Results 191 to 200 of about 10,066,750 (238)

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

open access: yesThe 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

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

Postcranial anatomy and osteohistology of an early prozostrodont cynodont from the Upper Triassic of Brazil

open access: yesThe Anatomical Record, EarlyView.
Abstract Prozostrodon brasiliensis, a probainognathian cynodont of the clade Prozostrodontia, is recognized as a key taxon for understanding the origin of Mammaliaformes and mammals. Despite detailed investigations of its cranial anatomy, the postcranial skeleton has received comparatively less attention.
Iasmim M. Michelotti   +4 more
wiley   +1 more source

Integrated microanatomy and microstructure of the maxillary tooth plate reveal a reinforced feeding system and tougher diet in Late Triassic Hyperodapedontinae (Rhynchosauria, Archosauromorpha)

open access: yesThe Anatomical Record, EarlyView.
Abstract Hyperodapedontine rhynchosaurs possessed a unique oral apparatus, long interpreted as an adaptation for processing abrasive and resistant plant material. However, the microanatomical and histological evidence supporting this interpretation remains poorly documented.
Caio A. Scartezini   +3 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

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

open access: yesThe 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

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