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23 Jan 2025
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New data on morphological evolution and dietary adaptations of Elephas recki from the Plio-Pleistocene Shungura Formation (Lower Omo Valley, Ethiopia)

Of elephant teeth and plants: mesowear and dental adaptations do not track in Plio-Pleistocene elephants of the Shungura formation (Omo Valley, Ethiopia)

Recommended by ORCID_LOGO based on reviews by Steven Zhang and 1 anonymous reviewer

Bedane et al. (2024) provide a beautifully illustrated demonstration of the difficulties in using dental adaptation as proxies for the diets of elephants, which are in turn often used to determine the vegetation in an area. This study set out to assess mesowear, which is the relief on the teeth that forms due to abrasion by food, and therefore a good proxy of dietary composition in herbivores. The team was interested in testing whether this mesowear relates to morphological adaptations of hypsodonty (high-crownedness) and enamel thickness over a period of ~3.4–~1.1 million years in an elephant species (Elephas recki) commonly found in the Plio/Pleistocene of the Shungura formation (Omo Valley, Ethiopia). To answer this question, the team scored these metrics in 140 molars between ~3.4 and ~1.1 million years of age, separated into time bins. Their results show surprisingly low levels of variation in mesowear, indicating relatively low variation in diet that was overall mostly composed of graze (as opposed to mixed or browsing diets, which are softer). Hypsodonty and enamel thickness were correlated, but changed erratically rather than suggesting a trend towards a particular dietary adaptation. The exciting conclusion is that dental morphologies that we often consider to be adaptive to certain conditions are very slow to evolve, and that a wide variety of morphologies can support the survival of a species despite little variation in diet. For me as a functional evolutionary morphologist, this clear case of many-to-one-mapping is a timely reminder that evolution does not work either quickly or just on the one character complex I might be considering. And in terms of using elephant teeth as ecological proxies – this job clearly just got a little harder.

References

Bedane, T. G., Mackaye, H. T., and Boisserie, J.-R. (2025). New data on morphological evolution and dietary adaptations of Elephas recki from the Plio-Pleistocene Shungura Formation (Lower Omo Valley, Ethiopia). PaleorXiv, qexuf, ver. 4, peer-reviewed by PCI Paleo. https://doi.org/10.31233/osf.io/qexuf

New data on morphological evolution and dietary adaptations of *Elephas recki* from the Plio-Pleistocene Shungura Formation (Lower Omo Valley, Ethiopia)Tomas Getachew Bedane, Hassane Taïsso Mackaye, Jean-Renaud Boisserie<p style="text-align: justify;">The proboscideans, abundant and diverse throughout the Cenozoic, are essential terrestrial megaherbivores for studying morphological adaptations and reconstructing paleoenvironments in Africa. This new study of the ...Fieldwork, Fossil record, Morphological evolution, Morphometrics, Paleoecology, Paleoenvironments, Vertebrate paleontologyVera Weisbecker2024-04-24 13:32:58 View
05 Sep 2024
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Introducing ‘trident’: a graphical interface for discriminating groups using dental microwear texture analysis

A step towards improved replicability and accessibility of 3D microwear analyses

Recommended by ORCID_LOGO 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 analysisThiery 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 paleontologyEmilia Jarochowska2023-09-30 22:56:03 View
18 Dec 2024
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Simple shell measurements do not consistently predict habitat in turtles: a reply to Lichtig and Lucas (2017)

Not-so-simple turtle ecomorphology

Recommended by based on reviews by Heather F. Smith and Donald Brinkman

I am a non-avian dinosaur palaeontologist by trade with a particular interest in their palaeoecology. This can be an endless source of both fascination and frustration. Fascination, because non-avian dinosaurs are quite unlike anything alive today, warranting some use of creative license when imagining them as living animals. Frustration, because the lack of good, extant ecological analogues frequently makes reconstruction of their ancient ecologies an almost insurmountable challenge.

The Canadian Museum of Nature where I work has a good collection of Late Cretaceous turtles. I took an interest in these some years ago because it struck me that, despite the quality of our collection, relatively few people come to study them. I thought, "Someone should work on these. Why not me?" I figured studying a new fossil group would present a fun change of pace and perhaps a more straightforward object of palaeoecological reconstruction. After all, fossil turtles are a lot like living turtles, so how hard can it be? Right?

In 2018, I took a special interest in one recently prepared fossil turtle, which I determined to be a new species of Basilemys (Mallon and Brinkman, 2018). Basilemys held my interest because, although it is a relatively common form, there has been some debate concerning the palaeohabitat of this animal and its closest relatives, the nanhsiungchelyids. Some have argued for an aquatic habitat for these animals; others, for a terrestrial one. It seems that where one comes down on the issue depends on which aspect of ecomorphology is emphasized. If it is on the flat carapace, nanhsiungchelyids must have been aquatic; if it is on the stout feet, terrestrial. This is how I came to appreciate the numerous ecomorphological proxies (e.g., skull shape, shell shape, limb proportions) that are used in turtle palaeoecology and how incongruent they can sometimes be. So much for easy answers!

