Title: A Pleistocene assemblage of near‐modern Papio hamadryas from the Middle Awash study area, Afar Rift, Ethiopia
AbstractObjectives
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.
Materials and Methods
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.
Results
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.
Discussion
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.
Brasil, Marianne F.; Monson, Tesla A.; Taylor, Catherine E.; Yohler, Ryan M.; Hlusko, Leslea J.(
, American Journal of Biological Anthropology)
AbstractObjectives
The aim of this study is to introduce and systematically assess a new assemblage of colobine fossils (n = 360) recovered from Late Pleistocene (ca. 100,000 years ago) sediments in the Middle Awash research area, Afar Rift, Ethiopia.
Materials and Methods
We describe the colobine fossils relative to extant colobine taxa and Middle Pleistocene fossil samples from “Andalee” and Asbole, Ethiopia using linear dental, cranial, and postcranial metrics, as well as qualitative features. We also document the ontogenetic and sex profiles of this sample.
Results
Based on morphological affinities to extant and fossilColobus, we refer these 360 individuals toColobuscf.guereza. The majority of the individuals (76%) fall into young‐ and middle‐adult age categories. Females are slightly better represented than males, although the majority of individuals (84%) could not be assigned to sex.
Discussion
Details of the last half million years ofColobusmorphological evolution have remained obscured by a sparse fossil record. The newly recovered, prepared, and curated fossils described herein add significantly to the record of this group. Several morphologies seen in these new fossils fall between the AsboleColobussample and extantColobus guereza, suggesting an ancestral‐descendant phyletic relationship among the three time‐successive samples. The populational variation documented among these samples indicates that the distinctive pattern of sexual dimorphism observed inC. guerezahad evolved by 100 ka.
Laird, Myra F.; Sawchuk, Elizabeth A.; Kwekason, Amandus; Mabulla, Audax Z. P.; Ndiema, Emmanuel; Tryon, Christian A.; Lewis, Jason E.; Ranhorn, Kathryn L.(
, American Journal of Physical Anthropology)
AbstractObjectives
The Late Pleistocene and early Holocene in eastern Africa are associated with complex evolutionary and demographic processes that contributed to the population variability observed in the region today. However, there are relatively few human skeletal remains from this time period. Here we describe six individuals from the Kisese II rockshelter in Tanzania that were excavated in 1956, present a radiocarbon date for one of the individuals, and compare craniodental morphological diversity among eastern African populations.
Materials and Methods
This study used standard biometric analyses to assess the age, sex, and stature of the Kisese II individuals. Eastern African craniodental morphological variation was assessed using measures of dental size and a subset of Howells' cranial measurements for the Kisese II individuals as well as early Holocene, early pastoralist, Pastoral Neolithic, and modern African individuals.
Results
Our results suggest a minimum of six individuals from the Kisese II collections with two adults and four juveniles. While the dating for most of the burials is uncertain, one individual is directly radiocarbon dated to ~7.1 ka indicating that at least one burial is early Holocene in age. Craniodental metric comparisons indicate that the Kisese II individuals extend the amount of human morphological diversity among Holocene eastern Africans.
Conclusions
Our findings contribute to a growing body of evidence that Late Pleistocene and early Holocene eastern Africans exhibited relatively high amounts of morphological diversity. However, the Kisese II individuals suggest morphological similarity at localized sites potentially supporting increased regionalization during the early Holocene.
Rossetto‐Harris, Gabriella; Wilf, Peter; Escapa, Ignacio H.; Andruchow‐Colombo, Ana(
, American Journal of Botany)
Premise
Eocene floras of Patagonia document biotic response to the final separation of Gondwana. The conifer genusAraucaria, distributed worldwide during the Mesozoic, has a disjunct extant distribution between South America and Australasia. Fossils assigned to AustralasianAraucariaSect.Eutactausually are represented by isolated organs, making diagnosis difficult.Araucaria pichileufensisE.W. Berry, from the middle Eocene Río Pichileufú (RP) site in Argentine Patagonia, was originally placed in Sect.Eutactaand later reported from the early Eocene Laguna del Hunco (LH) locality. However, the relationship ofA. pichileufensisto Sect.Eutactaand the conspecificity of theAraucariamaterial among these Patagonian floras have not been tested using modern methods.
Methods
We review the type material ofA. pichileufensisalongside large (n= 192) new fossil collections ofAraucariafromLHandRP, including multi‐organ preservation of leafy branches, ovuliferous complexes, and pollen cones. We use a total evidence phylogenetic analysis to analyze relationships of the fossils to Sect.Eutacta.
Results
We describeAraucaria huncoensissp. nov. fromLHand improve the whole‐plant concept forAraucaria pichileufensisfromRP. The two species respectively resolve in the crown and stem of Sect.Eutacta.
Conclusions
Our results confirm the presence and indicate the survival of Sect.Eutactain South America during early Antarctic separation. The exceptionally complete fossils significantly predate several molecular age estimates for crownEutacta. The differentiation of twoAraucariaspecies demonstrates conifer turnover during climate change and initial South American isolation from the early to middle Eocene.
