scholarly journals Reassessment of the phylogenetic relationships of the late Miocene apes Hispanopithecus and Rudapithecus based on vestibular morphology

2021 ◽  
Vol 118 (5) ◽  
pp. e2015215118
Author(s):  
Alessandro Urciuoli ◽  
Clément Zanolli ◽  
Sergio Almécija ◽  
Amélie Beaudet ◽  
Jean Dumoncel ◽  
...  
Keyword(s):  
Late Miocene ◽  
Phylogenetic Relationships ◽  
Three Dimensional ◽  
Semicircular Canals ◽  
Great Apes ◽  
Great Ape ◽  
Ongoing Debate ◽  
Evolutionary Patterns ◽  
Geometric Morphometric ◽  
Morphometric Analyses

Late Miocene great apes are key to reconstructing the ancestral morphotype from which earliest hominins evolved. Despite consensus that the late Miocene dryopith great apes Hispanopithecus laietanus (Spain) and Rudapithecus hungaricus (Hungary) are closely related (Hominidae), ongoing debate on their phylogenetic relationships with extant apes (stem hominids, hominines, or pongines) complicates our understanding of great ape and human evolution. To clarify this question, we rely on the morphology of the inner ear semicircular canals, which has been shown to be phylogenetically informative. Based on microcomputed tomography scans, we describe the vestibular morphology of Hispanopithecus and Rudapithecus, and compare them with extant hominoids using landmark-free deformation-based three-dimensional geometric morphometric analyses. We also provide critical evidence about the evolutionary patterns of the vestibular apparatus in living and fossil hominoids under different phylogenetic assumptions for dryopiths. Our results are consistent with the distinction of Rudapithecus and Hispanopithecus at the genus rank, and further support their allocation to the Hominidae based on their derived semicircular canal volumetric proportions. Compared with extant hominids, the vestibular morphology of Hispanopithecus and Rudapithecus most closely resembles that of African apes, and differs from the derived condition of orangutans. However, the vestibular morphologies reconstructed for the last common ancestors of dryopiths, crown hominines, and crown hominids are very similar, indicating that hominines are plesiomorphic in this regard. Therefore, our results do not conclusively favor a hominine or stem hominid status for the investigated dryopiths.

scholarly journals A hominin first rib discovered at the Sterkfontein Caves, South Africa

2016 ◽  
Vol Volume 112 (Number 5/6) ◽  
Author(s):  
Gaokgatlhee Tawan ◽  
Daniel García-Martínez ◽  
Jennifer Eyre ◽  
Markus Bastir ◽  
Lee Berger ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Fossil Record ◽  
Three Dimensional ◽  
Great Apes ◽  
Small Individual ◽  
Geometric Morphometric ◽  
First Rib ◽  
Morphometric Analyses ◽  
Fossil Hominin

Abstract First ribs – the first or most superior ribs in the thorax – are rare in the hominin fossil record, and when found, have the potential to provide information regarding the upper thorax shape of extinct hominins. Here, we describe a partial first rib from Member 4 of the Sterkfontein Caves, South Africa. The rib shaft is broken away, so only the head and neck are preserved. The rib is small, falling closest to small-bodied Australopithecus first ribs (AL 288-1 and MH1). Given that it was recovered near the StW 318 femur excavation, which also represents a small individual, we suggest that the two may be associated. Three-dimensional geometric morphometric analyses were used to quantify the rib fragment morphology and compare it to extant hominoid and other fossil hominin ribs. While only the proximal end is preserved, our analyses show that South African Australopithecus share derived features of the proximal first rib more closely resembling A. afarensis and later hominins than great apes.

