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| authority = [[Yohannes Haile-Selassie|Haile-Selassie]] ''et al.'', 2015
| authority = [[Yohannes Haile-Selassie|Haile-Selassie]] ''et al.'', 2015
| synonyms =
| synonyms =
*''[[Paranthropus]] deyiremeda'' <br><small>Nygren, 2018</small>
*''[[Paranthropus]] deyiremeda''<br><small>Nygren, 2018</small>
}}
}}


'''''Australopithecus deyiremeda''''' is an [[extinct]] [[species]] of [[australopithecine]] from [[Woranso–Mille]], [[Afar Region]], Ethiopia, about 3.5–3.3 million years ago during the [[Pliocene]]. Because it is known only from three partial jawbones, it is unclear if these specimens indeed represent a unique species or belong to the much better known ''[[Australopithecus afarensis|A. afarensis]]''. ''A. deyiremeda'' is distinguished by its forward facing cheek bones and small [[cheek teeth]] compared to those of other early [[hominin]]s. It is unclear if a partial foot specimen exhibiting a dextrous big toe (a characteristic unknown in any australopith) can be assigned to ''A. deyiremeda''. ''A. deyiremeda'' lived in a mosaic environment featuring both open grasslands and lake- or riverside forests, and anthropologist Fred Spoor suggests it may have been involved in the Kenyan [[Lomekwi]] [[stone tool]] [[industry (archaeology)|industry]] typically assigned to ''[[Kenyanthropus]]''. ''A. deyiremeda'' coexisted with ''A. afarensis'', and they may have exhibited [[niche partitioning]] to avoid [[interspecific competition|competing]] with each other for the same resources, such as by relying on different fallback foods during leaner times.
'''''Australopithecus deyiremeda''''' is an [[extinct]] [[species]] of [[australopithecine]] from [[Woranso–Mille]], [[Afar Region]], Ethiopia, about 3.5 to 3.3 million years ago during the [[Pliocene]]. Because it is known only from three partial jawbones, it is unclear if these specimens indeed represent a unique species or belong to the much better-known ''[[A. afarensis]]''. ''A. deyiremeda'' is distinguished by its forward-facing cheek bones and small [[cheek teeth]] compared to those of other early [[hominin]]s. It is unclear if a partial foot specimen exhibiting a dextrous big toe (a characteristic unknown in any australopithecine) can be assigned to ''A. deyiremeda''. ''A. deyiremeda'' lived in a mosaic environment featuring both open grasslands and lake- or riverside forests, and anthropologist Fred Spoor suggests it may have been involved in the Kenyan [[Lomekwi]] [[stone tool|stone-tool]] [[industry (archaeology)|industry]] typically assigned to ''[[Kenyanthropus]]''. ''A. deyiremeda'' coexisted with ''A. afarensis'', and they may have exhibited [[niche partitioning]] to avoid [[interspecific competition|competing]] with each other for the same resources, such as by relying on different fallback foods during leaner times.


==Taxonomy==
==Taxonomy==
''Australopithecus deyiremeda'' was first proposed in 2015 by Ethiopian palaeoanthropologist [[Yohannes Haile-Selassie]] and colleagues based on jawbone fossils from the Burtele and Waytaleyta areas of [[Woranso–Mille]], [[Afar Region]], Ethiopia. The [[holotype specimen]], a young adult left [[maxilla]] with all teeth except the first [[incisor]] and third [[molar (tooth)|molar]] BRT-VP-3/1, was discovered on 4 March 2011 by local resident Mohammed Barao. The [[paratype specimen]]s are a complete adult [[body of the mandible]] with all incisors BRT-VP-3/14, and an adult right toothless jawbone WYT-VP-2/10, which were discovered by Ethiopian fossil hunter Ato Alemayehu Asfaw {{bracket|[[:es:Ato Alemayehu Asfaw|es]]}}. A right maxilla fragment with the fourth [[premolar]] BRT-VP-3/37 was found {{cvt|5|m}} east of BRT-VP-3/14, and it is unclear if these belonged to the same individual. The sediments were [[radiometric dating|radiometrically dated]] to 3.5–3.3 million years ago, the Middle [[Pliocene]].<ref name=Haile2015/>
''Australopithecus deyiremeda'' was first proposed in 2015 by Ethiopian palaeoanthropologist [[Yohannes Haile-Selassie]] and colleagues based on jawbone fossils from the Burtele and Waytaleyta areas of [[Woranso–Mille]], [[Afar Region]], Ethiopia. The [[holotype]] specimen, a young adult left [[maxilla]] with all teeth except the first [[incisor]] and third [[molar (tooth)|molar]] BRT-VP-3/1, was discovered on 4 March 2011 by local resident Mohammed Barao. The [[paratype specimen]]s are a complete adult [[body of the mandible]] with all incisors BRT-VP-3/14, and an adult right toothless jawbone WYT-VP-2/10, which were discovered by Ethiopian fossil hunter Ato Alemayehu Asfaw {{bracket|[[:es:Ato Alemayehu Asfaw|es]]}}. A right maxilla fragment with the fourth [[premolar]] BRT-VP-3/37 was found {{cvt|5|m}} east of BRT-VP-3/14, and it is unclear if these belonged to the same individual. The sediments were [[radiometric dating|radiometrically dated]] to 3.5–3.3 million years ago, the [[Middle Pliocene]].<ref name=Haile2015/>


