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15 Dec 2022
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Spatio-temporal diversity of dietary preferences and stress sensibilities of early and middle Miocene Rhinocerotidae from Eurasia: impact of climate changes

New insights into the palaeoecology of Miocene Eurasian rhinocerotids based on tooth analysis

Recommended by based on reviews by Antigone Uzunidis, Christophe Mallet and Matthew Mihlbachler

Rhinocerotoidea originated in the Lower Eocene and diversified well during the Cenozoic in Eurasia, North America and Africa. This taxon encompasses a great diversity of ecologies and body proportions and masses. Within this group, the family Rhinocerotidae, which is the only one with extant representatives, appeared in the Late Eocene (Prothero & Schoch, 1989). They were well diversified during the Early and Middle Miocene, whereas they began to decline in both diversity and geographical range after the Miocene, throughout the Pliocene and Pleistocene, in conjunction with the marked climatic changes (Cerdeño, 1998). 

In Eurasian Early and Middle Miocene fossil localities, a variety of species are often associated. Therefore, it may be quite difficult to estimate how these large herbivores cohabited and whether competition for food resources is reflected in a diversity of ecological niches. The ecologies of these large mammals are rather poorly known and the detailed study of their teeth could bring new elements of answer. Indeed, if teeth carry a strong phylogenetic signal in mammals, they are also of great interest for ecological studies, and they have the additional advantage of being often numerous in the fossil record. 

Hullot et al. (2022) analysed both dental microwear texture, as an indicator of dietary preferences, and enamel hypoplasia, to identify stress sensitivity, in a large number of rhinocerotid fossil teeth from nine Neogene (Early to Middle Miocene) localities in Europe and Pakistan. Their aim was to analyse whether fossil species diversity is associated with a diversity of ecologies, and to investigate possible ecological differences between regions and time periods in relation to climate change. Their results show clear differences in time and space between and within species, and suggest that more flexible species are less vulnerable to environmental stressors. 

Very few studies focus on the palaeocology of Miocene rhinos. This study is therefore a great contribution to the understanding of the evolution of this group.

 

References

Cerdeño, E. (1998). Diversity and evolutionary trends of the Family Rhinocerotidae (Perissodactyla). Palaeogeography, Palaeoclimatology, Palaeoecology, 141, 13–34. https://doi.org/10.1016/S0031-0182(98)00003-0

Hullot, M., Merceron, G., and Antoine, P.-O. (2022). Spatio-temporal diversity of dietary preferences and stress sensibilities of early and middle Miocene Rhinocerotidae from Eurasia: Impact of climate changes. BioRxiv, 490903, ver. 4 peer-reviewed by PCI Paleo. https://doi.org/10.1101/2022.05.06.490903

Prothero, D. R., and Schoch, R. M. (1989). The evolution of perissodactyls. New York: Oxford University Press.

Spatio-temporal diversity of dietary preferences and stress sensibilities of early and middle Miocene Rhinocerotidae from Eurasia: impact of climate changesManon Hullot, Gildas Merceron, Pierre-Olivier Antoine<p>Major climatic and ecological changes are documented in terrestrial ecosystems during the Miocene epoch. The Rhinocerotidae are a very interesting clade to investigate the impact of these changes on ecology, as they are abundant and diverse in ...Paleobiodiversity, Paleobiology, Paleoecology, Paleopathology, Vertebrate paleontologyAlexandra Houssaye2022-05-09 09:33:30 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
26 Oct 2023
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OH 89: A newly described ~1.8-million-year-old hominid clavicle from Olduvai Gorge

A new method for measuring clavicular curvature

Recommended by based on reviews by 2 anonymous reviewers

The evolution of the hominid clavicle has not been studied in depth by paleoanthropologists given its high morphological variability and the scarcity of complete diagnosable specimens. A nearly complete Nacholapithecus clavicle from Kenya (Senut et al. 2004) together with a fragment from Ardipithecus from the Afar region of Ethiopia (Lovejoy et al. 2009) complete our knowledge of the Miocene record. The Australopithecus collection of clavicles from Eastern and South African Plio-Pleistocene sites is slightly more abundant but mostly represented by fragmentary specimens. The number of fossil clavicles increases for the genus Homo from more recent sites and thus our potential knowledge about the shoulder evolution. 

In their new contribution, Taylor et al. (2023) present a detailed analysis of OH 89, a ~1.8-million-year-old partial hominin clavicle recovered from Olduvai Gorge (Tanzania). The work goes over previous studies which included clavicles found in the hominid fossil record. The text is accompanied by useful tables of data and a series of excellent photographs. It is a great opportunity to learn its role in the evolution of the hominid shoulder gird as clavicles are relatively poorly preserved in the fossil record compared to other long bones. The study compares the specimen OH 89 with five other hominid clavicles and a sample of 25 modern clavicles, 30 Gorilla, 31 Pan and 7 Papio. The authors propose a new methodology for measuring clavicular curvature using measurements of sternal and acromial curvature, from which an overall curvature measurement is calculated. The study of OH 89 provides good evidence about the hominid who lived 1.8 million years ago in the Olduvai Gorge region. This time period is especially relevant because it can help to understand the morphological changes that occurred between Australopithecus and the appearance of Homo. The authors conclude that OH 89 is the largest of the hominid clavicles included in the analysis. Although they are not able to assign this partial element to species level, this clavicle from Olduvai is at the larger end of the variation observed in Homo sapiens and show similarities to modern humans, especially when analysing the estimated sinusoidal curvature.

