Latest recommendations
| Id | Title * | Authors * | Abstract * ▲ | Picture * | Thematic fields * | Recommender | Reviewers | Submission date | |
|---|---|---|---|---|---|---|---|---|---|
23 Apr 2021
The record of Deinotheriidae from the Miocene of the Swiss Jura Mountains (Jura Canton, Switzerland)The fossil record of deinotheres in the Jura Mountains and the specific diversity of European deinotheriidsRecommended by Lionel Hautier based on reviews by Martin Pickford and 1 anonymous reviewerProboscideans belong to the Afrotheria, a superorder of mammals with an African origin, which was recently recognized based on molecular data (see review in Asher et al., 2009). The fossil record of Proboscidea is well documented and shows that an important part of their evolutionary history took place in Africa, with their representatives inhabiting the continent for at least 60 million years (Gheerbrant, 2009). However, proboscideans also proved to be great travellers, and a flourishing diversity of proboscidean forms colonized most of the continents of the planet, including Europe, from where they have since completely disappeared. Nowadays, Loxodonta africana, L. cyclotis, and Elephas maximus are flagship species of the African and Asian faunas, but they only represent a minor part of the modern mammalian diversity. In contrast, their ancient relatives seemed to be relatively abundant in past ecosystems (Sanders et al., 2010), which raised a number of interesting, but challenging, questions relative to the structure and evolution of ancient megaherbivore communities (Calandra et al., 2008). Among proboscideans, deinotheres represent a special case. Their morphology clearly departs from that of other groups, notably in displaying distinctive downward curving lower tusks. Compared to their successful sister group the elephantiforms (i.e., all elephant-like proboscideans closely related to modern elephants; sensu Tassy, 1994), deinotheriids are often regarded as the poor sibling of the Proboscidea for showing a relatively low specific diversity and displaying a reduced morphological variability. In fact, many grey areas still exist regarding the evolution of this unique family. In their article, Gagliardi et al. (2021) revised the material of deinotheres recovered in the Miocene sands of the Swiss Jura Mountains. They described for the first time the material attributed to Prodeinotherium bavaricum and Deinotherium giganteum from the Delémont valley, and reported the presence of a third species, Deinotherium levius, from the locality of Charmoille in Ajoie. Based on comparisons made on specimens recovered from middle to the late Miocene localities, the authors discussed the potential link between the mode and tempo of deinothere dispersions and the evolution environmental and climatic conditions in Western and Eastern Europe during the Miocene. They also considered the evolution of ecological specializations in the group, especially with regard to size increase. Gagliardi et al. (2021) proposed to follow the two genera/five species concept (i.e., P. cuvieri, P. bavaricum, D. levius, D. giganteum, and D. proavum), which implies the co-existence of several deinothere species in Europe. The latter hypothesis contrasts with the recognition of a single African Deinotherium species (i.e., D. bozasi) in deposits dated from the late Miocene to the early Pleistocene (Sanders et al., 2010). Such a co-existence of European species was and still is debated; it was here questioned by both reviewers. However, as acknowledged by the authors, only an extensive revision of the material of all recognized species, in Europe and worldwide, will enable to shed more light on the deinothere morphological variability and specific diversity. There is no doubt that such a revision would have a profound impact on our view of the evolution of this enigmatic group.