The describers believed the remains were distinct enough from the contemporary and well-known ''[[Australopithecus afarensis|A. afarensis]]'' to warrant species distinction, and ''A. deyiremeda'' is counted among a growing diversity of [[Late Pliocene]] [[australopithecine]]s alongside ''A. afarensis'', ''[[Australopithecus bahrelghazali|A. bahrelghazali]]'', and ''[[Kenyanthropus platyops]]''. The name ''deyiremeda'' derives from the [[Afar language]] meaning "close relative" because, existing so early in time, the discoverers considered ''A. deyiremeda'' to have been closely related to future australopiths.<ref name=Haile2015>{{Cite journal |url=http://www.nature.com/nature/journal/v521/n7553/extref/nature14448-s1.pdf |doi=10.1038/nature14448|pmid=26017448|title=New species from Ethiopia further expands Middle Pliocene hominin diversity|journal=Nature|volume=521|issue=7553|pages=483–488|year=2015|last1=Haile-Selassie|first1=Yohannes|last2=Gibert|first2=Luis|last3=Melillo|first3=Stephanie M.|last4=Ryan|first4=Timothy M.|last5=Alene|first5=Mulugeta|last6=Deino|first6=Alan|last7=Levin|first7=Naomi E.|last8=Scott|first8=Gary|last9=Saylor|first9=Beverly Z.|bibcode=2015Natur.521..483H|s2cid=4455029}}</ref> However, though the proposed distinguishing characteristics are apparently [[statistically significant]], given how few specimens of ''A. deyiremeda'' exist, it is unclear if this indeed warrants species distinction or if these specimens simply add to the normal range of variation for ''A. afarensis''. If it is a valid species, then it could possibly indicate some ''A. afarensis'' specimens are currently classified into the wrong species.<ref name=Spoor2016/><ref name=Haile2016/>
The describers believed the remains were distinct enough from the contemporary and well-known ''[[A. afarensis]]'' to warrant species distinction, and ''A. deyiremeda'' is counted among a growing diversity of [[Late Pliocene]] [[australopithecine]]s alongside ''A. afarensis'', ''[[A. bahrelghazali]]'' and ''[[Kenyanthropus platyops]]''. The name ''deyiremeda'' derives from the [[Afar language]] meaning "close relative" because, existing so early in time, the discoverers considered ''A. deyiremeda'' to have been closely related to future australopiths.<ref name=Haile2015>{{Cite journal |url=http://www.nature.com/nature/journal/v521/n7553/extref/nature14448-s1.pdf |doi=10.1038/nature14448|pmid=26017448|title=New species from Ethiopia further expands Middle Pliocene hominin diversity|journal=Nature|volume=521|issue=7553|pages=483–488|year=2015|last1=Haile-Selassie|first1=Yohannes|last2=Gibert|first2=Luis|last3=Melillo|first3=Stephanie M.|last4=Ryan|first4=Timothy M.|last5=Alene|first5=Mulugeta|last6=Deino|first6=Alan|last7=Levin|first7=Naomi E.|last8=Scott|first8=Gary|last9=Saylor|first9=Beverly Z.|bibcode=2015Natur.521..483H|s2cid=4455029}}</ref> However, though the proposed distinguishing characteristics are apparently [[statistically significant]], given how few specimens of ''A. deyiremeda'' exist, it is unclear if this indeed warrants species distinction or if these specimens simply add to the normal range of variation for ''A. afarensis''. If it is a valid species, then it could possibly indicate some ''A. afarensis'' specimens are currently classified into the wrong species.<ref name=Spoor2016/><ref name=Haile2016/>


