Anatomy of the bony pelvis in parapithecid primates

Four partial innominate bones, attributed to the parapithecid primates Parapithecus grangeri and Apidium phiomense, have recently been recovered from Oligocene deposits in the Fayum of Egypt. These fossils provide the first documentation of pelvic morphology for early anthropoids. In pelvic anatomy, parapithecids show definite similarities to higher primates rather than to prosimians, but cannot be clearly allied with any one extant group. Functionally, the fossils indicate quadrupedal or leaping habits rather than suspensory or bipedal behaviors.     

Dental Ontogeny in Macroscelides proboscideus (Afrotheria) and Erinaceus europaeus (Lipotyphla)

We investigated the state of dental eruption in specimens of Macroscelides proboscideus and Erinaceus europaeus of known age. When M. proboscideus reaches adult size and sexual maturity, few or none of its replaced permanent cheek teeth have erupted. The approximate sequence of upper tooth eruption is P1, [I3, C, M1], [I1–2], M2, P4, [P2, P3]. Chronologically, E. europaeus erupts its molars and most premolars prior to M. proboscideus; but its first two upper incisors erupt after those of M. proboscideus, and its canines erupt around the same time. The approximate sequence of upper tooth eruption in E. europaeus is [M1, M2, P2, I3], C, M3, P4, P3, I2, I1. Unlike M. proboscideus, E. europaeus does not reach adult size until all permanent teeth except for the anterior incisors have erupted. While not unique among mammals, the attainment of adult body size prior to complete eruption of the permanent cheek teeth is particularly common among macroscelidids and other afrotherians.     

Origin of anthropoidea: dental evidence and recognition of early anthropoids in the fossil record, with comments on the Asian anthropoid radiation

Among the earliest fossil anthropoid primates known are Catopithecus browni, Serapia eocaena, Arsinoea kallimos, and Proteopithecus sylviae, from the late Eocene quarry L-41, Fayum Depression, Egypt. Two of these taxa, C. browni and S. eocaena, may be the oldest known members of the Propliopithecidae and Parapithecidae, respectively, while A. kallimos and P. sylviae are archaic anthropoids of less certain familial affiliation. Dental features of C. browni, S. eocaena, A. kallimos, and P. sylviae are compared with those of younger propliopithecids and parapithecids from the Fayum in order to determine the morphocline polarities of dental features among these early anthropoids. From this, a basal African anthropoid dental morphotype is constructed. Among the features of this morphotype are: dental formula of 2.1.3.3; incisors subvertically implanted and somewhat spatulate; p2 as large as p3, both lacking paraconids; p4 weakly obliquely oriented but not exodaenodont; all lower molars with small paraconids present; upper anterior premolars lacking protocone; upper molars with small, cingular hypocones, all cheek teeth nonbunodont; and canines projecting but not necessarily sexually dimorphic. Comparisons are made between this African anthropoid morphotype and two of the best-represented proposed basal anthropoids, Eosimias and Djebelemur, with the result that neither appears to be a good candidate to have been ancestral to the African anthropoids. Other possible basal simians such as Algeripithecus, Tabelia, and Biretia also are evaluated but are too poorly known for adequate analysis. The larger-bodied Asian primates Pondaungia, Amphipithecus, and Siamopithecus also are not likely ancestors for African anthropoids, but like Eosimias they may share a common ancestry. Despite many recent claims of an Asian origin for anthropoids, the evidence remains far from compelling. The true origins of Anthropoidea remain obscure.     

中华山蝠牙齿的脱换模式

笔者于1997年对中华山蝠(Nyctalus velutinus)牙齿的脱换模式进行了研究。共观察幼蝠200只次。中华山蝠初生仔共有22枚乳齿,齿式为2.1.2.0/3.1.2.0,各乳齿略向舌侧倾斜,除乳前臼齿齿冠不分叉外,其余乳齿齿冠均分为三叶。4d龄开始换齿,31d龄左右脱换完毕。乳齿的脱落顺序是:上颌,PM2→PM1→C1→I1→I2;下颌,I1→PM2.I2→I3→PM1→C1;恒齿萌生的顺序为:上颌,M1→PM2.C1→M2→PM1.M3→I1→I2,下颌,M1→I1.PM2→I2.M2→I3.PM1→C1→M3。     

Pattern and pace of dental eruption in Tarsius

This article uses data on the dental eruption pattern and life history of Tarsius to test the utility of Schultz's rule. Schultz's rule claims a relationship between the relative pattern of eruption and the absolute pace of dental development and life history and may be useful in reconstructing life histories in extinct primates. Here, we document an unusual eruption pattern in Tarsius combining early eruption (relative to molars) of anterior replacement teeth (P2 and incisors) and relatively late eruption of the posterior replacement teeth (C, P3, and P4). This eruption pattern does not accurately predict the "slow" pace of life documented for Tarsius [Roberts: Int J Primatol 15 (1994) 1-28], nor aspects of life history directly associated with dental development as would be expected using Schultz's rule. In Tarsius, the anterior teeth and M1 erupt at an early age and therefore are not only fast in a relative sense but also fast in an absolute sense. This seems to be related to a developmental anomaly in the deciduous precursor teeth, which are essentially skipped. This decoupling among dental eruption pattern, dental eruption pace, and life history pace in Tarsius undermines the assumptions that life histories can accurately be described as "fast" or "slow" and that dental eruption pattern alone can be used to infer overall life history pace. The relatively and absolutely early eruption of the anterior dentition may be due to the utility of these front teeth in early food acquisition rather than with the pace of life history.     

Ontogeny and homology of the dentition in dasyurid marsupials: Development inSminthopsis virginiae

Histological analysis of an ontogenetic series of the dasyurid marsupial,Sminthopsis virginiae, from birt to 60 days old, was undertaken to assess the developmental homologies of the deciduous and successional teeth. This period covers the time from the initiation of all teeth as epithelial buds up until the time of early eruption of some teeth. In addition, two older specimens, aged 81 and 97 days, were examined to provide additional information on the state of differentiation of the unerupted third premolar. In the postcanine dentition, only a single tooth position, dP3, was characterized by the later development of a replacing successional tooth (P3), following developmental pathways identical to those in eutherian mammals. In contrast, the anterior dentition is characterized by the formation of rudimentary, nonerupting deciduous incisors and canines, and by the accelerated development of normal, erupting successional incisors and canines in both jaws. Comparison of relative developmental stages for each tooth position throughout its preeruptive ontogeny suggests thatheterochrony (both developmental acceleration and retardation) has played an important role in the evolutionary history of the dasyurid dentition. Differing aspects of this phenomenon are identified and discussed for the anterior dentition, the anterior two premolars, P3, and the lower molars. Further evidence is presented to corroborate the identification of the anterior two premolars in the adult as dP1 and dP2, based on the relative retardation of their initiation and their lack of successor tooth germs. This developmental heterochrony has probably occurred in all three-premolared marsupials.     

