alteration and eventual coalification, causing specimens to become poorly defined from the surrounding coal matrix. Bone alteration at Jarrow has traditionally been linked to early diagenesis. A multi‐analytical approach, combining x‐ray scanning electron microscopy, cathodoluminescence, micro computed tomography and laser ablation quadrupole inductively coupled plasma mass spectrometry, was used to investigate the origin of alteration within the Jarrow fossil specimens. Original bone morphology is no longer present, being replaced by bituminous material and sphalerite surrounded by tabular apatite (a morphology atypical of bone apatite). Direct U–Pb dating of this recrystallized apatite provides an age of 302.03 ± 11.38 Ma. In this recrystallized apatite, core‐to‐rim variation in halogen elements, variably positive and negative Eu‐anomalies and depletion in light rare earth elements (REEs) suggest an influence of hydrothermal fluids sourced during the maturation of the Leinster Coalfield. A new taphonomic model for the Jarrow assemblage is proposed: alteration of primary fossil bone occurred primarily due to burial heating of the Leinster Coalfield caused by Variscan deformation. Bone apatite was dissolved and subsequently recrystalized as tabular crystals, probably concurrent with mineralization of sphalerite and during coalification, giving the Jarrow assemblage fossils their unique appearance.
{"title":"Metamorphism as the cause of bone alteration in the Jarrow assemblage (Langsettian, Pennsylvanian) of Ireland","authors":"Aodhán Ó Gogáin, G. O’Sullivan, Thomas Clements, Brendan C. Hoare, J. Murray, P. N. Wyse Jackson","doi":"10.1111/pala.12628","DOIUrl":"https://doi.org/10.1111/pala.12628","url":null,"abstract":"The Jarrow assemblage is a Lagerstätte of Pennsylvanian tetrapods and fish preserved in the Leinster Coalfield, Ireland. Fossils from this site have an interesting taphonomy that is not observed in other Pennsylvanian coal swamp assemblages. Jarrow tetrapod bone material has undergone alteration and eventual coalification, causing specimens to become poorly defined from the surrounding coal matrix. Bone alteration at Jarrow has traditionally been linked to early diagenesis. A multi‐analytical approach, combining x‐ray scanning electron microscopy, cathodoluminescence, micro computed tomography and laser ablation quadrupole inductively coupled plasma mass spectrometry, was used to investigate the origin of alteration within the Jarrow fossil specimens. Original bone morphology is no longer present, being replaced by bituminous material and sphalerite surrounded by tabular apatite (a morphology atypical of bone apatite). Direct U–Pb dating of this recrystallized apatite provides an age of 302.03 ± 11.38 Ma. In this recrystallized apatite, core‐to‐rim variation in halogen elements, variably positive and negative Eu‐anomalies and depletion in light rare earth elements (REEs) suggest an influence of hydrothermal fluids sourced during the maturation of the Leinster Coalfield. A new taphonomic model for the Jarrow assemblage is proposed: alteration of primary fossil bone occurred primarily due to burial heating of the Leinster Coalfield caused by Variscan deformation. Bone apatite was dissolved and subsequently recrystalized as tabular crystals, probably concurrent with mineralization of sphalerite and during coalification, giving the Jarrow assemblage fossils their unique appearance.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46885570","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}
We introduce probability plotting for general use in the analysis of biological and palaeontological morphometric data. When applied to morphometric data, this analytical tool can yield palaeoecological, ontogenetic and demographic information. We have adapted and expanded a statistical tool used in reliability engineering, mechanical or electrical lifetime analysis, geochemistry and ore mineral analysis to analyse fossil populations. The technique is explained stepwise in a ‘user's manual’ format. Its power is to characterize statistical distribution types, to determine whether these distributions are skewed or truncated, and to resolve and quantify the components of mixed distributions, which in palaeontological data potentially represent morphological groupings such as cohorts or sexual dimorphs. The ease of application and simplicity are surprising. A probability plot of growth series data (e.g. skull lengths, femoral lengths, snout‐to‐vent lengths or other morphometrics) typically shows complex non‐normal distribution of the data because of multimodal composition. We show that these component modes, which are generally, but not always normal (i.e. Gaussian), can be resolved, and that they correspond to yearly age groups (cohorts), sexual dimorphs, pre‐ and post‐metamorphic forms, other ontogenetic stages or possibly mixed taxa. When these component size distributions are associated with an age group or sex, several important palaeoecological calculations become possible. These include growth curves, age and sex distributions, sexual dimorphism indices, etc. We demonstrate the biological and palaeontological utility of probability plots with several examples including a Permian wingless insect, an extant unionid bivalve, a Triassic metoposaurid amphibian, an extant lizard, and a Triassic theropod dinosaur.
