Endostructural morphology in hominoid mandibular third premolars: Geometric morphometric analysis of dentine crown shape

Davies, Thomas W.; Delezene, Lucas K.; Gunz, Philipp; Hublin, Jean‐Jacques; Skinner, Matthew M.

doi:10.1016/j.jhevol.2019.06.004

Cited by 11 publications

(5 citation statements)

References 71 publications

(69 reference statements)

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“…We similarly find a homogenous EDJ morphology in H. naledi premolars both within the Dinaledi Chamber, and between the Dinaledi and Lesedi chambers. A previous study of the P 3 EDJ including a broader sample of fossil hominins and extant apes supports the suggestion that H. naledi is unusual in its homogeneity, with seemingly less variation in size and shape than a subspecies of chimpanzee ( Pan troglodytes verus ) 16 , which has itself been suggested to be less variable in dental morphology than other Pan subspecies 37 . Dental morphology is thought to be highly heritable, so it is possible that this low level of dental variation reflects low genetic diversity.…”

Section: Discussionsupporting

confidence: 54%

“…The terminology used here to describe premolar morphology follows that of Davies and colleagues 16 and is outlined in Supplementary Figure 2 . Terms refer to the EDJ rather than the OES unless otherwise specified.…”

Section: Methodsmentioning

confidence: 99%

“…3D landmarks were collected in Avizo 6.3, and homologous landmarks were derived using a software routine written by Philipp Gunz 31 , 32 implemented in Mathematica 10.0 ( https://www.wolfram.com ). This was done following a previously described protocol 16 outlined in Supplementary Figure 2 .…”

Section: Methodsmentioning

confidence: 99%

“…The tooth is absolutely small in size, double rooted, fully bicuspid, and has a symmetrical occlusal outline, a combination of features suggested to be unique among the hominin fossil record 1 . Recent morphometric studies of the mandibular premolar enamel-dentine junction (EDJ) demonstrate that this method has the potential to be a powerful tool in distinguishing between hominin taxa 16 , 17 . We therefore aim to further investigate this distinctive premolar morphology at the EDJ.…”

Section: Introductionmentioning

confidence: 99%

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Distinct mandibular premolar crown morphology in Homo naledi and its implications for the evolution of Homo species in southern Africa

Davies

Delezene

Gunz

et al. 2020

Sci Rep

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Homo naledi displays a combination of features across the skeleton not found in any other hominin taxon, which has hindered attempts to determine its placement within the hominin clade. Using geometric morphometrics, we assess the morphology of the mandibular premolars of the species at the enamel-dentine junction (EDJ). Comparing with specimens of Paranthropus, Australopithecus and Homo (n = 97), we find that the H. naledi premolars from the Dinaledi chamber consistently display a suite of traits (e.g., tall crown, well-developed P 3 and p 4 metaconid, strongly developed P 3 mesial marginal ridge, and a P 3 > p 4 size relationship) that distinguish them from known hominin groups. Premolars from a second locality, the Lesedi Chamber, are consistent with this morphology. We also find that two specimens from South Africa, SK 96 (usually attributed to Paranthropus) and Stw 80 (Homo sp.), show similarities to the species, and we discuss a potential evolutionary link between H. naledi and hominins from Sterkfontein and Swartkrans. Homo naledi is a hominin species first described in 2015 based on remains from the Dinaledi Chamber in the Rising Star cave system in South Africa 1 , and subsequently from a second chamber in the cave, the Lesedi Chamber 2. The species presents a combination of features not found in any other taxon, and attempts to interpret its phylogenetic position within the hominin clade have proved difficult. There are remarkably modern features such as the morphology of the foot 3 , as well as the morphology of the wrist and the relative length of the thumb 4. However, the cranial capacity is small, both absolutely and relative to body size 1,2 , and there are primitive Australopithecus-like traits in the fingers 4 , upper and lower limbs 5,6 and pelvis 7. Studies of the dental evidence have likewise revealed a unique combination of features. The permanent postcanine dentition is characterized by small teeth that retain principal molar cusps, but seemingly lack accessory crown traits common in other African hominin groups 1,8. However, the deciduous dentition shows a number of derived Paranthropus-like traits 9 , and molar root metrics find similarities between H. naledi and South African Homo specimens SK 15 and SK 45, as well as KNM-ER 1805 from Koobi Fora 10. Mandibular premolar morphology is particularly useful in studies of hominin taxonomy 11-15 , and initial descriptions suggest the P 3 of H. naledi is highly distinctive. The tooth is absolutely small in size, double rooted, fully bicuspid, and has a symmetrical occlusal outline, a combination of features suggested to be unique among the hominin fossil record 1. Recent morphometric studies of the mandibular premolar enamel-dentine junction (EDJ) demonstrate that this method has the potential to be a powerful tool in distinguishing between hominin taxa 16,17. We therefore aim to further investigate this distinctive premolar morphology at the EDJ.

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Section: Discussionsupporting

confidence: 54%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Distinct mandibular premolar crown morphology in Homo naledi and its implications for the evolution of Homo species in southern Africa

Davies

Delezene

Gunz

et al. 2020

Sci Rep

Self Cite

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“…Morphometric studies of the EDJ of both permanent and deciduous molars are well represented in the literature [31,33,[44][45][46], while for maxillary premolars, extensive comparative studies are very rare [47], or only focused on the descriptive assessment of the EDJ and OES [48][49][50][51]. Currently, 3D geometric morphometric (GM) analyses of the inner tooth crown variation in geographically diverse modern human samples have been published for permanent and deciduous molars [23,33,44,46,47,52], as well as lower premolars [53,54], and central incisors [55]. These studies did not detect geographically-dependent dental shape variation [33,54], thus, in the current study, we applied quantitative approaches to explore inter-and intra-population shape variation and covariation of modern human P3s and P4s, expecting to find similar outcomes.…”

Section: Introductionmentioning

confidence: 99%

Shape variation in modern human upper premolars

Šimková,

Wurm,

Fornai

et al. 2024

PLoS ONE

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Morphological variation in modern human dentition is still an open field of study. The understanding of dental shape and metrics is relevant for the advancement of human biology and evolution and is thus of interest in the fields of dental anthropology, as well as human anatomy and medicine. Of concern is also the variation of the inner aspects of the crown which can be investigated using the tools and methods of virtual anthropology. In this study, we explored inter- and intra-population morphometric variation of modern humans’ upper third and fourth premolars (P3s and P4s, respectively) considering both the inner and outer aspects of the crown, and discrete traits. We worked by means of geometric morphometrics on 3D image data from a geographically balanced sample of human populations from five continents, to analyse the shape of the dentinal crown, and the crown outline in 78 P3s and 76 P4s from 85 individuals. For the study of dental traits, we referred to the Arizona State University Dental Anthropology System integrated with more recent classification systems. The 3D shape variation of upper premolar crowns varied between short and mesio-distally broad, and tall and mesio-distally narrow. The observed shape variation was independent from the geographical origin of the populations, and resulted in extensive overlap. We noted a high pairwise correlation (r1 = 0.83) between upper P3s and P4s. We did not find any significant geographic differences in the analysed non-metric traits. Our outcomes thus suggest that geographical provenance does not play a determinant role in the shaping of the dental crown, whose genesis is under strict genetic control.

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