The present study by Evers et al. is a response to an original piece of research by Lichtig and Lucas (2017), who claimed to be able to use simple shell measurements (carapacial doming and relative plastral width) to accurately deduce/infer the habitats of living turtles and, by extension, fossil ones. In short, they found that terrestrial turtles tend to have more domed carapaces and wider plastra, yielding some unconventional palaeoecological reconstructions of particular stem turtles. Evers et al. take issue with several aspects of this study, including issues of faulty data entry, inappropriate removal of extant taxa from the model, and insufficient accounting for phylogenetic non-independence. By correcting for these overights, they find that the model of Lichtig and Lucas (2017) performs more poorly than advertised and that the palaeoecological classification it produces should be questioned. "The map is not the territory", as Alfred Korzybski put it, and this latest study by Evers et al. serves as an important reminder of that lesson.
Still, even if Lichtig and Lucas's model is overly simplistic, it is true that aquatic turtles, on average, have lower carapaces and narrower plastra, and that they have relatively lower skulls and longer toes. Surely, there is merit in each of these anatomical proxies, even if no single one predicts ecology with total accuracy. I would love to see a model that combines them all. Until then, Evers et al. have inched us closer to knowing what turtle morphology can (and cannot) tell us about habitat.

Thanks to D. Brinkman and H. Smith for their helpful reviews of the manuscript.

References

Evers, S. W., Foth, C., Joyce, W. G., and Hermanson, G. (2024). Simple shell measurements do not consistently predict habitat in turtles: A reply to Lichtig and Lucas (2017). bioRxiv, 586561, ver. 3 peer-reviewed by PCI Paleo. https://doi.org/10.1101/2024.03.25.586561

Lichtig, A. J., and Lucas, S. G. (2017). A simple method for inferring habitats of extinct turtles. Palaeoworld, 26(3), 581–588. https://doi.org/10.1016/j.palwor.2017.02.001

Mallon, J. C., and Brinkman, D. B. (2018). Basilemys morrinensis, a new species of nanhsiungchelyid turtle from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta, Canada. Journal of Vertebrate Paleontology, 38(2), e1431922. https://doi.org/10.1080/02724634.2018.1431922

Simple shell measurements do not consistently predict habitat in turtles: a reply to Lichtig and Lucas (2017)Serjoscha W. Evers, Christian Foth, Walter G. Joyce, Guilherme Hermanson<p>Inferring palaeoecology for fossils is a key interest of palaeobiology. For groups with extant representatives, correlations of aspects of body shape with ecology can provide important insights to understanding extinct members of lineages. The ...Evolutionary biology, Macroevolution, Morphological evolution, Morphometrics, Paleoecology, Vertebrate paleontologyJordan Mallon2024-04-19 13:31:59 View
14 Apr 2021
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The impact of allometry on vomer shape and its implications for the taxonomy and cranial kinesis of crown-group birds

Vomers aren't so different in crown group birds when considering allometric effects

Recommended by based on reviews by Sergio Martínez Nebreda and Roland Sookias

Today’s birds are divided into two deeply divergent and historically well-documented groups: Palaeognathae and Neognathae. Palaeognaths include both the flight-capable tinamous as well as the flightless ratites (ostriches, rheas, kiwis, cassowaries, and kin). Neognaths include all other modern birds, ranging from sparrows to penguins to hummingbirds. The clade names refer to the anatomy of the palate, with the “old jaws” (palaeognaths) originally thought to more closely resemble an ancestral reptilian condition and the “new jaws” (neognaths) showing a uniquely modified bony configuration. This particularly manifests in the pterygoid-palatine complex (PPC) in the palate, formed from pairs of pterygoids and palatines alongside a single midline vomer. In palaeognaths, the vomer is comparatively large and the pterygoid and palatine are relatively tightly connected. The PPC is more mobile in neognaths, with a variably shaped vomer, which is sometimes even absent. Although both groups of birds show cranial kinesis, neognaths exhibit a much more pronounced degree of kinesis versus palaeognaths, due in part to the tighter nature of the palaeognath pterygoid/palatine interfaces.

A previous paper (Hu et al. 2019) used 3D geometric morphometrics to compare the shape of the vomer across neognaths and palaeognaths. Among other findings, this work suggested that each clade had a distinct vomer morphology, with palaeognaths more similar to the ancestral condition (i.e., that of non-avian dinosaurs). This observation was extended to support inferences of limited vs. less limited cranial kinesis in various extinct species, based in part on observations of vomer shape. A new preprint by Plateau and Foth (2021) presents a reanalysis of Hu et al.’s data, specifically focusing on allometric effects. In short, the new analysis looks at how size correlates (or doesn't correlate) with vomer shape. 

Plateau and Foth (2021) found that when size effects are included, differences between palaeognaths and neognaths are less than the “raw” (uncorrected) shape data suggest. It is much harder to tell bird groups apart! Certainly, there are still some general differences, but some separations in morphospace close up when allometry—the interrelationship between shape and size—is considered. Plateau and Foth (2021) use this finding to suggest that 1) vomer shape alone is not a completely reliable proxy for inferring the phylogenetic affinities of a particular bird; and 2) the vomer is only one small component of the cranial kinetic system, and thus its shape is of limited utility for inferring cranial kinesis capabilities when considered independently from the rest of the relevant skull bones.