References Asher, R. J., Bennett, N., & Lehmann, T. (2009). The new framework for understanding placental mammal evolution. BioEssays, 31(8), 853–864. doi: 10.1002/bies.200900053 Calandra, I., Göhlich, U. B., & Merceron, G. (2008). How could sympatric megaherbivores coexist? Example of niche partitioning within a proboscidean community from the Miocene of Europe. Naturwissenschaften, 95(9), 831–838. doi: 10.1007/s00114-008-0391-y Gagliardi, F., Maridet, O., & Becker, D. (2021). The record of Deinotheriidae from the Miocene of the Swiss Jura Mountains (Jura Canton, Switzerland). BioRxiv, 244061, ver. 4 peer-reviewed by PCI Paleo. doi: 10.1101/2020.08.10.244061 Gheerbrant, E. (2009). Paleocene emergence of elephant relatives and the rapid radiation of African ungulates. Proceedings of the National Academy of Sciences, 106(26), 10717–10721. doi: 10.1073/pnas.0900251106 Sanders, W. J., Gheerbrant, E., Harris, J. M., Saegusa, H., & Delmer, C. (2010). Proboscidea. In L. Werdelin & W. J. Sanders (Eds.), Cenozoic Mammals of Africa (pp. 161–251). Berkeley: University of California Press. doi: 10.1525/california/9780520257214.003.0015 Tassy, P. (1994). Origin and differentiation of the Elephantiformes (Mammalia, Proboscidea). Verhandlungen Naturwissenschaftlichen Vereins in Hamburg, 34, 73–94. | The record of Deinotheriidae from the Miocene of the Swiss Jura Mountains (Jura Canton, Switzerland) | Fanny Gagliardi, Olivier Maridet, Damien Becker | <p>The Miocene sands of the Swiss Jura Mountains, long exploited in quarries for the construction industry, have yielded abundant fossil remains of large mammals. Among Deinotheriidae (Proboscidea), two species, Prodeinotherium bavaricum and Deino... | | Fossil record, Paleobiogeography, Taxonomy, Vertebrate paleontology | Lionel Hautier | 2020-08-11 10:17:38 | ||
30 Oct 2019
The Morrison Formation Sauropod Consensus: A freely accessible online spreadsheet of collected sauropod specimens, their housing institutions, contents, references, localities, and other potentially useful informationSauropods under one (very high) roofRecommended by Jordan Mallon based on reviews by Kenneth Carpenter and Femke HolwerdaFossils get around. Any one fossil locality might be sampled by several collectors from as many institutions around the world. Alternatively, a single collector might heavily sample a site, and sell or trade parts of their collection to other institutions, scattering the fossils far and wide. These practices have the advantage of making fossils from any one locality available to researchers across the globe. However, they also have the disadvantage that, in order to systematically survey any one species, a researcher must follow innumerable trails of breadcrumb to get to where the relevant materials are held. This is true of many famous fossil localities, such as the Eocene Green River Formation in the USA, the Cretaceous Kem Kem beds of Morocco, or the Devonian Miguasha cliffs of Canada. It is especially true of the Upper Jurassic deposits of the Morrison Formation in the western USA, which have yielded an impressive assemblage of megaherbivorous sauropod dinosaurs over the last 150 years. Today, these bones are to be found in museums not just in the USA, but also in Canada, Argentina, Japan, Australia, Malaysia, South Africa, and throughout Europe. Trawling museum databases in search of sauropod material from the Morrison Formation can therefore be a daunting task, never mind traveling the globe to actually study them. A new paper by Tschopp et al. (2019) seeks to ease the burden on sauropod researchers by introducing a database of Morrison Formation sauropods, consisting of over 3000 specimens housed in nearly 40 institutions around the world. The authors are themselves sauropod workers and, having suffered first-hand the plight of studying material from the Morrison Formation, came up with a solution to the problem of keeping track of it all. The database is founded largely on material personally seen by the authors, supplemented by information from the literature and museum catalogs. The database further provides information on bone representation, ontogeny, locality details, and fine-scale stratigraphy, among other fields. Like any database, it is a living document that will continue to grow as new finds are made. Tschopp et al. (2019) have