Colella, Jocelyn P.; Frederick, Lindsey M.; Talbot, Sandra L.; Cook, Joseph A.; Brito, ed., José(
, Diversity and Distributions)
AbstractAim
Refugial isolation during glaciation is an established driver of speciation; however, the opposing role of interglacial population expansion, secondary contact, and gene flow on the diversification process remains less understood. The consequences of glacial cycling on diversity are complex and especially so for archipelago species, which experience dramatic fluctuations in connectivity in response to both lower sea levels during glacial events and increased fragmentation during glacial recession. We test whether extended refugial isolation has led to the divergence of genetically and morphologically distinct species within Holarctic ermine (Mustela erminea), a small cosmopolitan carnivore species that harbours 34 extant subspecies, 14 of which are insular endemics.
Location
Holarctic.
Methods
We use genetic sequences (complete mitochondrial genomes, four nuclear genes) from >100 ermine (stoats) and geometric morphometric data for >200 individuals (27 of the 34 extant subspecies) from across their Holarctic range to provide an integrative perspective on diversification and endemism across this complex landscape. Multiple species delimitation methods (iBPP,bPTP) assessed congruence between morphometric and genetic data.
Results
Our results support the recognition of at least three species within theM. ermineacomplex, coincident with three of four genetic clades, tied to diversification in separate glacial refugia. We found substantial geographic variation within each species, with geometric morphometric results largely consistent with historical infraspecific taxonomy.
Main conclusions
Phylogeographic structure mirrors patterns of diversification in other Holarctic species, with a major Nearctic‐Palearctic split, but with greater intraspecific morphological diversity. Recognition of insular endemic speciesM. haidarumis consistent with a deep history of refugial persistence and highlights the urgency of mindful management of island populations along North America's North Pacific Coast. Significant environmental modification (e.g. industrial‐scale logging, mining) has been proposed for a number of these islands, which may elevate the risk of extinction of insular palaeoendemics.
Ruff, Christopher B.; Burgess, M. Loring; Junno, Juho‐Antti; Mudakikwa, Antoine; Zollikofer, Christophe P. E.; Ponce de León, Marcia S.; McFarlin, Shannon C.(
, American Journal of Physical Anthropology)
AbstractObjectives
The effects of phylogeny and locomotor behavior on long bone structural proportions are assessed through comparisons between adult and ontogenetic samples of extant gorillas.
Materials and Methods
A total of 281 wild‐collected individuals were included in the study, divided into four groups that vary taxonomically and ecologically: western lowland gorillas (G. g. gorilla), lowland and highland grauer gorillas(G. b. graueri), and Virunga mountain gorillas (G. b. beringei). Lengths and articular breadths of the major long bones (except the fibula) were measured, and diaphyseal cross‐sectional geometric properties determined using computed tomography. Ages of immature specimens (n = 145) were known or estimated from dental development. Differences between groups in hind limb to forelimb proportions were assessed in both adults and during development.
Results
Diaphyseal strength proportions among adults vary in parallel with behavioral/ecological differences, and not phylogeny. The more arboreal western lowland and lowland grauer gorillas have relatively stronger forelimbs than the more terrestrial Virunga mountain gorillas, while the behaviorally intermediate highland grauer gorillas have intermediate proportions. Diaphyseal strength proportions are similar in young infants but diverge after 2 years of age in western lowland and mountain gorillas, at the same time that changes in locomotor behavior occur. There are no differences between groups in length or articular proportions among either adults or immature individuals.
Conclusion
Long bone diaphyseal strength proportions in gorillas are developmentally plastic, reflecting behavior, while length and articular proportions are much more genetically canalized. These findings have implications for interpreting morphological variation among fossil taxa.
Brasil, Marianne F., Monson, Tesla A., Taylor, Catherine E., Yohler, Ryan M., and Hlusko, Leslea J. A Pleistocene assemblage of near‐modern Papio hamadryas from the Middle Awash study area, Afar Rift, Ethiopia. American Journal of Biological Anthropology 180.1 Web. doi:10.1002/ajpa.24634.
Brasil, Marianne F., Monson, Tesla A., Taylor, Catherine E., Yohler, Ryan M., & Hlusko, Leslea J. A Pleistocene assemblage of near‐modern Papio hamadryas from the Middle Awash study area, Afar Rift, Ethiopia. American Journal of Biological Anthropology, 180 (1). https://doi.org/10.1002/ajpa.24634
Brasil, Marianne F., Monson, Tesla A., Taylor, Catherine E., Yohler, Ryan M., and Hlusko, Leslea J.
"A Pleistocene assemblage of near‐modern Papio hamadryas from the Middle Awash study area, Afar Rift, Ethiopia". American Journal of Biological Anthropology 180 (1). Country unknown/Code not available: Wiley Blackwell (John Wiley & Sons). https://doi.org/10.1002/ajpa.24634.https://par.nsf.gov/biblio/10386753.
@article{osti_10386753,
place = {Country unknown/Code not available},
title = {A Pleistocene assemblage of near‐modern Papio hamadryas from the Middle Awash study area, Afar Rift, Ethiopia},
url = {https://par.nsf.gov/biblio/10386753},
DOI = {10.1002/ajpa.24634},
abstractNote = {Abstract ObjectivesThe 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. Materials and MethodsWe 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. ResultsThe 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. DiscussionThese 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.},
journal = {American Journal of Biological Anthropology},
volume = {180},
number = {1},
publisher = {Wiley Blackwell (John Wiley & Sons)},
author = {Brasil, Marianne F. and Monson, Tesla A. and Taylor, Catherine E. and Yohler, Ryan M. and Hlusko, Leslea J.},
}
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