Cross-generic Food Sharing in Tamarins

Adult-infant food-sharing behavior is a major component of the infant care strategies of callitrichids (marmosets and tamarins). It is particularly well-developed in cotton-top tamarins (Saguinus Oedipus) and lion tamarins (Leontopithecus spp), which show frequent adult-initiated food offering, as well as sharing of food in response to begging by infants. This report documents a case of cross-generic food sharing, in which a male golden-headed lion tamarin (Leontopithecus chrysomelas) shared food with an infant cotton-top tamarin. The lion tamarin provided more food to the infant than its mother did. This emphasizes the importance of this behavior in the reproductive strategies of the communally-rearing Callitrichidae and raises questions about mechanisms that underly it.     

Gum feeder as environmental enrichment for zoo marmosets and tamarins

Tamarins and marmosets are small-bodied social callitrichines. Wild callitrichines feed on exudates, such as sap and gum; particularly, marmosets are mainly gummivores, while tamarins consume gums only occasionally and opportunistically. Zoo marmosets and tamarins are usually provided with gum arabic as an alternative to the exudates normally found in the wild. The aim of this study was to evaluate the effects of a gum feeder on the behavior and well-being of four zoo-managed callitrichines. We studied four cotton-top tamarins (Saguinus oedipus), four red-handed tamarins (S. midas), two pygmy marmosets (Cebuella pygmaea), and three Geoffroy's marmosets (Callithrix geoffroyi) housed at Parco Natura Viva (Italy). We conducted the study over two different periods, a baseline (control, without the gum feeder) and then a gum feeder (when the gum feeder was provided) period. We used continuous focal animal sampling to collect behavioral data, including durations of social and individual behaviors. We collected 240 min of observations per period per study subject, with a total of 3,120 min for all the subjects in the same period and of 6,240 min in both periods. We analyzed data by using nonparametric statistical tests. First, we found that the gum feeder promoted species-specific behaviors, such as exploration, and diminished self-directed behaviors, suggesting an enriching effect on tamarin and marmoset behavior. Moreover, in red-handed tamarins, the provision of the gum feeder reduced the performance of self-directed and abnormal behavior, specifically coprophagy. These results confirm that gum feeders are effective foraging enrichment tools for zoo marmosets and tamarins.     

Does the milk of callitrichid monkeys differ from that of larger anthropoids?

The generalization that anthropoid primates produce dilute milks that are low in protein and energy is based primarily on data from large monkeys of the families Cebidae and Cercopithecidae, as well as humans. The marmosets and tamarins (Callitrichidae) are not only much smaller in body size, but also typically raise multiple offspring during a relatively brief lactation. We hypothesized that selection for small body size and high reproductive rate might favor secretion of milk of higher energy and protein concentrations. To test this hypothesis, 46 milk samples collected from 10 common marmosets (Callithrix jacchus, ca. 350 g) were assayed for dry matter (DM), crude protein (CP), fat, and sugar; and gross energy (GE) was calculated from these constituents. We also assayed five samples collected from three golden lion tamarins (Leontopithecus rosalia, ca. 700 g) and six samples collected from a single pygmy marmoset (Cebuella pygmaea, ca. 150 g) over two lactation periods. All samples were collected between days 10 and 57 post partum, representing mid lactation for these species. The milks of these three species were similar, containing 14.0%, 16.1%, and 13.7% DM; 2.7%, 2.6%, and 2.9% CP; 3.6%, 5.2%, and 3.7% fat; 7.4%, 7.2%, and 7.8% sugar; and 0.76, 0.90, and 0.82 kcal/g for common marmosets, golden lion tamarins, and the pygmy marmoset, respectively. These species produced milks with energy values that were within the range reported for large anthropoids, albeit with slightly higher protein concentration. However, milk composition did vary substantially among individual common marmoset females, especially in the proportion of milk energy derived from fat. In contrast, CP as expressed as a percent of GE was remarkably constant among common marmoset females. Callitrichid milk appeared to be similar to that of larger anthropoid primates in GE, but was higher in CP and in the proportion of GE from CP. However, the small sample sizes for the golden lion tamarin and the pygmy marmoset, and the wide variation in milk composition found among common marmoset females cautions against definitively characterizing the milks of callitrichids from these data.     