References

Lovejoy, C. O., Suwa, G., Simpson, S. W., Matternes, J. H., and White, T. D. (2009). The Great Divides: Ardipithecus ramidus peveals the postcrania of our last common ancestors with African apes. Science, 326(5949), 73–106. https://doi.org/10.1126/science.1175833

Senut, B., Nakatsukasa, M., Kunimatsu, Y., Nakano, Y., Takano, T., Tsujikawa, H., Shimizu, D., Kagaya, M., and Ishida, H. (2004). Preliminary analysis of Nacholapithecus scapula and clavicle from Nachola, Kenya. Primates, 45(2), 97–104. https://doi.org/10.1007/s10329-003-0073-5

Taylor, C., Masao, F., Njau, J. K., Songita, A. V., and Hlusko, L. J. (2023). OH 89: A newly described ∼1.8-million-year-old hominid clavicle from Olduvai Gorge. bioRxiv, 526656, ver. 6 peer-reviewed by PCI Paleo. https://doi.org/10.1101/2023.02.02.526656

OH 89: A newly described ~1.8-million-year-old hominid clavicle from Olduvai GorgeCatherine E. Taylor, Fidelis Masao, Jackson K. Njau, Agustino Venance Songita, Leslea J. Hlusko<p>Objectives: Here, we describe the morphology and geologic context of OH 89, a ~1.8-million-year-old partial hominid clavicle from Olduvai Gorge, Tanzania. We compare the morphology and clavicular curvature of OH 89 to modern humans, extant apes...Comparative anatomy, Evolutionary biology, Fossil record, Methods, Morphological evolution, Paleoanthropology, Vertebrate paleontologyNuria Garcia2023-02-08 19:45:01 View
04 Jun 2024
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New generic name for a small Triassic ray-finned fish from Perledo (Italy)

A new study on the halecomorph fishes from the Triassic of Perledo (Italy) highlights important issues in Palaeoichthyology

Recommended by based on reviews by Guang-Hui Xu and 1 anonymous reviewer

Mesozoic fishes are extremely diverse. In fact, fishes are the most diverse group of vertebrates during the Mesozoic─just as during any other era. Yet, their study is severely underrepresented in comparison to other fossil groups. There are just too few palaeoichthyologists to deal with such a vast diversity of fishes. Nonetheless, thanks to the huge efforts they have made over the last few decades, we have come a long way in our understanding of Mesozoic ichthyofaunas. One of such devoted palaeoichthyologists is Dr. Adriana López-Arbarello, whose contributions have been crucial in elucidating the phylogenetic interrelationships and taxonomic diversity of Mesozoic actinopterygian fishes (e.g., López-Arbarello, 2012; López-Arbarello & Sferco, 2018; López-Arbarello & Ebert, 2023). In her most recent manuscript, Dr. López-Arbarello has joined forces with Dr. Rainer Brocke to tackle the taxonomy and systematics of the halecomorph fishes from one of the most relevant Triassic sites, the upper Ladinian Perledo locality from Italy (López-Arbarello & Brocke, 2024). 

Fossil fishes were reported for the first time from Perledo in the first half of the 19th century (Balsamo-Crivelli, 1839), and up to 30 different species were described from the locality in the subsequent decades. Unfortunately, this is one of the multiple examples of fossil collections that suffered the effects of World War II, and most of the type material was lost. As a consequence, many of those 30 species that have been described over the years are in need of a revision. Based on the study of additional material that was transferred to Germany and is housed at the Senckenberg Research Institute and Natural History Museum, López-Arbarello & Brocke (2024) confirm the presence of four different species of halecomorph fishes in Perledo, which were previously put under synonymy (Lombardo, 2001). They provide new detailed information on the anatomy of two of those species, together with their respective diagnoses. But more importantly, they carry out a thorough exercise of taxonomy, rigorously applying the International Code of Zoological Nomenclature to disentangle the intricacies in the taxonomic story of the species placed in the genus Allolepidotus. As a result, they propose the presence of the species A. ruppelii, which they propose to be the type species for that genus (instead of A. bellottii, which they transfer to the genus Eoeugnathus). They also propose a new genus for the other species originally included in Allolepidotus, A. nothosomoides. Finally, they provide a set of measurements and ratios for Pholidophorus oblongus and Pholidophorus curionii, the other two species previously put in synonymy with A. bellottii, to demonstrate their validity as different species. However, due to the loss of the type material, the authors propose that these two species remain as nomina dubia

In summary, apart from providing new detailed anatomical descriptions of two species and solving some long-standing issues with the taxonomy of the halecomorphs from the relevant Triassic Perledo locality, the paper by López-Arbarello & Rainer (2024) highlights three important topics for the study of the fossil record: 1) we should never forget that world-scale problems, such as World Wars, also affect our capacity to understand the natural world in which we live, and the whole society should be aware if this; 2) the importance of exhaustively following the International Code of Zoological Nomenclature when describing new species; and 3) we are in need of new palaeoichthyologists to, in Dr. López-Arbarello’s own words, “unveil the mysteries of those marvellous Mesozoic ichthyofaunas.”

