scholarly journals Upright walking has driven unique vascular specialization of the hominin ilium

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12240
Author(s):  
Dexter Zirkle ◽  
Richard S. Meindl ◽  
C. Owen Lovejoy
Keyword(s):  
Body Size ◽  
Fossil Record ◽  
Great Apes ◽  
Anterior Inferior Iliac Spine ◽  
Canal System ◽  
Modern Humans ◽  
Fossil Hominins ◽  
Report Analysis ◽  
The Mean ◽  
African Great Apes

Background A novel physis in hominins modulates broadening and shortening of the ilium. We report analysis of a vascular canal system whose origin may be associated with this physis and which appears to be also unique to hominins. Its presence is potentially identifiable in the fossil record by its association with a highly enlarged foramen that is consistently present in modern humans and hominin fossils. Methods We measured the diameter of this foramen in humans, fossil hominins, and African great apes and corrected for body size. Results The mean relative human foramen diameter is significantly greater than those of either Pan or Gorilla. Moreover, eight of the nine values of the Cohen’s d for these differences in ratios are highly significant and support the ordering of magnitudes: Pan < Gorilla < Homo. The relative foramen diameter of A.L. 288-1 is above the 75th percentile of all other hominoids and at the high end of humans. The foramen is also present in ARA-VP-6/500. Conclusions We posit that the presence and significant enlargement of this foramen in fossils can reasonably serve as an indicator that its anterior inferior iliac spine emerged via the unique hominin physis. The foramen can therefore serve as an indicator of hominin iliac ontogenetic specialization for bipedality in fossil taxa.

scholarly journals Recent origin of low trabecular bone density in modern humans

2014 ◽  
Vol 112 (2) ◽  
pp. 366-371 ◽  
Author(s):  
Habiba Chirchir ◽  
Tracy L. Kivell ◽  
Christopher B. Ruff ◽  
Jean-Jacques Hublin ◽  
Kristian J. Carlson ◽  
...  
Keyword(s):  
Body Size ◽  
Trabecular Bone ◽  
Homo Sapiens ◽  
Modern Human ◽  
Homo Erectus ◽  
Lower Limbs ◽  
Modern Humans ◽  
Human Skeleton ◽  
Trabecular Density ◽  
Fossil Hominins

Humans are unique, compared with our closest living relatives (chimpanzees) and early fossil hominins, in having an enlarged body size and lower limb joint surfaces in combination with a relatively gracile skeleton (i.e., lower bone mass for our body size). Some analyses have observed that in at least a few anatomical regions modern humans today appear to have relatively low trabecular density, but little is known about how that density varies throughout the human skeleton and across species or how and when the present trabecular patterns emerged over the course of human evolution. Here, we test the hypotheses that (i) recent modern humans have low trabecular density throughout the upper and lower limbs compared with other primate taxa and (ii) the reduction in trabecular density first occurred in early Homo erectus, consistent with the shift toward a modern human locomotor anatomy, or more recently in concert with diaphyseal gracilization in Holocene humans. We used peripheral quantitative CT and microtomography to measure trabecular bone of limb epiphyses (long bone articular ends) in modern humans and chimpanzees and in fossil hominins attributed to Australopithecus africanus, Paranthropus robustus/early Homo from Swartkrans, Homo neanderthalensis, and early Homo sapiens. Results show that only recent modern humans have low trabecular density throughout the limb joints. Extinct hominins, including pre-Holocene Homo sapiens, retain the high levels seen in nonhuman primates. Thus, the low trabecular density of the recent modern human skeleton evolved late in our evolutionary history, potentially resulting from increased sedentism and reliance on technological and cultural innovations.

scholarly journals Hominin cranial fragments from Milner Hall, Sterkfontein, South Africa

2018 ◽  
Vol 114 (11/12) ◽  
Author(s):  
Amélie Beaudet ◽  
Jason L. Heaton ◽  
Ericka N. L’Abbé ◽  
Travis R. Pickering ◽  
Dominic Stratford
Keyword(s):  
Fossil Record ◽  
Structural Organization ◽  
Relative Proportion ◽  
Stone Tools ◽  
Quantitative Investigation ◽  
Sedimentary Deposits ◽  
Non Invasive ◽  
Fossil Hominins ◽  
The Mean ◽  
First Time

