Pub Date : 2024-02-19DOI: 10.1101/2024.02.15.578844
Ruizhe Jackevan Zhao
Body size is the key to understanding many biological properties. Sizes of extinct animals are usually estimated from body reconstructions since their masses can not be weighed directly. Plesiosaurs were Mesozoic marine reptiles that were diverse in both body plan and size. Attempts to estimate body masses of plesiosaurs were rare in the past two centuries, possibly due to lack of knowledge about their postcranial anatomy and body shapes in life. The burst of plesiosaur studies in the past two decades has greatly expanded our cognition of their physiology, taxonomy, potential behavior and even soft body outlines. Here I present a comprehensive review of relevant knowledge, and propose a uniform set of methodology for rigorous body reconstruction of plesiosaurs. Twenty-two plesiosaur models were constructed under these criteria, and they were subsequently used as samples to find proxies for body mass. It is revealed that multiple skeletal elements are good indicators of plesiosaur size. This study offers scaling equations for size estimation, enabling quick acquisition of body mass information from fragmented fossils. A summary of body size evolution of different plesiosaur clades is also provided.
{"title":"Body reconstruction and size estimation of plesiosaurs","authors":"Ruizhe Jackevan Zhao","doi":"10.1101/2024.02.15.578844","DOIUrl":"https://doi.org/10.1101/2024.02.15.578844","url":null,"abstract":"Body size is the key to understanding many biological properties. Sizes of extinct animals are usually estimated from body reconstructions since their masses can not be weighed directly. Plesiosaurs were Mesozoic marine reptiles that were diverse in both body plan and size. Attempts to estimate body masses of plesiosaurs were rare in the past two centuries, possibly due to lack of knowledge about their postcranial anatomy and body shapes in life. The burst of plesiosaur studies in the past two decades has greatly expanded our cognition of their physiology, taxonomy, potential behavior and even soft body outlines. Here I present a comprehensive review of relevant knowledge, and propose a uniform set of methodology for rigorous body reconstruction of plesiosaurs. Twenty-two plesiosaur models were constructed under these criteria, and they were subsequently used as samples to find proxies for body mass. It is revealed that multiple skeletal elements are good indicators of plesiosaur size. This study offers scaling equations for size estimation, enabling quick acquisition of body mass information from fragmented fossils. A summary of body size evolution of different plesiosaur clades is also provided.","PeriodicalId":501477,"journal":{"name":"bioRxiv - Paleontology","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139903559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-12DOI: 10.1101/2024.02.09.579723
Francois Clarac, Alexis Cornille, Sifra Bijl, Sophie Sanchez
Our study shows that the von Mises stress, induced by external load on the humerus of Eusthenopteron, dissipates through the cortex, trabeculae and the muscles of the pectoral appendage involved in elevation and protraction. As Eusthenopteron's microanatomy is similar to that of Devonian tetrapods, we expect them to share the same process of load dissipation and energy absorption through 1) cortical stress distribution; and 2) longitudinal trabecular conduction. Our FE simulations in hypothetical terrestrial conditions demonstrate that this type of microanatomical architecture could withstand the weight of Tiktaalik proportionally to the size of Eusthenopteron in standing posture. This tubular arrangement, including marrow processes originally involved in long-bone elongation, would have acquired a key secondary biomechanical function to increase the resistance and strength of the cancellous bone to external compressive load. As an exaptation, this specific trabecular architecture may have played a major role in the tetrapod land exploration about 400 million years ago.
