Tridentinosaurus antiquus represents one of the oldest fossil reptiles and one of the very few skeletal specimens with evidence of soft tissue preservation from the Cisuralian (Early Permian) of the Italian Alps. The preservation and appearance of the fossil have puzzled palaeontologists for decades and its taphonomy and phylogenetic position have remained unresolved. We reanalysed T. antiquus using ultraviolet light (UV), 3D surface modelling, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), micro x-ray diffraction (μ-XRD), Raman and attenuated total reflectance Fourier transformed infrared (ATR-FTIR) spectroscopy to determine the origin of the body outline and test whether this represents the remains of organically preserved soft tissues which in turn could reveal important anatomical details about this enigmatic protorosaur. The results reveal, however, that the material forming the body outline is not fossilized soft tissues but a manufactured pigment indicating that the body outline is a forgery. Our discovery poses new questions about the validity of this enigmatic taxon.
古戟龙（Tridentinosaurus antiquus）是最古老的爬行动物化石之一，也是意大利阿尔卑斯山西苏拉山期（早二叠世）极少数有软组织保存证据的骨骼标本之一。几十年来，该化石的保存和外观一直令古生物学家困惑不已，它的古生物学和系统发育地位也一直悬而未决。我们利用紫外线（UV）、三维表面建模、扫描电子显微镜与能量色散光谱（SEM-EDS）、微 X 射线衍射（μ-XRD）、拉曼光谱和衰减全反射傅立叶变换红外光谱（ATR-FTIR）对 T. antiquus 进行了重新分析，以确定身体轮廓的起源，并检验这是否代表有机保存的软组织残骸，进而揭示这只神秘原龙的重要解剖细节。然而，研究结果表明，构成身体轮廓的材料并非软组织化石，而是一种人造颜料，这表明身体轮廓是伪造的。我们的发现为这一神秘类群的有效性提出了新的问题。
{"title":"Forged soft tissues revealed in the oldest fossil reptile from the early Permian of the Alps","authors":"Valentina Rossi, Massimo Bernardi, Mariagabriella Fornasiero, Fabrizio Nestola, Richard Unitt, Stefano Castelli, Evelyn Kustatscher","doi":"10.1111/pala.12690","DOIUrl":"https://doi.org/10.1111/pala.12690","url":null,"abstract":"<i>Tridentinosaurus antiquus</i> represents one of the oldest fossil reptiles and one of the very few skeletal specimens with evidence of soft tissue preservation from the Cisuralian (Early Permian) of the Italian Alps. The preservation and appearance of the fossil have puzzled palaeontologists for decades and its taphonomy and phylogenetic position have remained unresolved. We reanalysed <i>T. antiquus</i> using ultraviolet light (UV), 3D surface modelling, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), micro x-ray diffraction (μ-XRD), Raman and attenuated total reflectance Fourier transformed infrared (ATR-FTIR) spectroscopy to determine the origin of the body outline and test whether this represents the remains of organically preserved soft tissues which in turn could reveal important anatomical details about this enigmatic protorosaur. The results reveal, however, that the material forming the body outline is not fossilized soft tissues but a manufactured pigment indicating that the body outline is a forgery. Our discovery poses new questions about the validity of this enigmatic taxon.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"115 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139948384","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}
Philip M. Novack-Gottshall, Jack Purcell, Ali Sultan, Isa Ranjha, Bradley Deline, Colin D. Sumrall
The Cambrian and Ordovician radiations marked the origins of all major echinoderm clades and established their Phanerozoic ecological blueprint. Recent claims of modest innovation of early echinoderms and other animals suggest constraints on novelty during the origins of phyla. Here, we document the life-habit richness, body size, tiering, habitat usage, mobility, diet and foraging habits of 366 Cambrian–Ordovician echinoderm genera across a time-scaled phylogeny to identify the timing and impact of novelty. Most early echinoderms were sedentary, filter-feeding microbivores, and their body sizes, diets and modes of locomotion were largely unchanged through time, despite major volatility in taxonomic composition. Cambrian echinoderms lived close to the seafloor, with stylophorans first evolving semi-infaunality. Many Ordovician echinoderms lived farther from the seafloor, with more complex filter-feeding organs and tiering structure, often using other organisms as substrates. Mobile carnivores and mass-feeders emerge then, too, across diverse asterozoans and echinozoans. Most of these novelties coincide with the origins of individual clades during the early and late Cambrian (Terreneuvian/Series 2 and Furongian), and 10–20 million years pass before most become ecologically important. Life-habit evolution within most taxa involved new variations in these traits, with crinoids and asterozoans better able to shift strategies. The Ordovician radiation records more new variability in pre-existing Cambrian life habits rather than radical re-invention, with important novelties (like mobile carnivory and mass-feeding, increased height off the seafloor, and biotic substrates) becoming ecologically more impactful. Taxa with these strategies were those best able to capitalize on the newly heterogeneous Ordovician world.