wisely chosen to allow others to contribute to the listing, but changes must first be vetted for accuracy. This product represents 10 years of work, and I have little doubt that it will be well-received by those of us who work on dinosaurs. Speaking personally, my PhD research on megaherbivorous dinosaurs from the Dinosaur Park Formation of Canada led me to institutions in Canada, the USA, and the UK, and further stops to Spain and Argentina would have been beneficial, if affordable. Planning for this work would have been greatly assisted by a database like the one provided us by Tschopp et al. (2019). Many a future graduate student will undoubtedly owe them a debt of gratitude. References Tschopp, E., Whitlock, J. A., Woodruff, D. C., Foster, J. R., Lei, R., & Giovanardi, S. (2019). The Morrison Formation Sauropod Consensus: A freely accessible online spreadsheet of collected sauropod specimens, their housing institutions, contents, references, localities, and other potentially useful information. PaleorXiv, version 3, peer-reviewed by PCI Paleo. doi: 10.31233/osf.io/ydvra | The Morrison Formation Sauropod Consensus: A freely accessible online spreadsheet of collected sauropod specimens, their housing institutions, contents, references, localities, and other potentially useful information | Emanuel Tschopp, John A. Whitlock, D. Cary Woodruff, John R. Foster, Roberto Lei, Simone Giovanardi | <p>The Morrison Formation has been explored for dinosaurs for more than 150 years, in particular for large sauropod skeletons to be mounted in museum exhibits around the world. Several long-term campaigns to the Jurassic West of the United States ... | | Fossil record, Methods, Paleobiodiversity, Taxonomy, Vertebrate paleontology | Jordan Mallon | 2019-07-19 16:13:45 | ||
16 Oct 2019
What do ossification sequences tell us about the origin of extant amphibians?The origins of LissamphibiaRecommended by Robert Asher ? based on reviews by Jennifer Olori and 2 anonymous reviewersAmong living vertebrates, there is broad consensus that living tetrapods consist of amphibians and amniotes. Crown clade Lissamphibia contains frogs (Anura), salamanders (Urodela) and caecilians (Gymnophiona); Amniota contains Sauropsida (reptiles including birds) and Synapsida (mammals). Within Lissamphibia, most studies place frogs and salamanders in a clade together to the exclusion of caecilians (see Pyron & Wiens 2011). Among fossils, there are a number of amphibian and amphibian-like taxa generally placed in Temnospondyli and Lepospondyli. In contrast to the tree of living tetrapods, affinities of these fossils to some or all of the three extant lissamphibian groups have proven to be much harder to resolve. For example, temnospondyls might be stem tetrapods and lissamphibians a derived group of lepospondyls; alternatively, temnospondyls might be closer to the clade of frogs and salamanders, and lepospondyls to caecilians (compare Laurin et al. 2019: fig. 1d vs. 1f). Here, in order to assess which of these and other mutually exclusive topologies is optimal, Laurin et al. (2019) extract phylogenetic information from developmental sequences, in particular ossification. Several major differences in ossification are known to distinguish vertebrate clades. For example, due to their short intrauterine development and need to climb from the reproductive tract into the pouch, marsupial mammals famously accelerate ossification of their facial skeleton and forelimb; in contrast to placentals, newborn marsupials can climb, smell & suck before they have much in the way of lungs, kidneys, or hindlimbs (Smith 2001). Divergences among living and fossil amphibian groups are likely pre-Triassic (San Mauro 2010; Pyron 2011), much older than a Jurassic split between marsupials and placentals (Tarver et al. 2016), and the quality of the fossil record generally decreases with ever-older divergences. Nonetheless, there are a number of well-preserved examples of "amphibian"-grade tetrapods representing distinct ontogenetic stages (Schoch 2003, 2004; Schoch and Witzmann 2009; Olori 2013; Werneburg 2018; among others), all amenable to analysis of ossification sequences. Putting together a phylogenetic dataset based on ossification sequences is not trivial; sequences are not static features apparent on individual specimens. Rather, one