The Sterkfontein Caves site is one of the richest early hominin localities in Africa. In addition to significant fossil assemblages from Members 2 and 4 of the Sterkfontein Formation, recent excavations have revealed hominin-bearing sedimentary deposits in the lesser-known Milner Hall. We describe two hominin cranial fragments excavated from the Milner Hall in 2015 and present the results of a high-resolution microtomographic-based approach to diagnosing the anatomical and taxonomical origin of these specimens. Based on external morphology, StW 671 and StW 672 are tentatively identified as frontal and occipital fragments, respectively. Our non-invasive bi-dimensional quantitative investigation of the two cranial fragments reveals a mean cranial thickness of 8.8 mm and 5.6 mm for StW 671 and StW 672 respectively and a contribution of the diploic layer to the cumulative cranial thickness that is less than 50%. While the mean cranial thickness of StW 671 falls within the range of Homo, the relative proportion of the diploë in both StW 671 and StW 672 is lower than in Australopithecus (>60%) and extant humans (>50%). Accordingly, in terms of both cranial thickness and inner structural organization, the Milner Hall hominins combine derived and unique traits, consistent with the condition of other postcranial and dental material already described from the deposit. Moreover, our study opens interesting perspectives in terms of analysis of isolated cranial fragments, which are abundant in the hominin fossil record. Significance: The Sterkfontein Caves have widely contributed to our understanding of human evolution. Besides the well-known Members 4 and 2, where the iconic ‘Mrs Ples’ and ‘Little Foot’ have been found, in this study we suggest that the Milner Hall locality represents an additional, stratigraphically associated source of not only fossil hominins, but also Oldowan stone tools. In particular, we describe for the first time two cranial fragments, StW 671 and StW 672, identified as frontal and occipital bones, respectively. Our microtomographic-based analysis of these materials reveals some affinities with Homo combined with unique characters. In this context, our study suggests an intriguing mosaicism consistent with the description of the two fossil hominins found in the Milner Hall.

Assessing the completeness of the fossil record: comparison of different methods applied to parareptilian tetrapods (Vertebrata: Sauropsida)

Paleobiology ◽  
2016 ◽  
Vol 42 (4) ◽  
pp. 680-695 ◽  
Author(s):  
Antoine Verrière ◽  
Neil Brocklehurst ◽  
Jörg Fröbisch
Keyword(s):  
Body Size ◽  
Strong Correlation ◽  
Fossil Record ◽  
Data Sets ◽  
Phylogenetic Information ◽  
Phylogenetic Data ◽  
Skeletal Material ◽  
Two Measures ◽  
The Mean ◽  
The Impact

AbstractAs paleontological studies are generally distorted by gaps and biases in the fossil record, it is important to assess its completeness. Here we address the fossil record of Parareptilia, a Permian–Triassic amniote clade, applying two measures of specimen completeness: the skeletal completeness metric (SCM) and the character completeness metric (CCM). The SCM quantifies how much of the skeletal material of a taxon is preserved, whereas the CCM measures the amount of phylogenetic information available. The latter was implemented using two different approaches. In this study, we compare three completeness metrics. Two CCM implementations show a strong correlation with each other, but only the second implementation of the CCM correlates significantly with the SCM, possibly due to character selection in phylogenetic data sets. There is no correlation between diversity of parareptiles and their completeness, implying that the observed fluctuations in diversity are not driven by the completeness of the fossils. The mean completeness of parareptiles through time is consistently high compared with previously studied tetrapod clades, suggesting that most parareptile taxa are based on reasonably complete specimens. Clade-specific differences reveal no link between body size and completeness. However, the analyses confirm the impact of ecology, with aquatic mesosaurids being better preserved than terrestrial taxa.