Comparative analysis of masseter fiber architecture in tree-gouging (Callithrix jacchus) and nongouging (Saguinus oedipus) callitrichids

Common marmosets (Callithrix jacchus) and cotton-top tamarins (Saguinus oedipus) (Callitrichidae, Primates) share a broadly similar diet of fruits, insects, and tree exudates. Common marmosets, however, differ from tamarins by actively gouging trees with their anterior teeth to elicit tree exudate flow. During tree gouging, marmosets produce relatively large jaw gapes, but do not necessarily produce relatively large bite forces at the anterior teeth. We compared the fiber architecture of the masseter muscle in tree-gouging Callithrix jacchus (n = 10) to nongouging Saguinus oedipus (n = 8) to determine whether the marmoset masseter facilitates producing these large gapes during tree gouging. We predict that the marmoset masseter has relatively longer fibers and, hence, greater potential muscle excursion (i.e., a greater range of motion through increased muscle stretch). Conversely, because of the expected trade-off between excursion and force production in muscle architecture, we predict that the cotton-top tamarin masseter has more pinnate fibers and increased physiological cross-sectional area (PCSA) as compared to common marmosets. Likewise, the S. oedipus masseter is predicted to have a greater proportion of tendon relative to muscle fiber as compared to the common marmoset masseter. Common marmosets have absolutely and relatively longer masseter fibers than cotton-top tamarins. Given that fiber length is directly proportional to muscle excursion and by extension contraction velocity, this result suggests that marmosets have masseters designed for relatively greater stretching and, hence, larger gapes. Conversely, the cotton-top tamarin masseter has a greater angle of pinnation (but not significantly so), larger PCSA, and higher proportion of tendon. The significantly larger PCSA in the tamarin masseter suggests that their masseter has relatively greater force production capabilities as compared to marmosets. Collectively, these results suggest that the fiber architecture of the common marmoset masseter is part of a suite of features of the masticatory apparatus that facilitates the production of relatively large gapes during tree gouging.     

Provisioning of Young in Golden Lion Tamarins (Callitrichidae, Leontopithecus rosalia): A Test of the Information Hypothesis

Provisioning of young after weaning or fledging is a highly variable phenomenon. Among cooperative breeders, such as marmosets and tamarins, both parents and natal adults may provision immatures. Experiments designed to measure the effects of food familiarity on food-transfer interactions were conducted on zoo-living golden lion tamarin, Leontopithecus rosalia , families to test one proposed benefit of provisioning to recipient young — that immature callitrichids learn food preferences through exposure to food items obtained from older group members. Adults transferred to immatures foods that were known to adults, but novel to immatures, and foods that were novel to all more frequently than foods that were familiar to both adults and immatures. Results suggest that adults alter their behavior such that learning by immatures is fostered. Immatures also were less likely to reject new foods acquired from other group members, compared with those obtained independently, suggesting the possibility that immatures attend to food transfer to facilitate incorporation of new foods into the diet. In contrast, anecdotal accounts of wild marmoset and tamarin food transfer have indicated that infants receive from adults foods that primarily are high in lipids and/or protein, as expected if provisioning acts to supplement nutrition. These apparently contradictory findings may reflect the differing effects of the captive and wild environment on food-transfer behavior or may point to a dual function of provisioning dependent on age of the recipient.     

Examination of the Taxonomy and Diversification of <Emphasis Type="Italic">Leontopithecus</Emphasis> using the Mitochondrial Control Region

Leontopithecus comprises 4 taxa: black lion tamarins (L. chrysopygus), golden lion tamarins (L. rosalia), black-faced lion tamarins (L. caissara), and golden-headed lion tamarins (L. chrysomelas). Endemic to the Atlantic Forest of Brazil, they are endangered (Appendix I, CITES; IUCN Critically Endangered: Leontopithecus chrysopygus, L. caissara; IUCN Endangered: L. rosalia, L. chrysomelas). The 4 taxa are differentiated morphologically and geographically and occupy different habitat types. However, it is not clear if all of them are separate species, particularly Leontopithecus caissara, or how they are related to one another evolutionarily. Therefore, we investigated lion tamarin differentiation and radiation. We sequenced the mtDNA control region and performed phylogenetic analyses, population aggregation analyses, and Mantel tests for geographic/genetic correlation. Mitochondrial genetic data suggest 3 distinct lion tamarin clades (Leontopithecus chrysomelas; L. caissara; and L. chrysopygus/L. rosalia). Phylogenetic analysis also supports: 1) the basal lion tamarin is Leontopithecus chrysomelas, and not L. chrysopygus, 2) L. caissara is not subspecific to L. chrysopygus, and 3) Quaternary forest refugia may have shaped lion tamarin diversification via a pattern that does not follow the theory of metachromism. Even though mitochondrial genetic analyses do not unequivocally support the 4 lion tamarins as separate species, one should consider the 4 lion tamarins, with equal conservation priority based on the combination of morphological, genetic, and habitat differentiation. Each of them is an extremely valuable flagship species that focuses attention on the diminishing, highly endemic Atlantic Forest of Brazil.     

Spontaneous pathology of the common marmoset (Callithrix jacchus) and tamarins (Saguinus oedipus, Saguinus mystax)

Background  Marmosets and tamarins are increasingly used in research, but their pathology remains poorly defined compared with Old World primates.

Methods  Necropsy records of 129 marmosets and 52 tamarins were reviewed; none was used experimentally.

Results  The most common marmoset lesions were dehydration, emaciation, nephritis, colitis, and inanition. The most common tamarin lesions were dehydration, ascites, emaciation, and congestive heart failure. Colitis and heart disease were the most common cause of death in marmosets and tamarins, respectively. Immature marmoset and tamarin deaths often occurred within the first month of life. Immature marmosets usually died from inanition, stillbirth, and colitis; immature tamarins from atelectasis, stillbirth, heart failure, and colitis. Lymphoma was the most common neoplasm for both marmosets and tamarins.

Conclusion  The findings were similar to prior reports with differences in frequency and severity. We report the first case of endometriosis in a marmoset.     

A Reexamination of the Phylogenetic Position of Callimico (Primates) Incorporating New Mitochondrial DNA Sequence Data

The New World monkeys are divided into two main groups, Callitrichidae and Cebidae. Callimico goeldii shares traits with both the Cebidae and the Callitrichidae. Recent morphological phyletic studies generally place Callimico as the most basal member of the Callitrichidae. In contrast, genetic studies (immunological, restriction fragment, and sequence data) have consistently placed Callimico somewhere within the Callitrichidae, not basal to this clade. A DNA sequence data set from the terminal 236 codons of the mitochondrial ND4 gene and the tRNA^His, tRNA^Ser, and tRNA^Leu genes was generated to clarify the position of Callimico. The sequences of 887 base pairs were analyzed by maximum-parsimony, neighbor-joining, and maximum-likelihood methods. The results of these various methods are generally congruent and place Callimico within the Callitrichidae between the marmosets (Callithrix and Cebuella) and the tamarins (Saguinus and Leontopithecus). Combined analyses of all suitable nuclear and mitochondrial gene sequences confirm the position of Callimico between the marmosets and the tamarins. As available molecular evidence indicates that Callimico is more closely related to the marmosets than to the tamarins, a reconsideration of the morphological evidence in light of the consensus tree from DNA sequence analyses is warranted. The marmosets and tamarins share four morphological characters (loss of the third molar, loss of the hypocone, reduced body size, reproductive twinning). Dwarfism may have evolved repeatedly among the Callitrichidae. It is well-known that the loss of a character can occur many times independently. The reproduction of marmosets and tamarins is extremely specialized and it is difficult to imagine that this complex and unique twinning system evolved separately in marmosets and tamarins. However, it is possible that a secondary reversal to single offspring took place in Callimico. Received: 20 March 1997 / Accepted: 17 December 1997     

Phylogeny of lion tamarins (Leontopithecus spp) based on interphotoreceptor retinol binding protein intron sequences

The evolutionary relationships of the lion tamarins (Leontopithecus) were investigated using nuclear interphotoreceptor retinol binding protein (IRBP) intron sequences. Phylogenetic reconstructions strongly support the monophyly of the genus, and a sister relationship between the golden lion tamarin, Leontopithecus rosalia, and the black lion tamarin, L. chrysopygus, to the exclusion of the golden-headed lion tamarin, L. chrysomelas. The most parsimonious evolutionary reconstruction suggests that the ancestral lion tamarin and the common ancestor of L. rosalia and L. chrysopygus had predominantly black coats. This reconstruction is not consistent with a theory of orthogenetic evolution of coat color that was based on coat color evolution in marmosets and tamarins. An alternative reconstruction that is consistent with metachromism requires that ancestral lion tamarins had agouti hairs.     