Platyrrhine dental eruption sequences

To determine dental eruption sequences of extant platyrrhines, 367 mandibles and maxillae of informative juvenile specimens from all 16 genera were scored for presence of permanent teeth including three intermediate eruption stages following Harvati (Am J Phys Anthropol 112 (2000) 69-85). The timing of molar eruption relative to that of the anterior dentition is variable in platyrrhines. Aotus is precocious, with all molars erupting in succession before replacement of any deciduous teeth, while Cebus is delayed in M2-3 eruption relative to I1-2. Callitrichines have a distinct tendency toward delayed canine and premolar development. Platyrrhine eruption sequences presented here show some evidence of conformity to Schultz's Rule, with relatively early replacement of deciduous dentition in "slower"-growing animals. The relationship of dental eruption sequences to degree of folivory, body mass, brain mass, and dietary quality is also examined. The early eruption of molars relative to anterior teeth in Pithecia, Chiropotes, and Cacajao, in comparison to genera such as Ateles, Lagothrix, and Alouatta, showing relatively later eruption of the molars, appears to be consistent with current phylogenetic hypotheses. Schultz (Am J Phys Anthropol 19 (1935) 489-581) postulated early relative molar eruption as the primitive dental eruption schedule for primates. The extremely early molar eruption of Aotus versus Callicebus (where both incisors erupt before M2 and M3, with M3 usually last) may lend support to the status of Aotus as a basal taxon. The early relative molar eruption of the fossil platyrrhine species Branisella boliviana is also consistent with this hypothesis (Takai et al.: Am J Phys Anthropol 111 (2000) 263-281).     

Critical revision of the alleged delayed dental eruption in South American “ungulates”

The endemic South American “ungulates” (SANU) were traditionally assumed to be a monophyletic offshoot of the Granorder Ungulata, but the current reorganization of the extant ungulates in Laurasiatheria and Afrotheria (based on molecular data) leaved them in an undetermined systematic position. The delayed dental eruption versus cranial growth was proposed as a hard-tissue synapomorphy of Afrotheria. In a recent paper, at least some endemic SANU (Notoungulata, Astrapotheria, and possibly Pyrotheria) were interpreted as allied to Afrotheres by having a late replacement of deciduous cheek teeth. This statement was based on: (1) the usual occurrence within these groups of individuals with deciduous and permanent teeth; (2) the individual size (estimated comparing the length/width ratio of cheek teeth) of specimens with permanent premolars erupted is indistinguishable from that of specimens with deciduous premolars (putative juveniles), and (3) the retention of at least dP1–dP3 in adult specimens of Parastrapotherium (Astrapotheria). Herein we critically examine the presumed existence of delayed dental eruption in astrapotheres, pyrotheres and xenungulates and the assumptions on which it was based. The alleged evidences supporting the occurrence of delayed dental eruption in SANU arise from misinterpreted information from the literature and conceptual mistakes (i.e. delayed dental eruption versus cranial growth was confused with delayed replacement of premolars versus molar eruption). Based on examination of at-hand specimens, we found that there is no evidence for a delayed premolar replacement relative to the eruption of the molars in astrapotheres, pyrotheres, and xenungulates. A delayed dental eruption in relation to jaw growth does not occur at least in Astrapotherium magnum. Although a very recent study proposed close relationships among afrotheres and at least notoungulates and xenungulates, a more complete analysis is still needed to elucidate the evolutionary relationships of astrapotheres and pyrotheres.     

Homologies of the anterior teeth in Indriidae and a functional basis for dental reduction in primates

In a recent paper Schwartz ('74) proposes revised homologies of the deciduous and permanent teeth in living lemuriform primates of the family Indriidae. However, new evidence provided by the deciduous dentition ofAvahi suggests that the traditional interpretations are correct, specifically: (1) the lateral teeth in the dental scraper of Indriidae are homologous with the incisors of Lemuridae and Lorisidae, not the canines; (2) the dental formula for the lower deciduous teeth of indriids is 2.1.3; (3) the dental formula for the lower permanent teeth of indriids is 2.0.2.3; and (4) decrease in number of incisors during primate evolution was usually in the sequence I3, then I2, then I1. It appears that dental reduction during primate evolution occurred at the ends of integrated incisor and cheek tooth units to minimize disruption of their functional integrity.     