{"title":"Ecological novelty at the start of the Cambrian and Ordovician radiations of echinoderms","authors":"Philip M. Novack-Gottshall, Jack Purcell, Ali Sultan, Isa Ranjha, Bradley Deline, Colin D. Sumrall","doi":"10.1111/pala.12688","DOIUrl":"https://doi.org/10.1111/pala.12688","url":null,"abstract":"The Cambrian and Ordovician radiations marked the origins of all major echinoderm clades and established their Phanerozoic ecological blueprint. Recent claims of modest innovation of early echinoderms and other animals suggest constraints on novelty during the origins of phyla. Here, we document the life-habit richness, body size, tiering, habitat usage, mobility, diet and foraging habits of 366 Cambrian–Ordovician echinoderm genera across a time-scaled phylogeny to identify the timing and impact of novelty. Most early echinoderms were sedentary, filter-feeding microbivores, and their body sizes, diets and modes of locomotion were largely unchanged through time, despite major volatility in taxonomic composition. Cambrian echinoderms lived close to the seafloor, with stylophorans first evolving semi-infaunality. Many Ordovician echinoderms lived farther from the seafloor, with more complex filter-feeding organs and tiering structure, often using other organisms as substrates. Mobile carnivores and mass-feeders emerge then, too, across diverse asterozoans and echinozoans. Most of these novelties coincide with the origins of individual clades during the early and late Cambrian (Terreneuvian/Series 2 and Furongian), and 10–20 million years pass before most become ecologically important. Life-habit evolution within most taxa involved new variations in these traits, with crinoids and asterozoans better able to shift strategies. The Ordovician radiation records more new variability in pre-existing Cambrian life habits rather than radical re-invention, with important novelties (like mobile carnivory and mass-feeding, increased height off the seafloor, and biotic substrates) becoming ecologically more impactful. Taxa with these strategies were those best able to capitalize on the newly heterogeneous Ordovician world.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"52 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139516635","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}
Wei Liu, Zongjun Yin, Bing Pan, Bing Shen, Lin Dong, Guoxiang Li
As a significant evolutionary innovation, multicellularity has independently evolved multiple times throughout the evolutionary history of eukaryotes, making a substantial contribution to their diversity. In retracing the multicellularity of eukaryotes, deep-time fossil records play an irreplaceable role. In this paper, we report a new acritarch Concavaesphaera ornata gen. et sp. nov. from the early Cambrian Kuanchuanpu biota (535 Ma). These fossils are generally spherical, with diameters ranging from 450 to 950 μm, and feature an envelope with complex ornament. Inside, there are two groups of cells varying in size. Larger cells are relatively fewer in number and each resides within a sac-like cavity distributed along the inner wall of the envelope. Statistical data show a positive correlation between the diameter and cavity volume during the development of large cells. Small cells are numerous, have a diameter of about 15 μm, and fill the entire interior of the specimens. We interpret the large cells as reproductive cells and the small cells as somatic cells. These observations show that Concavaesphaera evolved multicellular complexity equivalent to that of modern Volvox, with germ-soma differentiation and separation. Available evidence suggests that the similarities between Concavaesphaera and Volvox are more likely to be the result of convergent evolution. Therefore, Concavaesphaera may represent an extinct multicellular eukaryote which evolved during the Cambrian explosion and probably documented an independent innovation of multicellularity in eukaryotic evolutionary history. This implies that multicellularity evolved many more times in eukaryotes than previously estimated.