References

Balsamo-Crivelli, G. (1839). Descrizione di un nuovo rettile fossile, della famiglia dei Paleosauri, e di due pesci fossili, trovati nel calcare nero, sopra Varenna sul lago di Como, dal nobile sig. Ludovico Trotti, con alcune riflessioni geologiche. Il politecnico repertorio mensile di studj applicati alla prosperita e coltura sociale, 1, 421–431.

Lombardo, C. (2001). Actinopterygians from the Middle Triassic of northern Italy and Canton Ticino (Switzerland): Anatomical descriptions and nomenclatural problems. Rivista Italiana di Paleontologia e Stratigrafia, 107, 345–369. https://doi.org/10.13130/2039-4942/5439

López-Arbarello, A. (2012). Phylogenetic interrelationships of ginglymodian fishes (Actinopterygii: Neopterygii). PLOS ONE, 7(7), e39370. https://doi.org/10.1371/journal.pone.0039370

López-Arbarello, A., and Brocke, R. (2024). New generic name for a small Triassic ray-finned fish from Perledo (Italy). PaleorXiv, bxmg5, ver. 4, peer-reviewed by PCI Paleo. https://doi.org/10.31233/osf.io/bxmg5

López-Arbarello, A., and Ebert, M. (2023). Taxonomic status of the caturid genera (Halecomorphi, Caturidae) and their Late Jurassic species. Royal Society Open Science, 10(1), 221318. https://doi.org/10.1098/rsos.221318

López-Arbarello, A., and Sferco, E. (2018). Neopterygian phylogeny: The merger assay. Royal Society Open Science, 5(3), 172337. https://doi.org/10.1098/rsos.172337

New generic name for a small Triassic ray-finned fish from Perledo (Italy)Adriana López-Arbarello, Rainer Brocke<p>Our new study of the species originally included in the genus <em>Allolepidotus</em> led to the taxonomic revision of the halecomorph species from the Triassic of Perledo, Italy. The morphological variation revealed by the analysis of the type ...Fossil record, Systematics, Taxonomy, Vertebrate paleontologyHugo Martín Abad2024-03-21 11:53:53 View
20 Oct 2020
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Evidence of high Sr/Ca in a Middle Jurassic murolith coccolith species

New results and challenges in Sr/Ca studies on Jurassic coccolithophorids

Recommended by based on reviews by Kenneth De Baets and 1 anonymous reviewer

This interesting publication by Suchéras-Marx et al. (2020) highlights peculiar aspects of geochemistry in nannofossils, specifically coccolithophorids. One of the main application of geochemistry on fossil shells is to get hints on the physiology of such extinct taxa. Here, the authors try to get information on the calcification mechanism and processes in Jurassic coccoliths. Coccoliths build a test made of calcium carbonate and one of the most common geochemical proxies used for this fossil group is the Sr/Ca ratio. This isotopic ratio has good chances to be successfully used as a robust proxy for paleoenvironmental reconstruction, but, concerning Jurassic coccoliths things seem to be not straightforward.

The authors managed to compare the isotopic value of Sr/Ca measured on Jurassic coccoliths from different taxonomic groups: the murolith Crepidolithus crassus and the placoliths Watznaueria contracta and Discorhabdus striatus. The results they got clearly show that the Sr/Ca ratio cannot be used as a universal proxy because these species exhibit very different values despite coming from the same stratigraphic level and having undergone minimal diagenetic modification. Data seem to point to a Sr/Ca ratio up to 10 times higher in the murolith species than in the placolith taxa (Suchéras-Marx et al., 2020). One of the explanation given here takes advantage of modern coccolith data and hints to specific polysaccharides that would control the growth of the long R unit in the murolith species. As always, there is plenty of space for additional research, possibly on modern taxa, to sort out the scientific questions that arise from this work.

