Results 151 to 160 of about 291,535 (278)

The mechanism of labor in nonhuman primates: A look inside

open access: yesThe 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 morphology of claspers and clasper‐glands during maturation in Potamotrygon wallacei (Chondrichthyes: Potamotrygoninae)

open access: yesThe Anatomical Record, EarlyView.
Abstract The claspers are the copulatory organs in male elasmobranchs, responsible for directing the semen into the female cloaca (C). However, the microscopic morphology of the claspers remains poorly understood. This study describes the morphology of the claspers and clasper glands (CGs) of cururu stingray (Potamotrygon wallacei) at different ...
Matheus Samuel Cunha Braga   +4 more
wiley   +1 more source

Description of large, well‐preserved Enchodus specimens from the Bearpaw Formation of Alberta, Canada

open access: yesThe Anatomical Record, EarlyView.
Abstract Fishes of the genus Enchodus were abundant and cosmopolitan in the Late Cretaceous, but are primarily known from isolated remains in Canada. Four well‐preserved fish skulls were recovered in recent years from ammolite mines sampling the Bearpaw Formation of Southern Alberta, and are here referred to Enchodus petrosus Cope, 1874.
Luke E. Nelson   +2 more
wiley   +1 more source

Historical birth records from 1896 to 1944 from the Basel maternity hospital, Switzerland, reveal significant obstetric selection pressures

open access: yesThe Anatomical Record, EarlyView.
Abstract Maternal and neonatal morbidity and mortality have declined dramatically during the last century. Historical data are therefore important sources to study the evolutionary selection pressures related to childbirth and how they have fluctuated over time.
Mirella Woodert   +7 more
wiley   +1 more source

The pelvis doesn't walk by itself: Wider pelves reduce the cost of walking over unstable surfaces

open access: yesThe Anatomical Record, EarlyView.
Abstract Walking over variable and/or unstable terrain is a key aspect of daily life and was crucial to the evolution of bipedalism. The ability to find gait solutions that maintained stability over uneven terrain for the least increase in metabolic cost was likely a hallmark of locomotor effectiveness in early humans, in particular acting as an ...
Cara Wall‐Scheffler   +2 more
wiley   +1 more source

Human evolution and the obstetrical dilemma: The pelvic floor hypothesis

open access: yesThe Anatomical Record, EarlyView.
Abstract Human childbirth is mechanically difficult because a large‐headed, broad‐shouldered fetus must pass through a comparatively narrow, twisted bony birth canal. Traditional explanations of this “obstetrical dilemma” emphasize the role of bipedal locomotion in inhibiting the evolution of a wider, more spacious pelvis.
Barbara Fischer, Ekaterina Stansfield
wiley   +1 more source

Advanced abdominal ectopic pregnancy: Utility of MRI for operative planning. [PDF]

open access: yesRadiol Case Rep
Christine B   +3 more
europepmc   +1 more source

Osteology of the pectoral girdle and forelimb of Siriusgnathus niemeyerorum, a Late Triassic traversodontid cynodont from Brazil

open access: yesThe Anatomical Record, EarlyView.
Abstract Traversodontids are non‐mammaliaform cynodonts, herbivorous to omnivorous, that lived during the Triassic. In the Late Triassic, some members of this group increased in body size relative to other cynodont lineages and evolved postcranial adaptations associated with locomotion.
Jhonata H. A. Martins, Leonardo Kerber
wiley   +1 more source

Pelvic breadth and juvenile locomotor energetics: Implications for the obstetrical dilemma hypothesis across human growth in past and present humans

open access: yesThe Anatomical Record, EarlyView.
Abstract The obstetrical dilemma hypothesis (ODH) proposes an evolutionary trade‐off between obstetric requirements and locomotor performance. However, whether external pelvic breadth measures influence walking energetics during human growth remains poorly understood.
Guillermo Zorrilla‐Revilla   +4 more
wiley   +1 more source

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