needs multiple specimens representing discrete developmental stages for each taxon to be compared, meaning that sequences are usually available for only a few characters. Laurin et al. (2019) have nonetheless put together the most exhaustive matrix of tetrapod sequences so far, with taxon coverage ranging from 62 genera for appendicular characters to 107 for one of their cranial datasets, each sampling between 4-8 characters (Laurin et al. 2019: table 1). The small number of characters means that simply applying an optimality criterion (such as parsimony) is unlikely to resolve most nodes; treespace is too flat to be able to offer optimal peaks up which a search algorithm might climb. However, Laurin et al. (2019) were able to test each of the main competing hypotheses, defined a priori as a branching topology, given their ossification sequence dataset and a likelihood optimality criterion. Their most consistent result comes from their cranial ossification sequences and supports their "LH", or lepospondyl hypothesis (Laurin et al. 2019: fig. 1d). That is, relative to extinct, "amphibian"-grade taxa, Lissamphibia is monophyletic and nested within lepospondyls. Compared to mammals and birds (including dinosaurs), crown amphibian branches of the Tree of Life are exceptionally old. Each lissamphibian clade likely had diverged during Permian times (Marjanovic & Laurin 2008) and the crown group itself may even date to the Carboniferous (Pyron 2011). In contrast to mammoths and moas, no ancient DNA or collagen sequences are going to be available from >300 million-year-old fossils like the lepospondyl *Hyloplesion* (Olori 2013), although recently published methods for incorporating genomic signal from extant taxa (Beck & Baillie 2018; Asher et al. 2019) into studies of fossils could also be applied to these ancient divergences among amphibian-grade tetrapods. Ossification sequences represent another important, additional source of data with which to test the conclusion of Laurin et al. (2019) that monophyletic Lissamphibians shared a common ancestor with lepospondyls, among other hypotheses. **References** Asher, R. J., Smith, M. R., Rankin, A., & Emry, R. J. (2019). Congruence, fossils and the evolutionary tree of rodents and lagomorphs. Royal Society Open Science, 6(7), 190387. doi: [ 10.1098/rsos.190387 ](https://dx.doi.org/ 10.1098/rsos.190387 ) Beck, R. M. D., & Baillie, C. (2018). Improvements in the fossil record may largely resolve current conflicts between morphological and molecular estimates of mammal phylogeny. Proceedings of the Royal Society B: Biological Sciences, 285(1893), 20181632. doi: [ 10.1098/rspb.2018.1632](https://dx.doi.org/ 10.1098/rspb.2018.1632) Laurin, M., Lapauze, O., & Marjanović, D. (2019). What do ossification sequences tell us about the origin of extant amphibians? BioRxiv, 352609, ver. 4 peer-reviewed by PCI Paleo. doi: [ 10.1101/352609](https://dx.doi.org/ 10.1101/352609) Marjanović, D., & Laurin, M. (2008). Assessing confidence intervals for stratigraphic ranges of higher taxa: the case of Lissamphibia. Acta Palaeontologica Polonica, 53(3), 413–432. doi: [ 10.4202/app.2008.0305](https://dx.doi.org/ 10.4202/app.2008.0305) Olori, J. C. (2013). Ontogenetic sequence reconstruction and sequence polymorphism in extinct taxa: an example using early tetrapods (Tetrapoda: Lepospondyli). Paleobiology, 39(3), 400–428. doi: [ 10.1666/12031](https://dx.doi.org/ 10.1666/12031) Pyron, R. A. (2011). Divergence time estimation using fossils as terminal taxa and the origins of Lissamphibia. Systematic Biology, 60(4), 466–481. doi: [ 10.1093/sysbio/syr047](https://dx.doi.org/ 10.1093/sysbio/syr047) Pyron, R. A., & Wiens, J. J. (2011). A large-scale phylogeny of Amphibia including over 2800 species, and a revised classification of extant frogs, salamanders, and caecilians. Molecular Phylogenetics and Evolution, 61(2), 543–583. doi: [ 10.1016/j.ympev.2011.06.012](https://dx.doi.org/ 10.1016/j.ympev.2011.06.012) San Mauro, D. (2010). A multilocus timescale for the origin of extant amphibians. Molecular Phylogenetics and Evolution, 56(2), 554–561. doi: [ 10.1016/j.ympev.2010.04.019](https://dx.doi.org/ 10.1016/j.ympev.2010.04.019) Schoch, R. R. (2003). Early larval ontogeny of the Permo-Carboniferous temnospondyl *Sclerocephalus*. Palaeontology, 46(5), 1055–1072. doi: [ 