{"title":"Germ-soma differentiation and reproduction in a new species of early Cambrian acritarch","authors":"Wei Liu, Zongjun Yin, Bing Pan, Bing Shen, Lin Dong, Guoxiang Li","doi":"10.1111/pala.12687","DOIUrl":"https://doi.org/10.1111/pala.12687","url":null,"abstract":"As a significant evolutionary innovation, multicellularity has independently evolved multiple times throughout the evolutionary history of eukaryotes, making a substantial contribution to their diversity. In retracing the multicellularity of eukaryotes, deep-time fossil records play an irreplaceable role. In this paper, we report a new acritarch <i>Concavaesphaera ornata</i> gen. et sp. nov. from the early Cambrian Kuanchuanpu biota (535 Ma). These fossils are generally spherical, with diameters ranging from 450 to 950 μm, and feature an envelope with complex ornament. Inside, there are two groups of cells varying in size. Larger cells are relatively fewer in number and each resides within a sac-like cavity distributed along the inner wall of the envelope. Statistical data show a positive correlation between the diameter and cavity volume during the development of large cells. Small cells are numerous, have a diameter of about 15 μm, and fill the entire interior of the specimens. We interpret the large cells as reproductive cells and the small cells as somatic cells. These observations show that <i>Concavaesphaera</i> evolved multicellular complexity equivalent to that of modern <i>Volvox</i>, with germ-soma differentiation and separation. Available evidence suggests that the similarities between <i>Concavaesphaera</i> and <i>Volvox</i> are more likely to be the result of convergent evolution. Therefore, <i>Concavaesphaera</i> may represent an extinct multicellular eukaryote which evolved during the Cambrian explosion and probably documented an independent innovation of multicellularity in eukaryotic evolutionary history. This implies that multicellularity evolved many more times in eukaryotes than previously estimated.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"22 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139052906","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}
Trace fossils record the interactions between organisms and their surroundings, and can therefore provide unique insights into the coevolution of trace makers and the environment. However, identifying the producers of trace fossils is challenging because different animals can create very similar traces and many ichnotaxa can therefore only be attributed to broad morphological grades. For example, simple horizontal traces like Gordia are generally suggested to have been produced by vermiform organisms, potentially encompassing a range of animal phyla. This uncertainty makes it difficult to decipher their palaeobiological significance through major evolutionary events and episodes of environmental change. We have developed new mathematical approaches for identifying previously unrecognized signatures left by the trace makers of simple marine locomotory traces. We calculated the deviation angle series of self-crossing traces made by extant isopods, polychaetes, gastropods and nematodes, computing the frequency spectrum and autocorrelation function in each case. The results reveal that each of these taxa left unique markers during the trace-making process, reflecting differences in their anatomy and locomotory behaviour. We were able to identify the possible trace makers of several early Palaeozoic Gordia specimens, demonstrating that ichnospecies within the same ichnogenus can be created by distantly related animals with very different morphologies and/or behaviours. This novel mathematical framework has great potential for identifying the possible producers of diverse trace fossils through deep time, helping to uncover the earliest evidence of certain animals or behaviours. It also has great potential for quantifying ichnotaxonomy, consolidating the link between ichnology and palaeobiology.
