Reassessment of the TM 1517 odonto‐postcranial assemblage from Kromdraai B, South Africa, and the maturational pattern of Paranthropus robustus

Abstract

Objectives: The Pleistocene taxon Paranthropus robustus was established in 1938 following the discovery at Kromdraai B, South Africa, of the partial cranium TM 1517a and associated mandible TM 1517b. Shortly thereafter, a distal humerus (TM 1517g), a proximal ulna (TM 1517e), and a distal hallucial phalanx (TM 1517k) were collected nearby at the site, and were considered to be associated with the holotype. TM 1517a-b represents an immature individual; however, no analysis of the potentially associated postcranial elements has investigated the presence of any endostructural remnant of recent epiphyseal closure. This study aims at tentatively detecting such traces in the three postcranial specimens from Kromdraai B. Materials and Methods: By using μXCT techniques, we assessed the developmental stage of the TM 1517b's C-M3 roots and investigated the inner structure of TM 1517g, TM 1517e, and TM 1517k.Results: The M2 shows incompletely closed root apices and the M3 a half-completed root formation stage. The distal humerus was likely completely fused, while the

Growth and development of the third permanent molar in Paranthropus robustus from Swartkrans, South Africa

“…However, they provide another line of evidence for assessing maturation during late development in fossil hominins and, importantly, one that is independent of standards established for great apes and/or modern humans 1,2,37,66,67 . Specifically, if the 3-year range of initiation times and stages of M3 development in SK 835 were to encompass those in other fossil hominins, they would bracket the still debated chronological age at death in TM 1517, the holotype of P. robustus where M3 root formation is at stage R¾ 28 , to between 9.04 and 12.04 years. Extending these kind of age estimates to other P. robustus specimens with incomplete M3s seems reasonable in the absence of any other direct evidence, although age estimates for other early fossil hominins remain speculative.…”

“…These have been used to calibrate the eruption times of first permanent molars (M1s) in fossil hominins and this has proved to be a reasonably successful method for assessing the time and patterning of dento-skeletal maturation in a broad comparative context 6,[11][12][13][14][15][16] , if perhaps a less successful proxy for other life history variables [17][18][19][20] . Nonetheless, despite the fact that greater numbers of late juvenile and sub-adult fossil hominins of unknown chronological age are now associated with skeletal material approaching maturity [21][22][23][24][25][26][27][28] , assessing the end of the tooth maturation process remains problematic, as too few data exist to reconstruct the timing of late third permanent molar (M3) development. Indeed, to date, the age at completion of the "wisdom tooth", i.e., the measure of late dental maturity, has never been directly reconstructed, but only inferred in australopiths (Australopithecus and Paranthropus) and early Homo 29,30 .The initial mineralisation of the M3 tooth in both great apes and early fossil hominins occurs at a chronologically younger age than in modern humans.…”

“…A second aim of this study was thus to quantify the changing daily rates of enamel and dentine secretion throughout the entire growth of the SK 835 early hominin M3. A further aim was to put a time scale to the fractional stages of tooth formation commonly used in comparative radiographic and other imaging studies of modern humans, great apes and fossil hominins 28,37,38,66,67 . Since tooth growth is a continuous and seamless process, we also reconstructed growth curves describing cuspal enamel secretion and the increase in tooth length along the once developmental boundaries between tissues, the enamel-dentine junction (EDJ) and the cementum-dentine junction (CDJ), and compared these with similar data for living hominids and fossil hominins.…”

Addressing the growing fossil record of subadult hominins by reaching across disciplines

“…2023;32:180-184. wileyonlinelibrary.com/journal/evan individual, for example, brain and dentition, or dentition and the skeleton. [7][8][9][10][11][12] This scope of analysis is valuable in providing a more comprehensive view of how hominin bodies developed and grew, enabling more insights into how development and growth may have evolved across hominins.…”

A new early hominin calcaneus from Kromdraai (South Africa)

“…Some fossiliferous deposits in the Kromdraai area were discovered in 1895 by David Draper, who collected fossiliferous breccias and sent them to the British Museum of Natural History (de Graaff, 1961; Malan, 1959). The Kromdraai site became well known in 1938, when it yielded a partial skull and dentition (TM 1517) designated as the type specimen of a new genus and species, Paranthropus robustus (Broom, 1938a), and subsequently associated with a few postcranial elements to represent the partial skeleton of a single individual (Braga et al, 2017; Broom, 1938b, 1942, 1943; Cazenave et al, 2020). With the exception of the ongoing excavations (since 2014), the work that Broom initiated in 1938 at the “Kromdraai B" (KB) locality (or “hominid site”) was the first in a series of four phases of field research activities (not detailed here; see Braga et al, 2017; Braga & Thackeray, 2016).…”