 

References

Hu, H., Sansalone, G., Wroe, S., McDonald, P. G., O’Connor, J. K., Li, Z., Xu, X., & Zhou, Z. (2019). Evolution of the vomer and its implications for cranial kinesis in Paraves. Proceedings of the National Academy of Sciences, 116(39), 19571–19578. doi: 10.1073/pnas.1907754116

Plateau, O., & Foth, C. (2021). The impact of allometry on vomer shape and its implications for the taxonomy and cranial kinesis of crown-group birds. BioRxiv, 184101, ver. 3 peer-reviewed by PCI Paleo. doi: 10.1101/2020.07.02.184101

The impact of allometry on vomer shape and its implications for the taxonomy and cranial kinesis of crown-group birdsOlivia Plateau, Christian Foth<p>Crown birds are subdivided into two main groups, Palaeognathae and Neognathae, that can be distinguished, among others, by the organization of the bones in their pterygoid-palatine complex (PPC). Shape variation to the vomer, which is the most ...Comparative anatomy, Evolutionary biology, Macroevolution, Morphological evolution, Morphometrics, TaxonomyAndrew Farke2020-07-03 14:16:48 View
03 Jul 2024
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Identification of the mode of evolution in incomplete carbonate successions

Advances in understanding how stratigraphic structure impacts inferences of phenotypic evolution

Recommended by ORCID_LOGO based on reviews by Bjarte Hannisdal, Katharine Loughney, Gene Hunt and 1 anonymous reviewer

A fundamental question in evolutionary biology and paleobiology is how quickly populations and/or species evolve and under what circumstances. Because the fossil record affords us the most direct view of how species lineages have changed in the past, considerable effort has gone into developing methodological approaches for assessing rates of evolution as well as what has been termed “mode of evolution” which generally describes pattern of evolution, for example whether the morphological change captured in fossil time series are best characterized as static, punctuated, or trending (e.g., Sheets and Mitchell, 2001; Hunt, 2006, 2008; Voje et al., 2018). The rock record from which these samples are taken, however, is incomplete, due to spatially and temporally heterogenous sediment deposition and erosion. The resulting structure of the stratigraphic record may confound the direct application of evolutionary models to fossil time series, most of which come from single localities. This pressing issue is tackled in a new study entitled “Identification of the mode of evolution in incomplete carbonate successions” (Hohmann et al., 2024).

The “carbonate successions” part of the title is important. Previous similar work (Hannisdal, 2006) used models for siliciclastic depositional systems to simulate the rock record. Here, the authors simulate sediment deposition across a carbonate platform, a system that has been treated as fundamentally different from siliciclastic settings, from both the point of view of geology (see Wagoner et al., 1990; Schlager, 2005) and ecology (Hopkins et al., 2014). The authors do find that stratigraphic structure impacts the identification of mode of evolution but not necessarily in the way one might expect; specifically, it is less important how much time is represented compared to the size and distribution of gaps, regardless of where you are sampling along the platform. This result provides an important guiding principle for selecting fossil time series for future investigations. 

Another very useful result of this study is the impact of time series length, which in this case should be understood as the density of sampling over a particular time interval. Counterintuitively, the probability of selecting the data-generating model as the best model decreases with increased length. The authors propose several explanations for this, all of which should inspire further work. There are also many other variables that could be explored in the simulations of the carbonate models as well as the fossil time series. For example, the authors chose to minimize within-sample variation in order to avoid conflating variability with evolutionary trends. But greater variance also potentially impacts model selection results and underlies questions about how variation relates to evolvability and the potential for directional change. 

Lastly, readers of Hohmann et al. (2024) are encouraged to also peruse the reviews and author replies associated with the PCI Paleo peer review process. The discussion contained in these documents touch on several important topics, including model performance and model selection, the nature of nested model systems, and the potential of the forwarding modeling approach.  

References

Hannisdal, B. (2006). Phenotypic evolution in the fossil record: Numerical experiments. The Journal of Geology, 114(2), 133–153. https://doi.org/10.1086/499569

Hohmann, N., Koelewijn, J. R., Burgess, P., and Jarochowska, E. (2024). Identification of the mode of evolution in incomplete carbonate successions. bioRxiv, 572098, ver. 4 peer-reviewed by PCI Paleo. https://doi.org/10.1101/2023.12.18.572098

Hopkins, M. J., Simpson, C., and Kiessling, W. (2014). Differential niche dynamics among major marine invertebrate clades. Ecology Letters, 17(3), 314–323. https://doi.org/10.1111/ele.12232

Hunt, G. (2006). Fitting and comparing models of phyletic evolution: Random walks and beyond. Paleobiology, 32(4), 578–601. https://doi.org/10.1666/05070.1

Hunt, G. (2008). Gradual or pulsed evolution: When should punctuational explanations be preferred? Paleobiology, 34(3), 360–377. https://doi.org/10.1666/07073.1