10.1111/1475-4983.00333](https://dx.doi.org/ 10.1111/1475-4983.00333) Schoch, R. R. (2004). Skeleton formation in the Branchiosauridae: a case study in comparing ontogenetic trajectories. Journal of Vertebrate Paleontology, 24(2), 309–319. doi: [ 10.1671/1950](https://dx.doi.org/ 10.1671/1950) Schoch, R. R., & Witzmann, F. (2009). Osteology and relationships of the temnospondyl genus *Sclerocephalus*. Zoological Journal of the Linnean Society, 157(1), 135–168. doi: [ 10.1111/j.1096-3642.2009.00535.x](https://dx.doi.org/ 10.1111/j.1096-3642.2009.00535.x) Smith, K. K. (2001). Heterochrony revisited: the evolution of developmental sequences. Biological Journal of the Linnean Society, 73(2), 169–186. doi: [ 10.1111/j.1095-8312.2001.tb01355.x](https://dx.doi.org/ 10.1111/j.1095-8312.2001.tb01355.x) Tarver, J. E., dos Reis, M., Mirarab, S., Moran, R. J., Parker, S., O’Reilly, J. E., & Pisani, D. (2016). The interrelationships of placental mammals and the limits of phylogenetic inference. Genome Biology and Evolution, 8(2), 330–344. doi: [ 10.1093/gbe/evv261](https://dx.doi.org/ 10.1093/gbe/evv261) Werneburg, R. (2018). Earliest “nursery ground” of temnospondyl amphibians in the Permian. Semana, 32, 3–42. | What do ossification sequences tell us about the origin of extant amphibians? | Michel Laurin, Océane Lapauze, David Marjanović | <p>The origin of extant amphibians has been studied using several sources of data and methods, including phylogenetic analyses of morphological data, molecular dating, stratigraphic data, and integration of ossification sequence data, but a consen... | | Evo-Devo, Phylogenetics, Systematics, Vertebrate paleontology | Robert Asher | 2018-06-22 08:21:31 | ||
05 Sep 2024
Introducing ‘trident’: a graphical interface for discriminating groups using dental microwear texture analysisA step towards improved replicability and accessibility of 3D microwear analysesRecommended by Emilia Jarochowska based on reviews by Mugino Kubo and 1 anonymous reviewer
Three-dimensional microwear analysis is a very potent method in capturing the diet and, thus, reconstructing trophic relationships. It is widely applied in archaeology, palaeontology, neontology and (palaeo)anthropology. The method had been developed for mammal teeth (Walker et al., 1978; Teaford, 1988; Calandra and Merceron, 2016), but it has proven to be applicable to sharks (McLennan and Purnell, 2021) and reptiles, including fossil taxa with rather mysterious trophic ecologies (e.g., Bestwick et al., 2020; Holwerda et al., 2023). Microwear analysis has brought about landmark discoveries extending beyond autecology and reaching into palaeoenvironmental reconstructions (e.g., Merceron et al., 2016), niche evolution (e.g., Thiery et al., 2021), and assessment of food availability and niche partitioning (Ősi et al., 2022). Furthermore, microwear analysis is a testable method, which can be investigated experimentally in extant animals in order to ground-truth dietary interpretations in extinct organisms. The study by Thiery et al. (2024) addresses important limitations of 3D microwear analysis: 1) the unequal access to commercial software required to analyze surface data obtained using confocal profilometers; 2) lack of replicability resulting from the use of commercial software with graphical user interface only. The latter point results in that documenting precisely what has been analyzed and how is nearly impossible. The use of algorithms such as scale-sensitive fractal analysis (Ungar et al., 2003; Scott et al., 2006) and surface texture analysis has greatly improved replicability of DMTA and nearly eliminated intra- and inter-observer errors. Substantial effort has been made to quantify and minimize systematic and random errors in microwear analyses, such as intraspecific variation, use of different equipment (Arman et al., 2016), use of casts (Mihlbachler et al., 2019) or non-dietary variables (Bestwick et al., 2021). But even the best designed study cannot be replicated if the analysis is carried out with a “black box” software that many researchers may not afford. The trident package for R Software (https://github.com/nialsiG/trident) presented by Thiery et al. (2024) allows users to calculate 24 variables used in DMTA, transform them, calculate their variation across a surface, and rank them according to a