Distinct dental development patterns in early fossil hominids

Beynon, A.D.; Dean, Christopher

doi:10.1038/335509a0

Cited by 186 publications

(153 citation statements)

References 34 publications

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“…Australopithecus and differs from the condition in Old World monkeys, Paranthropus, and Homo (Beynon and Dean, 1988;Swindler and Meekins, 1991;Dirks, 1998Dirks, , 2003Dean and Reid, 2001;Dirks et al, 2002 (2004)]. Kelley (1997) cited M1 emergence times in various macaque species as being between 16 and 18 months, but only 9.9 months in the much smaller Cercopithecus aethiops.…”

Section: Crown Formation Timesmentioning

confidence: 99%

Dental development and life history in Anapithecus hernyaki

Nargolwalla

Begun

Dean

et al. 2005

Journal of Human Evolution

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Section: Crown Formation Timesmentioning

confidence: 99%

Dental development and life history in Anapithecus hernyaki

Nargolwalla

Begun

Dean

et al. 2005

Journal of Human Evolution

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“…These long-period striae manifest as enamel ridges, called perikymata, at the crown surface. Importantly, multiplying the total number of perikymata by the number of short-period cross-striations between them gives a very accurate estimate of the number of days over which a tooth crown formed, and hence, the age of an immature specimen (Dean, 1987;Beynon and Dean, 1988;Risnes, 1998). Of course, periodicity data can only be used to age individuals in whom dental development is not yet complete.…”

Section: Figmentioning

confidence: 99%

Biological spacetime and the temporal integration of functional modules: A case study of dento–gnathic developmental timing

Boughner¹,

Hallgrímsson²

2007

Developmental Dynamics

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For the individual, coordination between tooth and jaw development is important to proper food acquisition and ingestion later in life. Among and within species, variation in dental and gnathic size, shape, and, in the case of teeth, number, must be mutually accommodating and functionally compatible. For these reasons, the development and evolution of these two systems should be closely integrated. Furthermore, the timing of dental development correlates tightly with life history events such as weaning. This correlation hints at a central regulation of the developmental timing of multiple systems that have tandem effects on physiology and behaviour. Important work on embryonic oral development continues to tease apart the molecular mechanisms that pattern jaw identity and establish tooth morphology and position in the alveolar bone. Still very poorly understood is what underlies rates and periods of gene activity such that pre-and postnatal tooth and jaw development are coordinated. Recent literature suggests at least some level of autonomy between permanent tooth and mandibular ontogenetic timing. However, whether the timing of these various signaling pathways is directly regulated or is an outcome of the pathways themselves is untested. Here, we review what is currently known about the embryonic signaling pathways that regulate tooth and jaw development in the context of time rather than space, as has been traditional. We hypothesize that the timing of mandibular and dental development is not directly mediated by a common factor but is an indirect outcome of strong selection for coordinated molecular pathways and growth trajectories. The mandible and lower jaw dentition is a powerful model with which to investigate the mechanisms that facilitate morphological change-in this case, the development and evolution-of organs that are closely integrated in terms of function, space and time. Developmental Dynamics 237:1-17, 2008.

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“…Bromage and Dean (1985) reassessed the age at death of fossil hominids using incremental features, and concluded that early humans were characterized by ape-like dental development, in contrast to the previously assumed modern human pattern. These were followed by many more studies of fossil hominids that examined the nature of enamel development and enamel thickness as revealed by microstructure (Beynon and Wood, 1986;Dean et al, 1986;Beynon and Dean, 1987;Beynon and Wood, 1987;Dean, 1987a,b;Beynon and Dean, 1988;Grine and Martin, 1988;Mann et al, 1991;Beynon, 1992;Dean et al, 1993a;Ramirez Rozzi, 1993a,b;Mann et al, 1994;Ramirez Rozzi, 1994;Dean, 1995;Ramirez Rozzi, 1997;Ramirez Rozzi et al, 1997;Ramirez Rozzi, 1998;). These investigations have provided information on age at death in individuals with developing dentitions, the absolute and relative timing of dental development, differences in the developmental pathways of enamel formation, and life history characteristics.…”

Section: Introductionmentioning

confidence: 99%

Enamel thickness, microstructure and development in Afropithecus turkanensis

Smith

Martin

Leakey

2003

Journal of Human Evolution

119

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Afropithecus turkanensis, a 17-17.5 million year old large-bodied hominoid from Kenya, has previously been reported to be the oldest known thick-enamelled Miocene ape. Most investigations of enamel thickness in Miocene apes have been limited to opportunistic or destructive studies of small samples. Recently, more comprehensive studies of enamel thickness and microstructure in Proconsul, Lufengpithecus, and Dryopithecus, as well as extant apes and fossil humans, have provided information on rates and patterns of dental development, including crown formation time, and have begun to provide a comparative context for interpretation of the evolution of these characters throughout the past 20 million years of hominoid evolution. In this study, enamel thickness and aspects of the enamel microstructure in two A. turkanensis second molars were quantified and provide insight into rates of enamel apposition, numbers of cells actively secreting enamel, and the time required to form regions of the crown. The average value for relative enamel thickness in the two molars is 21.4, which is a lower value than a previous analysis of this species, but which is still relatively thick compared to extant apes. This value is similar to those of several Miocene hominoids, a fossil hominid, and modern humans. Certain aspects of the enamel microstructure are similar to Proconsul nyanzae, Dryopithecus laietanus, Lufengpithecus lufengensis, Graecopithecus freybergi and Pongo pygmaeus, while other features differ from extant and fossil hominoids. Crown formation times for the two teeth are 2.4-2.6 years and 2.9-3.1 years respectively. These times are similar to a number of extant and fossil hominoids, some of which appear to show additional developmental similarities, including thick enamel. Although thick enamel may be formed through several developmental pathways, most Miocene hominoids and fossil hominids with relatively thick enamel are characterized by a relatively long period of cuspal enamel formation and a rapid rate of enamel secretion throughout the whole cusp, but a shorter total crown formation time than thinner-enamelled extant apes.

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Distinct dental development patterns in early fossil hominids

Cited by 186 publications

References 34 publications

Dental development and life history in Anapithecus hernyaki

Dental development and life history in Anapithecus hernyaki

Biological spacetime and the temporal integration of functional modules: A case study of dento–gnathic developmental timing

Enamel thickness, microstructure and development in Afropithecus turkanensis

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