References

Suchéras-Marx, B., Giraud, F., Simionovici, A., Tucoulou, R., & Daniel, I. (2020). Evidence of high Sr/Ca in a Middle Jurassic murolith coccolith species. PaleorXiv, dcfuq, version 7, peer-reviewed by PCI Paleo. doi: 10.31233/osf.io/dcfuq

Evidence of high Sr/Ca in a Middle Jurassic murolith coccolith speciesBaptiste Suchéras-Marx, Fabienne Giraud, Alexandre Simionovici, Rémi Tucoulou, Isabelle Daniel<p>Paleoceanographical reconstructions are often based on microfossil geochemical analyses. Coccoliths are the most ancient, abundant and continuous record of pelagic photic zone calcite producer organisms. Hence, they could be valuable substrates...Microfossils, Micropaleontology, NanofossilsAntonino Briguglio2020-05-18 16:11:35 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
13 Aug 2024
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Postcranial anatomy of the long bones of colobines (Mammalia, Primates) from the Plio-Pleistocene Omo Group deposits (Shungura Formation and Usno Formation, 1967-2018 field campaigns, Lower Omo Valley, Ethiopia)

Postcrania from the Shungura and Usno Formations (Lower Omo Valley, Ethiopia) provide new insights into evolution of colobine monkeys (Primates, Cercopithecidae)

Recommended by based on reviews by Monya Anderson and 1 anonymous reviewer

In their analysis, Pallas and colleagues identify 32 postcranial elements from the Plio-Pleistocene collections of the Lower Omo Valley, Ethiopia as colobine (Pallas et al., 2024). This is a valuable contribution towards understanding colobine evolution, Plio-Pleistocene environments of the Turkana Basin, Kenya and Ethiopia, and how the many large-bodied catarrhines, including at least three hominins, four colobines, and three papionins, all with body masses over 30 Kg shared this ecosystem.

Today, colobine monkeys have greater diversity in Asia than in Africa, where they are represented by three small to medium-sized forms: olive, red, and black and white colobus (Grubb et al., 2003; Roos and Zinner, 2022). In the Pliocene and Pleistocene, however, they were significantly more diverse, with at least four additional large-bodied genera that varied considerably in body size, and as evidenced by multiple proxies, their preferred habitats, diets, and locomotor behaviors (Frost et al., 2022 and references therein). The highly fossiliferous sediments of the Shungura and Usno Formations in the Lower Omo Valley span the period from 3.75 to 1.0 Ma (Heinzelin, 1983; McDougall et al., 2012; Kidane et al., 2014) and have contributed greatly to understanding human and mammalian evolution during the African Plio-Pleistocene (Howell and Coppens, 1974; Boisserie et al., 2008), including the enigmatic large-bodied colobines (Leakey, 1982; 1987). Despite large samples of postcranial material from the Lower Omo Valley (Eck, 1977), most of our knowledge of fossil colobine postcrania is based on a relatively few associated skeletons from other eastern African sites (Birchette, 1982; Frost and Delson, 2002; Jablonski et al., 2008; Anderson, 2021). This is because the vast majority of postcrania from the Lower Omo Valley are not directly associated with taxonomically diagnostic elements.

Based on qualitative and quantitative comparison with an extensive database of extant cercopithecoid postcrania, Pallas et al. (2024) identify 32 long bones of the fore- and hindlimbs as colobine. These range in age from approximately 3.3 to 1.1 Ma. They made their identifications using a combination of body mass estimation and comparison with associated skeletons of Plio-Pleistocene and extant taxa. In this way, they tentatively allocate some of the larger material dated to 3.3. to 2.0 Ma to taxa previously recognized from craniodental remains, especially Rhinocolobus cf. turkanaensis and Paracolobus cf. mutiwa; and the smaller ca. 1.1 Ma to cf. Colobus. Interestingly, they also identify several specimens, especially from Members B and C, that are unlikely to represent taxa previously described for the Lower Omo Valley and make a possible link to Cercopithecoides meaveae, otherwise only known from the Afar Region, Ethiopia (Frost and Delson, 2002).

Based on these identifications, Pallas et al. (2024) hypothesize that Rhinocolobus may have been adapted to more suspensory postures compared to Cercopithecoides and Paracolobus which are estimated to have been more terrestrial. Additionally, they suggest that the possibly semi-terrestrial Paracolobus mutiwa may show adaptations for vertical climbing. These are novel observations, and if they are correct give further clues as to how these primates seemingly managed to co-exist in the same area for nearly a million years (Leakey, 1982; 1987; Jablonski et al., 2008). Better understanding the locomotor and positional behaviors of these taxa will also make them more useful in reconstructions of the paleoenvironments represented by the Shungura and Usno Formations.

References

Anderson, M. (2021). An assessment of the postcranial skeleton of the Paracolobus mutiwa (Primates: Colobinae) specimen KNM-WT 16827 from Lomekwi, West Turkana, Kenya. Journal of Human Evolution, 156, 103012. https://doi.org/10.1016/j.jhevol.2021.103012

Birchette, M. G. (1982). The postcranial skeleton of Paracolobus chemeroni [Unpublished PhD thesis]. Harvard University.

