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1. A Pleistocene assemblage of near‐modern Papio hamadryas from the Middle Awash study area, Afar Rift, Ethiopia

   https://doi.org/10.1002/ajpa.24634  

   Brasil, Marianne F. ; Monson, Tesla A. ; Taylor, Catherine E. ; Yohler, Ryan M. ; Hlusko, Leslea J. ( November 2022 , American Journal of Biological Anthropology)

   The aim of this study is to assess a new assemblage of papionin fossils (n = 143) recovered from later Pleistocene sediments in the Middle Awash study area in the Afar Rift of Ethiopia.

   We collected metric and qualitative data to compare the craniodental and postcranial anatomy of the papionin fossils with subspecies of modernPapio hamadryasand with Plio‐Pleistocene African papionins. We also estimated sex and ontogenetic age.

   The new fossils fit well within the range of morphological variation observed for extantP. hamadryas, overlapping most closely in dental size and proportions with theP. h. cynocephalusindividuals in our extant samples, and well within the ranges ofP. h. anubisandP. h. hamadryas. The considerable overlap in craniodental anatomy with multiple subspecies precludes subspecific diagnosis. We therefore referred 143 individuals toP. hamadryasssp. The majority of the individuals assessed for ontogenetic age fell into middle‐ and old‐adult age categories based on the degree of dental wear. Males (26%) were better represented than females (12%) among individuals preserving the canine‐premolar honing complex.

   These new near‐modernP. hamadryasfossils provide a window into population‐level variation in the later Pleistocene. Our findings echo previous suggestions from genomic studies that the papionin family tree may have included a ghost population and provide a basis for future testing of hypotheses regarding hybridization in the recent evolutionary history of this taxon.

    

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2. Ancient DNA and deep population structure in sub-Saharan African foragers

   https://doi.org/10.1038/s41586-022-04430-9  

   Lipson, Mark ; Sawchuk, Elizabeth A. ; Thompson, Jessica C. ; Oppenheimer, Jonas ; Tryon, Christian A. ; Ranhorn, Kathryn L. ; de Luna, Kathryn M. ; Sirak, Kendra A. ; Olalde, Iñigo ; Ambrose, Stanley H. ; et al ( March 2022 , Nature)

   Abstract Multiple lines of genetic and archaeological evidence suggest that there were major demographic changes in the terminal Late Pleistocene epoch and early Holocene epoch of sub-Saharan Africa 1–4 . Inferences about this period are challenging to make because demographic shifts in the past 5,000 years have obscured the structures of more ancient populations 3,5 . Here we present genome-wide ancient DNA data for six individuals from eastern and south-central Africa spanning the past approximately 18,000 years (doubling the time depth of sub-Saharan African ancient DNA), increase the data quality for 15 previously published ancient individuals and analyse these alongside data from 13 other published ancient individuals. The ancestry of the individuals in our study area can be modelled as a geographically structured mixture of three highly divergent source populations, probably reflecting Pleistocene interactions around 80–20 thousand years ago, including deeply diverged eastern and southern African lineages, plus a previously unappreciated ubiquitous distribution of ancestry that occurs in highest proportion today in central African rainforest hunter-gatherers. Once established, this structure remained highly stable, with limited long-range gene flow. These results provide a new line of genetic evidence in support of hypotheses that have emerged from archaeological analyses but remain contested, suggesting increasing regionalization at the end of the Pleistocene epoch. 

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3. Yedoma Cryostratigraphy of Recently Excavated Sections of the CRREL Permafrost Tunnel Near Fairbanks, Alaska

   https://doi.org/10.3389/feart.2021.758800  

   Kanevskiy, Mikhail ; Shur, Yuri ; Bigelow, Nancy H. ; Bjella, Kevin L. ; Douglas, Thomas A. ; Fortier, Daniel ; Jones, Benjamin M. ; Jorgenson, M. Torre ( March 2022 , Frontiers in Earth Science)

   Recent excavation in the new CRREL Permafrost Tunnel in Fox, Alaska provides a unique opportunity to study properties of Yedoma — late Pleistocene ice- and organic-rich syngenetic permafrost. Yedoma has been described at numerous sites across Interior Alaska, mainly within the Yukon-Tanana upland. The most comprehensive data on the structure and properties of Yedoma in this area have been obtained in the CRREL Permafrost Tunnel near Fairbanks — one of the most accessible large-scale exposures of Yedoma permafrost on Earth, which became available to researchers in the mid-1960s. Expansion of the new ∼4-m-high and ∼4-m-wide linear excavations, started in 2011 and ongoing, exposes an additional 300 m of well-preserved Yedoma and provides access to sediments deposited over the past 40,000 years, which will allow us to quantify rates and patterns of formation of syngenetic permafrost, depositional history and biogeochemical characteristics of Yedoma, and its response to a warmer climate. In this paper, we present results of detailed cryostratigraphic studies in the Tunnel and adjacent area. Data from our study include ground-ice content, the stable water isotope composition of the variety of ground-ice bodies, and radiocarbon age dates. Based on cryostratigraphic mapping of the Tunnel and results of drilling above and inside the Tunnel, six main cryostratigraphic units have been distinguished: 1) active layer; 2) modern intermediate layer (ice-rich silt); 3) relatively ice-poor Yedoma silt reworked by thermal erosion and thermokarst during the Holocene; 4) ice-rich late Pleistocene Yedoma silt with large ice wedges; 5) relatively ice-poor fluvial gravel; and 6) ice-poor bedrock. Our studies reveal significant differences in cryostratigraphy of the new and old CRREL Permafrost Tunnel facilities. Original syngenetic permafrost in the new Tunnel has been better preserved and less affected by erosional events during the period of Yedoma formation, although numerous features (e.g., bodies of thermokarst-cave ice, thaw unconformities, buried gullies) indicate the original Yedoma silt in the recently excavated sections was also reworked to some extent by thermokarst and thermal erosion during the late Pleistocene and Holocene. 