The primitive brain of early Homo

Science ◽  
2021 ◽  
Vol 372 (6538) ◽  
pp. 165-171 ◽  
Author(s):  
Marcia S. Ponce de León ◽  
Thibault Bienvenu ◽  
Assaf Marom ◽  
Silvano Engel ◽  
Paul Tafforeau ◽  
...  
Keyword(s):  
Frontal Lobe ◽  
Great Apes ◽  
Homo Erectus ◽  
Cognitive Tasks ◽  
Great Ape ◽  
Ongoing Debate ◽  
Brain Organization ◽  
Cortical Organization ◽  
Early Homo ◽  
Western Asia

The brains of modern humans differ from those of great apes in size, shape, and cortical organization, notably in frontal lobe areas involved in complex cognitive tasks, such as social cognition, tool use, and language. When these differences arose during human evolution is a question of ongoing debate. Here, we show that the brains of early Homo from Africa and Western Asia (Dmanisi) retained a primitive, great ape–like organization of the frontal lobe. By contrast, African Homo younger than 1.5 million years ago, as well as all Southeast Asian Homo erectus, exhibited a more derived, humanlike brain organization. Frontal lobe reorganization, once considered a hallmark of earliest Homo in Africa, thus evolved comparatively late, and long after Homo first dispersed from Africa.

scholarly journals A new Late Miocene great ape from Kenya and its implications for the origins of African great apes and humans

2007 ◽  
Vol 104 (49) ◽  
pp. 19220-19225 ◽  
Author(s):  
Y. Kunimatsu ◽  
M. Nakatsukasa ◽  
Y. Sawada ◽  
T. Sakai ◽  
M. Hyodo ◽  
...  
Keyword(s):  
Late Miocene ◽  
Great Apes ◽  
Great Ape ◽  
African Great Apes

scholarly journals Morphological diversity of the bony labyrinth (inner ear) in extant Xenarthrans and its relation to phylogeny

2015 ◽  
Vol 96 (4) ◽  
pp. 658-672 ◽  
Author(s):  
Guillaume Billet ◽  
Lionel Hautier ◽  
Renaud Lebrun
Keyword(s):  
Inner Ear ◽  
Semicircular Canal ◽  
Phylogenetic Relationships ◽  
Morphological Diversity ◽  
Lateral Semicircular Canal ◽  
Geometric Morphometric ◽  
Bony Labyrinth ◽  
Morphometric Analyses ◽  
Ground Sloth ◽  
Weak Influence

Abstract We present a survey of the morphological diversity of the bony labyrinth of the inner ear in Xenarthra, including the fossil ground sloth Megatherium. Using a combination of traditional and geometric morphometrics, correlation analyses, and qualitative observations, we attempt to extract independent and informative phylogenetic characters of the bony labyrinth for the superorder. Geometric morphometric analyses demonstrate a strong imprint of phylogenetic history on the shape of the bony labyrinth of xenarthrans and a weak influence of allometry. Discrete characters mapped on a consensus cladogram for xenarthrans show support for many traditional nodes within the superorder and may also provide critical information for problematic nodes within Cingulata. A relatively large lateral semicircular canal may, for instance, represent a synapomorphy for the molecular clade allying fairy armadillos (Chlamyphorinae) to the Tolypeutinae. Striking convergences were detected when comparing Megatherium, the giant ground sloth, with extant armadillos and Chlamyphorus, the pink fairy armadillo, with the extant three- and two-toed sloths. These findings have the potential to help understand the phylogenetic relationships of fossil xenarthrans. Presentamos un estudio de la diversidad morfológica del laberinto óseo del oído interno de los xenartros, incluyendo el perezoso fósil Megatherium. Utilizamos una combinación de morfométrica tradicional y geométrica, análisis de correlación y observaciones cuantitativas para intentar extraer caracteres filogenéticos independientes e informativos del laberinto óseo para el superorden. Los análisis geométricos morfométricos muestran una fuerte impronta de la historia filogenética de la forma del laberinto óseo de los xenartros y una baja influencia de la alometría. Los caracteres discretos mapeados en un cladograma de consenso para xenartros apoyan varios nodos tradicionales dentro del superorden y podrían también brindar información importante para los nodos problemáticos dentro de los Cingulata. Un canal semicircular lateral relativamente largo podría, por ejemplo, representar una sinapomorfía que apoye el clado molecular que une a los pichiciegos con los Tolypeutinae. Se hallaron notables convergencias al comparar Megatherium con los armadillos actuales, y Chlamyphorus con los perezosos actuales. Estos hallazgos tienen el potencial para ayudar a entender las relaciones filogenéticas de los xenartros fósiles.

scholarly journals 3D Digitization in Functional Morphology: Where is the Point of Diminishing Returns?

