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Discovery
[edit]In August 2019, scientists announced the discovery of a nearly intact skull, for the first time, and dated to 3.8 million years ago, of A. anamensis in Ethiopia.[1][2] The skull itself was found by Afar herder Ali Bereino in 2016.[3] This skull is important in supplementing the evolutionary lineage of hominins. The skull has a unique combination of derived and ancestral characteristics.[1] It was determined that the cranium is older than A. afarensis through analyzing that the cranial capacity is much smaller and the face is very prognathic, both of which indicate that it is earlier than A. afarensis.[1] Known as the MRD cranium, it is that of a male who was at an "advanced developmental age" determined by the worn down post-canine teeth.[1] The teeth show mesiodistal elongation, which differs from A. afarensis.[1] Similar to other australopiths, however, it has a narrow upper face (no forehead) and a large mid-face with broad zygomatic bones.[1] Before this new discovery, it was widely believed that Australopithecus anamensis and Australopithecus afarensis evolved one right after the other in a single lineage.[1] However, with the discovery of MRD, it suggests that A. afarensis did not result from anagenesis, but that the two hominin species lived side by side for at least 100,000 years.[1][4]
Relation to other hominin species
[edit]Australopithecus anamensis is the intermediate species between Ardipithecus ramidus and Australopithecus afarensis and has multiple shared traits with apes and humans.[5][6] Fossil studies of the wrist morphology of A. anamensis suggest knuckle-walking, which is a derived trait shared with African apes. The A. anamensis hand portrays robust phalanges and metacarpals, and long middle phalanges, much like those shared by humans and apes. These characteristics show that the A. anamensis likely engaged in arboreal living but were largely bipedal, although not in an identical way to later Homo genus.[7]
There are three major features of Australopithecus: all were bipedal, small-brained, and had large teeth.[8] A. anamensis is often confused with Australopithecus afarensis due to their similar bone structure, apelike and human-like traits, and their habitation of woodland areas.[9] These similarities include thick tooth enamel, which is a shared derived trait of all Australopithecus and shared with most Miocene hominoids.[6] Tooth size variability in A. anamensis suggests that there was significant body size variation.[6] In relation to their diet, A. anamensis has similarities with their predecessor Ardipithecus ramidus.[6] A. anamensis sometimes had much larger canines than later Australopithecus species.[6] A. anamensis and A. afarensis have similarities in the humerus and the tibia.[6] They both have human-like features and matching sizes.[6] It has also been found that the bodies of A. anamensis are larger than those of A. afarensis.[6] Based on additional afarensis collections from the Hadar, Ethiopia site, the A. anamensis radius is similar to that of afarensis in the lunate and scaphoid surfaces.[6] Additional findings suggest that A. anamensis have long arms compared to modern humans.[6]
Era in which they lived
[edit]A. anamensis is the earliest known species of Australopithecus and the least studied because of lack of skeletal findings. The first fossils of the A. anamensis are dated to around 3.8 and 4.2 million years ago and were found in Kanapoi and Allia Bay in Northern Kenya.[6] They are the earliest Australopithecus species, living during the Plio-Pleistocene era.[8]
More on diet
[edit]A. anamensis had thick, long, and narrow jaws with their side teeth arranged in parallel lines. [5] The palate, rows of teeth, and other characteristics of A. anamensis dentition suggests that they were omnivores and their diets were composed heavily on fruit, similar to chimpanzees.[6] These characteristics came from Ar. ramidus, who were thought to have preceded A. anamensis. Evidence of a dietary shift was also found, suggesting the consumption of harder foods.[6] This was indicated by thicker enamel in teeth and more intense molar crowns.[6]
References
[edit]https://www.nature.com/articles/s41586-019-1513-8
https://science.sciencemag.org/content/365/6456/850.full
https://link.springer.com/chapter/10.1007/978-3-030-19349-2_7
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- ^ a b c d e f g h Haile-Selassie, Yohannes; M. Melillo, Stephanie; Vazzana, Antonino; Benazzi, Stefano; Timothy, M. Ryan (2019). "A 3.8-million-year-old hominin cranium from Woranso-Mille, Ethiopia". Nature. doi:10.1038/s41586-019-1513-8.
{{cite journal}}: Cite journal requires|journal=(help) - ^ Dvorsky, George (28 August 2019). "Incredible Fossil Discovery Finally Puts a Face on an Elusive Early Hominin". Gizmodo. Retrieved 28 August 2019.
- ^ Greshko, Michael, 'Unprecedented' skull reveals face of human ancestor, National Geographic, August 28, 2019
- ^ "Revealing the new face of a 3.8-million-year-old early human ancestor".
{{cite web}}: CS1 maint: url-status (link) - ^ a b "Australopithecus anamensis". The Smithsonian Institution's Human Origins Program. 2010-02-11. Retrieved 2019-11-10.
- ^ a b c d e f g h i j k l m n Ward, Carol; Leakey, Meave; Walker, Alan (1999). "The new hominid species Australopithecus anamensis". Evolutionary Anthropology: Issues, News, and Reviews. 7 (6): 197–205. doi:10.1002/(SICI)1520-6505(1999)7:63.0.CO;2-T. ISSN 1520-6505.
- ^ Richmond, Brian (23 March 2000). "Evidence that Humans Evolved from a Knuckle-walking Ancestor". Nature.
{{cite web}}: CS1 maint: url-status (link) - ^ a b Lewis, Barry; et al. (2013). Understanding Humans: Introduction to Physical Anthropology and Archaeology (11th Edition ed.). Belmont, CA: Wadsworth Publishing.
{{cite book}}:|edition=has extra text (help); Explicit use of et al. in:|first=(help)CS1 maint: location missing publisher (link) - ^ "Australopithecus - Australopithecus afarensis and Au. garhi". Encyclopedia Britannica. Retrieved 2019-11-10.