Reconstructions of habitat at sites like Kanapoi are key to understanding the environmental circumstances in which hominins evolved during the early Pliocene. While Australopithecus anamensis shows evidence of terrestrial bipedality traditionally associated with a more open setting, its enamel has low δC values consistent with consumption of C foods, which predominate in wooded areas of tropical Africa. Habitat proxies, ranging from paleosols and their carbonates to associated herbivore fauna and their carbon isotope ratios, suggest a heterogeneous setting with both grass and woody plant components, though the proportions of each have been difficult to pin down. Here we bring dental microwear texture analysis of herbivorous fauna to bear on the issue. We present texture data for fossil bovids, primates, rodents, and suids (n = 107 individuals in total) from the hominin bearing deposits at Kanapoi, and interpret these in the light of closely related extant mammals with known differences in diet. The Kanapoi bovid results, for example, are similar to those for extant variable grazers or graze-browse intermediate taxa. The Kanapoi suid data vary by taxon, with one similar to the pattern of extant grazers and the other more closely resembling mixed feeders. The Kanapoi primates and rodents are more difficult to associate with a specific environment, though it seems that grass was likely a component in the diets of both. All taxa evince microwear texture patterns consistent with a mosaic of discrete microhabitats or a heterogeneous setting including both tree and grass components.
The southeastern tip of Cuba Island is limited to the south by the N‐Caribbean boundary. By revisiting the impressive sequences of coastal terraces of this region, we decipher the Quaternary deformation pattern of this plate boundary. We present a detailed mapping of coastal terraces uplifted over a hundred kilometers of coastline, and U/Th dating. At Punta de Maisí, the deformation pattern shows (a) a faster uplift close to the transform boundary and (b) a northward propagation of folding produced by the convergence of the Bahamas platform toward the Caribbean plate. Along the southern coast of Punta de Maisí, the sequence displays 29 coastal terraces up to 520 m in elevation and a upper Pleistocene uplift rate of 0.23 ± 0.07 mm yr−1. We interpret this deformation as resulting from an offshore north‐dipping reverse fault near the coast. This uplift rate corresponds to 3% to 1.6% of the short‐term horizontal slip rate of Septentrional Oriente Fault Zone (10 ± 0.1 mm yr−1). Along the northern coast of Punta de Maisí, the sequence displays height coastal terraces up to 220 m in elevation and the uplift rates amount to 0.1 ± 0.05 mm yr−1 and likely result from the reverse faulting and folding associated with the offshore North Hispaniola Fault Zone. Uplift rates quickly decrease to the West, in agreement with the westward decrease in the activity of the North Hispaniola Fault Zone due to the docking of the Bahamas Platform against Cuba, while the platform more gently underthrusts Cuba to the East.
Introduction Laetoli, Tanzania preserves the earliest fossils attributed to Australopithecus afarensis (3.7 mya). A diversity of non‐human primates including cercopithecoid monkeys have also been recovered. Cercopithecoids provide valuable insights into the paleoenvironments they shared with early humans and, by extension, early hominin paleobiology. Although cercopithecoid fossils at Laetoli represent both more omnivorous cercopihecines and more folivorous and arboreal colobines, the former is more abundant. The diversity and proportion of cercopithecoids figures prominently in debate over the prevalence of closed woodland/forested environments vs more open scrub/bushland. This study uses dental morphometrics to establish the morphological affinity of molar crowns from additional cercopithecoid craniodental fossils recovered from Laetoli localities 1, 2, 6 and 7 to clarify the paleoenvironmental context of our early human ancestors. Methods Standard linear metric data (mesiodistal length, buccolingual breadth) were collected using dental calipers and total occlusal and individual cusp areas (mm2) were obtained for all molar crowns in an extant cercopithecoid sample (n=90; 18 genera) using high‐resolution 2D images and ImageJ. These data are a comparative baseline for a fossil cercopithecoid sample including a complete (LP) mandible (M1‐M3), maxillary fragment (M1‐M3) and four isolated maxillary molars (n=3 M1’s, n=1 M2). Discriminant function analysis (DFA) using subfamily (n=2 groups) and tribe (n=5 groups) was used to predict group membership and morphological affinity of the fossil sample. Results DFA results indicate that predictive accuracy is highest when subfamily is used as the grouping variable and ranges from 62.8% (M3) to 87.2% (M2). Mandibular molars more reliably segregate subfamilies (77.1% ‐ 87.2%) than do maxillary molars (64.4% ‐ 70.2%). The associated mandibular molars group are most closely associated with African colobines. All maxillary specimens cluster with cercopithecines and, more specifically, the papioni. Colobines have expanded hypoconids and metacones but reduced metaconids, entoconids and paracones relative to cercopithecoids. Conclusion Molar cusp proportions discriminate colobines from cercopithecines. This study provides additional evidence for the continued presence of both groups in the upper beds at Laetoli and confirms that the complete LP mandible is most closely aligned with the Colobinae. The presence of a large colobine is consistent with palaeoecological reconstructions supporting the significant presence of closed woodland/forested habitats. Significance Despite obligate bipedalism, early hominins retain numerous upper limb and torso adaptations consistent with the use of arboreal substrates. The continued presence of colobines at Laetoli confirms the presence of closed woodland/forested environments and suggests that Au. afarensis at Laetoli may have potentially exploited a variety of habitats including arboreal substrates.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.