2019 ◽  
Vol 59 (3) ◽  
pp. 656-668 ◽  
Author(s):  
Sharlene E Santana ◽  
Jessica H Arbour ◽  
Abigail A Curtis ◽  
Kathryn E Stanchak
Keyword(s):  
Functional Morphology ◽  
Three Dimensional ◽  
Comparative Morphology ◽  
Micro Computed Tomography ◽  
Evolutionary Patterns ◽  
Geometric Morphometric ◽  
Critical Dimensions ◽  
Contrast Enhanced Ct ◽  
2D Data ◽  
3D Digitization

Abstract Modern computational and imaging methods are revolutionizing the fields of comparative morphology, biomechanics, and ecomorphology. In particular, imaging tools such as X-ray micro computed tomography (µCT) and diffusible iodine-based contrast enhanced CT allow observing and measuring small and/or otherwise inaccessible anatomical structures, and creating highly accurate three-dimensional (3D) renditions that can be used in biomechanical modeling and tests of functional or evolutionary hypotheses. But, do the larger datasets generated through 3D digitization always confer greater power to uncover functional or evolutionary patterns, when compared with more traditional methodologies? And, if so, why? Here, we contrast the advantages and challenges of using data generated via (3D) CT methods versus more traditional (2D) approaches in the study of skull macroevolution and feeding functional morphology in bats. First, we test for the effect of dimensionality and landmark number on inferences of adaptive shifts during cranial evolution by contrasting results from 3D versus 2D geometric morphometric datasets of bat crania. We find sharp differences between results generated from the 3D versus some of the 2D datasets (xy, yz, ventral, and frontal), which appear to be primarily driven by the loss of critical dimensions of morphological variation rather than number of landmarks. Second, we examine differences in accuracy and precision among 2D and 3D predictive models of bite force by comparing three skull lever models that differ in the sources of skull and muscle anatomical data. We find that a 3D model that relies on skull µCT scans and muscle data partly derived from diceCT is slightly more accurate than models based on skull photographs or skull µCT and muscle data fully derived from dissections. However, the benefit of using the diceCT-informed model is modest given the effort it currently takes to virtually dissect muscles from CT scans. By contrasting traditional and modern tools, we illustrate when and why 3D datasets may be preferable over 2D data, and vice versa, and how different methodologies can complement each other in comparative analyses of morphological function and evolution.

Using three-dimensional geometric morphometric and dental topographic analyses to infer the systematics and paleoecology of fossil treeshrews (Mammalia, Scandentia)

2020 ◽  
Vol 94 (6) ◽  
pp. 1202-1212
Author(s):  
Keegan R. Selig ◽  
Eric J. Sargis ◽  
Stephen G.B. Chester ◽  
Mary T. Silcox
Keyword(s):  
Evolutionary History ◽  
Effective Means ◽  
Three Dimensional ◽  
Dental Morphology ◽  
Geometric Morphometric ◽  
Second Molar ◽  
Morphometric Analyses ◽  
History Of ◽  
Dietary Ecology ◽  
Molar Morphology

AbstractTreeshrews are small, Indomalayan mammals closely related to primates. Previously, three-dimensional geometric morphometric analyses were used to assess patterns of treeshrew lower second molar morphology, which showed that the positions of molar landmarks covary with intraordinal systematics. Another analysis used dental topographic metrics to test patterns of functional dental morphology and found that molar curvature, complexity, and relief were an effective means for examining patterns of variation in treeshrew dietary ecology. Here, we build on these analyses by adding two fossil taxa, Prodendrogale yunnanica Qiu, 1986 from the Miocene of China and Ptilocercus kylin Li and Ni, 2016 from the Oligocene of China. Our results show that Pr. yunnanica had a dental bauplan more like that of a tupaiid than that of a ptilocercid, but that the extant tupaiids, including Tupaia and Dendrogale, are more similar to one another in this regard than any are to Prodendrogale. This is contrary to our expectations as Prodendrogale is hypothesized to be most closely related to Dendrogale. Ptilocercus kylin, which has been proposed to be the sister taxon of Pt. lowii Gray, 1848, is characterized by dental morphology like that of Pt. lowii in crest and cuspal position but is interpreted to have been more frugivorous. It has been claimed that Ptilocercus has undergone little morphological change through time. Our results suggest that Pt. kylin was more ecologically distinct from Pt. lowii than previously proposed, providing a glimpse into a more complex evolutionary history of the group than had been inferred.