Haile-Selassie and colleagues noted that, though it shares many similarities with the [[robustness (morphology)|robust]] ''[[Paranthropus]]'', it may not have been closely related because it lacked enlarged molars which are characteristic of ''Paranthropus''.<ref>{{cite journal|first1=Y.|last1=Haile-Selassie|author-link=Yohannes Haile-Selassie|first2=L.|last2=Gilbert|first3=S. M.|last3=Melillo|display-authors=et al.|year=2015|title=New species from Ethiopia further expands Middle Pliocene hominin diversity|journal=Nature|volume=521|issue=14448|pages=483–488|doi=10.1038/nature14448|pmid=26017448|url=https://afanporsaber.com/wp-content/uploads/2017/09/New-species-from-Ethiopia-further-expands-Middle-Pliocene-hominin-diversity.pdf|bibcode=2015Natur.521..483H|s2cid=4455029}}</ref>
Haile-Selassie and colleagues noted that, though it shares many similarities with the robust ''[[Paranthropus]]'', it may not have been closely related because it lacked enlarged molars which are characteristic of ''Paranthropus''.<ref>{{cite journal|first1=Y.|last1=Haile-Selassie|author-link=Yohannes Haile-Selassie|first2=L.|last2=Gilbert|first3=S. M.|last3=Melillo|display-authors=et al.|year=2015|title=New species from Ethiopia further expands Middle Pliocene hominin diversity|journal=Nature|volume=521|issue=14448|pages=483–488|doi=10.1038/nature14448|pmid=26017448|url=https://afanporsaber.com/wp-content/uploads/2017/09/New-species-from-Ethiopia-further-expands-Middle-Pliocene-hominin-diversity.pdf|bibcode=2015Natur.521..483H|s2cid=4455029}}</ref>


{{African hominin timeline}}
{{African hominin timeline}}


==Anatomy==
==Anatomy==
Despite being so early, the jaws of ''A. deyiremeda'' show some similarities to those of the later ''[[Homo]]'' and ''Paranthropus''. The jaw jutted out somewhat ([[prognathism]]) at perhaps a 39° angle, similar to most other early [[hominin]]s. The cheekbone is positioned more forward than most ''A. afarensis'' specimens. Unlike ''A. afarensis'' but like ''Paranthropus'', the walls of the [[cheek teeth]] are inclined rather than coming straight up. The upper [[canine tooth|canines]] are proportionally smaller than those of other ''Australopithecus'', but are otherwise morphologically similar to those of ''[[Australopithecus anamensis|A. anamensis]]''. The cheek teeth are quite small for an early hominin, and the first molar is the smallest reported for an adult Pliocene hominin. Nonetheless, the [[tooth enamel|enamel]] was still thick as other early hominins, and the enamel on the second molar is quite high and more similar to ''[[Paranthropus robustus|P. robustus]]''. The jawbone, though small, is [[robustness (morphology)|robust]] and more similar to that of ''Paranthropus''.<ref name=Haile2015/>
Despite being so early, the jaws of ''A. deyiremeda'' show some similarities to those of the later ''[[Homo]]'' and ''Paranthropus''. The jaw jutted out somewhat ([[prognathism]]) at perhaps a 39-degree angle, similar to most other early [[hominin]]s. The cheekbone is positioned more forward than most ''A. afarensis'' specimens. Unlike ''A. afarensis'' but like ''Paranthropus'', the walls of the [[cheek teeth]] are inclined rather than coming straight up. The upper [[canine tooth|canines]] are proportionally smaller than those of other ''Australopithecus'', but are otherwise morphologically similar to those of ''[[A. anamensis]]''. The cheek teeth are quite small for an early hominin, and the first molar is the smallest reported for an adult Pliocene hominin. Nonetheless, the [[tooth enamel|enamel]] was still thick as other early hominins, and the enamel on the second molar is quite high and more similar to ''[[Paranthropus robustus|P. robustus]]''. The jawbone, though small, is robust and more similar to that of ''Paranthropus''.<ref name=Haile2015/>