{"title":"The utility of probability plotting in palaeobiology","authors":"L. Rinehart, A. Heckert, S. Lucas","doi":"10.1111/pala.12633","DOIUrl":"https://doi.org/10.1111/pala.12633","url":null,"abstract":"We introduce probability plotting for general use in the analysis of biological and palaeontological morphometric data. When applied to morphometric data, this analytical tool can yield palaeoecological, ontogenetic and demographic information. We have adapted and expanded a statistical tool used in reliability engineering, mechanical or electrical lifetime analysis, geochemistry and ore mineral analysis to analyse fossil populations. The technique is explained stepwise in a ‘user's manual’ format. Its power is to characterize statistical distribution types, to determine whether these distributions are skewed or truncated, and to resolve and quantify the components of mixed distributions, which in palaeontological data potentially represent morphological groupings such as cohorts or sexual dimorphs. The ease of application and simplicity are surprising. A probability plot of growth series data (e.g. skull lengths, femoral lengths, snout‐to‐vent lengths or other morphometrics) typically shows complex non‐normal distribution of the data because of multimodal composition. We show that these component modes, which are generally, but not always normal (i.e. Gaussian), can be resolved, and that they correspond to yearly age groups (cohorts), sexual dimorphs, pre‐ and post‐metamorphic forms, other ontogenetic stages or possibly mixed taxa. When these component size distributions are associated with an age group or sex, several important palaeoecological calculations become possible. These include growth curves, age and sex distributions, sexual dimorphism indices, etc. We demonstrate the biological and palaeontological utility of probability plots with several examples including a Permian wingless insect, an extant unionid bivalve, a Triassic metoposaurid amphibian, an extant lizard, and a Triassic theropod dinosaur.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43728033","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}
Temnospondyli are a morphologically varied and ecologically diverse clade of tetrapods that survived for over 200 million years. The body mass of temnospondyls is a key variable in inferring their ecological, physiological and biomechanical attributes. However, estimating the body mass of these extinct creatures has proven difficult because the group has no extant descendants. Here we apply a wide range of body mass estimation techniques developed for tetrapods to the iconic temnospondyls Paracyclotosaurus davidi and Eryops megacephalus. These same methods are also applied to a collection of extant organisms that serve as ecological and morphological analogues. These include the giant salamanders Andrias japonicus and Andrias davidianus, the tiger salamander Ambystoma tigrinum, the California newt Taricha torosa and the saltwater crocodile, Crocodylus porosus. We find that several methods can provide accurate mass estimations across this range of living taxa, suggesting their suitability for estimating the body masses of temnospondyls. Based on this, we estimate the mass of Paracyclotosaurus to have been between 159 and 365 kg, and that of Eryops between 102 and 222 kg. These findings provide a basis for examining body size evolution in this clade across their entire temporal span.