Schlager, W. (Ed.). (2005). Carbonate Sedimentology and Sequence Stratigraphy. SEPM Concepts in Sedimentology and Paleontology No. 8. https://doi.org/10.2110/csp.05.08

Sheets, H. D., and Mitchell, C. E. (2001). Why the null matters: Statistical tests, random walks and evolution. Genetica, 112, 105–125. https://doi.org/10.1023/A:1013308409951

Voje, K. L., Starrfelt, J., and Liow, L. H. (2018). Model adequacy and microevolutionary explanations for stasis in the fossil record. The American Naturalist, 191(4), 509–523. https://doi.org/10.1086/696265

Wagoner, J. C. V., Mitchum, R. M., Campion, K. M., and Rahmanian, V. D. (1990). Siliciclastic Sequence Stratigraphy in Well Logs, Cores, and Outcrops: Concepts for High-Resolution Correlation of Time and Facies. AAPG Methods in Exploration Series No. 7. https://doi.org/10.1306/Mth7510

Identification of the mode of evolution in incomplete carbonate successionsNiklas Hohmann, Joel R. Koelewijn, Peter Burgess, Emilia Jarochowska<p><strong>Background:</strong> The fossil record provides the unique opportunity to observe evolution over millions of years, but is known to be incomplete. While incompleteness varies spatially and is hard to estimate for empirical sections, com...Evolutionary biology, Evolutionary patterns and dynamics, Fossil record, Methods, SedimentologyMelanie Hopkins2023-12-19 08:10:00 View
25 Oct 2022
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Morphometric changes in two Late Cretaceous calcareous nannofossil lineages support diversification fueled by long-term climate change

Insights into mechanisms of coccolithophore speciation: How useful is cell size in delineating species?

Recommended by ORCID_LOGO based on reviews by Andrej Spiridonov and 1 anonymous reviewer

Calcareous plankton gives us perhaps the most complete record of microevolutionary changes in the fossil record (e.g. Tong et al., 2018; Weinkauf et al., 2019), but this opportunity is not exploited enough, as it requires meticulous work in documenting assemblage-level variation through time. Especially in organisms such as coccolithophores, understanding the meaning of secular trends in morphology warrants an understanding of the functional biology and ecology of these organisms. Razmjooei and Thibault (2022) achieve this in their painstaking analysis of two coccolithophore lineages, Cribrosphaerella ehrenbergii and Microrhabdulus, in the Late Cretaceous of Iran. They propose two episodes of morphological change. The first one, starting around 76 Ma in the late Campanian, is marked by a sudden shift towards larger sizes of C. ehrenbergii and the appearance of a new species M. zagrosensis from M. undulatus. The second episode around 69 Ma (Maastrichtian) is inferred from a gradual size increase and morphological changes leading to probably anagenetic speciation of M. sinuosus n.sp.

The study remarkably analyzed the entire distributions of coccolith length and rod width, rather than focusing on summary statistics (De Baets et al., in press). This is important, because the range of variation determines the taxon’s evolvability with respect to the considered trait (Love et al., 2022). As the authors discuss, cell size in photosymbiotic unicellular organisms is not subject to the same constraints that will be familiar to researchers working e.g. on mammals (Niklas, 1994; Payne et al., 2009; Smith et al., 2016). Furthermore, temporal changes in size alone cannot be interpreted as evolutionary without knowledge of phenotypic plasticity and environmental clines present in the basin (Aloisi, 2015). The more important is that this study cross-tests size changes with other morphological parameters to examine whether their covariation supports inferred speciation events. The article addresses as well the effects of varying sedimentation rates (Hohmann, 2021) by, somewhat implicitly, correcting for the stratophenetic trend using an age-depth model and accounting for a hiatus. Such multifaceted approach as applied in this work is fundamental to unlock the dynamics of speciation offered by the microfossil record. 

The study highlights also the link between shifts in size and diversity. Klug et al. (2015) have previously demonstrated that these two variables are related, as higher diversity is more likely to lead to extreme values of morphological traits, but this study suggests that the relationship is more intertwined: environmentally-driven rise in morphological variability (and thus in size) can lead to diversification. It is a fantastic illustration of the complexity of morphological evolution that, if it can be evaluated in terms of mechanisms, provides an insight into the dynamics of speciation.

 

References

Aloisi, G. (2015). Covariation of metabolic rates and cell size in coccolithophores. Biogeosciences, 12(15), 4665–4692. doi: 10.5194/bg-12-4665-2015

De Baets, K., Jarochowska, E., Buchwald, S. Z., Klug, C., and Korn, D. (In Press). Lithology controls ammonoid size distribution. Palaios.

Hohmann, N. (2021). Incorporating information on varying sedimentation rates into palaeontological analyses. PALAIOS, 36(2), 53–67. doi: 10.2110/palo.2020.038

Klug, C., De Baets, K., Kröger, B., Bell, M. A., Korn, D., and Payne, J. L. (2015). Normal giants? Temporal and latitudinal shifts of Palaeozoic marine invertebrate gigantism and global change. Lethaia, 48(2), 267–288. doi: 10.1111/let.12104

Love, A. C., Grabowski, M., Houle, D., Liow, L. H., Porto, A., Tsuboi, M., Voje, K.L., and Hunt, G. (2022). Evolvability in the fossil record. Paleobiology, 48(2), 186–209. doi: 10.1017/pab.2021.36

Niklas, K. J. (1994). Plant allometry: The scaling of form and process. Chicago: University of Chicago Press.