Predation risk and the interspecific association of two Brazilian Atlantic forest primates in Cabruca agroforest

Forming interspecific associations is one of many strategies adopted by primates in order to avoid predation. In addition to improved predator detection and avoidance, benefits of interspecific associations relate to improved foraging efficiency. In this study we tested these two hypotheses explaining associations between the endangered golden-headed lion tamarin, Leontopithecus chrysomelas and the sympatric Wied's marmoset, Callithrix kuhlii. We estimated predation risk by recording the number of encounters between lion tamarins and potential predators in cabruca agroforest (shaded cacao plantation) and in mosaic forest (a mix of cabruca, primary and secondary forest). To evaluate if the association between the two species was related to foraging benefits we recorded the number of associations between the two species when the lion tamarins were eating and when they were not eating. To test if the association occurred to improve predator detection and avoidance, we evaluated if associations between the species were more frequent in areas with higher predation risk and during the part of the day when predation risk is higher. We also compared the number of associations 3 months before birth events and 3 months after, when the lion tamarins are more susceptible to predation. Predation risk, mainly by raptors, was significantly higher in cabruca than in mosaic forest (0.17 and 0.05 encounters with predators per hour of observation, respectively). Associations were significantly more frequent after birth events and during the part of the day when predation risk was also higher (5-6 am until noon). We did not observe any direct evidence of foraging-related advantages of interspecific associations for the lion tamarins. The tamarins did not associate more when they were foraging. Our findings suggest that lion tamarins are more exposed to predation in cabruca than in mosaic forest and associations between lion tamarins and Wied's marmosets are related to predation avoidance.     

Mixed‐species Groups of Marmosets and Tamarins Across a Gradient of Agroforestry Intensification

Polyspecific associations are commonly observed in social animals, including primates, and have been interpreted as adaptations either to improve access to resources or to provide protection against predators. Mixed‐species associations between Wied's marmosets (Callithrix kuhlii) and golden‐headed lion tamarins (Leontopithecus chrysomelas) have been documented, and are unique among Atlantic forest primates. Both species are endemic to southern Bahia where part of the forest has been converted into cacao agroforests, which have been subjected to management intensification. Tree density and canopy connectivity decrease in more intensively managed agroforests, potentially increasing predation risk and the frequency of mixed‐species groups between these primates. Here, we test this hypothesis using a standardized, large spatial‐scale data set obtained from camera‐trapping in 30 sites across an agroforestry landscape mosaic. As expected, the frequency of mixed‐species groups increased in more intensively managed agroforests, but only relative to the total number of records of tamarins. Our results highlight that the benefits of mixed‐species groups can be asymmetrical among species and variable across the landscape. They corroborate that predation avoidance is an important advantage of mixed‐species groups in callitrichids, especially for conspicuous species living in smaller groups, such as the tamarin. Despite the importance of agroforests to conservation, our results indicate that management intensification can increase predation risk for species of conservation concern. To maintain the conservation value of agroforests, management practices should be planned to avoid any loss of canopy connectivity, taking into account the biodiversity vs. productivity trade‐off associated with shade management.     

Monitoring ovarian function in marmosets and tamarins by the measurement of urinary estrogen metabolites

Practical aspects of urinary estrogen analysis were considered with regard to establishing simple and reliable methods for monitoring ovarian function in marmosets and tamarins. Changes in the hormone:creatinine ratio in small volumes of urine from the common marmoset were significantly correlated with changes in 24-h excretion. Comparison of the metabolism and excretion of estrogens during the ovarian cycle in the common marmoset and cottontop tamarin revealed interesting species differences. High concentrations of conjugated estrone were measured in marmoset plasma, but estradiol 17β was the predominant estrogen in urine. In contrast, estrone was the most abundant estrogen measured in tamarin urine. Both species excreted very little estriol. Sulfates and glucuronides were present in urine in similar proportions before ovulation in the marmoset, although after ovulation sulfates were the more abundant. Conversely, most of the estrogens in tamarin urine appeared to be conjugated as glucuronides. Direct assay for estrone sulfate was applied to the measurement of urinary estrogen excretion during the ovarian cycle in a marmoset. The results compared well with those for total estradiol 17β after hydrolysis and ether extraction. The use of direct assays for conjugated estrogens in small volumes of urine is suggested as a practical method for monitoring ovarian function in marmosets and tamarins.     