[[File:Burtele foot.png|thumb|upright=1.3|Reconstruction of BRT-VP-2/73]]
[[File:Burtele foot.png|thumb|upright=1.3|Reconstruction of BRT-VP-2/73]]
In 2012, a 3.4 million year old partial foot, BRT-VP-2/73, was recovered from Woranso–Mille. It strongly diverges from contemporary and later hominins by having a dextrous big toe like the earlier ''[[Ardipithecus ramidus]]'', and consequently has not been assigned to a species.<ref>{{cite journal|first=Y.|last=Haile-Selassie|author-link=Yohannes Haile-Selassie|year=2012|title=A new hominin foot from Ethiopia shows multiple Pliocene bipedal adaptations|journal=Nature|volume=483|issue=7391|pages=565–570|doi=10.1038/nature10922|pmid=22460901|s2cid=4425418}}</ref> Though more diagnostic facial elements have since been discovered in the area, they are not clearly associated with the foot.<ref name=Haile2015/>
In 2012, a 3.4-million-year-old partial foot, BRT-VP-2/73, was recovered from Woranso–Mille. It strongly diverges from contemporary and later hominins by having a dextrous big toe like the earlier ''[[Ardipithecus ramidus]]'', and consequently has not been assigned to a species.<ref>{{cite journal|first=Y.|last=Haile-Selassie|author-link=Yohannes Haile-Selassie|year=2012|title=A new hominin foot from Ethiopia shows multiple Pliocene bipedal adaptations|journal=Nature|volume=483|issue=7391|pages=565–570|doi=10.1038/nature10922|pmid=22460901|bibcode=2012Natur.483..565H|s2cid=4425418}}</ref> Though more diagnostic facial elements have since been discovered in the area, they are not clearly associated with the foot.<ref name=Haile2015/>


==Palaeoecology==
==Palaeoecology==
''A. deyiremeda'' features a strong jawbone and thick enamel, consistent with a diet of tough [[sedge]]s and similar foods which australopiths are generally thought to have primarily subsisted upon. The enamel on the upper incisor, canine, and first premolar exhibits [[hypoplasia]], probably caused by a period of malnutrition or illness during [[amelogenesis|enamel growth]] in infancy while the teeth were still growing.<ref>{{cite journal|first=G. H.|last=Sperber|year=2015|title=Teeth, Genes, and Genealogy|journal=Quintessence International|volume=46|issue=9|pages=747–749|doi=10.3290/j.qi.a34622|pmid=26287023|url=http://www.quintpub.com/userhome/qi/qi_46_9_sperber_p747.pdf}}</ref> ''A. deyiremeda'' was likely a [[generalist and specialist species|generalist]] feeder. ''A. deyiremeda'' and ''A. afarensis'' may have exhibited [[niche partitioning]] given they cohabited the same area. That is, given dental and chewing differences, they may have had different dietary and/or habitat preferences, unless these differences were simply a product of [[genetic drift]].<ref name=Spoor2016>{{cite journal|first1=F.|last1=Spoor|first2=M. G.|last2=Leakey|author2-link=Meave Leakey|first3=P.|last3=O'Higgins|year=2016|title=Middle Pliocene hominin diversity: ''Australopithecus deyiremeda'' and ''Kenyanthropus platyops''|journal=Philosophical Transactions of the Royal Society B|volume=371|issue=1698|doi=10.1098/rstb.2015.0231|pmid=27298462|pmc=4920288|doi-access=free}}</ref><ref name="Spoor2015">{{cite journal|last1=Spoor|first1=Fred|title=Palaeoanthropology: The middle Pliocene gets crowded|journal=Nature|volume=521|issue=7553|year=2015|pages=432–433|issn=0028-0836|doi=10.1038/521432a|pmid=26017440|s2cid=4472489|doi-access=free}}</ref> Much like [[chimp]]s and gorillas which have more or less the same diet and inhabit the same areas, ''A. deyiremeda'' and ''A. afarensis'' may have shared typical foods when in abundance, and resorted to different fallback foods in times of food scarcity.<ref name=Haile2016>{{cite journal|first1=Y.|last1=Haile-Selassie|author-link=Yohannes Haile-Selassie|first2=S. M.|last2=Melillo|first3=D. F.|last3=Su|year=2016|title=The Pliocene hominin diversity conundrum: Do more fossils mean less clarity?|journal=Proceedings of the National Academy of Sciences|volume=113|issue=23|pages=6364–6371|doi=10.1073/pnas.1521266113|pmid=27274043|pmc=4988594|doi-access=free}}</ref>
''A. deyiremeda'' features a strong jawbone and thick enamel, consistent with a diet of tough [[sedge]]s and similar foods which australopiths are generally thought to have primarily subsisted upon. The enamel on the upper incisor, canine and first premolar exhibits [[hypoplasia]], probably caused by a period of malnutrition or illness during [[amelogenesis|enamel growth]] in infancy while the teeth were still growing.<ref>{{cite journal|first=G. H.|last=Sperber|year=2015|title=Teeth, Genes, and Genealogy|journal=Quintessence International|volume=46|issue=9|pages=747–749|doi=10.3290/j.qi.a34622|pmid=26287023|url=http://www.quintpub.com/userhome/qi/qi_46_9_sperber_p747.pdf|access-date=July 13, 2020|archive-date=October 2, 2020|archive-url=https://web.archive.org/web/20201002023220/http://www.quintpub.com/userhome/qi/qi_46_9_sperber_p747.pdf|url-status=dead}}</ref> ''A. deyiremeda'' was likely a [[generalist and specialist species|generalist]] feeder. ''A. deyiremeda'' and ''A. afarensis'' may have exhibited [[niche partitioning]] given they cohabited the same area. That is, given dental and chewing differences, they may have had different dietary and/or habitat preferences, unless these differences were simply a product of [[genetic drift]].<ref name=Spoor2016>{{cite journal|first1=F.|last1=Spoor|first2=M. G.|last2=Leakey|author2-link=Meave Leakey|first3=P.|last3=O'Higgins|year=2016|title=Middle Pliocene hominin diversity: ''Australopithecus deyiremeda'' and ''Kenyanthropus platyops''|journal=Philosophical Transactions of the Royal Society B|volume=371|issue=1698|doi=10.1098/rstb.2015.0231|pmid=27298462|pmc=4920288|doi-access=free}}</ref><ref name="Spoor2015">{{cite journal|last1=Spoor|first1=Fred|title=Palaeoanthropology: The middle Pliocene gets crowded|journal=Nature|volume=521|issue=7553|year=2015|pages=432–433|issn=0028-0836|doi=10.1038/521432a|pmid=26017440|bibcode=2015Natur.521..432S|s2cid=4472489|doi-access=free}}</ref> Much like [[chimpanzee]]s and gorillas which have more or less the same diet and inhabit the same areas, ''A. deyiremeda'' and ''A. afarensis'' may have shared typical foods when in abundance, and resorted to different fallback foods in times of food scarcity.<ref name="Haile2016">{{cite journal|first1=Y.|last1=Haile-Selassie|author-link=Yohannes Haile-Selassie|first2=S. M.|last2=Melillo|first3=D. F.|last3=Su|year=2016|title=The Pliocene hominin diversity conundrum: Do more fossils mean less clarity?|journal=Proceedings of the National Academy of Sciences|volume=113|issue=23|pages=6364–6371|doi=10.1073/pnas.1521266113|pmid=27274043|pmc=4988594|bibcode=2016PNAS..113.6364H |doi-access=free}}</ref>


The [[Lomekwi]] [[stone tool]] [[industry (archaeology)|industry]] from northern Kenya is loosely associated with the Middle Pliocene ''[[Kenyanthropus]]'' based on an upper jaw fragment assigned to ''Kenyanthropus'' based on forward cheekbones, three-rooted premolars, and a small first molar. Since these features are also exhibited in ''A. deyiremeda'', anthropologist Fred Spoor suggested that ''A. deyiremeda'' was actually present at the site.<ref name="Spoor2015"/> Identified at 3.3 million years old, the Lomekwian is the earliest culture. These knappers [[flake (archaeology)|flaked]] off pieces of [[core (archaeology)|cores]] made of [[basalt]], [[phonolite]], and [[trachyphonolite]].<ref>{{cite journal|last1=Harmand|first1=S.|display-authors=et al.|title=3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya|journal=Nature|date=2015|volume=521|issue=7552|pages=310–315|doi=10.1038/nature14464|pmid=25993961|s2cid=1207285}}</ref> They held the core with one hand and struck it vertically with a [[hammerstone]], which is a simple process, though more complex than the tool-making behaviours of non-human primates.<ref>{{cite journal|first1=M.|last1=Lombard|first2=A.|last2=Högberg|first3=M. N.|last3=Haidle|year=2018|title=Cognition: From Capuchin Rock Pounding to Lomekwian Flake Production|journal=Cambridge Archaeological Journal|volume=29|issue=2|pages=201–231|doi=10.1017/S0959774318000550|doi-access=free}}</ref>
The [[Lomekwi]] [[stone tool|stone-tool]] [[industry (archaeology)|industry]] from northern Kenya is loosely associated with the Middle Pliocene ''[[Kenyanthropus]]'' based on an upper jaw fragment assigned to ''Kenyanthropus'' based on forward cheekbones, three-rooted premolars, and a small first molar. Since these features are also exhibited in ''A. deyiremeda'', anthropologist Fred Spoor suggested that ''A. deyiremeda'' was actually present at the site.<ref name="Spoor2015"/> Identified at 3.3 million years old, the Lomekwian is the earliest culture. These knappers [[Lithic flake|flaked]] off pieces of [[core (archaeology)|cores]] made of [[basalt]], [[phonolite]] and [[trachyphonolite]].<ref>{{cite journal|last1=Harmand|first1=S.|display-authors=et al.|title=3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya|journal=Nature|date=2015|volume=521|issue=7552|pages=310–315|doi=10.1038/nature14464|pmid=25993961|bibcode=2015Natur.521..310H|s2cid=1207285}}</ref> They held the core with one hand and struck it vertically with a [[hammerstone]], which is a simple process, though more complex than the tool-making behaviours of non-human primates.<ref>{{cite journal|first1=M.|last1=Lombard|first2=A.|last2=Högberg|first3=M. N.|last3=Haidle|year=2018|title=Cognition: From Capuchin Rock Pounding to Lomekwian Flake Production|journal=Cambridge Archaeological Journal|volume=29|issue=2|pages=201–231|doi=10.1017/S0959774318000550|doi-access=free}}</ref>