{"title":"Tetrapod terrestrialisation: a weight-bearing potential already present in the humerus of the stem-tetrapod fish Eusthenopteron foordi","authors":"Francois Clarac, Alexis Cornille, Sifra Bijl, Sophie Sanchez","doi":"10.1101/2024.02.09.579723","DOIUrl":"https://doi.org/10.1101/2024.02.09.579723","url":null,"abstract":"Our study shows that the von Mises stress, induced by external load on the humerus of Eusthenopteron, dissipates through the cortex, trabeculae and the muscles of the pectoral appendage involved in elevation and protraction. As Eusthenopteron's microanatomy is similar to that of Devonian tetrapods, we expect them to share the same process of load dissipation and energy absorption through 1) cortical stress distribution; and 2) longitudinal trabecular conduction. Our FE simulations in hypothetical terrestrial conditions demonstrate that this type of microanatomical architecture could withstand the weight of Tiktaalik proportionally to the size of Eusthenopteron in standing posture. This tubular arrangement, including marrow processes originally involved in long-bone elongation, would have acquired a key secondary biomechanical function to increase the resistance and strength of the cancellous bone to external compressive load. As an exaptation, this specific trabecular architecture may have played a major role in the tetrapod land exploration about 400 million years ago.","PeriodicalId":501477,"journal":{"name":"bioRxiv - Paleontology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139760847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-12DOI: 10.1101/2024.02.08.579492
Corentin C. Loron, Ferenc Borondics
The identification of preserved organic material within fossils is challenging. Well-established vibrational spectroscopy techniques, such as micro-FTIR (Fourier Transform Infra-Red spectroscopy), have been widely used to investigate organic fossils molecular composition. However, even when well-adapted to study objects several tens of micrometre across, they still suffer from limitations, notably regarding resolution and sample preparation requirements. Optical Photothermal Infrared Spectroscopy (O-PTIR), a recently developed technique, overcomes the challenges of bench-top FTIR spectroscopy. By combining an IR excitation laser with a 532 nm green probe laser, this technique allows molecular characterization at high spectral resolution (~2 cm-1) and with extremely fine spatial resolution (~500 nanometres). Additionally, problems linked with sample thickness, surface roughness and particle shape/size are mitigated when compared with FTIR or Atomic Force Microscopy-based nanoIR techniques. Here we show that O-PTIR can be used to easily and successfully map the molecular composition of small organic fossils preserved in silica matrix (chert) in petrographic thin sections. Our study reveals that O-PTIR resolves spatial heterogeneities in the preserved molecular composition of organic fossils (spores and plants) at a sub-micron scale, and that such heterogeneities occur in the cuticle in an early Devonian plant, where they suggest a structural organisation comparable to modern plants. These results on 400 million years old fossils, validate O-PTIR as a powerful and extremely promising new tool for nanoanalytical palaeontology.
{"title":"Optical photothermal infrared spectroscopy (O-PTIR): a promising new tool for bench-top analytical palaeontology at the sub-micron scale","authors":"Corentin C. Loron, Ferenc Borondics","doi":"10.1101/2024.02.08.579492","DOIUrl":"https://doi.org/10.1101/2024.02.08.579492","url":null,"abstract":"The identification of preserved organic material within fossils is challenging. Well-established vibrational spectroscopy techniques, such as micro-FTIR (Fourier Transform Infra-Red spectroscopy), have been widely used to investigate organic fossils molecular composition. However, even when well-adapted to study objects several tens of micrometre across, they still suffer from limitations, notably regarding resolution and sample preparation requirements. Optical Photothermal Infrared Spectroscopy (O-PTIR), a recently developed technique, overcomes the challenges of bench-top FTIR spectroscopy. By combining an IR excitation laser with a 532 nm green probe laser, this technique allows molecular characterization at high spectral resolution (~2 cm-1) and with extremely fine spatial resolution (~500 nanometres). Additionally, problems linked with sample thickness, surface roughness and particle shape/size are mitigated when compared with FTIR or Atomic Force Microscopy-based nanoIR techniques. Here we show that O-PTIR can be used to easily and successfully map the molecular composition of small organic fossils preserved in silica matrix (chert) in petrographic thin sections. Our study reveals that O-PTIR resolves spatial heterogeneities in the preserved molecular composition of organic fossils (spores and plants) at a sub-micron scale, and that such heterogeneities occur in the cuticle in an early Devonian plant, where they suggest a structural organisation comparable to modern plants. These results on 400 million years old fossils, validate O-PTIR as a powerful and extremely promising new tool for nanoanalytical palaeontology.","PeriodicalId":501477,"journal":{"name":"bioRxiv - Paleontology","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139769044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-30DOI: 10.1101/2024.01.26.577348
Stephen Pates, Harriet B. Drage