sophisticated workflow that takes into account their normality and heteroscedasticity. A graphical user interface (GUI) is included in the form of a ShinyApp, but the power of the package, in my opinion, lies in that all steps of the analyses can be saved as R code and shared together with a study. This is a fundamental contribution to replicability and validation of microwear analyses. As best practices in code quality and replication become better known and accessible to palaeobiologists (The Turing Way Community, 2022; Trisovic et al., 2022). The presentation of the trident package is associated with three case studies, each with associated instructions on reproducing the results. These instructions partly use the literate programming approach, so that each step of the analysis is discussed and the methods are presented, either as screen shots when the GUI is used, or code. This is an excellent contribution, which hopefully will be followed by future microwear studies. References Arman, S. D., Ungar, P. S., Brown, C. A., DeSantis, L. R. G., Schmidt, C., and Prideaux, G. J. (2016). Minimizing inter-microscope variability in dental microwear texture analysis. Surface Topography: Metrology and Properties, 4(2), 024007. https://doi.org/10.1088/2051-672X/4/2/024007 Bestwick, J., Unwin, D. M., Butler, R. J., and Purnell, M. A. (2020). Dietary diversity and evolution of the earliest flying vertebrates revealed by dental microwear texture analysis. Nature Communications, 11(1), 5293. https://doi.org/10.1038/s41467-020-19022-2 Bestwick, J., Unwin, D. M., Henderson, D. M., and Purnell, M. A. (2021). Dental microwear texture analysis along reptile tooth rows: Complex variation with non-dietary variables. Royal Society Open Science, 8(2), 201754. https://doi.org/10.1098/rsos.201754 Calandra, I., and Merceron, G. (2016). Dental microwear texture analysis in mammalian ecology. Mammal Review, 46(3), 215–228. https://doi.org/10.1111/mam.12063 Holwerda, F. M., Bestwick, J., Purnell, M. A., Jagt, J. W. M., and Schulp, A. S. (2023). Three-dimensional dental microwear in type-Maastrichtian mosasaur teeth (Reptilia, Squamata). Scientific Reports, 13(1), 18720. https://doi.org/10.1038/s41598-023-42369-7 McLennan, L. J., and Purnell, M. A. (2021). Dental microwear texture analysis as a tool for dietary discrimination in elasmobranchs. Scientific Reports, 11(1), 2444. https://doi.org/10.1038/s41598-021-81258-9 Merceron, G., Novello, A., and Scott, R. S. (2016). Paleoenvironments inferred from phytoliths and Dental Microwear Texture Analyses of meso-herbivores. Geobios, 49(1–2), 135–146. https://doi.org/10.1016/j.geobios.2016.01.004 Mihlbachler, M. C., Foy, M., and Beatty, B. L. (2019). Surface replication, fidelity and data loss in traditional dental microwear and dental microwear texture analysis. Scientific Reports, 9(1), 1595. https://doi.org/10.1038/s41598-018-37682-5 Ősi, A., Barrett, P. M., Evans, A. R., Nagy, A. L., Szenti, I., Kukovecz, Á., Magyar, J., Segesdi, M., Gere, K., and Jó, V. (2022). Multi-proxy dentition analyses reveal niche partitioning between sympatric herbivorous dinosaurs. Scientific Reports, 12(1), 20813. https://doi.org/10.1038/s41598-022-24816-z Scott, R. S., Ungar, P. S., Bergstrom, T. S., Brown, C. A., Childs, B. E., Teaford, M. F., and Walker, A. (2006). Dental microwear texture analysis: Technical considerations. Journal of Human Evolution, 51(4), 339–349. https://doi.org/10.1016/j.jhevol.2006.04.006 Teaford, M. F. (1988). A review of dental microwear and diet in modern mammals. Scanning Microscopy, 2, 1149–1166. The Turing Way Community. (2022). The Turing Way: A handbook for reproducible, ethical and collaborative research (Version 1.0.2). Zenodo. https://doi.org/10.5281/ZENODO.3233853 Thiery, G., Francisco, A., Louail, M., Berlioz, É., Blondel, C., Brunetière, N., Ramdarshan, A., Walker, A. E. C., and Merceron, G. (2024). Introducing “trident”: A graphical interface for discriminating groups using dental microwear texture analysis. HAL, hal-04222508, ver. 4 peer-reviewed by PCI Paleo. https://hal.science/hal-04222508v4 Thiery, G., Gibert, C., Guy, F., Lazzari, V., Geraads, D., Spassov, N., and Merceron, G. (2021). From leaves to seeds? The dietary shift in late Miocene colobine monkeys of southeastern Europe. Evolution, 75(8), 1983–1997. https://doi.org/10.1111/evo.14283 