Payne, J. L., Boyer, A. G., Brown, J. H., Finnegan, S., Kowalewski, M., Krause, R. A., Lyons, S.K., McClain, C.R., McShea, D.W., Novack-Gottshall, P.M., Smith, F.A., Stempien, J.A., and Wang, S. C. (2009). Two-phase increase in the maximum size of life over 3.5 billion years reflects biological innovation and environmental opportunity. Proceedings of the National Academy of Sciences, 106(1), 24–27. doi: 10.1073/pnas.0806314106

Razmjooei, M. J., and Thibault, N. (2022). Morphometric changes in two Late Cretaceous calcareous nannofossil lineages support diversification fueled by long-term climate change. PaleorXiv, nfyc9, ver. 4, peer-reviewed by PCI Paleo. doi: 10.31233/osf.io/nfyc9

Smith, F. A., Payne, J. L., Heim, N. A., Balk, M. A., Finnegan, S., Kowalewski, M., Lyons, S.K., McClain, C.R., McShea, D.W., Novack-Gottshall, P.M., Anich, P.S., and Wang, S. C. (2016). Body size evolution across the Geozoic. Annual Review of Earth and Planetary Sciences, 44(1), 523–553. doi: 10.1146/annurev-earth-060115-012147

Tong, S., Gao, K., and Hutchins, D. A. (2018). Adaptive evolution in the coccolithophore Gephyrocapsa oceanica following 1,000 generations of selection under elevated CO2. Global Change Biology, 24(7), 3055–3064. doi: 10.1111/gcb.14065

Weinkauf, M. F. G., Bonitz, F. G. W., Martini, R., and Kučera, M. (2019). An extinction event in planktonic Foraminifera preceded by stabilizing selection. PLOS ONE, 14(10), e0223490. doi: 10.1371/journal.pone.0223490

Morphometric changes in two Late Cretaceous calcareous nannofossil lineages support diversification fueled by long-term climate changeMohammad Javad Razmjooei, Nicolas Thibault<p>Morphometric changes have been investigated in the two groups of calcareous nannofossils, <em>Cribrosphaerella ehrenbergii</em> and <em>Microrhabdulus undosus</em> across the Campanian to Maastrichtian of the Zagros Basin of Iran. Results revea...Biostratigraphy, Evolutionary theory, Fossil record, Microfossils, Micropaleontology, Morphological evolution, Morphometrics, Nanofossils, Paleobiodiversity, Paleobiology, Paleoceanography, Paleoclimatology, Paleoecology, Paleoenvironments, TaxonomyEmilia Jarochowska2020-08-29 12:23:51 View
16 Oct 2019
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What do ossification sequences tell us about the origin of extant amphibians?

The origins of Lissamphibia

Recommended by Robert Asher ? based on reviews by Jennifer Olori and 2 anonymous reviewers

Among 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 paleontologyRobert Asher 2018-06-22 08:21:31 View
27 Jan 2020
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A simple generative model of trilobite segmentation and growth