scholarly journals New fossils of Australopithecus sediba reveal a nearly complete lower back

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Scott A Williams ◽  
Thomas Cody Prang ◽  
Marc R Meyer ◽  
Thierra K Nalley ◽  
Renier Van Der Merwe ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Lumbar Vertebrae ◽  
Lumbar Vertebra ◽  
Great Apes ◽  
Geometric Morphometric ◽  
Lower Back ◽  
Pyramidal Configuration ◽  
Fossil Hominins ◽  
Trunk Musculature ◽  
Lower Lumbar

Adaptations of the lower back to bipedalism are frequently discussed but infrequently demonstrated in early fossil hominins. Newly discovered lumbar vertebrae contribute to a near-complete lower back of Malapa Hominin 2 (MH2), offering additional insights into posture and locomotion in Australopithecus sediba. We show that MH2 possessed a lower back consistent with lumbar lordosis and other adaptations to bipedalism, including an increase in the width of intervertebral articular facets from the upper to lower lumbar column (‘pyramidal configuration’). These results contrast with some recent work on lordosis in fossil hominins, where MH2 was argued to demonstrate no appreciable lordosis (‘hypolordosis’) similar to Neandertals. Our three-dimensional geometric morphometric (3D GM) analyses show that MH2’s nearly complete middle lumbar vertebra is human-like in overall shape but its vertebral body is somewhat intermediate in shape between modern humans and great apes. Additionally, it bears long, cranially and ventrally oriented costal (transverse) processes, implying powerful trunk musculature. We interpret this combination of features to indicate that A. sediba used its lower back in both bipedal and arboreal positional behaviors, as previously suggested based on multiple lines of evidence from other parts of the skeleton and reconstructed paleobiology of A. sediba.

scholarly journals Geometric morphometric investigation of craniofacial morphological change in domesticated silver foxes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Timothy M. Kistner ◽  
Katherine D. Zink ◽  
Steven Worthington ◽  
Daniel E. Lieberman
Keyword(s):  
Three Dimensional ◽  
Cranial Base ◽  
Craniofacial Morphology ◽  
Wild Populations ◽  
Linear Measurements ◽  
Skeletal Morphology ◽  
Geometric Morphometric ◽  
Domestication Syndrome ◽  
Morphometric Investigation ◽  
Unselected Population

AbstractTo test the effects of domestication on craniofacial skeletal morphology, we used three-dimensional geometric morphometrics (GM) along with linear and endocranial measurements to compare selected (domesticated) and unselected foxes from the Russian Farm-Fox Experiment to wild foxes from the progenitor population from which the farmed foxes are derived. Contrary to previous findings, we find that domesticated and unselected foxes show minimal differences in craniofacial shape and size compared to the more substantial differences between the wild foxes and both populations of farmed foxes. GM analyses and linear measurements demonstrate that wild foxes differ from farmed foxes largely in terms of less cranial base flexion, relatively expanded cranial vaults, and increased endocranial volumes. These results challenge the assumption that the unselected population of foxes kept as part of the Russian Farm-Fox experiment are an appropriate proxy for ‘wild’ foxes in terms of craniofacial morphology and highlight the need to include wild populations in further studies of domestication syndrome to disentangle the phenotypic effects of multiple selection pressures. These findings also suggest that marked increases in docility cannot be reliably diagnosed from shape differences in craniofacial skeletal morphology.

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