Trilobites, a diverse clade of Palaeozoic arthropods, repeatedly converged on the trinucleimorph morphology. Trinucleimorphs possessed vaulted cephala with a broad anterior fringe and prominent posteriorly orientated genal prolongations. Various functional hypotheses have been proposed for the fringe, however the possible function of the genal prolongations has received less attention. Here we use a computational fluid dynamics approach to test whether these prolongations served a hydrodynamic function: generating negative lift to allow trinucleimorphs to remain in place on the seafloor and prevent overturning within fast flowing water. We simulated the performance of cephala with broad, narrow, and absent genal prolongations in a benthic environment with flow speeds ranging from 0.05 to 0.5 m s-1, in two cephalic postures. The first posture had the anterior of the cephalon parallel to the seafloor, while for the second the genal prolongations were parallel to the seafloor. Posture and presence of genal prolongations were found to be important for generating negative lift, with performance improving under faster flow speeds. No significant difference between narrow and broad genal prolongations was detected. This study provides support for genal prolongations serving a hydrodynamic function, similar to the femurs of some insect larvae, however, it does not preclude prolongations also serving additional functions as snowshoes or antipredatory deterrents.
{"title":"Hydrodynamic function of genal prolongations in trinucleimorph trilobites revealed by computational fluid dynamics","authors":"Stephen Pates, Harriet B. Drage","doi":"10.1101/2024.01.26.577348","DOIUrl":"https://doi.org/10.1101/2024.01.26.577348","url":null,"abstract":"Trilobites, a diverse clade of Palaeozoic arthropods, repeatedly converged on the trinucleimorph morphology. Trinucleimorphs possessed vaulted cephala with a broad anterior fringe and prominent posteriorly orientated genal prolongations. Various functional hypotheses have been proposed for the fringe, however the possible function of the genal prolongations has received less attention. Here we use a computational fluid dynamics approach to test whether these prolongations served a hydrodynamic function: generating negative lift to allow trinucleimorphs to remain in place on the seafloor and prevent overturning within fast flowing water. We simulated the performance of cephala with broad, narrow, and absent genal prolongations in a benthic environment with flow speeds ranging from 0.05 to 0.5 m s-1, in two cephalic postures. The first posture had the anterior of the cephalon parallel to the seafloor, while for the second the genal prolongations were parallel to the seafloor. Posture and presence of genal prolongations were found to be important for generating negative lift, with performance improving under faster flow speeds. No significant difference between narrow and broad genal prolongations was detected. This study provides support for genal prolongations serving a hydrodynamic function, similar to the femurs of some insect larvae, however, it does not preclude prolongations also serving additional functions as snowshoes or antipredatory deterrents.","PeriodicalId":501477,"journal":{"name":"bioRxiv - Paleontology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139588268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-30DOI: 10.1101/2024.01.30.578036
Jack O. Shaw, Alexander M. Dunhill, Andrew P. Beckerman, Jennifer A. Dunne, Pincelli M. Hull
Food webs provide quantitative insights into the structure and dynamics of ecological communities. Previous work has shown their utility in understanding community responses to modern and ancient perturbations, including anthropogenic change and mass extinctions. However, few ancient food webs have been reconstructed due to difficulties assessing trophic interactions amongst extinct species derived from an incomplete fossil record. We present and assess the Paleo Food web Inference Model (PFIM). PFIM uses functional trait data--predictive of interactions in modern ecosystems and commonly available for fossil organisms--to reconstruct ancient food webs. We test the model by (i) applying it to four modern ecosystems with empirical constrained food webs to directly compare PFIM-constructed networks to their empirical counterparts, (ii) by carefully comparing discrepancies between PFIM-inferred and empirical webs in one of those systems, and (iii) by comparing networks describing feasible trophic interactions ("feasible webs") with networks to which we superimpose characteristic interaction distributions derived from modern theory ("realized webs"). As a proof of concept, we then apply the method to faunal data from two Cambrian fossil deposits to reconstruct ancient trophic systems. PFIM-inferred feasible food webs successfully predict ~70% of trophic interactions across four modern systems. Furthermore, inferred food webs with enforced interaction distributions (i.e., realized webs) accurately predict ~90% of interactions. Comparisons with a global database of trophic interactions and other food web models, suggest that under sampling of empirical webs accounts for up to 21% of the remaining differences between PFIM and empirical food webs. Food webs can be reasonably approximated by inferring trophic interactions based upon life habit traits. This study provides the foundation to use trait-based inference models across the fossil record to examine ancient food webs and community evolution.