Deep insights into trilobite development

Recommended by based on reviews by Kenneth De Baets and Lukas Laibl

Trilobites are arthropods that became extinct at the greatest marine mass extinction over 250 Ma ago. Because of their often bizarre forms, their great diversity and disparity of shapes, they have attracted the interest of researchers and laypersons alike. Due to their calcified exoskeleton, their remains are quite abundant in many marine strata. One particularly interesting aspect, however, is the fossilization of various molting stages. This allows the reconstruction of both juvenile strategies (lecitotrophic versus planktotrophic) and the entire life history of at least some well-documented taxa (e.g., Hughes 2003, 2007; Laibl 2017). For example, life history of trilobites is, based on certain morphological changes, classically subdivided in the three phases protaspis (hatchling, one dorsal shield with few segments with no articulation between), meraspis (juvenile, two and more shields connected by articulations) and holaspis (when the terminal number of thoracic segments is reached). At most molting events, a new skeletal element is added (only in the holaspis, the number of thoracic segments does not change). Nevertheless, many trilobites are known mainly from late meraspid and holaspid stages, because the dorsal shields of the first ontogenetic stages are usually very small and thus often either dissolved or overlooked. An improved understanding of trilobite ontogeny could thus help filling in these gaps in fossil preservation and subsequently, to better understand evolutionary pathways. This is where this paper comes in. In a very clever approach, the New-York-based researcher Melanie Hopkins modeled the growth of these segmented animals (Hopkins 2020). Previous growth models of invertebrates focused on, e.g., mollusks, whose shells grow by accretion. Modelling arthropod ontogeny represented a challenge, which is now overcome by Hopkins' brilliant paper. Her generative growth model is based on empirical data of *Aulacopleura koninckii* (Barrande, 1846). Hong et al. (2014) and Hughes et al. (2017) documented the ontogeny of this 429 Ma old trilobite species in great detail. In the Silurian of the Barrandian region (Czech Republic), this species is locally very common and all growth stages are well known. I could imagine that the paper of Hughes et al. (2017) planted the seed into Melanie Hopkins’ mind to approach trilobite development in general in a quantitative way with a mathematical approach comparable to the mollusk-research by, e.g., David Raup (1961, 1966) and George McGhee (2015). Hopkins’ growth model requires “a minimum of nine parameters […] to model basic trilobite growth and segmentation, and three additional parameters […] to allow a transition to a new growth gradient for the trunk region during ontogeny” (Hopkins 2020: p. 21). It is now possible to play with parameters such as protaspid size, segment dimensions, segment numbers, etc., in order to estimate changes in body size or morphology. Furthermore, the model could be applied to similarly organized arthropod exoskeletons like many early Cambrian arthropods (e.g., marellomorphs) or even crustaceans (e.g., conchostracans or copepods). Of great interest could also be to assess influences of environmental changes on arthropod ontogeny. Also, her work will help to reconstruct unknown developmental information missing from trilobite species (and possibly other arthropods) and also to explore their morphospace. **References** Barrande, J. (1846). Notice préliminaire sur le système Silurien et les trilobites de Bohême. Leipzig: Hirschfield. Hong, P. S., Hughes, N. C., & Sheets, H. D. (2014). Size, shape, and systematics of the Silurian trilobite *Aulacopleura koninckii*. Journal of Paleontology, 88(6), 1120–1138. doi: [ 10.1666/13-142](https://dx.doi.org/ 10.1666/13-142) Hopkins, M. J. (2020). A simple generative model of trilobite segmentation and growth. PaleorXiv, version 3, peer-reviewed by PCI Paleo. doi: [ 10.31233/osf.io/zt642](https://dx.doi.org/ 10.31233/osf.io/zt642) Hughes, N. C. (2003). Trilobite tagmosis and body patterning from morphological and developmental perspectives. Integrative and Comparative Biology, 43(1), 185–206. doi: [ 10.1093/icb/43.1.185](https://dx.doi.org/ 10.1093/icb/43.1.185) Hughes, N. C. (2007). The evolution of trilobite body patterning. Annual Review of Earth and Planetary Sciences, 35(1), 401–434. doi: [ 10.1146/annurev.earth.35.031306.140258](https://dx.doi.org/ 10.1146/annurev.earth.35.031306.140258) Hughes, N. C., Hong, P. S., Hou, J., & Fusco, G. (2017). The development of the Silurian trilobite *Aulacopleura koninckii* reconstructed by applying inferred growth and segmentation dynamics: A case study in paleo-evo-devo. Frontiers in Ecology and Evolution, 5, 00037. doi: [ 10.3389/fevo.2017.00037](https://dx.doi.org/ 10.3389/fevo.2017.00037) Laibl, L. (2017). Patterns in Palaeontology: The development of trilobites. Palaeontology Online, 7(10), 1–9. McGhee, G. R. (2015). Limits in the evolution of biological form: a theoretical morphologic perspective. Interface Focus, 5(6), 20150034. doi: [ 10.1098/rsfs.2015.0034](https://dx.doi.org/ 10.1098/rsfs.2015.0034) Raup, D. M. (1961). The geometry of coiling in gastropods. Proceedings of the National Academy of Sciences, 47(4), 602–609. doi: [ 10.1073/pnas.47.4.602](https://dx.doi.org/ 10.1073/pnas.47.4.602) Raup, D. M. (1966). Geometric analysis of shell coiling: general problems. Journal of Paleontology, 40, 1178–1190.

A simple generative model of trilobite segmentation and growthMelanie J Hopkins<p>Generative growth models have been the basis for numerous studies of morphological diversity and evolution. Most work has focused on modeling accretionary growth systems, with much less attention to discrete growth systems. Generative growth mo...Evo-Devo, Evolutionary biology, Invertebrate paleontology, PaleobiologyChristian Klug2019-10-06 00:27:25 View
26 Mar 2024
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Calibrations without raw data - a response to "Seasonal calibration of the end-cretaceous Chicxulub impact event"

Questioning isotopic data from the end-Cretaceous

Recommended by based on reviews by Thomas Cullen and 1 anonymous reviewer

Being able to follow the evidence and verify results is critical if we are to be confident in the findings of a scientific study. Here, During et al. (2024) comment on DePalma et al. (2021) and provide a detailed critique of the figures and methods presented that caused them to question the veracity of the isotopic data used to support a spring-time Chicxulub impact at the end-Cretaceous. Given DePalma et al. (2021) did not include a supplemental file containing the original isotopic data, the suspicions rose to accusations of data fabrication (Price, 2022). Subsequent investigations led by DePalma’s current academic institution, The University of Manchester, concluded that the study contained instances of poor research practice that constitute research misconduct, but did not find evidence of fabrication (Price, 2023). Importantly, the overall conclusions of DePalma et al. (2021) are not questioned and both the DePalma et al. (2021) study and a study by During et al. (2022) found that the end-Cretaceous impact occurred in spring.