{"title":"Quantitative ichnology: a novel framework to determine the producers of locomotory trace fossils with the ichnogenus Gordia as a case study","authors":"Zekun Wang, Imran A. Rahman","doi":"10.1111/pala.12686","DOIUrl":"https://doi.org/10.1111/pala.12686","url":null,"abstract":"Trace fossils record the interactions between organisms and their surroundings, and can therefore provide unique insights into the coevolution of trace makers and the environment. However, identifying the producers of trace fossils is challenging because different animals can create very similar traces and many ichnotaxa can therefore only be attributed to broad morphological grades. For example, simple horizontal traces like <i>Gordia</i> are generally suggested to have been produced by vermiform organisms, potentially encompassing a range of animal phyla. This uncertainty makes it difficult to decipher their palaeobiological significance through major evolutionary events and episodes of environmental change. We have developed new mathematical approaches for identifying previously unrecognized signatures left by the trace makers of simple marine locomotory traces. We calculated the deviation angle series of self-crossing traces made by extant isopods, polychaetes, gastropods and nematodes, computing the frequency spectrum and autocorrelation function in each case. The results reveal that each of these taxa left unique markers during the trace-making process, reflecting differences in their anatomy and locomotory behaviour. We were able to identify the possible trace makers of several early Palaeozoic <i>Gordia</i> specimens, demonstrating that ichnospecies within the same ichnogenus can be created by distantly related animals with very different morphologies and/or behaviours. This novel mathematical framework has great potential for identifying the possible producers of diverse trace fossils through deep time, helping to uncover the earliest evidence of certain animals or behaviours. It also has great potential for quantifying ichnotaxonomy, consolidating the link between ichnology and palaeobiology.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"1 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138823677","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}
Jingqi Liu, Yang Zhang, Xiaoying Shi, Anfeng Chen, Dongjie Tang, Tinglu Yang
Multicellular algae are the core topic for understanding the early life evolution on Earth. The timing of origin and cellular differentiation of multicellular algae, however, remains poorly constrained. The Palaeoproterozoic to early Mesoproterozoic is a critical period during which multicellular algae began to occur and evolve in marine environments. This paper reports well-preserved multicellular fossils from shales of the Chuanlinggou Formation (c. 1.64 Ga) in North China, with emphasis on their holdfast and putative cellular structures. These macroalgal fossils are reasonably diversified and include Chuaria circularis, Tawuia sinensis, Tawuia robusta, Glossophyton ovalis, Glossophyton sp., Tuanshanzia sp. and Changchengia sp.; mainly preserved as carbonaceous compressions, with a few sideritized forms. Field emission scanning electron microscope (FESEM) observation revealed multicellular structures in Chuaria, confirming its biological attributes of a multicellular eukaryote and providing direct evidence that multicellular algae had already originated by the terminal Palaeoproterozoic, earlier than previously speculated. Tuanshanzia sp. and Changchengia sp. developed with a bare rhizome holdfast, suggesting that they had a benthic sessile lifestyle in their late Palaeoproterozoic oceanic habitat.
{"title":"Macroscopic fossils from the Chuanlinggou Formation of North China: evidence for an earlier origin of multicellular algae in the late Palaeoproterozoic","authors":"Jingqi Liu, Yang Zhang, Xiaoying Shi, Anfeng Chen, Dongjie Tang, Tinglu Yang","doi":"10.1111/pala.12685","DOIUrl":"https://doi.org/10.1111/pala.12685","url":null,"abstract":"Multicellular algae are the core topic for understanding the early life evolution on Earth. The timing of origin and cellular differentiation of multicellular algae, however, remains poorly constrained. The Palaeoproterozoic to early Mesoproterozoic is a critical period during which multicellular algae began to occur and evolve in marine environments. This paper reports well-preserved multicellular fossils from shales of the Chuanlinggou Formation (<i>c</i>. 1.64 Ga) in North China, with emphasis on their holdfast and putative cellular structures. These macroalgal fossils are reasonably diversified and include <i>Chuaria circularis</i>, <i>Tawuia sinensis</i>, <i>Tawuia robusta</i>, <i>Glossophyton ovalis</i>, <i>Glossophyton</i> sp., <i>Tuanshanzia</i> sp. and <i>Changchengia</i> sp.; mainly preserved as carbonaceous compressions, with a few sideritized forms. Field emission scanning electron microscope (FESEM) observation revealed multicellular structures in <i>Chuaria</i>, confirming its biological attributes of a multicellular eukaryote and providing direct evidence that multicellular algae had already originated by the terminal Palaeoproterozoic, earlier than previously speculated. <i>Tuanshanzia</i> sp. and <i>Changchengia</i> sp. developed with a bare rhizome holdfast, suggesting that they had a benthic sessile lifestyle in their late Palaeoproterozoic oceanic habitat.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"31 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138823539","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}