{"title":"A framework for reconstructing ancient food webs using functional trait data","authors":"Jack O. Shaw, Alexander M. Dunhill, Andrew P. Beckerman, Jennifer A. Dunne, Pincelli M. Hull","doi":"10.1101/2024.01.30.578036","DOIUrl":"https://doi.org/10.1101/2024.01.30.578036","url":null,"abstract":"Food webs provide quantitative insights into the structure and dynamics of ecological communities. Previous work has shown their utility in understanding community responses to modern and ancient perturbations, including anthropogenic change and mass extinctions. However, few ancient food webs have been reconstructed due to difficulties assessing trophic interactions amongst extinct species derived from an incomplete fossil record. We present and assess the Paleo Food web Inference Model (PFIM). PFIM uses functional trait data--predictive of interactions in modern ecosystems and commonly available for fossil organisms--to reconstruct ancient food webs. We test the model by (i) applying it to four modern ecosystems with empirical constrained food webs to directly compare PFIM-constructed networks to their empirical counterparts, (ii) by carefully comparing discrepancies between PFIM-inferred and empirical webs in one of those systems, and (iii) by comparing networks describing feasible trophic interactions (\"feasible webs\") with networks to which we superimpose characteristic interaction distributions derived from modern theory (\"realized webs\"). As a proof of concept, we then apply the method to faunal data from two Cambrian fossil deposits to reconstruct ancient trophic systems.\u0000PFIM-inferred feasible food webs successfully predict ~70% of trophic interactions across four modern systems. Furthermore, inferred food webs with enforced interaction distributions (i.e., realized webs) accurately predict ~90% of interactions. Comparisons with a global database of trophic interactions and other food web models, suggest that under sampling of empirical webs accounts for up to 21% of the remaining differences between PFIM and empirical food webs.\u0000Food webs can be reasonably approximated by inferring trophic interactions based upon life habit traits. This study provides the foundation to use trait-based inference models across the fossil record to examine ancient food webs and community evolution.","PeriodicalId":501477,"journal":{"name":"bioRxiv - Paleontology","volume":"154 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139648395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-27DOI: 10.1101/2024.01.25.577179
Laura P. A. Mulvey, Michael R. May, Jeremy M. Brown, Sebastian Hoehna, April M. Wright, Rachel C. M. Warnock
Reconstructing the evolutionary history of different groups of organisms provides insight into how life originated and diversified on Earth. Phylogenetic trees are commonly used to estimate this evolutionary history, providing a hypothesis of the events. Within Bayesian phylogenetics a major step in estimating a tree is in choosing an appropriate model of character evolution. In the case of most extinct species, our only source of information to decipher their phylogenetic relationships is through the morphology of fossils. We therefore use a model of morphological character evolution, the most common of which being the Mk Lewis model. While it is frequently used in palaeobiology, it is not known whether the simple Mk substitution model, or any extensions to it, provide a sufficiently good description of the process of morphological evolution. To determine whether or not the Mk model is appropriate for fossil data we used posterior predictive simulations, a model adequacy approach, to estimate absolute fit of the model to morphological data sets. We first investigate the impact that different versions of the Mk model have on key parameter estimates using tetrapod data sets. We show that choice of substitution model has an impact on both topology and branch lengths, highlighting the importance of model choice. Next, we use simulations to investigate the power of posterior predictive simulations for morphology. Having validated this approach we show that current variations of the Mk model are in fact performing adequately in capturing the evolutionary dynamics that generated our data. We do not find any preference for a particular model extension across multiple data sets, indicating that there is no `one size fits all' when it comes to morphological data and that careful consideration should be given to choosing models of discrete character evolution. By using suitable models of character evolution, we can increase our confidence in our phylogenetic estimates, which should in turn allow us to gain more accurate insights into the evolutionary history of both extinct and extant taxa.
