Results 111 to 120 of about 914,664 (294)

Twin pregnancies and the limits of the energetics of gestation and growth hypothesis

The Anatomical Record, EarlyView.
Abstract The “Energetics of Gestation and Growth” (EGG) hypothesis proposes that human birth timing and the associated secondary altriciality of human newborns is determined by limits in maternal metabolic capacity. According to this model, labor is triggered when the increasing fetal energy requirements exceed the expectant mother's maximum sustained ...
Cédric Cordey, Nicole M. Webb, Martin Haeusler   +2 more
wiley   +1 more source

The fossil record stays silent: Confusions and conundrums for hominin pelvis evolution

The Anatomical Record, EarlyView.
Abstract The evolution of the hominin pelvis is commonly modeled as a series of stages driven largely by the requirements of bipedal locomotion, reproduction, thermoregulation, and pelvic floor muscular support. These patterns are complicated by variation in canal dimensions in relationship with different changes in overall pelvic breadths. To quantify
Helen K. Kurki, Cara M. Wall‐Scheffler
wiley   +1 more source

Sex-related head size and shape dimorphism in Mapaná snakes (Bothrops asper) kept in captivity

Revista Colombiana de Ciencias Pecuarias, 2013
Background: sexual size dimorphism in snakes is generally well documented, however, sexual shape dimorphism has been poorly studied. As snakes are considered gape-limited predators, identifying patterns of sexual size and head shape dimorphism can help ...
Ana M Henao-Duque, Claudia P Ceballos
doaj  

Evolution of craniofacial shape in relation to sexual dimorphism in Theropithecus and Papio

Frontiers in Ecology and Evolution
IntroductionSexual dimorphism in cranial morphology is a significant aspect of primate evolution, providing insights into evolutionary pressures and mating systems in different species.
Ángeles Ossorio, Ambra Figueroa-Torrejón, Rodrigo Buston, Matteo Caldon, Jacinto Mathe, Jacinto Mathe, Giuliano Doria, Spartaco Gippoliti, Spartaco Gippoliti, Antonella Volta, María Joana Ferreira da Silva, María Joana Ferreira da Silva, María Joana Ferreira da Silva, René Bobe, René Bobe, René Bobe, Susana Carvalho, Susana Carvalho, Susana Carvalho, Susana Carvalho, Cristian Capelli, Felipe I. Martínez   +21 more
doaj   +1 more source

The mechanism of labor in nonhuman primates: A look inside

The Anatomical Record, EarlyView.
Abstract While in humans, the flexed position of the fetus and its rotating course down the birth canal are well documented, in other primates the mechanism of labor is unknown. Despite the lack of comparative data, it is commonly assumed that the human obstetric mechanism is unique, and anthropologists have disputed when and why the transition to the ...
Melissa K. Stoller
wiley   +1 more source

Developmental differences in cortical bone structure in chimpanzee and human femora reflect early locomotor independence in humans

The Anatomical Record, EarlyView.
Abstract The cortical bone structure of long bone diaphyses changes throughout growth via skeletal modeling and has important implications for bone strength and structural integrity. Ontogenetic trends in diaphyseal structure have been identified in both chimpanzees and humans but it is not yet clear how these trends compare given notable differences ...
Karen R. Swan, Rachel Ives, Zewdi J. Tsegai, Louise T. Humphrey   +3 more
wiley   +1 more source

Ecological Aspects of Sexual Dimorphism [PDF]

, 2017
Sexual dimorphism represents a striking source of diversity in nature. This thesis focuses on empirically testing and conceptually unifying some of the non-exclusive adaptive causes of sexual dimorphism.
De Lisle, Stephen Paul
core   +2 more sources

Local variation in age‐related cortical expansion within and between cross‐sections of distal human long bones

The Anatomical Record, EarlyView.
Abstract Cortical bone expansion is an age‐related process where, through endosteal resorption and periosteal apposition, cross‐sectional diameter increases while cortical thickness decreases in long bone diaphyses. Local variation has been observed in this process between cross‐sectional locations, but few studies have examined directional variation ...
Gregory J. Wehrman, Alice F. Gooding, Adam D. Sylvester, Dawnie W. Steadman, Benjamin M. Auerbach   +4 more
wiley   +1 more source

Postnatal craniomandibular growth in Harbor seals (Phoca vitulina vitulina)

The Anatomical Record, EarlyView.
Postnatal ontogeny in Harbor seals (Phoca vitulina vitulina). Cranium and mandible grow rapidly until 5 years of age, followed by a deceleration and finally a stagnation. Abstract As secondarily aquatic carnivores, seals display several phenotypic differences compared to their terrestrial relatives.
Elisabeth Steinbach, Julia Schaar, Christine Böhmer   +2 more
wiley   +1 more source

Evaluating Bergmann's and Allen's rules in the long bones of the eastern gray squirrel

The Anatomical Record, EarlyView.
Abstract Ecogeographical rules predict variation in body size and appendage proportions across climatic gradients, yet intraspecific tests using long bones from wild populations remain limited among small mammals. This study tests the hypothesis that eastern gray squirrels (Sciurus carolinensis) conform to Bergmann's rule, that is, body size increases ...
Tyler Blake, Habiba Chirchir
wiley   +1 more source