Li Zhang, Yongdong Wang, Micha Ruhl, Yuanyuan Xu, Yanbin Zhu, Pengcheng An, Hongyu Chen, Defei Yan
Leaf stomata form an essential conduit between plant tissue and the atmosphere, thus presenting a link between plants and their environments. Changes in their properties in fossil leaves have been studied widely to infer palaeo-atmospheric-CO2 in deep time, ranging from the Palaeozoic to the Cenozoic. Epidermal cells of leaves, however, have often been neglected for their usefulness in reconstructing past-environments, as their irregular shape makes the manual analyses of epidermal cells a challenging and error-prone task. Here, we used machine-learning (using the U-Net architecture, which evolved from a fully convolutional network) to segment epidermal cells automatically, to efficiently reduce artificial errors. We furthermore applied minimum bounding rectangles to extract length-to-width ratios (RL/W) from the irregularly shaped cells. We applied this to a dataset including over 21 000 stomata and 170 000 epidermal cells in 114 Ginkgo leaves from 16 locations spanning three climate zones in China. Our results show negative correlations between the RL/W and specific climatic parameters, suggesting that local temperature and precipitation conditions may have affected the RL/W of epidermal cells. We subsequently tested this methodology and the observations from the modern dataset on 15 fossil ginkgoaleans from the Lower to the Middle Jurassic (China). It suggested that the RL/W values of fossil ginkgo generally had a similar negative response to warmer climatic backgrounds as modern G. biloba. The automated analyses of large palaeo-floral datasets provide a new direction for palaeoclimate reconstructions and emphasize the importance of hidden morphological characters of epidermal cells in ginkgoaleans.
{"title":"Machine-learning-based morphological analyses of leaf epidermal cells in modern and fossil ginkgo and their implications for palaeoclimate studies","authors":"Li Zhang, Yongdong Wang, Micha Ruhl, Yuanyuan Xu, Yanbin Zhu, Pengcheng An, Hongyu Chen, Defei Yan","doi":"10.1111/pala.12684","DOIUrl":"https://doi.org/10.1111/pala.12684","url":null,"abstract":"Leaf stomata form an essential conduit between plant tissue and the atmosphere, thus presenting a link between plants and their environments. Changes in their properties in fossil leaves have been studied widely to infer palaeo-atmospheric-CO<sub>2</sub> in deep time, ranging from the Palaeozoic to the Cenozoic. Epidermal cells of leaves, however, have often been neglected for their usefulness in reconstructing past-environments, as their irregular shape makes the manual analyses of epidermal cells a challenging and error-prone task. Here, we used machine-learning (using the U-Net architecture, which evolved from a fully convolutional network) to segment epidermal cells automatically, to efficiently reduce artificial errors. We furthermore applied minimum bounding rectangles to extract length-to-width ratios (<i>R</i><sub>L/W</sub>) from the irregularly shaped cells. We applied this to a dataset including over 21 000 stomata and 170 000 epidermal cells in 114 <i>Ginkgo</i> leaves from 16 locations spanning three climate zones in China. Our results show negative correlations between the <i>R</i><sub>L/W</sub> and specific climatic parameters, suggesting that local temperature and precipitation conditions may have affected the <i>R</i><sub>L/W</sub> of epidermal cells. We subsequently tested this methodology and the observations from the modern dataset on 15 fossil ginkgoaleans from the Lower to the Middle Jurassic (China). It suggested that the <i>R</i><sub>L/W</sub> values of fossil ginkgo generally had a similar negative response to warmer climatic backgrounds as modern <i>G. biloba</i>. The automated analyses of large palaeo-floral datasets provide a new direction for palaeoclimate reconstructions and emphasize the importance of hidden morphological characters of epidermal cells in ginkgoaleans.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"35 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138714786","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}
Guillaume Houée, Jérémie Bardin, Damien Germain, Philippe Janvier, Nicolas Goudemand