The reproductive status of nonbreeding group members in captive golden lion tamarin social groups

Reproductive activity is limited to only one female in many species of callitrichid primates (marmosets and tamarins): daughters and subordinate females do not produce offspring. A suppression of ovulatory cyclicity is responsible for the lack of reproductive activity in three species of callitrichids studied to date. This study evaluated the endocrine status of golden lion tamarins (Leontopithecus rosalia) housed as daughters or sons in family groups and of individuals housed in isosexual peer groups. Daughters 17 months of age and older and a subordinate female had high levels of estrogen excretion. Mean levels of estrogen excretion in these females were similar to those of nonpregnant, breeding adult females (17.14 ± 6.82 versus 11.93 ± 6.33 μg/mg creatinine, respectively). Estrogen profiles were similar to those of breeding adult females, with sinusoidal cycles in estrogen excretion. Younger daughters in family groups (10 and 12 months old) showed markedly lower levels of estrogen excretion (0.84 ± 0.58 μg/mg creatinine). Estrogen profiles lacked the sinusoidal nature of cycles in older daughters and breeding females, and elevations in estrogen excretion occurred frequently and remained elevated for 1 or 2 days. Plasma testosterone levels in males varied widely, but mean concentrations did not differ among males housed in different social conditions. These results suggest that older daughters and subordinate females may be capable of expressing normal ovarian function in the presence of a breeding adult female. This finding may account for two unusual observations in the lion tamarin: the high level of female-female aggression and the presence of groups in the wild with more than one actively breeding female.     

Diet of Buffy Tufted-Eared Marmosets (Callithrix aurita) in a Forest Fragment in Southeastern Brazil

The feeding ecology of the Atlantic forest marmosets (Callithrix spp.) in southeastern Brazil is poorly known, and few studies have focused on buffy tufted-eared marmosets, Callithrix aurita. We determined the food items and investigated the seasonal variation in the diet of a group of four Callithrix aurita in a 17-ha semideciduous forest fragment in southern Minas Gerais State, Brazil. We recorded daily feeding activities between October 1994 and September 1995 using scan sampling at 5-min intervals. The marmosets devoted feeding time to gums (50.5%), fruits (11%), and animal prey (38.5%) in a total of 499 records. Plant resources comprised 27 species from 16 families. They used Acacia paniculata (Mimosoideae, Leguminosae), the main gum source (82%), year-round. Maclura tinctoria (Moraceae) was the fruit species that they consumed most (22%). The marmosets preyed on caterpillars (33%), katydids (5%), and homopterans (4%). Feeding on fruits varied seasonally and was inversely related to gum feeding. Consumption of animal prey remained constant over the year. The wide and year-round dependence on gum suggests that Acacia may play a critical role in marmoset persistence in forest fragments.     

Infection with Trypanosoma cruzi TcII and TcI in free-ranging population of lion tamarins (Leontopithecus spp): an 11-year follow-up

Here, we present a review of the dataset resulting from the 11-years follow-up of Trypanosoma cruzi infection in free-ranging populations of Leontopithecus rosalia (golden lion tamarin) and Leontopithecus chrysomelas (golden-headed lion tamarin) from distinct forest fragments in Atlantic Coastal Rainforest. Additionally, we present new data regarding T. cruzi infection of small mammals (rodents and marsupials) that live in the same areas as golden lion tamarins and characterisation at discrete typing unit (DTU) level of 77 of these isolates. DTU TcII was found to exclusively infect primates, while TcI infected Didelphis aurita and lion tamarins. The majority of T. cruzi isolates derived from L. rosalia were shown to be TcII (33 out 42) Nine T. cruzi isolates displayed a TcI profile. Golden-headed lion tamarins demonstrated to be excellent reservoirs of TcII, as 24 of 26 T. cruzi isolates exhibited the TcII profile. We concluded the following: (i) the transmission cycle of T. cruzi in a same host species and forest fragment is modified over time, (ii) the infectivity competence of the golden lion tamarin population fluctuates in waves that peak every other year and (iii) both golden and golden-headed lion tamarins are able to maintain long-lasting infections by TcII and TcI.     

The benefits of helpers: Effects of group and litter size on infant care in tamarins (Saguinus oedipus)

The Callitrichidae (marmosets and tamarins) typically give birth to twins, and infant care is shared by all group members. The potential benefits to callitrichids of having helpers were investigated in a study of 21 captive cotton-top tamarin (Saguinus oedipus) infants, living in groups with two to 12 older members. Time carried and suckled and amount of food received from other family members were recorded for each infant during the first 12 weeks of life. The results showed that infants in larger groups were carried more and received more food than those in smaller groups. Twin infants in larger families were less likely to be on the same carrier. Singleton infants were carried more than twins but did not receive more food. On average, individual caretakers in larger groups carried less and shared less food with infants than those in smaller groups. When parental contributions to care were analyzed, no effects of group size were found on mothers' contributions to carrying or food sharing, but fathers in larger groups both carried infants less and shared less food with them. There appear to be several benefits of a communal rearing system to cotton-top tamarins. 1) Infants may receive more care in larger families, thus increasing their chances of survival. 2) The burden of care is spread over several animals, reducing the costs to a given individual. 3) The parents, particularly fathers, may benefit most from reducing the costs of investing in the present litter and increasing their ability to invest in future litters.     