Boisserie, J.-R., Guy, F., Delagnes, A., Hlukso, L. J., Bibi, F., Beyene, Y., and Guillemot, C. (2008). New palaeoanthropological research in the Plio-Pleistocene Omo Group, Lower Omo Valley, SNNPR (Southern Nations, Nationalities and People Regions), Ethiopia. Comptes Rendus Palevol, 7(7), 429–439. https://doi.org/10.1016/j.crpv.2008.07.010

Eck, G. (1977). Diversity and frequency distribution of Omo Group Cercopithecoidea. Journal of Human Evolution, 6(1), 55–63. https://doi.org/10.1016/S0047-2484(77)80041-9

Frost, S. R., and Delson, E. (2002). Fossil Cercopithecidae from the Hadar Formation and surrounding areas of the Afar Depression, Ethiopia. Journal of Human Evolution, 43(5), 687–748. https://doi.org/10.1006/jhev.2002.0603

Frost, S. R., Gilbert, C. C., and Nakatsukasa, M. (2022). The colobine fossil record. In I. Matsuda, C. C. Grueter, and J. A. Teichroeb (Eds.), The Colobines: Natural History, Behaviour and Ecological Diversity. Cambridge University Press. Pp. 13–31. https://doi.org/10.1017/9781108347150

Grubb, P., Butynski, T. M., Oates, J. F., Bearder, S. K., Disotell, T. R., Groves, C. P., and Struhsaker, T. T. (2003). Assessment of the diversity of African primates. International Journal of Primatology, 24(6), 1301–1357. https://doi.org/10.1023/B:IJOP.0000005994.86792.b9

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.

Howell, F. C., and Coppens, Y. (1974). Inventory of remains of Hominidae from Pliocene/Pleistocene formations of the lower Omo basin, Ethiopia (1967–1972). American Journal of Physical Anthropology, 40(1), 1–16. https://doi.org/10.1002/ajpa.1330400102

Jablonski, N. G., Leakey, M. G., Ward, C. V., and Antón, M. (2008). Systematic paleontology of the large colobines. In N. G. Jablonski and M. G. Leakey (Eds.), Koobi Fora Research Project Volume 6: The Fossil Monkeys. California Academy of Sciences. Pp. 31–102.

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

Leakey, M. G. (1982). Extinct large colobines from the Plio‐Pleistocene of Africa. American Journal of Physical Anthropology, 58(2), 153–172. https://doi.org/10.1002/ajpa.1330580207

Leakey, M. G. (1987). Colobinae (Mammalia, Primates) from the Omo Valley, Ethiopia. In Y. Coppens and F. C. Howell (Eds.), Les faunes Plio-Pléistocènes de la Basse Vallée de l’Omo (Ethiopie). Tome 3, Cercopithecidae de la Formation de Shungura. CNRS, Paris, pp. 148-169.

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

Pallas, L., Daver, G., Merceron, G., and Boisserie, J.-R. (2024). Postcranial anatomy of the long bones of colobines (Mammalia, Primates) from the Plio-Pleistocene Omo Group deposits (Shungura Formation and Usno Formation, 1967-2018 field campaigns, Lower Omo Valley, Ethiopia). PaleorXiv, bwegt, ver. 8, peer-reviewed by PCI Paleo. https://doi.org/10.31233/osf.io/bwegt

Roos, C., and Zinner, D. (2022). Molecular phylogeny and phylogeography of colobines. In I. Matsuda, C. C. Grueter, and J. A. Teichroeb (Eds.), The Colobines: Natural History, Behaviour and Ecological Diversity. Cambridge University Press. Pp. 32-43. https://doi.org/10.1017/9781108347150

 

Postcranial anatomy of the long bones of colobines (Mammalia, Primates) from the Plio-Pleistocene Omo Group deposits (Shungura Formation and Usno Formation, 1967-2018 field campaigns, Lower Omo Valley, Ethiopia)Laurent Pallas, Guillaume Daver, Gildas Merceron, Jean-Renaud Boisserie<p style="text-align: justify;">Our knowledge of the functional and taxonomic diversity of the fossil colobine fauna (Colobinae Jerdon, 1867) from the Lower Omo Valley is based only on craniodental remains. Here we describe postcranial specimens o...Comparative anatomy, Evolutionary patterns and dynamics, Fossil record, Macroevolution, Morphological evolution, Morphometrics, Paleobiology, Systematics, Vertebrate paleontologyStephen Frost2023-02-05 06:01:30 View
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
19 Aug 2021
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The origin and early evolution of arthropods

Through a glass darkly, but with more understanding of arthropod origin

Recommended by based on reviews by Gerhard Scholtz and Jean Vannier ?

Arthropods constitute 85% of all described animal species on Earth (Brusca et al., 2016), being the most successful animal phylum at present. This phylum did not even have a shabby beginning. The fossil record shows that they were dominating the sea even in the early Cambrian (Caron and Jackson, 2008; Zhao et al., 2014; Fu et al., 2019). This planet is and has been indeed dominated by arthropods. Within the context of the Big Bang of animal evolution known as the Cambrian Explosion, delving into the origin of arthropods has been one of the all-time fascinating research themes in paleontology, and discussions on the ‘origin’ and ‘early evolution’ of arthropods from the paleontological perspective have not been infrequent (e.g., Budd and Telford, 2009; Edgecombe and Legg, 2014; Daley et al., 2018; Edgecombe, 2020).

In this context, Aria (2021) provides an interesting integration of his view on arthropod origin and early evolution. Based on well-preserved Burgess Shale materials, together with other impressive researches mainly with Jean-Bernard Caron (e.g., Aria and Caron, 2015; Caron and Aria, 2017), Cédric Aria made his name known with papers searching for the stem-groups of the two major euarthropod lineages, the Mandibulata and the Chelicerata (Aria and Caron, 2017, 2019), for which (and for his subsequent researches) assembling a large dataset for arthropod phylogeny was inevitable. Subsequently, there have been several major discoveries which could improve our understanding on early arthropod evolution (e.g., Lev and Chipman, 2020; Liu et al., 2020; Zeng et al., 2020). For Cédric Aria, therefore, this timely presentation of his own perspective on the origin of early evolution of arthropods may have been preordain.

This review stands out because it discusses almost all aspects of arthropod origin and early evolution that can be possibly covered by paleontology (many, if not all, of which are still controversial). Some of his views may be considered a brave attempt. For instance, based on the widespread occurrences of suspension feeders, Aria (2021) proposes the early Cambrian “planktonic revolution,” which has been associated rather with the Great Ordovician Biodiversification Event (Servais et al., 2016). Given the presence of lophotrochozoans and echinoderms in which the presence of planktonic larvae was likely to have been one of the most inclusive features, the “early Cambrian planktonic revolution” might be plausible, but I wonder if including arthropods into the “earlier revolution” can be readily acceptable. Arthropods arose from direct-developing ancestors, and crustaceans (the main group with planktonic larvae) are pretty much derived in the arthropod phylogenetic tree. Trilobites, inarguably the best-studied Cambrian arthropods, for example, began with direct-developing benthic protaspides in the early Cambrian and Miaolingian. The first hint of planktonic protaspides appeared in the Furongian, and it was not until the Tremadocian when such indirect developing protaspides began to be widespread (Park and Kihm, 2015), which complies well with the onset of the ‘Ordovician Planktonic Revolution’ in the Furongian, as suggested by Servais et al. (2016).

But in general, this review presents well-organized views worth hearing, and since many of the points are subject to debate, this review could be a friendly manual for those who have similar views, while it could form a fresh ground to attack for those who have disparate views. One of the endless debates in arthropod research comes from the arthropod head problem (Budd, 2002), which centers on the homology of frontal-most appendages in radiodonts, megacheirans, chelicerates, and mandibulates, as well as on the hypostome-labrum complex. Based on recent interesting discoveries of early arthropods from the Chengjiang biota (Aria, 2020; Zeng et al., 2020), Aria (2021) pertinently coined a term ‘cheirae’ for the frontalmost prehensile appendages of radiodonts and megacheirans, implying homology of them. I assume that not all researchers would agree with this though, as well as with his model of hypostome/labrum complex evolution. Notorious disaccords have also occurred around the phylogenetic positions of early arthropods, such as isoxyids, megacheirans, fuxianhuiids, and artiopodans; different research groups have invariably come up with different topologies. Cédric Aria has presented his own topologies (Aria, 2019, 2020), and figure 2 of Aria (2021) summarizes his perspective very well in combination with major character evolutions.

What makes this review especially interesting is a courageous discussion about the origin of biramous appendage, a subject that has been only briefly discussed or overlooked in recent literature. In the current mainstream of this debate lies the concept of ‘gilled lobopodians’ (Budd, 1998), which was complicated by the weird two separate rows of lateral flaps of Aegirocassis (Van Roy et al., 2015). Aria (2021) adds an interesting alternative scenario to this: biramicity originated from the split of main limb axis, as seen in the isoxyid Surusicaris (Aria and Caron, 2015). The figure 3d of his review, therefore, is worth giving thoughts for any arthropodologists who are interested in the origin of arthropod legs.

It is true that our understanding of the origin and early evolution of arthropods is still in a mist. Nevertheless, we have recently seen advancements, such as those aided by new types of analysis (Liu et al., 2020), the discoveries of new early arthropods with unexpected morphologies (Aria et al., 2020; Zeng et al., 2020), and the groundbreaking Evo-Devo research (Lev and Chipman, 2020). We will keep jousting on various aspects of the origin and early evolution of arthropods, but for some aspects we are seemingly heading for the final, as implicitly alluded in Aria (2021).

 

References

Aria C (2019). Reviewing the bases for a nomenclatural uniformization of the highest taxonomic levels in arthropods. Geological Magazine 156, 1463–1468.

Aria C (2020). Macroevolutionary patterns of body plan canalization in euarthropods. Paleobiology 46, 569–593. doi: 10.1017/pab.2020.36

Aria C (2021). The origin and early evolution of arthropods. PaleorXiv, 4zmey, ver. 4, peer-reviewed by PCI Paleo. doi: 10.31233/osf.io/4zmey

Aria C and Caron JB (2015). Cephalic and limb anatomy of a new isoxyid from the Burgess Shale and the role of "stem bivalved arthropods" in the disparity of the frontalmost appendage. PLOS ONE 10, e0124979. doi: 10.1371/journal.pone.0124979

Aria C and Caron JB (2017). Burgess Shale fossils illustrate the origin of the mandibulate body plan. Nature 545, 89–92.

Aria C and Caron JB (2019). A middle Cambrian arthropod with chelicerae and proto-book gills. Nature 573, 586–589. doi: 10.1038/s41586-019-1525-4

Aria C, Zhao F, Zeng H, Guo J, and Zhu M (2020). Fossils from South China redefine the ancestral euarthropod body plan. BMC Evolutionary Biology 20, 4.

Brusca RC, Moore W, and Shuster SM (2016). Invertebrates. Third edition. Sunderland, Massachusetts U.S.A: Sinauer Associates. isbn: 978-1-60535-375-3

Budd GE (1998). Stem-group arthropods from the Lower Cambrian Sirius Passet fauna of North Greenland. In: Arthropod Relationships. Ed. by Fortey RA and Thomas RH. London, UK: Chapman & Hall, pp. 125–138.

Budd GE (2002). A palaeontological solution to the arthropod head problem. Nature 417, 271–275. doi: 10.1038/417271a

Budd GE and Telford MJ (2009). The origin and evolution of arthropods. Nature 457, 812–817. doi: 10.1038/Nature07890

Caron JB and Aria C (2017). Cambrian suspension-feeding lobopodians and the early radiation of panarthropods. BMC Evolutionary Biology 17, 29. doi: 10.1186/s12862-016-0858-y

Caron JB and Jackson DA (2008). Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology 258, 222–256. doi: 10.1016/j.palaeo.2007.05.023

Daley AC, Antcliffe JB, Drage HB, and Pates S (2018). Early fossil record of Euarthropoda and the Cambrian Explosion. Proceedings of the National Academy of Sciences of the United States of America 115, 5323–5331. doi: 10.1073/pnas.1719962115

Edgecombe GD (2020). Arthropod origins: Integrating paleontological and molecular evidence. Annual Review of Ecology, Evolution, and Systematics 51, 1–25. doi: 10.1146/annurev-ecolsys-011720-124437

Edgecombe GD and Legg DA (2014). Origins and early evolution of arthropods. Palaeontology 57, 457–468.

Fu D, Tong G, Dai T, Liu W, Yang Y, Zhang Y, Cui L, Li L, Yun H, Wu Y, Sun A, Liu C, Pei W, Gaines RR, and Zhang X (2019). The Qingjiang biota—A Burgess Shale–type fossil Lagerstätte from the early Cambrian of South China. Science 363, 1338–1342. doi: 10.1126/science.aau8800

Lev O and Chipman AD (2020). Development of the pre-gnathal segments of the insect head indicates they are not serial homologues of trunk segments. bioRxiv, 2020.09.16.299289. doi: 10.1101/2020.09.16.299289

Liu Y, Ortega-Hernández J, Zhai D, and Hou X (2020). A reduced labrum in a Cambrian great-appendage euarthropod. Current Biology 30, 3057–3061.e2. doi: 10.1016/j.cub.2020.05.085

Park TYS and Kihm JH (2015). Post-embryonic development of the Early Ordovician (ca. 480 Ma) trilobite Apatokephalus latilimbatus Peng, 1990 and the evolution of metamorphosis. Evolution & Development 17, 289–301. doi: 10.1111/ede.12138

Servais T, Perrier V, Danelian T, Klug C, Martin R, Munnecke A, Nowak H, Nützel A, Vandenbroucke TR, Williams M, and Rasmussen CM (2016). The onset of the ‘Ordovician Plankton Revolution’ in the late Cambrian. Palaeogeography, Palaeoclimatology, Palaeoecology 458, 12–28. doi: 10.1016/j.palaeo.2015.11.003

Van Roy P, Daley AC, and Briggs DEG (2015). Anomalocaridid trunk limb homology revealed by a giant filter-feeder with paired flaps. Nature 522, 77–80. doi: 10.1038/nature14256

Zeng H, Zhao F, Niu K, Zhu M, and Huang D (2020). An early Cambrian euarthropod with radiodont-like raptorial appendages. Nature 588, 101–105. doi: 10.1038/s41586-020-2883-7

Zhao F, Caron JB, Bottjer DJ, Hu S, Yin Z, and Zhu M (2014). Diversity and species abundance patterns of the Early Cambrian (Series 2, Stage 3) Chengjiang Biota from China. Paleobiology 40, 50–69. doi: 10.1666/12056