{"title":"Assessing the Adequacy of Morphological Models used in Palaeobiology","authors":"Laura P. A. Mulvey, Michael R. May, Jeremy M. Brown, Sebastian Hoehna, April M. Wright, Rachel C. M. Warnock","doi":"10.1101/2024.01.25.577179","DOIUrl":"https://doi.org/10.1101/2024.01.25.577179","url":null,"abstract":"Reconstructing the evolutionary history of different groups of organisms provides insight into how life originated and diversified on Earth. Phylogenetic trees are commonly used to estimate this evolutionary history, providing a hypothesis of the events. Within Bayesian phylogenetics a major step in estimating a tree is in choosing an appropriate model of character evolution. In the case of most extinct species, our only source of information to decipher their phylogenetic relationships is through the morphology of fossils. We therefore use a model of morphological character evolution, the most common of which being the Mk Lewis model. While it is frequently used in palaeobiology, it is not known whether the simple Mk substitution model, or any extensions to it, provide a sufficiently good description of the process of morphological evolution. To determine whether or not the Mk model is appropriate for fossil data we used posterior predictive simulations, a model adequacy approach, to estimate absolute fit of the model to morphological data sets. We first investigate the impact that different versions of the Mk model have on key parameter estimates using tetrapod data sets. We show that choice of substitution model has an impact on both topology and branch lengths, highlighting the importance of model choice. Next, we use simulations to investigate the power of posterior predictive simulations for morphology. Having validated this approach we show that current variations of the Mk model are in fact performing adequately in capturing the evolutionary dynamics that generated our data. We do not find any preference for a particular model extension across multiple data sets, indicating that there is no `one size fits all' when it comes to morphological data and that careful consideration should be given to choosing models of discrete character evolution. By using suitable models of character evolution, we can increase our confidence in our phylogenetic estimates, which should in turn allow us to gain more accurate insights into the evolutionary history of both extinct and extant taxa.","PeriodicalId":501477,"journal":{"name":"bioRxiv - Paleontology","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139588267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-18DOI: 10.1101/2024.01.16.575973
Deng Wang, Yaqin Qiang, Junfeng Guo, Jean Vannier, Zucheng Song, Jiaxin Peng, Boyao Zhang, Jie Sun, Yilun Yu, Yiheng Zhang, Tao Zhang, Xiaoguang Yang, Jian Han
Extant ecdysozoans (moulting animals) are represented by a great variety of vermiform or articulated organisms. However, controversies remain about the nature of their ancestral body plan although the vermiform hypothesis seems to prevail. We describe here Beretella spinosa gen et sp. nov. a tiny ecdysozoan from the early Cambrian, Yanjiahe Formation, South China, with an unusual sack-like appearance, single opening, and spiny ornament. Beretella has no equivalent among animals, except Saccorhytus from the basal Cambrian. Phylogenetic analyses resolve both forms as a sister group (Saccorhytida) to all known Ecdysozoa, thus suggesting that ancestral ecdysozoans may have been non-vermiform animals. Saccorhytids are likely to represent an early dead-end off-shot along the stem-line Ecdysozoa that possibly evolved through anatomical simplification (e.g. lack of anus). Although extinct during the Cambrian, this animal lineage provides precious insight into the early evolution of Ecdysozoa and the nature (possibly non-vermiform) of the earliest representatives of the group.