{"title":"On the estimation of body mass in temnospondyls: a case study using the large‐bodied Eryops and Paracyclotosaurus","authors":"Lachlan J. Hart, N. Campione, M. McCurry","doi":"10.1111/pala.12629","DOIUrl":"https://doi.org/10.1111/pala.12629","url":null,"abstract":"Temnospondyli are a morphologically varied and ecologically diverse clade of tetrapods that survived for over 200 million years. The body mass of temnospondyls is a key variable in inferring their ecological, physiological and biomechanical attributes. However, estimating the body mass of these extinct creatures has proven difficult because the group has no extant descendants. Here we apply a wide range of body mass estimation techniques developed for tetrapods to the iconic temnospondyls Paracyclotosaurus davidi and Eryops megacephalus. These same methods are also applied to a collection of extant organisms that serve as ecological and morphological analogues. These include the giant salamanders Andrias japonicus and Andrias davidianus, the tiger salamander Ambystoma tigrinum, the California newt Taricha torosa and the saltwater crocodile, Crocodylus porosus. We find that several methods can provide accurate mass estimations across this range of living taxa, suggesting their suitability for estimating the body masses of temnospondyls. Based on this, we estimate the mass of Paracyclotosaurus to have been between 159 and 365 kg, and that of Eryops between 102 and 222 kg. These findings provide a basis for examining body size evolution in this clade across their entire temporal span.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44779689","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}
A. Tomašovỳch, Diego A. García-Ramos, Rafał Nawrot, J. Nebelsick, M. Zuschin
Carbonate skeletal remains are altered and disintegrate at yearly to decadal scales in present‐day shallow‐marine environments with intense bioerosion and dissolution. Present‐day brachiopod death assemblages are invariably characterized by poor preservation on continental shelves, and abundant articulated shells of brachiopods with complete brachidia are thus not expected to be preserved if not rapidly buried. However, such preservation is paradoxically observed in shallow‐water Palaeozoic and Mesozoic brachiopod assemblages. Here, we show that a bathyal death assemblage time‐averaged to several millennia (Adriatic Sea) consists of sediment‐filled articulated shells of Gryphus vitreus with complete brachidia. Post‐mortem age distributions indicate that disintegration half‐lives exceed several centuries (c. 500–1700 years). The high frequency of articulated but centuries‐old shells (>50%) and the fitting of taphonomic models to post‐mortem ages indicate that disarticulation half‐life is unusually long (c. 200 years). Rapid sediment filling of shells: (1) inhibited disarticulation, loop fragmentation and colonization by coelobites; and (2) induced precipitation of ferromanganese oxides at redox fronts within shells. Sediment‐filled articulated shells, however, still resided at the sediment–water interface as indicated by encrusters and sponges that infested them after death. Sediment‐filled shells disintegrated through bioerosion and physical wear when residence in the taphonomically active zone exceeded c. 2000 years. We suggest that the articulation paradox is driven by the Mesozoic Marine Revolution (MMR) that escalated predation, bioturbation and organic matter recycling, all intensifying shell disintegration. A scenario with slow disarticulation in bathyal environments may have lead to preservation of articulated shells in shallow‐water assemblages prior to the MMR.
{"title":"How long does a brachiopod shell last on a seafloor? Modern mid‐bathyal environments as taphonomic analogues of continental shelves prior to the Mesozoic Marine Revolution","authors":"A. Tomašovỳch, Diego A. García-Ramos, Rafał Nawrot, J. Nebelsick, M. Zuschin","doi":"10.1111/pala.12631","DOIUrl":"https://doi.org/10.1111/pala.12631","url":null,"abstract":"Carbonate skeletal remains are altered and disintegrate at yearly to decadal scales in present‐day shallow‐marine environments with intense bioerosion and dissolution. Present‐day brachiopod death assemblages are invariably characterized by poor preservation on continental shelves, and abundant articulated shells of brachiopods with complete brachidia are thus not expected to be preserved if not rapidly buried. However, such preservation is paradoxically observed in shallow‐water Palaeozoic and Mesozoic brachiopod assemblages. Here, we show that a bathyal death assemblage time‐averaged to several millennia (Adriatic Sea) consists of sediment‐filled articulated shells of Gryphus vitreus with complete brachidia. Post‐mortem age distributions indicate that disintegration half‐lives exceed several centuries (c. 500–1700 years). The high frequency of articulated but centuries‐old shells (>50%) and the fitting of taphonomic models to post‐mortem ages indicate that disarticulation half‐life is unusually long (c. 200 years). Rapid sediment filling of shells: (1) inhibited disarticulation, loop fragmentation and colonization by coelobites; and (2) induced precipitation of ferromanganese oxides at redox fronts within shells. Sediment‐filled articulated shells, however, still resided at the sediment–water interface as indicated by encrusters and sponges that infested them after death. Sediment‐filled shells disintegrated through bioerosion and physical wear when residence in the taphonomically active zone exceeded c. 2000 years. We suggest that the articulation paradox is driven by the Mesozoic Marine Revolution (MMR) that escalated predation, bioturbation and organic matter recycling, all intensifying shell disintegration. A scenario with slow disarticulation in bathyal environments may have lead to preservation of articulated shells in shallow‐water assemblages prior to the MMR.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49062714","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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