Trisovic, A., Lau, M. K., Pasquier, T., and Crosas, M. (2022). A large-scale study on research code quality and execution. Scientific Data, 9(1), 60. https://doi.org/10.1038/s41597-022-01143-6 Ungar, P. S., Brown, C. A., Bergstrom, T. S., and Walker, A. (2003). Quantification of dental microwear by tandem scanning confocal microscopy and scale‐sensitive fractal analyses. Scanning, 25(4), 185–193. https://doi.org/10.1002/sca.4950250405 Walker, A., Hoeck, H. N., and Perez, L. (1978). Microwear of mammalian teeth as an indicator of diet. Science, 201(4359), 908–910. https://doi.org/10.1126/science.684415 | Introducing ‘trident’: a graphical interface for discriminating groups using dental microwear texture analysis | Thiery G., Francisco A., Louail M., Berlioz E., Blondel C., Brunetière N., Ramdarshan A., Walker A. E. C., Merceron G. | <p>This manuscript introduces trident, an R package for performing dental microwear texture analysis and subsequently classifying variables based on their ability to separate discrete categories. Dental microwear textures reflect the physical prop... | | Paleoecology, Vertebrate paleontology | Emilia Jarochowska | 2023-09-30 22:56:03 | ||
22 Sep 2018
Palaeobiological inferences based on long bone epiphyseal and diaphyseal structure - the forelimb of xenarthrans (Mammalia)Inferences on the lifestyle of fossil xenarthrans based on limb long bone inner structureRecommended by Alexandra Houssaye based on reviews by Andrew Pitsillides and 1 anonymous reviewerBone inner structure bears a strong functional signal and can be used in paleontology to make inferences about the ecology of fossil forms. The increasing use of microtomography enables to analyze both cortical and trabecular features in three dimensions, and thus in long bones to investigate the diaphyseal and epiphyseal structures. Moreover, this can now be done through quantitative, and not only qualitative analyses. Studies focusing on the diaphyseal inner structure (cortical bone and sometimes also spongious bone) of long bones are rather numerous, but essentially based on 2D sections. It is only recently that analyses of the whole diaphyseal structure have been investigated. Studies on the trabecular architecture are much rarer. Amson & Nyakatura (2018) propose a comparative quantitative analysis combining parameters of the epiphyseal trabecular architecture and of the diaphyseal structure, using phylogenetically informed discriminant analyses, and with the aim of inferring the lifestyle of extinct taxa. The group of interest is xenarthrans, one of the four major extant clades of placental mammals. Xenarthrans exhibit different lifestyles, from fully terrestrial to arboreal, and show various degrees of fossoriality. The authors analyzed forelimb long bones of some fossil sloths and made comparisons with several species of extant xenarthrans. The aim was notably to discuss the degree of arboreality and fossoriality of these fossil forms. This study is among the first ones to conjointly analyze both diaphyseal and trabecular parameters to characterize lifestyles, and the first one outside of primates. No fossil form could undoubtedly be assigned to one lifestyle exhibited by extant xenarthrans, though some previous ecological hypotheses could be corroborated. This study also raised some technical challenges, linked to the sample and to the parameters studied, and thus constitutes a great step, from which to go further. References Amson, E., & Nyakatura, J. A. (2018). Palaeobiological inferences based on long bone epiphyseal and diaphyseal structure - the forelimb of xenarthrans (Mammalia). bioRxiv, 318121, ver. 5 peer-reviewed and recommended by PCI Paleo. doi: 10.1101/318121 | Palaeobiological inferences based on long bone epiphyseal and diaphyseal structure - the forelimb of xenarthrans (Mammalia) | Eli Amson & John A. Nyakatura | <p>Trabecular architecture (i.e., the main orientation of the bone trabeculae, their number, mean thickness, spacing, etc.) has been shown experimentally to adapt with great accuracy and sensitivity to the loadings applied to the bone during life.... | | Biomechanics & Functional morphology, Comparative anatomy, Evolutionary biology, Histology, Methods, Morphological evolution, Paleobiology, Vertebrate paleontology | Alexandra Houssaye | 2018-05-14 08:35:20 |