现生蜕皮动物（蜕皮动物）有多种蛭形或节肢动物。然而，尽管疣状假说似乎占了上风，但关于其祖先身体结构的性质仍存在争议。我们在此描述了一种来自华南严家河地层早寒武世的微小蜕膜动物--Beretella spinosa gen et sp.除了寒武纪基底层的 Saccorhytus 外，Beretella 在动物中没有同类。系统发育分析表明，这两种形态与所有已知的蜕皮动物都是姊妹类（Saccorhytida），从而表明蜕皮动物的祖先可能是非畸形动物。鞘翅目很可能是蜕皮动物干系的一个早期末端分支，可能是通过解剖学上的简化（如缺乏肛门）进化而来的。虽然在寒武纪已经灭绝，但这一动物谱系为我们了解Ecdysozoa的早期演化和该类群最早代表的性质（可能是非畸形）提供了宝贵的资料。
{"title":"Early evolution of the ecdysozoan body plan","authors":"Deng Wang, Yaqin Qiang, Junfeng Guo, Jean Vannier, Zucheng Song, Jiaxin Peng, Boyao Zhang, Jie Sun, Yilun Yu, Yiheng Zhang, Tao Zhang, Xiaoguang Yang, Jian Han","doi":"10.1101/2024.01.16.575973","DOIUrl":"https://doi.org/10.1101/2024.01.16.575973","url":null,"abstract":"Extant ecdysozoans (moulting animals) are represented by a great variety of vermiform or articulated organisms. However, controversies remain about the nature of their ancestral body plan although the vermiform hypothesis seems to prevail. We describe here <em>Beretella spinosa</em> gen et sp. nov. a tiny ecdysozoan from the early Cambrian, Yanjiahe Formation, South China, with an unusual sack-like appearance, single opening, and spiny ornament. <em>Beretella</em> has no equivalent among animals, except <em>Saccorhytus</em> from the basal Cambrian. Phylogenetic analyses resolve both forms as a sister group (Saccorhytida) to all known Ecdysozoa, thus suggesting that ancestral ecdysozoans may have been non-vermiform animals. Saccorhytids are likely to represent an early dead-end off-shot along the stem-line Ecdysozoa that possibly evolved through anatomical simplification (e.g. lack of anus). Although extinct during the Cambrian, this animal lineage provides precious insight into the early evolution of Ecdysozoa and the nature (possibly non-vermiform) of the earliest representatives of the group.","PeriodicalId":501477,"journal":{"name":"bioRxiv - Paleontology","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139495801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-08DOI: 10.1101/2023.12.07.570666
Nathan Lloyd Wright, Adiël A Klompmaker, Elizabeth Petsios
The fossil record of parasitism is poorly understood, due largely to the scarcity of strong fossil evidence of parasites. Understanding the preservation potential for fossil parasitic evidence is critical to contextualizing the fossil record of parasitism. Here, we present the first use of X-ray computed tomography (CT) scanning and finite elements analysis (FEA) to analyze the impact of a parasite-induced fossil trace on host preservation. Four fossil and three modern decapod crustacean specimens with branchial swellings attributed to an epicaridean isopod parasite were CT scanned and examined with FEA to assess differences in the magnitude and distribution of stress between normal and swollen branchial chambers. The results of the FEA show highly localized stress peaks in reaction to point forces, with higher peak stress on the swollen branchial chamber for nearly all specimens and different forces applied, suggesting a possible shape-related decrease in the preservation potential of these parasitic swellings. Broader application of these methods as well as advances in the application of 3D data analysis in paleontology are critical to understanding the fossil record of parasitism and other poorly represented fossil groups.