During et al. (2024) also propose some best practices for reporting isotopic data that can help future authors make sure the evidence underlying their conclusions are well documented. Some of these suggestions are commonly reflected in the methods sections of papers working with similar data, but they are not universally required of authors to report. Authors, research mentors, reviewers, and editors, may find this a useful set of guidelines that will help instill confidence in the science that is published.​

References

DePalma, R. A., Oleinik, A. A., Gurche, L. P., Burnham, D. A., Klingler, J. J., McKinney, C. J., Cichocki, F. P., Larson, P. L., Egerton, V. M., Wogelius, R. A., Edwards, N. P., Bergmann, U., and Manning, P. L. (2021). Seasonal calibration of the end-cretaceous Chicxulub impact event. Scientific Reports, 11(1), 23704. https://doi.org/10.1038/s41598-021-03232-9​

During, M. A. D., Smit, J., Voeten, D. F. A. E., Berruyer, C., Tafforeau, P., Sanchez, S., Stein, K. H. W., Verdegaal-Warmerdam, S. J. A., and Van Der Lubbe, J. H. J. L. (2022). The Mesozoic terminated in boreal spring. Nature, 603(7899), 91–94. https://doi.org/10.1038/s41586-022-04446-1

During, M. A. D., Voeten, D. F. A. E., and Ahlberg, P. E. (2024). Calibrations without raw data—A response to “Seasonal calibration of the end-cretaceous Chicxulub impact event.” OSF Preprints, fu7rp, ver. 5, peer-reviewed by PCI Paleo. https://doi.org/10.31219/osf.io/fu7rp​

​Price, M. (2022). Paleontologist accused of fraud in paper on dino-killing asteroid. Science, 378(6625), 1155–1157. https://doi.org/10.1126/science.adg2855

​Price, M. (2023). Dinosaur extinction researcher guilty of research misconduct. Science, 382(6676), 1225–1225. https://doi.org/10.1126/science.adn4967

Calibrations without raw data - a response to "Seasonal calibration of the end-cretaceous Chicxulub impact event"Melanie A. D. During, Dennis F. A. E. Voeten, Per E. Ahlberg<p>A recent paper by DePalma et al. reported that the season of the End-Cretaceous mass extinction was confined to spring/summer on the basis of stable isotope analyses and supplementary observations. An independent study that was concurrently und...Fossil calibration, Geochemistry, Methods, Vertebrate paleontologyChristina Belanger2023-06-22 10:43:31 View
26 Apr 2024
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New insights on feeding habits of Kolpochoerus from the Shungura Formation (Lower Omo Valley, Ethiopia) using dental microwear texture analysis

Dental microwear texture analysis of suid teeth from the Shungura Formation of the Omo Valley, Ethiopia

Recommended by based on reviews by Daniela E. Winkler and Kari Prassack

Suidae are well-represented in Plio-Pleistocene African hominin sites and are particularly important for biochronological assessments. Their ubiquity in hominin sites combined with multiple appearances of what appears to be graminivorous adaptations in the lineage (Harris & White, 1979) suggest that they have the potential to contribute to our understanding of Plio-Pleistocene paleoenvironments. While they have been generally understudied in this respect, there has been recent focus on their diets to understand the paleoenvironments of early hominin habitats. Of particular interest is Kolpochoerus, one of the most abundant suid genera in the Plio-Pleistocene with a wide geographic distribution and diverse dental morphologies (Harris & White, 1979). 

In this study, Louail et al. (2024) present the results of the first dental microwear texture analysis (DMTA) conducted on suids from the Shungura Formation of the Omo Valley, an important Plio-Pleistocene hominin site that records an almost continuous sedimentary record from ca. 3.75 Ma to 1.0 Ma (Heinzelin 1983; McDougall et al., 2012; Kidane et al., 2014). Dental microwear is one of the main proxies in understanding diet in fossil mammals, particularly herbivores, and DMTA has been shown to be effective in differentiating inter- and intra-species dietary differences (e.g., Scott et al., 2006; 2012; Merceron et al., 2010). However, only a few studies have applied this method to extinct suids (Souron et al., 2015; Ungar et al., 2020), making this study especially pertinent for those interested in suid dietary evolution or hominin paleoecology.

In addition to examining DMT variations of Kolpochoerus specimens from Omo, Louail et al. (2024) also expanded the modern comparative data set to include larger samples of African suids with different diets from herbivores to omnivores to better interpret the fossil data. They found that DMTA distinguishes between extant suid taxa, reflecting differences in diet, indicating that DMT can be used to examine the diets of fossil suids. The results suggest that Kolpochoerus at Omo had a substantially different diet from any extant suid taxon and that although its anistropy values increased through time, they remain well below those observed in modern Phacochoerus that specializes in fibrous, abrasive plants. Based on these results, in combination with comparative and experimental DMT, enamel carbon isotopic, and morphological data, Louail et al. (2024) propose that Omo Kolpochoerus preferred short, soft and low abrasive herbaceous plants (e.g., fresh grass shoots), probably in more mesic habitats. Louail et al. (2024) note that with the wide temporal and geographic distribution of Kolpochoerus, different species and populations may have had different feeding habits as they exploited different local habitats. However, it is noteworthy that similar inferences were made at other hominin sites based on other types of dietary data (e.g., Harris & Cerling, 2002; Rannikko et al., 2017, 2020; Yang et al., 2022). If this is an indication of their habitat preferences, the wide-ranging distribution of Kolpochoerus may suggest that mesic habitats with short, soft herbaceous plants were present in various proportions at most Plio-Pleistocene hominin sites. 