3. Fossil hominins

2019 ◽  
pp. 24-37
Author(s):  
Bernard Wood
Keyword(s):  
Fossil Record ◽  
Modern Humans ◽  
Archaeological Evidence ◽  
Fossil Hominins

‘Fossil hominins: their discovery and context’ discusses what the hominin fossil record consists of, how it is discovered and recovered, and how it and its context are investigated, which includes the processes of dating fossils and reconstructing past environments. It reviews the evidence that can be used to investigate what the 6–8 million-year-old hominin clade looks like. How much of it can be reconstructed by looking at variation in modern humans, and what needs to be investigated by searching for, finding, and then interpreting fossil and archaeological evidence? How do researchers decide where to look for new fossil sites, and how do they date any fossils they find at those sites?

scholarly journals Shared Pattern of Endocranial Shape Asymmetries among Great Apes, Anatomically Modern Humans, and Fossil Hominins

PLoS ONE ◽  
2012 ◽  
Vol 7 (1) ◽  
pp. e29581 ◽  
Author(s):  
Antoine Balzeau ◽  
Emmanuel Gilissen ◽  
Dominique Grimaud-Hervé
Keyword(s):  
Great Apes ◽  
Modern Humans ◽  
Anatomically Modern Humans ◽  
Fossil Hominins

scholarly journals Measures of maturation in early fossil hominins: events at the first transition from australopiths to early Homo

2016 ◽  
Vol 371 (1698) ◽  
pp. 20150234 ◽  
Author(s):  
M. Christopher Dean
Keyword(s):  
Growth Period ◽  
Great Apes ◽  
Way Of Life ◽  
Limited Evidence ◽  
Modern Humans ◽  
Dental Maturation ◽  
Major Transitions ◽  
Early Homo ◽  
Incremental Growth ◽  
Fossil Hominins

An important question in palaeoanthropology is whether, among the australopiths and the first fossil hominins attributed to early Homo , there was a shift towards a more prolonged period of growth that can be distinguished from that of the living great apes and whether between the end of weaning and the beginning of puberty there was a slow period of growth as there is in modern humans. Evidence for the pace of growth in early fossil hominins comes from preserved tooth microstructure. A record of incremental growth in enamel and dentine persists, which allows us to reconstruct tooth growth and compare key measures of dental maturation with modern humans and living great apes. Despite their diverse diets and way of life, it is currently difficult to identify any clear differences in the timing of dental development among living great apes, australopiths and the earliest hominins attributed to the genus Homo . There is, however, limited evidence that some early hominins may have attained a greater proportion of their body mass and stature relatively earlier in the growth period than is typical of modern humans today. This article is part of the themed issue ‘Major transitions in human evolution’.

Dinosaur Macroevolution and Macroecology

2018 ◽  
Vol 49 (1) ◽  
pp. 379-408 ◽  
Author(s):  
Roger B.J. Benson
Keyword(s):  
Life History ◽  
Body Size ◽  
Reproductive Biology ◽  
Fossil Record ◽  
Structural Diversity ◽  
Body Plan ◽  
Adaptive Landscape ◽  
Species Diversification ◽  
Size Evolution ◽  
Body Size Evolution

Dinosaurs were large-bodied land animals of the Mesozoic that gave rise to birds. They played a fundamental role in structuring Jurassic–Cretaceous ecosystems and had physiology, growth, and reproductive biology unlike those of extant animals. These features have made them targets of theoretical macroecology. Dinosaurs achieved substantial structural diversity, and their fossil record documents the evolutionary assembly of the avian body plan. Phylogeny-based research has allowed new insights into dinosaur macroevolution, including the adaptive landscape of their body size evolution, patterns of species diversification, and the origins of birds and bird-like traits. Nevertheless, much remains unknown due to incompleteness of the fossil record at both local and global scales. This presents major challenges at the frontier of paleobiological research regarding tests of macroecological hypotheses and the effects of dinosaur biology, ecology, and life history on their macroevolution.

scholarly journals Assessing Host-Virus Codivergence for Close Relatives of Merkel Cell Polyomavirus Infecting African Great Apes