The origin and early evolution of arthropodsCédric Aria<p style="text-align: justify;">The rise of arthropods is a decisive event in the history of life. Likely the first animals to have established themselves on land and in the air, arthropods have pervaded nearly all ecosystems and have become pilla...Comparative anatomy, Evo-Devo, Evolutionary biology, Fossil record, Invertebrate paleontology, Macroevolution, Paleobiodiversity, Paleobiology, Paleoecology, Phylogenetics, Systematics, Taphonomy, TaxonomyTae-Yoon Park2021-04-26 13:51:21 View
13 Jul 2023
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A baenid turtle shell from the Mesaverde Formation (Campanian, Late Cretaceous) of Park County, Wyoming, USA

New baenid turtle material from the Campanian of Wyoming

Recommended by ORCID_LOGO based on reviews by Heather F. Smith and Brent Adrian

The Baenidae form a diverse extinct clade of exclusively North American paracryptodiran turtles known from the Early Cretaceous to the Eocene (Hay, 1908; Gaffney, 1972; Joyce and Lyson, 2015). Their fossil record was recently extended down to the Berriasian-Valanginian (Joyce et al. 2020), but the group probably originates in the Late Jurassic because it is usually retrieved as the sister group of Pleurosternidae in phylogenetic analyses. However, baenids only became abundant during the Late Cretaceous, when they are restricted in distribution to the western United States, Alberta and Saskatchewan (Joyce and Lyson, 2015).

During the Campanian, baenids are abundant in the northern (Alberta, Montana) and southern (Texas, New Mexico, Utah) parts of their range, but in the middle part of this range they are mostly represented by poorly diagnosable shell fragments. In their new contribution, Wu et al. (2023) describe a new articulated baenid specimen from the Campanian Mesaverde Formation of Wyoming. Despite its poor preservation, they are able to confidently assign this partial shell to Neurankylus sp., hence definitively confirming the presence of baenids and Neurankylus in this formation. Incidentally, this new specimen was found in a non-fluvial depositional environment, which would also confirm the interpretation of Neurankylus as a pond turtle (Hutchinson and Archibald, 1986; Sullivan et al., 1988; Wu et al., 2023; see also comments from the second reviewer).

The study of Wu et al. (2023) also includes a detailed account of the state of the fossil when it was discovered and the subsequent extraction and preparation procedures followed by the team. This may seem excessive or out of place to some, but I agree with the authors that such information, when available, should be more commonly integrated into scientific articles describing new fossil specimens. Preparation and restoration can have a significant impact on the perceived morphology. This must be taken into account when working with fossil specimens. The chemicals or products used to treat, prepare, or consolidate the specimens are also important information for long-term curation. Therefore, it is important that such information is recorded and made available for researchers, curators, and preparators.

References

Gaffney, E. S. (1972). The systematics of the North American family Baenidae (Reptilia, Cryptodira). Bulletin of the American Museum of Natural History, 147(5), 241–320.

Hay, O. P. (1908). The Fossil Turtles of North America. Carnegie Institution of Washington, Washington, D.C. https://doi.org/10.5962/bhl.title.12500

Hutchison, J. H., and Archibald, J. D. (1986). Diversity of turtles across the Cretaceous/Tertiary boundary in Northeastern Montana. Palaeogeography, Palaeoclimatology, Palaeoecology, 55(1), 1–22. https://doi.org/10.1016/0031-0182(86)90133-1

Joyce, W. G., and Lyson, T. R. (2015). A review of the fossil record of turtles of the clade Baenidae. Bulletin of the Peabody Museum of Natural History, 56(2), 147–183. https://doi.org/10.3374/014.058.0105

Joyce, W. G., Rollot, Y., and Cifelli, R. L. (2020). A new species of baenid turtle from the Early Cretaceous Lakota Formation of South Dakota. Fossil Record, 23(1), 1–13. https://doi.org/10.5194/fr-23-1-2020

Sullivan, R. M., Lucas, S. G., Hunt, A. P., and Fritts, T. H. (1988). Color pattern on the selmacryptodiran turtle Neurankylus from the Early Paleocene (Puercan) of the San Juan Basin, New Mexico. Contributions in Science, 401, 1–9. https://doi.org/10.5962/p.241286

Wu, K. Y., Heuck, J., Varriale, F. J., and Farke, A. (2023). A baenid turtle shell from the Mesaverde Formation (Campanian, Late Cretaceous) of Park County, Wyoming, USA. PaleorXiv, uk3ac, ver. 5, peer-reviewed and recommended by Peer Community In Paleontology. https://doi.org/10.31233/osf.io/uk3ac

A baenid turtle shell from the Mesaverde Formation (Campanian, Late Cretaceous) of Park County, Wyoming, USAKa Yan Wu, Jared Heuck, Frank J. Varriale, and Andrew A. Farke<p>The Mesaverde Formation of the Wind River and Bighorn basins of Wyoming preserves a rich yet relatively unstudied terrestrial and marine faunal assemblage dating to the Campanian. To date, turtles within the formation have been represented prim...Paleobiodiversity, Paleobiogeography, Vertebrate paleontologyJérémy Anquetin2023-01-16 16:26:43 View