The mixed dentition and associated skull fragments of a juvenile fossil hominid from Sterkfontein, South Africa

Abstract

In April-May 1983, the late A.R. Hughes and his field team recovered more than 40 bone fragments and teeth from a single solution pocket of the Sterkfontein Formation. After preparation and reconstruction by JMC, it was recognised that these fragments represent a single juvenile individual (Stw 151), consisting of more than 40 cranial and dental parts, with mixed dentition. It constitutes the most complete set of jaws and teeth of an early hominid child since the Taung child was recovered in 1924. In this paper, the morphological and metrical features of the individual teeth are described. The other associated skull fragments (right ramus of the mandible, left petrous bone, right glenoid region) are also described. Comparisons are made with other South (and East) African fossil hominids. The beautiful preservation simultaneously of most of the deciduous teeth and of the permanent teeth exposed in their crypts allows an accurate analysis of the developmental sequence. A report on the dental developmental status of this juvenile is presented. On the basis of the microanatomical study of the developing permanent teeth, the estimated age at death is 5.2-5.3 years. Reconstructions of the maxillary and mandibular arcades are also offered. The morphological and metrical features of Stw 151 raise the possibility that it may represent a hominid more derived towards an early Homo condition than the rest of the A. africanus sample from Member 4.

Humanity from African Naissance to Coming Millennia

“…Together with the two Homo habilis specimens, I have added a specimen from Sterkfontein, South Africa (Stw 151), which, although not formally attributed to early Homo, shows a number of features closely allying it with other early Homo specimens (MoggiCecchi, Tobias & Beynon, 1998). The two early Homo specimens, plus Stw 151, seem to fall at the lower end of the range for A. africanus (Stw 183 removed), whereas the three Homo erectus specimens are Figure 3.…”

Measures of maturation in early fossil hominins: events at the first transition from australopiths to earlyHomo

“…The evidence that growth markings in enamel and dentine have a daily periodicity [57][58][59] has recently strengthened with new studies documenting the control of enamel matrix protein secretion by various clock-genes [60][61][62]. The ages at death cited in this study and the ages for defined stages of tooth development used here have all previously been published [34,35,[63][64][65][66][67][68][69][70] and are based on the daily incremental record preserved within fossil tooth enamel and dentine. The measures, or indicators, of maturation used in this study are limited to dental eruption, a few defined stages of dental development and to one or two estimates of stature and body mass in subadult fossil hominins.…”

“…The second, StW 151, is a juvenile fossil hominin recovered in 1983 from a single solution pocket at Member 4, Sterkfontein, South Africa, dated to approximately 2 Ma. This has been considered on balance to be an early Homo specimen by Moggi-Cecchi et al [65] and others. The third, KNM-WT 15000, is a near-complete 1.5 Ma partial skeleton of a subadult male H. erectus recovered from Nariokotome, West Turkana, Kenya [88].…”

Retrieving chronological age from dental remains of early fossil hominins to reconstruct human growth in the past

“…Stw 151, from the late Member 4 breccia deposit at Sterkfontein, is described as a specimen with a dentition 'not fully distinct from that of Au. africanus but with a cranial morphology more derived in some characters' (Moggi-Cecchi et al 1998). While there is a small mandibular M3 crypt in Stw 151, it is still too small to have accommodated a mineralizing tooth germ, which must, therefore, have initiated after M2 crown completion.…”

“…Stw 151 is aged histologically to between 5.2 and 5.3 years at death (Moggi-Cecchi et al 1998). It had M1s with one or more incomplete root apex at the time M2, premolar and canine crowns had just completed enamel formation.…”