Fossils of extinct jawless vertebrates are pivotal to deciphering the evolutionary paths that led to the various forms of the vertebrate skeleton. For example, Pteraspidomorphs (stem-gnathostomes), such as the Ordovician Astraspis, display some of the oldest remains of bony and ‘dental’ (dentine and enameloid) tissues. However, the identification of the very nature of these early mineralized tissues has been hampered by a lack of unambiguous diagnostic characters. As development is key to identifying the derivation of these tissues, we developed an integrative and generic histogenetic model, testing several ontogenetic scenarios. We illustrate our approach on the basis of the well-preserved Astraspis samples and show how this can be used to infer key developmental features from extinct species. This study suggests that in the odontodes of Astraspis: (1) the initial curvature of the epithelium was close to the shape of the final external surface; (2) the mesenchymal cells differentiate synchronously in the whole inner periphery; and (3) the capping tissue was produced by both mesenchymal and epithelial cells (enameloid rather than enamel). Astraspis specimens also provide evidence of a dual growth periodicity, possibly homologous to Andresen and von Ebner growth lines observed in amniotes, suggesting this type of dual periodicity may be shared by most vertebrates. We estimated that an Astraspis odontode grew up in around 60–70 days at a rate of 0.5–5 μm/day. The new developmental approach proposed in this study could be a robust framework for critically evaluating the tissues of extinct taxa in the future.
{"title":"Developmental models shed light on the earliest dental tissues, using Astraspis as an example","authors":"Guillaume Houée, Jérémie Bardin, Damien Germain, Philippe Janvier, Nicolas Goudemand","doi":"10.1111/pala.12682","DOIUrl":"https://doi.org/10.1111/pala.12682","url":null,"abstract":"Fossils of extinct jawless vertebrates are pivotal to deciphering the evolutionary paths that led to the various forms of the vertebrate skeleton. For example, Pteraspidomorphs (stem-gnathostomes), such as the Ordovician <i>Astraspis</i>, display some of the oldest remains of bony and ‘dental’ (dentine and enameloid) tissues. However, the identification of the very nature of these early mineralized tissues has been hampered by a lack of unambiguous diagnostic characters. As development is key to identifying the derivation of these tissues, we developed an integrative and generic histogenetic model, testing several ontogenetic scenarios. We illustrate our approach on the basis of the well-preserved <i>Astraspis</i> samples and show how this can be used to infer key developmental features from extinct species. This study suggests that in the odontodes of <i>Astraspis</i>: (1) the initial curvature of the epithelium was close to the shape of the final external surface; (2) the mesenchymal cells differentiate synchronously in the whole inner periphery; and (3) the capping tissue was produced by both mesenchymal and epithelial cells (enameloid rather than enamel). <i>Astraspis</i> specimens also provide evidence of a dual growth periodicity, possibly homologous to Andresen and von Ebner growth lines observed in amniotes, suggesting this type of dual periodicity may be shared by most vertebrates. We estimated that an <i>Astraspis</i> odontode grew up in around 60–70 days at a rate of 0.5–5 μm/day. The new developmental approach proposed in this study could be a robust framework for critically evaluating the tissues of extinct taxa in the future.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"1 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138575623","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}
Phillip E. Jardine, Matthew S. Kent, Wesley T. Fraser, Klaus-Holger Knorr, Barry H. Lomax
Sporomorphs (pollen and spores) are a mainstay of research into past vegetation, and increasingly sporomorph chemistry is being used as a palaeoecological tool. To make extant sporomorphs directly comparable to fossil specimens, fresh material is processed to remove labile compounds and isolate the sporopollenin wall. A range of processing approaches are currently in use, but the chemistries produced by these different techniques have not yet been compared across a range of taxa. It is therefore not clear how they compare in terms of efficiently isolating sporopollenin without changing its chemical structure, and what impact they have on relative chemical similarities and differences among taxa (i.e. whether more closely related species will always appear chemically more similar, regardless of how they have been processed). Here, we test this by applying five different processing approaches to sporomorphs from 15 taxa from across the vascular plant phylogeny. We show that each approach has its own idiosyncrasies in terms of impacts on sporomorph chemistry. For the most part a common pattern of among-taxon chemical variability is uncovered, and a phylogenetic signal within sporopollenin chemistry is supported. Working with spectral derivatives generally increases agreement among the different processing approaches, but decreases the strength of the phylogenetic signal. No one processing approach is ideal, and the choice of which to use is likely to depend on the goal of the study, the type and quantity of material being processed, and the laboratory facilities available for processing.
