Haasgat is a primate-rich fossil locality in the northeastern part of the Fossil Hominid Sites of South Africa UNESCO World Heritage Site. Here we report the first hominin identified from Haasgat, a partial maxillary molar (HGT 500), that was recovered from an
Upright walking absent a bent-hip-bent-knee gait requires lumbar lordosis, a ubiquitous feature in all hominids for which it can be observed. Its first appearance is therefore a central problem in human evolution. Atelids, which use the tail during suspension, exhibit demonstrable lordosis and can achieve full extension of their hind limbs during terrestrial upright stance. Although obviously homoplastic with hominids, the pelvic mechanisms facilitating lordosis appear largely similar in both taxa with respect to abbreviation of upper iliac height coupled with broad sacral alae. Both provide spatial separation of the most caudal lumbar(s) from the iliac blades. A broad sacrum is therefore a likely facet of earliest hominid bipedality. All tailed monkeys have broad alae. By contrast all extant apes have very narrow sacra, which promote “trapping” of their most caudal lumbars to achieve lower trunk rigidity during suspension. The alae in the tailless proconsul
- NSF-PAR ID:
- 10013029
- Publisher / Repository:
- PeerJ
- Date Published:
- Journal Name:
- PeerJ
- Volume:
- 4
- ISSN:
- 2167-8359
- Page Range / eLocation ID:
- Article No. e1521
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ex situ calcified sediment block sampled from the locality. Thein situ fossil bearing deposits of the Haasgat paleokarstic deposits are estimated to date to slightly older than 1.95 Ma based on magnetobiostratigraphy. This places the hominin specimen at a critical time period in South Africa that marks the last occurrence ofAustralopithecus around 1.98 Ma and the first evidence ofParanthropus andHomo in the region between ∼2.0 and 1.8 Ma. A comprehensive morphological evaluation of the Haasgat hominin molar was conducted against the current South African catalogue of hominin dental remains and imaging analyses using micro-CT, electron and confocal microscopy. The preserved occlusal morphology is most similar toAustralopithecus africanus or earlyHomo specimens but different fromParanthropus . Occlusal linear enamel thickness measured from micro-CT scans provides an average of ∼2.0 mm consistent withAustralopithecus and earlyHomo . Analysis of the enamel microstructure suggests an estimated periodicity of 7–9 days. Hunter–Schreger bands appear long and straight as in someParanthropus , but contrast with this genus in the short shape of the striae of Retzius. Taken together, these data suggests that the maxillary fragment recovered from Haasgat best fits within theAustralopithecus —earlyHomo hypodigms to the exclusion of the genusParanthropus . At ∼1.95 Ma this specimen would either represent another example of late occurringAustralopithecus or one of the earliest examples ofHomo in the region. While the identification of this first hominin specimen from Haasgat is not unexpected given the composition of other South African penecontemporaneous site deposits, it represents one of the few hominin localities in the topographically-distinct northern World Heritage Site. When coupled with the substantial differences in the mammalian faunal communities between the northern localities (e.g., Haasgat, Gondolin) and well-sampled Bloubank Valley sites (e.g., Sterkfontein, Swartkrans, Kromdraai), the recovery of the HGT 500 specimen highlights the potential for further research at the Haasgat locality for understanding the distribution and interactions of hominin populations across the landscape, ecosystems and fossil mammalian communities of early Pleistocene South Africa. Such contextual data from sites like Haasgat is critical for understanding the transition in hominin representation at ∼2 Ma sites in the region fromAustralopithecus toParanthropus and earlyHomo . -
Abstract Evidence from the earliest-known crinoids (Tremadocian, Early Ordovician), called protocrinoids, is used to hypothesize initial steps by which elements of the calyx evolved. Protocrinoid calyces are composed of extraxial primary and surrounding secondary plates (both of which have epispires along their sutures) that are unlike those of more crownward fossil and extant crinoids in which equivalent calycinal plating is strongly organized. These reductions inspired several schemes by which to name the plates in these calyces. However, the primary-secondary systems seen in protocrinoids first appeared among Cambrian stem radial echinoderms, with primaries representing centers around which secondaries were sequentially added during ontogeny. Therefore, the protocrinoid calyx represents an intermediate condition between earliest echinoderms and crownward crinoids. Position and ontogeny indicate certain primaries remained as loss of secondaries occurred, resulting in abutting of primaries into the conjoined alternating circlets characteristic of crinoids. This transformative event included suppression