Ontogenetic Evidence for Dental Homologies and Premolar Replacement in Fossil and Extant Caenolestids (Marsupialia)

It is generally accepted that the South American marsupial family Caenolestidae is characterized in part by the absence or noneruption of the third deciduous premolar (dP3) in both jaws, although juvenile stages have rarely been identified in extant or fossil representatives of the family. Published illustrations of the dentary of the Miocene caenolestid Stilotherium suggested to us, however, that P3 erupted relatively late during ontogeny, after the eruption of M4. In extant marsupials, this eruption sequence appears to represent the plesiomorphic state and this pattern is generally associated with the eruption of dP3 earlier in ontogeny, and its subsequent replacement by the erupting P3. Therefore, we suspected that a dP3 erupted in earlier ontogenetic stages of caenolestids; to test this hypothesis we searched the mammalogy collections of three museums for evidence of dP3 in juvenile specimens of caenolestids. Examination of more than 180 specimens of the three extant genera of caenolestid marsupials resulted in the identification of only nine juvenile or subadult stages of dental eruption. Seven specimens of Caenolestes and Rhyncholestes corroborated our hypotheses of late eruption of P3 in Caenolestidae. In addition, the two youngest specimens of Caenolestes possessed a tiny, rudimentary dP3, measuring about 0.4 to 0.5 mm in greatest length, associated with a mesiolingual eruption pit containing the apex of the larger P3 in very early phases of eruption above the alveolar margins. The tiny dP3 is clearly nonfunctional in occlusion, and it is questionable whether it erupted above the gun margins in life. Comparison of the dentaries of subadult caenolestids with four dentaries of the Miocene genus Stilotherium corroborated our initial impression that the fossil genus exhibited evidence of a late-erupting P3, comparable to the condition in extant caenolestids. We suggest that examination of other specimens of juvenile dentitions, skulls, and skeletons in museum collections can provide additional insight into the developmental and evolutionary biology of mammals.     

Dental eruption sequence among colobine primates

Dental development is one aspect of growth that is linked to diet and to life history but has not been investigated among colobines since the work of Schultz [1935]. This study establishes the dental eruption sequence for several colobine species and compares it to that of other catarrhines. The mandibles and maxillae of two hundred and four juvenile colobine specimens were scored for presence or absence of permanent teeth and for stages of partial eruption. Eruption was defined as ranging between tooth emergence (any part of a tooth crown above the alveolar margin) and full occlusion, with three intermediate levels manifest between these boundaries. In African colobines, represented by C. guereza, C. angolensis and P. badius, M2 erupts before I2, and in C. angolensis it also erupts before I1. The canine is delayed, erupting after the premolars in females and after M3 in males. Asian colobines show greater diversity in eruption sequences. Nasalis shows no early eruption of the molars and is very similar to Macaca. In Trachypithecus and Pygathrix M(2) erupts before I(2). The canine in Trachypithecus is delayed, erupting after the premolars and, in some males, after M3. In Presbytis M2 erupts before both incisors; M3 erupts before C in both sexes, and often before both premolars. Although the actual timing of eruption is unknown, all colobine species examined except N. larvatus showed some degree of relatively early eruption of M2 and M3. The lack of this tendency in Nasalis sets this genus apart from all other colobines represented in this study. Dental eruption sequence is thought to reflect life history patterns. Early molar eruption in colobines was thought by Schultz (1935) to be a primitive character reflecting shorter life history. Faster growth rates found in folivorous primates have been interpreted as being related to an adaptation to folivory (Leigh 1994), and early eruption of molars may be part of this dietary specialization. The relationships between dental development and both diet and life history are investigated.     

Dentition in Pacific walrus (Odobenus rosmarus divergens) calves of the year

The oral cavity and teeth were examined in Pacific walrus calves of the year that died or were harvested on Cape Vancarem and Koluchin Island, the Chukchi Sea, in September to October 2010. The order of gingival eruption of teeth, the resultant dental formula in calves of the year and 1.5-year-old animals, and the dental formula after alveolar eruption of teeth were determined. The number of teeth after gingival eruption in calves of the year did not depend on their body length and sex. The loss of some teeth, mainly incisors, was recorded in individuals aged 5?C6 months. Already at early developmental stages, functional teeth were found to differ significantly from other (rudimentary) teeth in their weight, total size, and the size of apical foramen. Some individuals had milk teeth, which were either gingivally erupted or partly remained within soft tissues. Cases of aberration in dentition that require additional studies were recorded.     

First record of an upper deciduous molar in Desmanella (Uropsilinae,Talpidae, Mammalia)

The dP4 of Desmanella engesseri Ziegler, 1985 from a maxillary which includes the P2 and P3 in crypt, the P4 in eruption and fully erupted dP4 and M1, is described from Petersbuch 28 (Germany; Lower Miocene, MN3/4). The maxillary was studied using X-ray microtomography to make detailed images of the internal and external features of the sample. This is the first record of a dP4 from Desmanella Engesser, 1972. Its shape is unique for fossil talpids, possessing the apomorphic feature of replacing the protocone with a large lingual cingulum. The functional use of deciduous teeth and the process that led to the complete loss of milk teeth in extant talpids are discussed.     

金丝猴的牙齿

牙齿对古生物、古人类研究是十分重要的。牙齿也是动物分类学所依据的重要特征之一,它所提供的亲缘证据和来自其他方面的材料多是相吻合的。在讨论和评价现生灵长类时,牙齿同样是不可缺少的材料之一。就目前所知,已发表的金丝猴(Rhinopithecus)牙齿的研究资料较少。Hooiier(1952)和Swindler(1976)对川金丝猴的牙齿只作了一个简单的记录和扼要的形态描述。至于滇金丝猴和黔金丝猴牙齿的研究纯属空白。为此,有必要对这三个类群牙齿的形态结构作一个简要的比较观察,试图找出它们之间和属间的异同点,为今后的综合性探讨提供基本材料。     

宁夏同心中新世铲齿象化石

本文记述了宁夏同心地区中中新世哺乳动物群中铲齿象化石——同心铲齿象 (Platybelodon tongxinensis) (原定为同心嵌齿象 (Gomphotherium tongxinensis). 通过与国内外已现的有关铲齿象对比,确认其与国内已发现的葛氏种关系最近,可能属同一枝系.同心种与葛氏种相比,是性质相对原始分布层位较低的我国第二个铲齿象种.文章初步讨论了其 M_3 的某些变异性状.并结合现有的其它标本初步阐述了铲齿象类下门齿的两种结构类型,原始型的同心层状结构和衍生型的齿质柱状结构.建议根据这两种结构仍将铲齿象类划分为 Platybelodontinae 和 Amebelodontinae.     

Schultz's unruly rule: dental developmental sequences and schedules in small-bodied, folivorous lemurs

Schultz's rule (as reconstructed by Smith) states that there is a relationship between the pattern (or relative order) of eruption of molar versus secondary (replacement) teeth and the overall pace (or absolute timing) of growth and maturation. Species with 'fast' life histories (rapid dental development, rapid growth, early sexual maturation, short life spans) are said to exhibit relatively early eruption of the molars and late eruption of the secondary replacement teeth (premolars, canines, incisors), whereas species with 'slow' life histories are said to exhibit relatively late eruption of the molars and early eruption of the secondary dentition. In a recent review, B.H. Smith noted that primates with tooth combs might violate this rule because tooth combs tend to erupt early, regardless of the pace of life history. We show that exceptions to Schultz's rule among lemurs are not limited to the relative timing of eruption of the tooth comb. Rather, among lemurs, some species with extremely accelerated dental development exhibit a pattern of eruption of molars and of secondary teeth in direct opposition to the expectations of Schultz's rule. We focus particularly on the pattern (order) and pace (absolute timing) of dental development and eruption in Avahi and Lepilemur - two relatively small, nocturnal folivores with rapid dental development. These taxa differ markedly in their eruption sequences (the premolars erupt after M2 and M3 in Lepilemur but not Avahi ). We offer an explanation for the failure of Schultz's rule to predict these differences. Schultz's rule presumes that eruption timing is dependent on the size of the jaw and that, therefore, molar crown formation and eruption will be delayed in species with slow-growing jaws. We show that a variety of processes (including developmental imbrication) allows the crowns of permanent teeth to form and to erupt into jaws that might appear to be too small to accommodate them.     

From Embryo to Adult: The Complete Development and Unusual Replacement of the Dentition of the Tammar Wallaby (Macropus eugenii)

Unlike their reptile-like ancestors with continuous tooth replacement, mammals have evolved to replace each tooth either only once, or not at all. In previous large-scale comparative studies, it has been suggested that this tooth replacement only occurs from a successional dental lamina produced lingually to the primary tooth. This study aims to document the complete tooth development and replacement pattern of the tammar wallaby (Macropus eugenii). The tammar wallaby is a diprotodont marsupial, a group defined by their two procumbent lower incisors. To provide a comprehensive documentation of the spatio-temporal pattern of tooth development, we used Lugol’s Iodine staining and microCT scanning (diceCT) of embryos and pouch young into adulthood, resulting in high resolution 3D models for both soft and mineralised stages of development for all tooth positions. Our results reveal that the eponymous lower incisors are the successional generation at the third incisor locus, where the primary dentition initiates but never erupts. Furthermore, we track the development of the only replacement tooth, the permanent third premolar (P3), from initiation to eruption, and found it develops from the primary dental lamina, mesial to the dP3. This is contrary to the conventional view of lingual replacement from successional lamina in mammals. Our findings indicate that no functional tooth replacement occurs in the tammar wallaby, and expands the diversity of tooth replacement patterns found in mammals. We also conclude that since almost all marsupial and placental mammals produce replacement teeth from the distalmost deciduous premolar, this tooth should be considered homologous in these two groups.

     

The study of animal bones from archaeological sites. By Raymond E. Chaplin. ix + 170 pp., figures,tables, bibliography,index. Seminar press,London. 1971. $5.75 (cloth)

A review of the literature reveals a long history of disagreement on the interpretation of the lower deciduous and permanent dentition of the Indriidae. This disagreement has centered on the existence and/or replacement of a canine as a member of the indriid toothcomb. The presence of a pair of canines in the toothcomb of lemurids and lorisids has rarely been questioned, and there is no evidence to indicate that this interpretation is incorrect. There has, however, been no consistency nor substantiating evidence presented for any interpretation of the indriid toothcomb. By comparing the morphology of the teeth of the lemurid, lorisid, and indriid toothcomb, both deciduous and permanent, comparing the mode of dental development in these three families, identifying the indriid lower deciduous dentition, and by relating the data to an ontogenetic and phylogenetic framework, this study proposes: (1) in all three families, the lateral teeth of the toothcomb are canines, (2) the dental formula for the lower deciduous teeth of indriids is 1.1.4, (3) the dental formula for the lower permanent teeth of indriids is 1.1.2.3, and (4) that decrease in number of incisors during primate evolution was most likely I1 to I2 to I3.     

Ontogenetic features of <Emphasis Type="Italic">Dolichopithecus</Emphasis> (Primates,Colobidae) from the Pliocene of Pridnestrovie

In the permanent dentition of the extinct genus Dolichopithecus, M₁, I₁, and I₂ were the first to erupt, followed by M₂, canine, P₄, and P₃. M₃ was the last permanent tooth to erupt. At the stage of eruption of P₄ and P₃, M₃ was incompletely mineralized. The difference from the extant Cercopithecoidea is the loss of all deciduous teeth after eruption of incisors and M1 and the similarity is observed in the succession of eruption of permanent teeth. In Dolichopithecus, the lower jaw body retained constant in thickness after eruption of M₂. The lower jaw increased in length and depth, as the horizontal ramus grew with the formation and eruption of M₃.