人们对寄生现象的化石记录知之甚少，这主要是由于寄生虫化石证据的缺乏。了解寄生虫化石证据的保存潜力对于了解寄生虫化石记录的来龙去脉至关重要。在这里，我们首次利用 X 射线计算机断层扫描（CT）和有限元分析（FEA）来分析寄生虫引起的化石痕迹对宿主保存的影响。对四具化石和三具现代十足目甲壳类标本进行了CT扫描和有限元分析，以评估正常鳃腔和肿胀鳃腔之间应力大小和分布的差异。有限元分析的结果表明，在点力作用下，应力峰值高度局部化，几乎所有标本和不同作用力下，肿胀鳃腔的应力峰值都较高，这表明这些寄生肿胀体的保存潜力可能与形状有关。更广泛地应用这些方法以及在古生物学中应用三维数据分析的进展，对于了解寄生虫化石记录和其他代表性较差的化石类群至关重要。
{"title":"Exploring the preservation of a parasitic trace in decapod crustaceans using finite elements analysis","authors":"Nathan Lloyd Wright, Adiël A Klompmaker, Elizabeth Petsios","doi":"10.1101/2023.12.07.570666","DOIUrl":"https://doi.org/10.1101/2023.12.07.570666","url":null,"abstract":"The fossil record of parasitism is poorly understood, due largely to the scarcity of strong fossil evidence of parasites. Understanding the preservation potential for fossil parasitic evidence is critical to contextualizing the fossil record of parasitism. Here, we present the first use of X-ray computed tomography (CT) scanning and finite elements analysis (FEA) to analyze the impact of a parasite-induced fossil trace on host preservation. Four fossil and three modern decapod crustacean specimens with branchial swellings attributed to an epicaridean isopod parasite were CT scanned and examined with FEA to assess differences in the magnitude and distribution of stress between normal and swollen branchial chambers. The results of the FEA show highly localized stress peaks in reaction to point forces, with higher peak stress on the swollen branchial chamber for nearly all specimens and different forces applied, suggesting a possible shape-related decrease in the preservation potential of these parasitic swellings. Broader application of these methods as well as advances in the application of 3D data analysis in paleontology are critical to understanding the fossil record of parasitism and other poorly represented fossil groups.","PeriodicalId":501477,"journal":{"name":"bioRxiv - Paleontology","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138563830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-08DOI: 10.1101/2023.12.07.570709
Aihua Yang, Cui Luo, Jian Han, Andrey Yu. Zhuravlev, Joachim Reitner, Haijing Sun, Han Zeng, Fangchen Zhao, Shixue Hu
The compacted macrofossil Protomelission? sp. from the early Cambrian Xiaoshiba Lagerstaette was recently ascribed to early dasycladalean green algae and used to disprove the bryozoan affinity of coeval phosphatized microfossils, which made the puzzling question whether the bryozoans originated in early Cambrian pending again. Our new analyses of multiple specimens which are conspecific with Protomelission? from the Chengjiang Lagerstaette indicate that they are not dasycladaleans but one of the three groups of archaeocyath-like sponges that atypically inhabited siliciclastic substrates. All the archaeocyath-like fossils share the same preservation mode and exhibit archaeocyath-type external skeletal features. Particularly, the Protomellision? -like fossils preserve structures indicative of archaeocyath aquiferous system and ontogeny. They represent the first recognized one-walled archaeocyath sponges in South China and evidence the niche expansion of archaeocyaths on their way of global radiation from Siberia, 518 million years ago. The origin of the bryozoans remains a mystery.