of secondary plating and modification or, more commonly, elimination of respiratory structures. These data indicate subradial calyx plate terminology does not correspond with most common usage, but rather, supports an alternative redefinition of these traditional expressions. Extension and adoral growth of fixed rays during calyx ontogeny preceded conjoined primaries in earliest crinoids. Restriction with modification or elimination of calyx respiratory structures also accompanied this modification. Phylogenetic analyses strongly support crinoid origination from early pentaradiate echinoderms, separate from blastozoans. Accordingly, all Tremadocian crinoids express a distinctive aggregate of plesiomorphic and apomorphic commonalities; all branch early within the crinoid clade, separate from traditional subclass-level clades. Nevertheless, each taxon within this assemblage expresses at least one diagnostic apomorphy of camerate, cladid, or disparid clades.more » « less
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nov. den .). The provenance analysis of the Río delos Patos Formation indicates a sediment input from western sources located in the Coastal Cordillera and Western Principal Cordillera. Facies associations suggest that the Río de los Patos Formation represents the distal synorogenic deposits during the construction of an Eocene relief to the west. Therefore, the Manantiales Basin started during the late Eocene as a distal foreland basin, indicating that Eocene compression reached latitudes as far south as 32° S. Our results shed light into the characterization of the earliest infill of the Manantiales Basin, as well as into the tectonic evolution of the basin. -
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Abstract Objectives Pelvic form is hypothesized to reflect locomotor adaptation in anthropoids. Most observed variation is found in the ilium, which traditionally is thought to reflect thoracic and shoulder morphology. This article examines the articulated bony pelvis of anthropoids in three dimensions (3D) to test hypothesized variation in pelvic anatomy related to overall torso form.
Materials and Methods Sixty landmarks were collected on articulated pelves from 240 anthropoid individuals. Landmark data were subjected to a Generalized Procrustes Analysis. Principal Components Analysis was used to identify trends among taxa. Linear metrics were extracted, and bivariate allometric analysis was used to compare intergroup differences and scaling trends of specific dimensions.
Results The combination of 3D and bivariate allometric analysis demonstrates a complex pattern of locomotor/phylogenetic and allometric influences on pelvic morphology. Apes have relatively narrower dorsal interiliac spacing than do most monkeys, with relatively smaller spinal muscle attachment areas but only minimally wider ventral bi‐iliac breadths. Hylobatids and atelids have a relatively more cranial position of their sacra than do other taxa, and hylobatids and cercopithecids relatively more retroflexed ischia. Within groups, the three pelvic joints (lumbosacral, sacroiliac, and hip) become relatively closer together with increasing body size.
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Abstract Objectives The taxonomic status of isolated hominoid teeth from the Asian Pleistocene has long been controversial due to difficulties distinguishing between pongine and hominin molars given their high degree of morphometrical variation and overlap. Here, we combine nonmetric and geometric morphometric data to document a dental pattern that appears to be taxonomically diagnostic among
Pongo . We focus on the protoconule, a cuspule of well‐documented evolutionary history, as well as on shape differences of the mesial fovea of the upper molars.Materials and methods We examined 469 upper molars of eight hominid genera (
Australopithecus ,Paranthropus ,Homo ,Meganthropus ,Sivapithecus ,Pan ,Gorilla , andPongo ), including representatives ofHomo erectus and extinct and recentPongo . Analyses were conducted at the enamel‐dentine junction to overcome the limitations introduced by dental wear.Results We found that a moderate or large protoconule is present in ~80% of Pleistocene and extant
Pongo . Conversely, a moderate to pronounced protoconule in hominins,Meganthropus , and African great apes occurs in low frequencies (~0–20%). Canonical variate analyses for the mesial fovea show that Pleistocene and extantPongo cluster together and are clearly differentiated from all other groups, except forSivapithecus .Discussion This study suggests that the protoconule and the shape of the mesial fovea in upper molars are useful features for the taxonomic identification of isolated hominid teeth. By identifying these new features, our results can contribute to the better understanding of hominoid evolutionary history and biogeography during the Asian Pleistocene. However, we emphasize that the reported features should be used in combination with other diagnostic variables for the most accurate taxonomic assessments.