Moving callitrichid monkeys from cages to outside areas

To assess the important aspects of a large area for environmental enrichment, the behavior of families of common marmosets Callithrix jacchus and cotton-top tamarins Saguinus oedipus when in laboratory cages and when in much larger outside areas was compared. All animals avoided areas with little cover. The two tamarin families preferred an indoor cage to a large open area with little cover and consequently only showed a limited range of behavior when outside. When dense cover was provided to the marmoset family, they used this area extensively, showing a wider range of behavior than when in cages and shifting to less active behavior patterns. By feeding marmosets in a central area, it was possible to allow unlimited access to the outside while effectively containing them.     

Diet, foraging, and use of space in wild golden-headed lion tamarins

Lion tamarins (Callitrichidae: Leontopithecus) are small frugi-faunivores that defend large home ranges. We describe results from the first long-term investigation of wild golden-headed lion tamarins (L. chrysomelas; GHLTs). We present data about activity budgets, daily activity cycles, diet, daily path length, home range size, home range overlap, and territorial encounters for three groups of GHLTs that were studied for 1.5-2.5 years in Una Biological Reserve, Bahia State, Brazil, an area characterized by aseasonal rainfall. We compare our results to those from other studies of lion tamarins to identify factors that may influence foraging and ranging patterns in this genus. Ripe fruit, nectar, insects, and small vertebrates were the primary components of the GHLT diet, and gums were rarely eaten. Fruit comprised the majority of plant feeding bouts, and the GHLTs ate at least 79 different species of plants from 32 families. The most common foraging sites for animal prey were epiphytic bromeliads. The GHLTs defended large home ranges averaging 123 ha, but showed strong affinities for core areas, spending 50% of their time in approximately 11% of their home range. Encounters with neighboring groups averaged two encounters every 9 days, and they were always aggressive. Data about time budgets and daily activity cycles reveal that the GHLTs spent most of their time foraging for resources or traveling between foraging sites distributed throughout their home ranges. The GHLTs spent much less time consuming exudates compared to lion tamarins in more seasonal environments. Additionally, the GHLTs had much larger home ranges than golden lion tamarins (L. rosalia), and did not engage in territorial encounters as frequently as L. rosalia. GHLT ranging patterns appear to be strongly influenced by resource acquisition and, to a lesser extent, by resource defense.     

Reproduction of the emperor tamarin (Saguinus imperator) in captivity,with comparisons to cotton-top and golden lion tamarins

Little information has been published on the reproductive biology and behavior of the emperor tamarin (Saguinus imperator). We analyzed twelve years of data on emperor tamarins at the Los Angeles Zoo and made comparisons with data on cotton-top tamarins (Saguinus o. oedipus) and golden lion tamarins (Leontopithecus rosalia) from the same collection. Secondary sex ratios did not differ significantly from 50:50. Births were not strictly seasonal for any species. The number of infants reared had a significant effect on interbirth interval for all species, with shorter intervals when only one or no infants were reared, but females did sometimes conceive early in lactation. In emperor tamarin families, all fathers and most older siblings carried new infants, usually beginning within a few days after a birth. Previous exposure to younger siblings did not appear to be critical to the development of competent parental behavior by zooborn emperor tamarin females.     

Sequences of dental ontogeny and callitrichid taxonomy

Sequences of dental development and eruption radiographically determined for 160 immature callitrichids were combined with nonontogenetic criteria in an investigation of callitrichid affinities. Marmosets (Callithrix andCebuella) are distinct from tamarins (Leontopithecus andSaguinus) in both sequences of dental ontogeny and nonontogenetic characters.Callimico presents a tamarin-like pattern in its dental ontogeny and overall appearance. A new callitrichid classification which separates marmosets and tamarins into different subfamilies (Callitrichinae, Leontopithecinae and Callimiconinae) is proposed. Dental ontogenetic data suggest that callitrichids are derived platyrrhine taxa.