{"title":"Not dasycladalean alga, but an Odyssey of the earliest Phanerozoic animal reef-builders","authors":"Aihua Yang, Cui Luo, Jian Han, Andrey Yu. Zhuravlev, Joachim Reitner, Haijing Sun, Han Zeng, Fangchen Zhao, Shixue Hu","doi":"10.1101/2023.12.07.570709","DOIUrl":"https://doi.org/10.1101/2023.12.07.570709","url":null,"abstract":"The compacted macrofossil Protomelission? sp. from the early Cambrian Xiaoshiba Lagerstaette was recently ascribed to early dasycladalean green algae and used to disprove the bryozoan affinity of coeval phosphatized microfossils, which made the puzzling question whether the bryozoans originated in early Cambrian pending again. Our new analyses of multiple specimens which are conspecific with Protomelission? from the Chengjiang Lagerstaette indicate that they are not dasycladaleans but one of the three groups of archaeocyath-like sponges that atypically inhabited siliciclastic substrates. All the archaeocyath-like fossils share the same preservation mode and exhibit archaeocyath-type external skeletal features. Particularly, the Protomellision? -like fossils preserve structures indicative of archaeocyath aquiferous system and ontogeny. They represent the first recognized one-walled archaeocyath sponges in South China and evidence the niche expansion of archaeocyaths on their way of global radiation from Siberia, 518 million years ago. The origin of the bryozoans remains a mystery.","PeriodicalId":501477,"journal":{"name":"bioRxiv - Paleontology","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138564015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-07DOI: 10.1101/2023.12.05.570041
Landon A Anderson
The 3-D structure and organization of type-1 collagen protein and vasculature for a set of ancient permafrost bones is extensively documented at the nanoscale (up to 150,000x magnification) for the first time. The chemical mapping technique ToF-SIMS is additionally used to directly localize chemical signal to these structures; C:N and isotope measurements are also reported for the bulk organic bone matrix. These analyses test the hypothesis that biomolecular histology of collagen and vasculature from the permafrost bones supports their taphonomic classification as 'subfossils' rather than 'fossils'. Results indicate the original collagenous scaffolding and vasculature are still present, the former of which is well-preserved, thus supporting the hypothesis. This study is the first to taphonomically classify a set of pre-Holocene bones as 'subfossils' based on the preserved state of their biomolecular histology. These methods can be readily expanded to specimens of warmer thermal settings and earlier geologic strata. Doing so has potential to establish/formalize at what point a bone has been truly 'fossilized'; that is, when it has transitioned from 'subfossil' status to being a true 'fossil' bone. This will elucidate the fossilization process for ancient vertebrates and lead to a deeper understanding of what it means to be a 'fossil'.
{"title":"Nanoscale Imaging and Microanalysis of Ice Age Bone Offers New Perspective on 'Subfossils' and Fossilization","authors":"Landon A Anderson","doi":"10.1101/2023.12.05.570041","DOIUrl":"https://doi.org/10.1101/2023.12.05.570041","url":null,"abstract":"The 3-D structure and organization of type-1 collagen protein and vasculature for a set of ancient permafrost bones is extensively documented at the nanoscale (up to 150,000x magnification) for the first time. The chemical mapping technique ToF-SIMS is additionally used to directly localize chemical signal to these structures; C:N and isotope measurements are also reported for the bulk organic bone matrix. These analyses test the hypothesis that biomolecular histology of collagen and vasculature from the permafrost bones supports their taphonomic classification as 'subfossils' rather than 'fossils'. Results indicate the original collagenous scaffolding and vasculature are still present, the former of which is well-preserved, thus supporting the hypothesis. This study is the first to taphonomically classify a set of pre-Holocene bones as 'subfossils' based on the preserved state of their biomolecular histology. These methods can be readily expanded to specimens of warmer thermal settings and earlier geologic strata. Doing so has potential to establish/formalize at what point a bone has been truly 'fossilized'; that is, when it has transitioned from 'subfossil' status to being a true 'fossil' bone. This will elucidate the fossilization process for ancient vertebrates and lead to a deeper understanding of what it means to be a 'fossil'.","PeriodicalId":501477,"journal":{"name":"bioRxiv - Paleontology","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138580148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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