{"title":"Uncovering a phylogenetic signal in plant biopolymer chemistry: a comparison of sporopollenin isolation approaches for use in palynological research","authors":"Phillip E. Jardine, Matthew S. Kent, Wesley T. Fraser, Klaus-Holger Knorr, Barry H. Lomax","doi":"10.1111/pala.12683","DOIUrl":"https://doi.org/10.1111/pala.12683","url":null,"abstract":"Sporomorphs (pollen and spores) are a mainstay of research into past vegetation, and increasingly sporomorph chemistry is being used as a palaeoecological tool. To make extant sporomorphs directly comparable to fossil specimens, fresh material is processed to remove labile compounds and isolate the sporopollenin wall. A range of processing approaches are currently in use, but the chemistries produced by these different techniques have not yet been compared across a range of taxa. It is therefore not clear how they compare in terms of efficiently isolating sporopollenin without changing its chemical structure, and what impact they have on relative chemical similarities and differences among taxa (i.e. whether more closely related species will always appear chemically more similar, regardless of how they have been processed). Here, we test this by applying five different processing approaches to sporomorphs from 15 taxa from across the vascular plant phylogeny. We show that each approach has its own idiosyncrasies in terms of impacts on sporomorph chemistry. For the most part a common pattern of among-taxon chemical variability is uncovered, and a phylogenetic signal within sporopollenin chemistry is supported. Working with spectral derivatives generally increases agreement among the different processing approaches, but decreases the strength of the phylogenetic signal. No one processing approach is ideal, and the choice of which to use is likely to depend on the goal of the study, the type and quantity of material being processed, and the laboratory facilities available for processing.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"11 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138534723","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}
Tai Kubo, Mugino O. Kubo, Manabu Sakamoto, Daniela E. Winkler, Masateru Shibata, Wenjie Zheng, Xingsheng Jin, Hai-Lu You
Dinosaurs were the dominant megaherbivores during the Cretaceous when angiosperms, the flowering plants, emerged and diversified. How herbivorous dinosaurs responded to the increasing diversity of angiosperms is largely unknown due to the lack of methods that can reconstruct diet directly from body fossils. We applied dental microwear texture analysis (DMTA), an approach that quantifies microtopography of diet-induced wear marks on tooth surfaces, to ornithopods, the dinosaur clade that includes taxa with the most sophisticated masticatory system. We found that Late Cretaceous ornithopods have significantly rougher dental microwear texture (DMT) compared to pre-Late Cretaceous ornithopods, and DMT variation increased in hadrosaurids, a derived Late Cretaceous ornithopod clade. These changes indicate a likely temporal dietary shift towards more abrasive foodstuffs within ornithopods, probably due to the increased ingestion of phytoliths (amorphous silica bodies in plants). Phytoliths are a main source of rough DMT in modern herbivores, along with exogenous dust and grit, and were generally more concentrated in Late Cretaceous angiosperms than in other major plant groups. Our results show that DMTA of the occlusal enamel surface can be used to reconstruct the diets of herbivorous dinosaurs, with a resolution superior to conventional methods.
{"title":"Dental microwear texture analysis reveals a likely dietary shift within Late Cretaceous ornithopod dinosaurs","authors":"Tai Kubo, Mugino O. Kubo, Manabu Sakamoto, Daniela E. Winkler, Masateru Shibata, Wenjie Zheng, Xingsheng Jin, Hai-Lu You","doi":"10.1111/pala.12681","DOIUrl":"https://doi.org/10.1111/pala.12681","url":null,"abstract":"Dinosaurs were the dominant megaherbivores during the Cretaceous when angiosperms, the flowering plants, emerged and diversified. How herbivorous dinosaurs responded to the increasing diversity of angiosperms is largely unknown due to the lack of methods that can reconstruct diet directly from body fossils. We applied dental microwear texture analysis (DMTA), an approach that quantifies microtopography of diet-induced wear marks on tooth surfaces, to ornithopods, the dinosaur clade that includes taxa with the most sophisticated masticatory system. We found that Late Cretaceous ornithopods have significantly rougher dental microwear texture (DMT) compared to pre-Late Cretaceous ornithopods, and DMT variation increased in hadrosaurids, a derived Late Cretaceous ornithopod clade. These changes indicate a likely temporal dietary shift towards more abrasive foodstuffs within ornithopods, probably due to the increased ingestion of phytoliths (amorphous silica bodies in plants). Phytoliths are a main source of rough DMT in modern herbivores, along with exogenous dust and grit, and were generally more concentrated in Late Cretaceous angiosperms than in other major plant groups. Our results show that DMTA of the occlusal enamel surface can be used to reconstruct the diets of herbivorous dinosaurs, with a resolution superior to conventional methods.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"6 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138534732","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}
Nicolás Mongiardino Koch, Russell J. Garwood, Luke A. Parry
Time-scaled phylogenies underpin the interrogation of evolutionary processes across deep timescales, as well as attempts to link these to Earth's history. By inferring the placement of fossils and using their ages as temporal constraints, tip dating under the fossilized birth–death (FBD) process provides a coherent prior on divergence times. At the same time, it also links topological and temporal accuracy, as incorrectly placed fossil terminals should misinform divergence times. This could pose serious issues for obtaining accurate node ages, yet the interaction between topological and temporal error has not been thoroughly explored. We simulate phylogenies and associated morphological datasets using methodologies that incorporate evolution under selection, and are benchmarked against empirical datasets. We find that datasets of 300 characters and realistic levels of missing data generally succeed in inferring the correct placement of fossils on a constrained extant backbone topology, and that true node ages are usually contained within Bayesian posterior distributions. While increased fossil sampling improves the accuracy of inferred ages, topological and temporal errors do not seem to be linked: analyses in which fossils resolve less accurately do not exhibit elevated errors in node age estimates. At the same time, inferred divergence times are biased, probably due to a mismatch between the FBD prior and the shape of our simulated trees. While these results are encouraging, suggesting that even fossils with uncertain affinities can provide useful temporal information, they also emphasize that palaeontological information cannot overturn discrepancies between model priors and the true diversification history.
{"title":"Inaccurate fossil placement does not compromise tip-dated divergence times","authors":"Nicolás Mongiardino Koch, Russell J. Garwood, Luke A. Parry","doi":"10.1111/pala.12680","DOIUrl":"https://doi.org/10.1111/pala.12680","url":null,"abstract":"Time-scaled phylogenies underpin the interrogation of evolutionary processes across deep timescales, as well as attempts to link these to Earth's history. By inferring the placement of fossils and using their ages as temporal constraints, tip dating under the fossilized birth–death (FBD) process provides a coherent prior on divergence times. At the same time, it also links topological and temporal accuracy, as incorrectly placed fossil terminals should misinform divergence times. This could pose serious issues for obtaining accurate node ages, yet the interaction between topological and temporal error has not been thoroughly explored. We simulate phylogenies and associated morphological datasets using methodologies that incorporate evolution under selection, and are benchmarked against empirical datasets. We find that datasets of 300 characters and realistic levels of missing data generally succeed in inferring the correct placement of fossils on a constrained extant backbone topology, and that true node ages are usually contained within Bayesian posterior distributions. While increased fossil sampling improves the accuracy of inferred ages, topological and temporal errors do not seem to be linked: analyses in which fossils resolve less accurately do not exhibit elevated errors in node age estimates. At the same time, inferred divergence times are biased, probably due to a mismatch between the FBD prior and the shape of our simulated trees. While these results are encouraging, suggesting that even fossils with uncertain affinities can provide useful temporal information, they also emphasize that palaeontological information cannot overturn discrepancies between model priors and the true diversification history.","PeriodicalId":56272,"journal":{"name":"Palaeontology","volume":"1 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138534724","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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