摘要:

AbstractSeveral prosimian species begin a leap from a vertical support with their back toward the landing target. To reorient themselves from this dorsally facing, head‐first lift‐off to a ventrally facing, feet‐first landing, the animals combine an initial twist with a partial backward somersault. Cinefilms of a captive colony of ringtailed lemurs (Lemur catta) revealed that during leaps from vertical poles to horizontal supports, the backward somersaulting rotations were ofteninitiatedwhile the animals were airborne. How could these prosimians initiate rotations in the absence of externally applied forces without violating angular momentum conservation? The problem was approached through vector analysis to demonstrate angular momentum (H) changes about the three principal (symmetrical) axes of rotation for a series of critical body positions that were extracted from the filmed sequences. OneL. cattaspecimen was segmented to provide the dimensions and weights necessary for modeling the various body positions. These data were also used to calculate moments of inertia about the three principal axes in order to predict if rotations about these axes were stable or metastable. Lemurs, like any projectile, must conserve thetotalangular momentum (HT) established at lift‐off. HT, however, is a vector quantity that is the resultant of component vectors about the three principal axes. Thus, H about the individual axes may change as long as HTremains constant. Strategically timed tail movements tilted the body, thereby changing the H value about the head‐to‐toe (twisting) axis. To conserve HT, also aligned along the twisting axis, angular momentum transferred to the somersaulting axis. Owing to the direction of tail‐throw, the initiated rotations were partial backward somersaults that brought the hindlimbs forward for landing. This strategy for initiating specific rotations parallels that practiced by human sprin

ISSN:0275-2565    

DOI:10.1002/ajp.1350160402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractMortality statistics for 25 populations of the larger Old World monkeys (members of the subfamilyCercopithecinae) were evaluated with a competing hazard model of mortality. The best eight of these life tables were combined to generate a standard model life table representative of the mortality patterns of these primates. Two applications of the standard model to smooth, graduate, and compare life tables based on limited and defective data are presented.

ISSN:0275-2565    

DOI:10.1002/ajp.1350160403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe excretion pattern of estradiol was studied in the slow lorisNycticebus coucang)and the ring‐tailed lemur(Lemur catta)in order to compare steroid excretion in two representative prosimian species. Daily urinary estrone conjugate measurements in the female loris provided little information when applied over prolonged periods. As a result of these negative data, a metabolic study was performed to determine if estrogen excretion patterns in the slow loris differed from those in the lemur, where urinary assays proved a useful tool in characterizing reproductive cycles. Radio‐labeled estradiol was injected intravenously, and serial urine and fecal collections were analyzed for radiolabeled metabolites. The results of these studies demonstrate that more than 92% of the radiolabel was excreted in the feces of the loris, in contrast to only 16% excreted in the feces of the le

ISSN:0275-2565    

DOI:10.1002/ajp.1350160404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe reproductive biology of the slow loris(Nycticebus coucang)is poorly documented because of infrequent captive breeding success and the absence of field studies of this species. Reproductive data were collected from a breeding colony of slow lorises held at the Duke University Primate Center for the past 10 years. Nineteen infants were born, with a sex ratio of 1:1 and a neonatal mortality rate of 15.8%. In all cases, litter size was one. Females born in the colony copulated for the first time between 18 and 24 months of age. A male that reached sexual maturity in the colony sired his first offspring at the age of 17 months. Estrous cycles ranged in duration from 29–45 days, with copulations usually occurring for 1 day of estrus. Gestation length averaged 192.2 days. Although a postpartum estrus was observed in three cases of infant death, no conceptions resulted. Lactation lasted approximately 6 months. A clear birth peak was observed, with 12 out of 19 births occurring in March, April, and May. The comparatively low basal metabolic rate of this species may account for the unusually low reproductive rate of the slow loris in comparison with other prosimian primate

ISSN:0275-2565    

DOI:10.1002/ajp.1350160405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractJuvenile and adult females in two wild groups of wedge‐capped capuchin monkeys(Cebus olivaceus)were observed nursing from other adult females. The context of the interactions varied with participants but always involved a higher‐ranking female nursing from a lower‐ranking female. This behavior appears to be an example of an exploitative interaction in which the suckling female benefits at the expense of the nursing f

ISSN:0275-2565    

DOI:10.1002/ajp.1350160406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractAfter an attack on her 6‐day‐old infant, a capuchin monkey manufactured, modified, and used simple tools to manipulate her infant's head wound, and applied modified plant materials to the wound. The monkey's preparation and use of plant materials were varied and skillful. Several contextual factors probably facilitated the extension of tool‐using behaviors that this female used in treating her own wounds to treating another's wound. We consider these in relation to the prehistorical development of social medicine in our own sp

ISSN:0275-2565    

DOI:10.1002/ajp.1350160407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0275-2565    

DOI:10.1002/ajp.1350160408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0275-2565    

DOI:10.1002/ajp.1350160409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0275-2565    

DOI:10.1002/ajp.1350160410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0275-2565    

DOI:10.1002/ajp.1350160401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY