The application of microtomography (mCT) to dental morphological studies has unveiled a new source of palaeobiological information, particularly in the analysis of the internal structures of teeth. In this study, we assess the expression of talonid crests at the enamel and dentine surfaces in lower permanent and second deciduous molars (M2 and dm2) of H. sapiens, H. neanderthalensis and Atapuerca-Sima de los Huesos (SH) hominins. In modern humans, talonid crests are described exclusively in the deciduous teeth (Korenhof, 1982) and interpreted as a primitive mammalian remnant of the talonid attachment to the trigonid. Here we report for the first time the expression of talonid crests of deciduous and permanent molars in H. sapiens, H. neanderthalensis and Middle Pleistocene hominins. We discuss possible evolutionary interpretations and suggest the importance of recording this feature in future studies.
L’application de la microtomographie (mCT) aux études de morphologie dentaire a dévoilé une nouvelle source d’information paléobiologique, particulièrement dans l’analyse des structures internes des dents. Dans cette étude, nous évaluons l’expression des crêtes du talonide à la surface de l’émail et de la dentine de molaires inférieures et caduques (M2 et dm2) de H. sapiens, H. neanderthalensis et d’Homininés d’Atapuerca-Sima de los Huevos (SH). Chez les humains modernes, les crêtes du talonide sont exclusivement décrites dans le cas des dents caduques (Korenhof, 1982) et interprétées comme un vestige mammalien primitif de l’attache du talonide au trigonide. Ici, nous présentons pour la première fois l’expression de crêtes du talonide de molaires temporaires et permanentes chez H. sapiens, H. neanderthalensis et chez des Homininés du Pléistocène moyen. Nous discutons les interprétations évolutionnistes possibles et proposons de prendre en compte cet élément dans les futures études.
Microcomputed tomography, Enamel–dentine junction, Sima de los Huesos, Atapuerca, SpainMicrotomographie informatisée, Jonction émail–dentine, Sima de los Huesos, Atapuerca, EspagneIntroduction
The frequency and degree of expression of many dental discrete traits expressed on the outer enamel surface (OES) is strongly heritable. Thus, these features have become a valuable source of information to infer evolutionary relatedness among modern humans (e.g. Pilbrow, 2006 and Scott and Turner, 1997), fossil hominins (e.g. Bailey, 2002a, Bailey, 2004, Bermúdez de Castro et al., 2003, Gómez-Robles et al., 2008, Gómez-Robles et al., 2012, Guatelli-Steinberg and Irish, 2005, Irish and Guatelli-Steinberg, 2003, Martinón-Torres et al., 2006, Martinón-Torres et al., 2007b, Martinón-Torres et al., 2012 and Wood and Abbott, 1983), and other hominoids (e.g. Pilbrow, 2006), as well as to investigate the evolutionary scenario in which these species evolved (e.g. Bermúdez de Castro and Martinón-Torres, 2013, Martinón-Torres et al., 2007b and Martinón-Torres et al., 2011).
The morphology of the enamel–dentine junction (EDJ) has been also studied in the past in an attempt to relate the dentine core topography with OES features (e.g. Corruccini, 1987a, Corruccini, 1987b, Korenhof, 1960, Korenhof, 1961, Korenhof, 1978, Korenhof, 1982, Nager, 1960 and Saki et al., 1969). It is now widely accepted that the EDJ is predominantly responsible for the external morphology of a tooth, although the precise level of concordance between both surfaces is still under study (Bailey et al., 2011, Macchiarelli et al., 2006, Martínez de Pinillos et al., 2014, Nager, 1960, Schwartz et al., 1998, Skinner et al., 2008a, Skinner et al., 2009a and Skinner et al., 2009b). In the past, in order to access the EDJ surface, it was necessary to apply destructive techniques or that the teeth were broken or incomplete (Korenhof, 1982, Nager, 1960 and Saki et al., 1969). Using microtomography (mCT) it is now possible to virtually “segment” or separate the different tissues, and produce a 3D reconstruction of each surface in a non-destructive manner (e.g. Macchiarelli et al., 2006 and Olejniczak et al., 2007).
Dental mCT studies have provided a new source of palaeobiological information, revealing a number of crests, ridges and tubercles that seem to be of evolutionary significance, but were inaccessible or did not receive systematic attention (Bailey et al., 2011 and Skinner et al., 2008a). In this context, the trigonid crest pattern of variation in human species has been extensively analyzed at the OES (e.g. Bailey, 2002b, Bailey et al., 2011, Irish, 1998, Martinón-Torres et al., 2007a, Martinón-Torres et al., 2012, Scott and Turner, 1997 and Turner et al., 1991). Following the pioneer work of Korenhof during the last century (Korenhof, 1978 and Korenhof, 1982), trigonid crests have been recently studied at the EDJ by means of mCT (Bailey et al., 2011, Martínez de Pinillos et al., 2014 and Skinner et al., 2008a, Zanolli and Mazurier, 2013). These studies have added new and interesting observations about the morphological variability and origin of the trigonid crests.
In contrast, the expression of a distinct crest extending from the distal trigonid crest to the talonid, also referred as “talonid crest” (Korenhof, 1982) (Fig. 1) has not been systematically studied in human populations. One reason for this lack of assessment may be the difficultly in accessing the EDJ surface non-destructively (prior to the use of mCT). Furthermore, this crest was defined as an anatomical feature only present in human deciduous lower molars and, historically, the deciduous dentition has received significantly less attention than the permanent dentition. Korenhof (1982) suggested that the talonid crest resembled the original attachment of the primitive talonid to the more derived trigonid in mammals, and that its expression in human deciduous molars (but not in permanent teeth) was a proof that temporary dentitions were morphologically more conservative.
In this study, we investigate the expression of talonid crests in the deciduous and permanent lower molars from Atapuerca-Sima de los Huesos, H. neanderthalensis and H. sapiens by means of mCT. Sima de los Huesos (SH) (Atapuerca, Spain) has provided the largest Middle Pleistocene human sample coming from a single locality, providing an exceptional opportunity to explore intrapopulational variability in a fossil population (Arsuaga et al., 1991, Arsuaga et al., 1993, Arsuaga et al., 1997 and Martinón-Torres et al., 2012). The aims of our study are to explore the possibility that talonid crests can be expressed by other human species than H. sapiens, to test whether its manifestation is restricted to deciduous dentitions, and to explore its evolutionary significance.
Material and methods
Table 1 lists the samples included in this study. Following Korenhof (1982), apart from analyzing permanent lower molars, we also assessed the presence of talonid crests in the deciduous second molar (dm2), because of their resemblance to the morphology of permanent molars. We have only included teeth with dental wear ≤ 5 (Molnar, 1971). Thus, the SH subsample consists of 63 out of 123 permanent molars and 1 out of 4 dm2s. The H. sapiens group includes specimens from the early Late Pleistocene (Qafzeh, Israel and Equus Cave, South Africa), late Late Pleistocene (Lagar Velho, Portugal and La Madeleine 4, France), Calcolithic and Bronze Age (Mirador Cave, Sierra de Atapuerca) and a modern human collection (CENIEH's dental sample) composed of clinically extracted teeth from patients of known age and sex, representing a modern Spanish population.
Each molar of the SH sample, as well as those from El Mirador and the CENIEH's dental collections, were scanned with a mCT 80 (Scanco Medical, Switzerland) held at the CENIEH installations. Teeth were scanned with the following parameters: 70Kv, 114 μA and 512 × 512 to 4096 × 4096 image matrix. The resulting isometric voxel size ranged from 18 μm3 to 74 μm3. The obtained image stack was imported into Amira 5.3.3 (Visage Imaging, Inc.) and the segmentation of the tissues was done semi-automatically with manual corrections. No filters were applied. For the rest of the comparative dental sample, we have obtained the microCT scans from the NESPOS and ESRF databases (see Table 1).
Talonid crests were scored at the EDJ according to Korenhof's classifications. He described six types as follows (Korenhof, 1982: 357–358; see Fig. 1).
Type 1. From the middle of the distal trigonid crest a small crest runs for some length in distal direction, but is not connected to any other distinct landmark.
Type 2. From the middle of the distal trigonid crest an uninterrupted crest runs to the tip of the entoconid.
Type 3. From the middle of the distal trigonid crest an interrupted crest runs to the tip of the entoconid.
Type 4. From the middle of the distal trigonid crest a small crest runs to the lingual side, which is reached slightly mesially from the tip of the entoconid.
Type 5. From the tip of the protoconid a crest runs to the tip of the entoconid.
Type 6. From the tip of the metaconid a crest runs for some distance in a distobuccal direction.
In his definition of the talonid crest, Korenhof (1982:357) states that it “extends from some part of the distal trigonid crest”. However, from Table 24.3 (Korenhof, 1982), we can see that the author correlated the expression of some talonid crests with some trigonid crest types where the distal trigonid crest was absent or it was discontinuous (e.g. trigonid crest types 3, 4, 5 and 6). Thus, following his work, we suggest it would be more appropriate to define talonid crests as starting from “some part of the distal trigonid” (removing the term crest).
We calculated the absolute and relative frequencies of expression of talonid crests for SH, H. neanderthalensis and H. sapiens. We also recorded the expression of an entoconid ridge that we interpreted as a “trace” of Korenhof's type 4 (see Results). We performed a non-parametric Chi2 test (PAST, Hammer et al., 2001) to determine if the frequencies of expression of the talonid crests and the mesial entoconid ridge in each dental class, as well as the total molar sample, were significantly different (P < 0.05) among groups. Due to the small sample size, the statistical analyses were only applied to permanent molars. We provide the results of the Chi2 test with both antimeres included (to maximize the N) and with only one antimere [following the individual count method of Turner et al. (1991)].
ResultsPermanent molars
Table 2 presents the frequencies of expression of talonid crests in each of the studied groups. Table 3 lists the specimens that present this feature. For SH permanent molars, the crest was absent in M1s and M2s, but it was present in four M3s, representing the 6.3% of the SH permanent lower molars sample (4 out of 63) and the 18.2% of the SH M3s sample (4 out of 22). If we choose only one antimere per individual, following the individual count method (Turner et al., 1991) the frequency of expression of talonid crests is 3 out of 43 SH lower permanent molars (7%) and 3 out of 18 (16.7%) of SH M3s.
For the H. neanderthalensis sample we found two M1 s and three M3s with a talonid crest, all of them from the Krapina collection. These represent 12.5% of the total Neanderthal sample (5 out of 40), the 10.5% of the Neanderthal M1s (2 out of 19) and 27.3% of the Neanderthal M3s (3 out of 11). If we choose only one antimere (Turner et al., 1991) per individual, the frequencies are 14.2% (5 out of 35) for the total lower molar Neanderthal sample, 12.5% (2 out of 16) of the Neanderthal M1s, and 30% (3 out of 10) of the Neanderthal M3s. We did not find any talonid crests in our H. sapiens permanent molar sample.
There are no significant differences between SH and H. neanderthalensis for any of the categories studied (Table 4). If both antimeres are included, the differences are significant between SH and H. sapiens and between H. neanderthalensis and H. sapiens for the M3s and the total molar sample. If only one antimere is included, only the differences between H. neanderthalensis and H. sapiens for the total molar sample remain significant.
Table 5 specifies the frequency of occurrence of each of the six types of talonid crest patterns described by Korenhof (1982) at the EDJ of the SH, H. neanderthalensis and H. sapiens samples. In order to compare our values for the deciduous sample with those obtained by Korenhof (1982) we included both antimeres.
The most common pattern in SH is Type 2, present in 3 out of 4 cases and representing a 4.8% of the total SH lower molar sample and a 13.6% of the SH M3s sample. Only one individual presents a type 1 (1.6% of the total SH molar sample and 4.5% of the SH M3 sample).
The four SH teeth with a talonid crest present a relatively complex occlusal morphology, due to the expression of accessory cusps and the rotation of the main cusps. The expression of a talonid crest contributes to the atypical conformation of these teeth (Fig. 2). AT-2277 (Fig. 2A) presents a clear type 2 pattern, also evident at the OES, with a distinct crest that runs from the mid-point of the distal trigonid crest to the tip of the entoconid. The same type is found in AT-1959 (Fig. 2B), although the talonid is strongly reduced in its lingual side and the crests are mesially rotated. In AT-2273 (Fig. 2C) the talonid crest is particularly evident at the OES. At the EDJ we can distinguish a short crest running from a low distal trigonid crest to the tip of the entoconid. The strong lingual deviation of the central groove results in an atrophied metaconid and thus, the talonid crest is also lingually deviated and less symmetrical than in Korenhof's prototype 2. Finally, AT-2271 (Fig. 2D) has been scored as Korenhof's type 1, since it displays a small crest running from the distal trigonid crest in a distal direction, that it is not connected to the any distinct landmark.
Of the four cases we scored a talonid crest in SH, two belong to the same individual (Individual XVIII) but the left molar expresses type 1 (AT-2271) whereas the right molar (AT-2277) expresses type 2. We think that AT-2271 (Fig. 2D) could be a case of a “truncated” type 2, where the strong reduction of the lingual cusps (metaconid and the entoconid) together with the concomitant expression of a C7 has interrupted the connection of the talonid crest with the entoconid. For AT-2273 (Fig. 2C) there is no corresponding antimere, and in AT-1959 (Fig. 2B) the talonid crest is absent in its antimere (AT-1945).
For the Neanderthal M1 sample (Fig. 3), D105 presents type 4 and D81 (Fig. 3B) presents type 6. Although in his definition Korenhof (1982) stated that in type 6 the talonid crest runs from the tip of the metaconid for some distance in distobuccal direction, in D81 the crest would run as far as the tip of the hypoconid. For the Neanderthal M3s we scored type 1 (in D5, Fig. 3C), type 4 (in D7, Fig. 3D) and type 5 (in D106, Fig. 3A).
Deciduous molars
Regarding the dm2 (Fig. 4), we only identified three cases with a talonid crest as defined by Korenhof (1982): 2 out of 6 H. sapiens specimens (33.3%) and 1 out of 8 H. neanderthalensis specimens (12.5%) (Table 3). The dm2 from La Madeleine 4 (Fig. 4B) expresses type 1, the commonest pattern in Korenhof's sample. In the dm2 from Lagar Velho (Fig. 4C) we scored type 3, which is the third most frequent in Korenhof's sample. Finally, D65 (Fig. 4A) displays a type 6 crest that runs from the metaconid tip to the entoconid tip. This crest was the second most frequent in Korenhof's sample after type 1.
The percentages of talonid crests in our deciduous samples are remarkably lower than those recorded by Korenhof in his medieval Javanese human sample (Table 6). However, it is interesting to note that in 8 out of 8 (100%) dm2s from the H. neanderthalensis sample, 2 out of 6 (33%) dm2s of the H. sapiens sample, and in the single dm2 from SH, we identified a small ridge, mesial to the entoconid essential ridge (Table 7). This ridge could resemble a talonid crest of type 4, where a small crest runs from the distal trigonid crest to the lingual side, ending at a point that is mesial to the tip of the entoconid. However, this ridge is too short and does not connect with the trigonid, so we consider that it does not fulfill Korenhof's standards to be termed a “talonid crest”. In a few cases, the mesial entoconid ridge can be identified also at the OES (see Fig. 5), but its expression is less clear than at the EDJ.
A similar ridge can be found in a large number of permanent lower molars (Table 7). For the M1s, this mesial entoconid ridge was present in 86.4% of SH, 89.5% of Neanderthals and only a 50% of the H. sapiens sample. For the M2s, the mesial ridge of the entoconid was present in 47.4% of SH, 40% of H. neanderthalensis and 14.3% of H. sapiens. Finally, for the M3s, the mesial ridge was expressed in 27.3% of SH, 18.2% of H. neanderthalensis and 25% of H. sapiens sample. If we include both antimeres, H. sapiens is significantly different to SH for the M1, and to H. neanderthalensis for the M1 and the total molar sample (Table 4). If only one antimere is included, the differences between SH and H. sapiens become significant for the M2 and for the total molar sample.
As stated above, and until the morphological variability of the entoconid cusp is better known, we have preferred not to include this mesial entoconid ridge in the talonid crest scoring. As an example, the Equus Cave molar (Fig. 5E) presents a ridge in the area of interest, but not only does this ridge not reach the trigonid, it is too small to be considered a crest. Thus, we have preferred to be conservative regarding this feature. However, if we were to include this mesial entoconid ridge in the talonid crest scoring, the percentages would clearly change (Table 8). For permanent molars, the prevalence in M1 would change from 0% to 86.4% in SH, from 10.5% to 100% in H. neanderthalensis, and from 0% to 56% in H. sapiens. For M2s, frequencies would shift from 0% to 47.4% in SH, from 0% to 50% in Neanderthals, and from 0% to 14.3% in modern humans. If we include the mesial entoconid ridge within talonid crest types, in M3s frequencies would change from 6.3% to 45.4% in SH, from 27.3% to 45.4% in H. neanderthalensis, and from 0% to 25%. For the total molar sample, the frequency of expression of talonid crests in SH would change from 6.3% to 60.3%, from 12.5% to 72.5% in H. neanderthalensis, and from 0% to 31.2% in modern humans. However, with clearer proportions in all cases, SH and H. neanderthalensis would still show higher frequencies for this feature than H. sapiens. For the dm2, frequencies would change from 12.5% to 100% in H. neanderthalensis, and from 33.3% to 66.6% in H. sapiens, and it would be also present in the only dm2 from SH.
Discussion
In 1982, Korenhof published a “new landmark” on modern human dentitions, based on his study of the dm2 endocasts of a Sangiran medieval population, and called it a “talonid crest”. He considered it “a new and constant feature not observed in permanent molars”, and interpreted it as a primitive feature because of its resemblance to the primitive attachment of the trigonid to the talonid (Korenhof, 1982: 357).
In our study, we have identified the expression of a talonid crest in some permanent molars at both the EDJ and the OES of a hominin Middle Pleistocene population and Neanderthals, but this crest is absent in our H. sapiens sample. According to Korenhof (1982) this trait was only present in deciduous teeth and was proof of a more conservative morphology in these teeth than in permanent ones. However, this statement would not be supported by our data because we have also scored it in permanent teeth, and its frequencies of expression in the dm2 of SH and H. neanderthalensis are lower than in permanent molars. However, it could be that our results are conditioned by our small sample sizes, particularly for temporary dentitions.
Furthermore, the frequency of expression of talonid crests in Korenhof's H. sapiens dm2 sample is remarkably higher (88.5%) than that obtained in our study for this species (33.3%). This is particularly surprising because Korenhof described this feature as almost ubiquitous in deciduous dentitions. It could be that the high frequencies of talonid crests in Korenhof's modern sample is a peculiarity of the medieval Javanese population and cannot be extrapolated to the H. sapiens species. It could also be that we are underestimating the frequencies of expression of talonid crests in our sample. Indeed, we have identified in our study the frequent expression of a mesial ridge in the entoconid of the dm2 and some permanent molars that could be interpreted as a “trace” or vestige of Korenhof's type 4. This mesial ridge is more frequent in SH and H. neanderthalensis et permanent and deciduous molars than in H. sapiens (except for the M3). This ridge is too short and does not attach to the trigonid, so from a conservative perspective we have not included its expression within Korenhof's type 4. Future studies may shed light on whether this ridge should be understood as a feature related to the morphological variability of the entoconid cusp or is indeed a component of a talonid crest. Currently, beyond hominoids (Skinner et al., 2008b) or the trigonid cusps (e.g. Bailey et al., 2011 and Martínez de Pinillos et al., 2014), little is known about the crests and ridges that consistently form at the EDJ on other molar cusps such as the entoconid. Interestingly, a similar ridge seems to be present in PCG.2, a dm2 from the Sangiran Dome (see Fig. 5C from Zanolli et al., 2012) and in Tighenif 2, possibly confirming the presence of a talonid crest type 4 in the latter (Zanolli and Mazurier, 2013.). If demonstrated that this mesial entoconid ridge is related to Korenhof's Type 4, the number of talonid crests for permanent and deciduous molars would be substantially higher in all groups, and would remain higher for SH and H. neanderthalensis than for H. sapiens. Frequencies would be also higher in temporary dentitions, although in the case of our H. sapiens it would still not reach the 100% that Korenhof scored in his medieval sample.
Regarding the polarity of this feature, it would be necessary to explore the pattern of talonid crest variation in other hominin groups. Indeed, attending to the expression of crests at the trigonid, we know that a continuous mid-trigonid crest is a primitive feature that can be found in early hominin groups such as H. erectus, H. georgicus and H. antecessor (Martinón-Torres et al., 2007b, Martinón-Torres et al., 2008 and Zanolli and Mazurier, 2013) However, the particularly high frequencies of expression of this trait in SH and H. neanderthalensis (Bailey, 2000, Bailey, 2002a, Bailey et al., 2011, Martínez de Pinillos et al., 2014 and Martinón-Torres et al., 2012) can be interpreted as derived in this group with regard to H. sapiens. We know now that many of the so-called “typical Neanderthal” features are not apomorphies but distinctive combinations of primitive features (e.g. Bailey, 2002b, Bermúdez de Castro et al., 2012, Franciscus and Trinkaus, 1995, Martinón-Torres et al., 2006 and Patte, 1962). Thus, although the talonid crest could be a primitive feature as suggested by Korenhof (1982), the higher frequencies of talonid crests in European Middle Pleistocene populations and Neanderthals could be a derived feature in this lineage. Interestingly, the high frequency of distal trigonid crests on M3s was cited as diagnostic in the differentiation of H. neanderthalensis and H. sapiens (Bailey, 2002a, Bailey, 2002c and Bailey et al., 2011). The same pattern was also found in the SH dentitions (Martinón-Torres et al., 2012) where the frequencies of distal trigonid crests in M3s were particularly high (Martínez de Pinillos et al., 2014 and Martinón-Torres et al., 2012). Our study reveals that most talonid crests in permanent molars are displayed by M3s, so it might be that talonid crests follow a similar pattern of variation as distal trigonid crests in SH and H. neanderthalensis with regard to H. sapiens (Bailey et al., 2011 and Martinón-Torres et al., 2012).
However, we should not ignore the fact that the only two populations where talonid crests were scored in permanent teeth (Krapina and SH) are the only groups with a sample large enough to assess intrapopulational variability. Future studies in more and larger hominin samples may provide more representative frequencies of expression for this trait.
Finally, we suggest that talonid crests may represent an interesting morphological variable to score in dental anthropological studies and possibly to include in the Arizona State University Dental Anthropology System (ASUDAS, Turner et al., 1991). The significant differences between groups in the pattern of expression despite the small sample sizes, merits further exploration in other hominins in order to understand its real evolutionary meaning.
Acknowledgments
We thank all members of the Atapuerca research team, in particular those who excavated the Sima de los Huesos site, for their dedicated work. We also acknowledge several people for providing access to the studied material and for their helpful assistance: R. Macchiarelli, P. Semal and P. Bayle from NESPOS society; E. Carbonell and M. Lozano (Institut Català de Paleoecologia Humana i Evolució Social, Tarragona, Spain). We are also grateful to G.R. Scott for his always enlightening insights on dental morphology. Special thanks are given to C. Zanolli for kindly sharing the Tighenif EDJ images and his opinion on the morphology of these specimens. We thank P. Fernández-Colón and E. Lacasa-Marquina from the Restoration and Conservation Department of the CENIEH, and M.C. Ortega from Centro de Evolución y Comportamiento Humanos (ISCIII, Madrid) for the restoration and conservation of the SH collection. We also thank R. Macchiarelli and two anonymous reviewers for their valuable comments that helped to improve the quality of the manuscript. The mCT scanner of the SH, Mirador and CENIEH dental collections were performed at CENIEH with the collaboration of CENIEH staff. This research was supported with funding from the Dirección General de Investigación of the Spanish Ministerio de Educación y Ciencia (Project N_ CGL2009-12703-C03-01); Secretaría de Estado, Investigación, Desarrollo e Innovación of the Spanish Ministerio de Economía y Competitividad (Project CGL2012-38434-C03-02); Consejería de Educación de la Junta de Castilla y León (Project CEN074A12-1), and Leakey Foundation. Fieldwork at Atapuerca is supported by the Consejería de Cultura y Turismo of the Junta de Castilla y León and the Fundación Atapuerca. M.M.-P. and L. M.-F. had the benefit of a predoctoral grant from the Fundación Atapuerca and the Fundación Duques de Soria.
Grant sponsorship:Spanish Ministerio de Educación y Ciencia, Consejería de Educación de la Junta de Castilla y León, Spanish Ministerio de Economía y Competitividad, Leakey Foundation, Fundación Duques de Soria.
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Korenhof's types of talonid crest (modified from Korenhof, 1982; Fig. 24.8). Type 1. From the middle of the distal trigonid crest a small crest runs for some length in distal direction, but is not connected to any other distinct landmark. Type 2. From the middle of the distal trigonid crest an uninterrupted crest runs to the tip of the entoconid. Type 3. From the middle of the distal trigonid crest an interrupted crest runs to the tip of the entoconid. Type 4. From the middle of the distal trigonid crest a small crest runs to the lingual side, which is reached slightly mesially from the tip of the entoconid. Type 5. From the tip of the protoconid a crest runs to the tip of the entoconid. Type 6. From the tip of the metaconid a crest runs for some distance in a distobuccal direction. Prd: protoconid, med: metaconid, end: entoconid, mmr: mesial marginal ridge, mc: middle trigonid crest, dc: distal trigonid crest.
Types de crête du talonide de Korenhof (modifié d’après Korenhof, 1982, Fig. 24.8). Type 1. À partir du milieu de la crête du trigonide distale, une petite crête se développe sur une certaine longueur dans la direction distale, mais n’est pas connectée à quelque point que ce soit. Type 2. À partir du milieu de la crête du trigonide distale, une crête ininterrompue se développe jusqu’à l’extrémité de l’entoconide. Type 3. À partir du milieu de la crête du trigonide distale, une crête interrompue se développe jusqu’à l’extrémité de l’entoconide. Type 4. À partir du milieu de la crête du trigonide distale, une petite crête se développe du côté lingual qui est atteint à peu près mésialement par rapport à l’extrémité de l’entoconide. Type 5. À partir de l’extrémité du protoconide, une crête se développe jusqu’à l’extrémité de l’entoconide. Type 6. À partir de l’extrémité du métaconide, une crête se développe sur une certaine distance, dans une direction disto-buccale. Prd : protoconide ; med : métaconide ; end : entoconide ; mmr :arête marginale mésiale ; mc : crête du trigonide moyenne ; dc : crête du trigonide distale.
(Color online) Talonid crest types of the SH permanent lower molar sample. (A) AT-2277 (right M3, type 2); (B) AT-1959 (right M3, type 2); (C) AT-2273 (left M3, type 2); (D) AT-2271 (left M3, type 1). C and D have been mirrored. Teeth not to scale.
(Couleur en ligne) Types de crête du talonide d’un échantillonnage de molaires inférieures permanentes de SH. (A) AT-2277 (M3 droite, type 2) ; (B) AT-1959 (M3, type 2) ; (C) AT-2273 (M3, type 2) ; (D) AT-2271 M3 gauche, type1). C et D sont présentées en miroir. Les dents ne sont pas à l’échelle.
(Color online) Examples of talonid crest types of the Neanderthal permanent lower molar sample. (A) D106 from Krapina (left M3, type 5); (B) D81 from Krapina (left M1, type 6); (C) D5 (left M3, type 1) and D7 (right M3, type 4). A, B and C specimens have been mirrored. Teeth not to scale.
(Couleur en ligne) Exemples de types de crête du talonide d’un échantillonnage de molaires inférieures permanentes de Néandertal. (A) D106 de Krapina (M3 gauche, type 5) ; (B) D81 de Krapina (M1 gauche, type 6) ; (C) D5 (M3 gauche, type 1) et D7 (M3 droite, type 4) ; Les spécimens A, B et C ont été présentés en miroir. Les dents ne sont pas à l’échelle.
(Color online) Examples of talonid crest types in the dm2 sample. (A) D65 from Krapina (type 6); (B) Madeleine 4 (type 1); (C) Lagar Velho (type 3). A has been mirrored. Teeth not to scale.
(Couleur en ligne) Exemples de types de crête du talonide d’un échantillonnage de dm2. (A) D65 de Krapina (Type 6) ; (B) Madeleine 4 (type 1) ; (C) Lagar Velho (type 3) ; A est présenté en miroir. Les dents ne sont pas à l’échelle.
(Color online) Examples of the expression of a mesial ridge at the entoconid in (A) AT-2398 (right dm2), (B) Gibraltar HA 40.26 (right dm2), (C) Qafzeh 15 (right dm2), (D) AT-3933 (right M1) and (E) Equus Cave (right M1) that could resemble Korenhof's type 4. Teeth not to scale.
(Couleur en ligne) Exemples d’expression d’une arête mésiale à l’entoconide pour (A) AT-2398 (dm2 droite), (B) Gibraltar HA 40,26 (dm2 droite), (C) Qafzeh 15 (dm2 droite), (D) AT-3933 (M1 droite) et (E) grotte Equus (M1 droite) qui pourraient ressembler au type 4 de Korenhof. Les dents ne sont pas à l’échelle.
Study sample composition. Numbers in brackets refer to the sample size, counting only one antimere per individual.
Composition de l’échantillonnage étudié. Les nombres entre parenthèses renvoient à la taille de l’échantillon, en comptant seulement un antimère par individu.
Frequency of occurrence of talonid crests in lower permanent molars.
Fréquence d’occurrence des crêtes du talonide dans les molaires inférieures permanentes.
SHH. neanderthalensisH. sapiensTalonid crestTotal sampleOnly one antimereTotal sampleOnly one antimereTotal sampleOnly one antimerePresentn435500%6.3712.514.200Absentn594035303228%93.79387.585.7100100Total634340353228
Summary of the specimens with a talonid crest in this study.
Présentation des spécimens à crête talonide étudiés.
Chi2 comparison of the frequencies of expression of talonid crests and mesial entoconid ridge (see text for explanation) between each pair of groups.
Comparaison « Chi2 » des fréquences d’expression des crêtes du talonide et d’une arête mésiale à l’entoconide (voir texte pour plus d’explications) entre chaque paire de groupes.
M1M2M3Total molar sampleTalonidMesial End ridgeTalonidMesial End ridgeTalonidMesial End ridgeTalonid crestMesial End ridgeSH vs. NEAP: 0.12P: 0.76–P:0.89P: 0.54P:0.57P: 0.28P:0.55SH vs. SAP–P: 0.02*–P:0.89P: 0.00*P: 0.92P:<0.001*P: 0.55NEA vs. SAPP: 0.21P: 0.01*–P:0.06P: 0.01*0.77P:<0.001*P:0.02*
Denotes statistical significance (P < 0.05). In this chart, both antimeres were included (see text for Chi2 results when following the individual count method).
Frequency of occurrence of the six types of talonid crest pattern in the SH lower permanent molars. In order to compare with Korenhof's sample (Korenhof, 1982), frequencies are calculated including both antimeres.
Fréquence d’occurrence des six types de patron de crêtes du talonide dans les molaires inférieures permanentes de SH. Pour une comparaison avec l’échantillon de Korenhof (Korenhof, 1982), les fréquences sont calculées incluant les deux antimères.
Frequency of occurrence of the six types of talonid crest pattern in the lower deciduous second molars. In order to compare with Korenhof's sample (Korenhof, 1982), frequencies are calculated including both antimeres.
Fréquence d’occurrence des six types de patron de crêtes du talonide dans les molaires inférieures temporaires secondes. Pour une comparaison avec l’échantillon de Korenhof (Korenhof, 1982), les fréquences sont calculées en incluant les deux antimères.
Although it is not clear from his manuscript, we assume that 46 out of 52 of the dm2s studied by Korenhof have talonid crest, that is, 6 teeth do not present a talonid crest
Frequency of occurrence of the mesial entoconid ridge in our sample (see text for explanation). Both antimeres are included.
Fréquence d’occurrence de l’arête mésiale d’entoconide dans notre échantillonnage (voir le texte pour plus d’explications). Les deux antimères sont inclus.