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4. Cretaceous chloranthoids: early prominence, extinct diversity and missing links

   https://doi.org/10.1093/aob/mcad137  

   Friis, Else Marie ; Crane, Peter R. ; Pedersen, Kaj Raunsgaard ; Marone, Federica ( April 2024 , Annals of Botany)

   The Chloranthaceae comprise four extant genera (Hedyosmum, Ascarina, Chloranthus and Sarcandra), all with simple flowers. Molecular phylogenetics indicates that the Chloranthaceae diverged very early in angiosperm evolution, although how they are related to eudicots, magnoliids, monocots and Ceratophyllum is uncertain. Fossil pollen similar to that of Ascarina and Hedyosmum has long been recognized in the Early Cretaceous, but over the last four decades evidence of extinct Chloranthaceae based on other types of fossils has expanded dramatically and contributes significantly to understanding the evolution of the family.

   Studies of fossils from the Cretaceous, especially mesofossils of Early Cretaceous age from Portugal and eastern North America, recognized diverse flowers, fruits, seeds, staminate inflorescences and stamens of extinct chloranthoids. These early chloranthoids include forms related to extant Hedyosmum and also to the Ascarina, Chloranthus and Sarcandra clade. In the Late Cretaceous there are several occurrences of distinctive fossil androecia related to extant Chloranthus. The rich and still expanding Cretaceous record of Chloranthaceae contrasts with a very sparse Cenozoic record, emphasizing that the four extant genera are likely to be relictual, although speciation within the genera might have occurred in relatively recent times. In this study, we describe three new genera of Early Cretaceous chloranthoids and summarize current knowledge on the extinct diversity of the group.

   The evolutionary lineage that includes extant Chloranthaceae is diverse and abundantly represented in Early Cretaceous mesofossil floras that provide some of the earliest evidence of angiosperm reproductive structures. Extinct chloranthoids, some of which are clearly in the Chloranthaceae crown group, fill some of the morphological gaps that currently separate the extant genera, help to illuminate how some of the unusual features of extant Chloranthaceae evolved and suggest that Chloranthaceae are of disproportionate importance for a more refined understanding of ecology and phylogeny of early angiosperm diversification.

    

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5. NEW PHYLOGENY OF LITOPTERNA AND “ARCHAIC” PALEOGENE UNGULATES ENLIGHTENS THE INTERFAMILIARY AFFINITIES WITHIN THE ORDER

   Puschel, Hans P. ; Shelley, Sarah L. ; Williamson, Thomas E. ; Perini, Fernando ; Wible, John R. ; Brusatte, Stephen L. ( November 2022 , Journal of vertebrate paleontology)

   South American Ungulates (SANUs) exhibit astonishing morphological and ecological diversity due to their almost complete isolation during their early evolution. This unique diversity coupled with the limited fossil record of their earliest evolution makes it difficult to establish their phylogenetic position within the placental mammal tree. Litopterna is the second most diverse order of SANUs after only Notoungulata, with species ranging from the middle Paleocene (~63 Ma) to the late Pleistocene. Among SANUs, litopterns are characterized by having cursorial limbs similar to Holarctic groups like Perissodactyla. Currently there are 67 genera of litopterns grouped into nine families, and the affinities of the Paleogene families remain unclear. Furthermore, it is unclear how litopterns are related to older groups of “archaic” Paleogene ungulates of South America (Kollpaninae and Didolodontidae) and North America (e.g., Mioclaenidae), and other SANUs. To test the phylogenetic relationships of Litopterna, we assembled a new morphological matrix with ~1000 craniodental and postcranial characters for 79 taxa. The data were subjected to Bayesian and maximum parsimony analyses. We conducted tip-dated and undated Bayesian analyses using a Mk + G model of morphological evolution. Fifty percent majority rule consensus trees were obtained from the sampled trees from each analysis. The parsimony analysis resulted in ten most parsimonious trees and a strict consensus was computed. The consensus trees derived from the different analyses were largely congruent. A traditional monophyletic Litopterna failed to be recovered as Protolipternidae was closely related to Didolodontidae. Litopterna was found more closely related to Kollpaninae than to North American Mioclaenidae, and Kollpaninae did not form a monophyletic group with the latter. Adianthidae and Indaleciidae were found in a relatively basal position within Litopterna. Macraucheniidae was found as a sister group to Proterotheriidae, whereas Anisolambdidae was the sister group of Sparnotheriodontidae, these four families forming a monophyletic group. By utilizing a more comprehensive approach, these results alter previous conceptions of the intrafamilial affinities within Litopterna and their position among other Paleogene ungulates, shedding new light on how litopterns evolved and diversified during the Paleogene of South America. Funding Sources ANID-PFCHA-Doctorado en el extranjero Becas Chile-2018-72190003, ERC starting grant PalM 756226, NSF DEB 1654949 and 1654952 

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