References

Harris, J. M., and Cerling, T. E. (2002). Dietary adaptations of extant and Neogene African suids. Journal of Zoology, 256(1), 45–54. https://doi.org/10.1017/S0952836902000067

Harris, J. M., and White, T. D. (1979). Evolution of the Plio-Pleistocene African Suidae. Transactions of the American Philosophical Society, 69(2), 1–128. https://doi.org/10.2307/1006288

Heinzelin, J. de. (1983). The Omo Group. Archives of the International Omo Research Expedition. Volume 85. Annales du Musée Royal de l’Afrique Centrale, série 8, Sciences géologiques, Tervuren, 388 p.

Kidane, T., Brown, F. H., and Kidney, C. (2014). Magnetostratigraphy of the fossil-rich Shungura Formation, southwest Ethiopia. Journal of African Earth Sciences, 97, 207–223. https://doi.org/10.1016/j.jafrearsci.2014.05.005

Louail, M., Souron, A., Merceron, G., and Boisserie, J.-R. (2024). New insights on feeding habits of Kolpochoerus from the Shungura Formation (Lower Omo Valley, Ethiopia) using dental microwear texture analysis. PaleorXiv, dbgtp, ver. 3, peer-reviewed by PCI Paleo. https://doi.org/10.31233/osf.io/dbgtp

McDougall, I., Brown, F. H., Vasconcelos, P. M., Cohen, B. E., Thiede, D. S., and Buchanan, M. J. (2012). New single crystal 40Ar/39Ar ages improve time scale for deposition of the Omo Group, Omo–Turkana Basin, East Africa. Journal of the Geological Society, 169(2), 213–226. https://doi.org/10.1144/0016-76492010-188

Merceron, G., Escarguel, G., Angibault, J.-M., and Verheyden-Tixier, H. (2010). Can dental microwear textures record inter-individual dietary variations? PLoS ONE, 5(3), e9542. https://doi.org/10.1371/journal.pone.0009542

Rannikko, J., Adhikari, H., Karme, A., Žliobaitė, I., and Fortelius, M. (2020). The case of the grass‐eating suids in the Plio‐Pleistocene Turkana Basin: 3D dental topography in relation to diet in extant and fossil pigs. Journal of Morphology, 281(3), 348–364. https://doi.org/10.1002/jmor.21103

Rannikko, J., Žliobaitė, I., and Fortelius, M. (2017). Relative abundances and palaeoecology of four suid genera in the Turkana Basin, Kenya, during the late Miocene to Pleistocene. Palaeogeography, Palaeoclimatology, Palaeoecology, 487, 187–193. https://doi.org/10.1016/j.palaeo.2017.08.033

Scott, R. S., Teaford, M. F., and Ungar, P. S. (2012). Dental microwear texture and anthropoid diets. American Journal of Physical Anthropology, 147(4), 551–579. https://doi.org/10.1002/ajpa.22007

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

Souron, A., Merceron, G., Blondel, C., Brunetière, N., Colyn, M., Hofman-Kamińska, E., and Boisserie, J.-R. (2015). Three-dimensional dental microwear texture analysis and diet in extant Suidae (Mammalia: Cetartiodactyla). Mammalia, 79(3). https://doi.org/10.1515/mammalia-2014-0023

Ungar, P. S., Abella, E. F., Burgman, J. H. E., Lazagabaster, I. A., Scott, J. R., Delezene, L. K., Manthi, F. K., Plavcan, J. M., and Ward, C. V. (2020). Dental microwear and Pliocene paleocommunity ecology of bovids, primates, rodents, and suids at Kanapoi. Journal of Human Evolution, 140, 102315. https://doi.org/10.1016/j.jhevol.2017.03.005

Yang, D., Pisano, A., Kolasa, J., Jashashvili, T., Kibii, J., Gomez Cano, A. R., Viriot, L., Grine, F. E., and Souron, A. (2022). Why the long teeth? Morphometric analysis suggests different selective pressures on functional occlusal traits in Plio-Pleistocene African suids. Paleobiology, 48(4), 655–676. https://doi.org/10.1017/pab.2022.11

New insights on feeding habits of *Kolpochoerus* from the Shungura Formation (Lower Omo Valley, Ethiopia) using dental microwear texture analysisMargot Louail, Antoine Souron, Gildas Merceron, Jean-Renaud Boisserie<p>During the Neogene and the Quaternary, African suids show dental morphological changes considered to reflect adaptations to increasing specialization on graminivorous diets, notably in the genus <em>Kolpochoerus</em>. They tend to exhibit elong...Paleoecology, Vertebrate paleontologyDenise Su2023-08-28 10:38:33 View