2016 ◽  
Vol 90 (19) ◽  
pp. 8531-8541 ◽  
Author(s):  
Nadège F. Madinda ◽  
Bernhard Ehlers ◽  
Joel O. Wertheim ◽  
Chantal Akoua-Koffi ◽  
Richard A. Bergl ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Host Specificity ◽  
Viral Evolution ◽  
Great Apes ◽  
Merkel Cell Polyomavirus ◽  
Merkel Cell ◽  
Human Pathogens ◽  
Content Type ◽  
Animal Hosts ◽  
African Great Apes

ABSTRACTIt has long been hypothesized that polyomaviruses (PyV; familyPolyomaviridae) codiverged with their animal hosts. In contrast, recent analyses suggested that codivergence may only marginally influence the evolution of PyV. We reassess this question by focusing on a single lineage of PyV infecting hominine hosts, the Merkel cell polyomavirus (MCPyV) lineage. By characterizing the genetic diversity of these viruses in seven African great ape taxa, we show that they exhibit very strong host specificity. Reconciliation analyses identify more codivergence than noncodivergence events. In addition, we find that a number of host and PyV divergence events are synchronous. Collectively, our results support codivergence as the dominant process at play during the evolution of the MCPyV lineage. More generally, our results add to the growing body of evidence suggesting an ancient and stable association of PyV and their animal hosts.IMPORTANCEThe processes involved in viral evolution and the interaction of viruses with their hosts are of great scientific interest and public health relevance. It has long been thought that the genetic diversity of double-stranded DNA viruses was generated over long periods of time, similar to typical host evolutionary timescales. This was also hypothesized for polyomaviruses (familyPolyomaviridae), a group comprising several human pathogens, but this remains a point of controversy. Here, we investigate this question by focusing on a single lineage of polyomaviruses that infect both humans and their closest relatives, the African great apes. We show that these viruses exhibit considerable host specificity and that their evolution largely mirrors that of their hosts, suggesting that codivergence with their hosts played a major role in their diversification. Our results provide statistical evidence in favor of an association of polyomaviruses and their hosts over millions of years.

Respiratory Exchange and Body Size in the Aldabra Giant Tortoise

1971 ◽  
Vol 55 (3) ◽  
pp. 651-665 ◽  
Author(s):  
G. M. HUGHES ◽  
R. GAYMER ◽  
MARGARET MOORE ◽  
A. J. WOAKES
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Metabolic Rate ◽  
Relative Proportion ◽  
The Body ◽  
O2 Consumption ◽  
Weight Range ◽  
Testudo Hermanni ◽  
The Mean ◽  
Good Agreement

1. The O2 consumption and CO2 release of nine giant tortoises Testudo gigantea (weight range 118 g-35·5 kg) were measured at a temperature of about 25·5°C. Four European tortoises Testudo hermanni (weight range 640 g-2·16 kg) were also used. The mean RQ values obtained were 1·01 for T. gigantea and 0·97 for T. hermanni. These values were not influenced by activity or size. 2. The data was analysed by plotting log/log regression lines relating body weight to O2 consumption. Both maximum and minimum metabolic rates recorded for each individual T. gigantea showed a negative correlation with body weight. For active rates the relation was O2 consumption = 140·8W0·97, whereas for inactive animals O2 consumption = 45·47W0·82. 3. The maximum rates were obtained from animals that were observed to be active in the respirometer and the minimum rates from animals that remained quiet throughout. The scope for activity increased with body size, being 82 ml/kg/h for animals of 100 g and 103 ml/kg/h for 100 kg animals. The corresponding ratio between maximum and minimum rates increases from about 2 to 6 for the same weight range. 4. Values for metabolic rate in T. hermanni seem to be rather lower than in T. gigantea. Analysis of the relative proportion of the shell and other organs indicates that the shell forms about 31% of the body weight in adult T. hermanni but only about 18% in T. gigantea of similar size. The shell is not appreciably heavier in adult T. gigantea (about 20%). 5. Data obtained for inactive animals is in good agreement with results of other workers using lizards and snakes. Previous evidence suggesting that chelonians show no reduction in metabolic rate with increasing size is not considered to conflict with data obtained in the present work.

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