The Middle Pliocene of Woranso–Mille features [[grazing]] [[impala]]s, [[Alcelaphinae|alcelaphins]], and [[proboscidea|elephants]], as well as [[browsing]] [[giraffe]]s, [[Tragelaphini|tragelephins]], and forest-dwelling [[monkey]]s. The feet of the [[bovid]] species do not seem to be specialised for any particular type of ground (such as wet, pliable, or hard), and the teeth of hoofed species indicates an equal abundance of grazers, browsers, and mixed feeders. These suggest a mixed environment which features both open grasslands as well as forests probably growing on a lake- or riverside. Similar mosaic landscapes were inhabited by ''A. anamensis'' and ''A. afarensis'' who seem to have had no preferred environment.<ref>{{cite journal|first1=S. C.|last1=Curran|first2=Y.|last2=Haile-Selassie|author2-link=Yohannes Haile-Selassie|year=2016|title=Paleoecological reconstruction of hominin-bearing middle Pliocene localities at Woranso-Mille, Ethiopia|journal=Journal of Human Evolution|volume=96|pages=97–112|doi=10.1016/j.jhevol.2016.04.002|pmid=27343774|doi-access=free}}</ref>
The Middle Pliocene of Woranso–Mille features [[grazing]] [[impala]]s, [[Alcelaphinae|alcelaphins]], and [[proboscidea|elephants]], as well as [[browsing]] [[giraffe]]s, [[Tragelaphini|tragelaphins]], and forest-dwelling [[monkey]]s. The feet of the [[bovid]] species do not seem to be specialised for any particular type of ground (such as wet, pliable, or hard), and the teeth of hoofed species indicates an equal abundance of grazers, browsers and mixed feeders. These suggest a mixed environment which features both open grasslands as well as forests probably growing on a lake- or riverside. Similar mosaic landscapes were inhabited by ''A. anamensis'' and ''A. afarensis'' who seem to have had no preferred environment.<ref>{{cite journal|first1=S. C.|last1=Curran|first2=Y.|last2=Haile-Selassie|author2-link=Yohannes Haile-Selassie|year=2016|title=Paleoecological reconstruction of hominin-bearing middle Pliocene localities at Woranso-Mille, Ethiopia|journal=Journal of Human Evolution|volume=96|pages=97–112|doi=10.1016/j.jhevol.2016.04.002|pmid=27343774|doi-access=free}}</ref>


==See also==
==See also==

Latest revision as of 04:34, 23 May 2024

Australopithecus deyiremeda
Temporal range: Pliocene, 3.5–3.3 Ma
↓
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Hominidae
Subfamily: Homininae
Tribe: Hominini
Genus: †Australopithecus
Species:
†A. deyiremeda
Binomial name
†Australopithecus deyiremeda
Haile-Selassie et al., 2015
Synonyms

Australopithecus deyiremeda is an extinct species of australopithecine from Woranso–Mille, Afar Region, Ethiopia, about 3.5 to 3.3 million years ago during the Pliocene. Because it is known only from three partial jawbones, it is unclear if these specimens indeed represent a unique species or belong to the much better-known A. afarensis. A. deyiremeda is distinguished by its forward-facing cheek bones and small cheek teeth compared to those of other early hominins. It is unclear if a partial foot specimen exhibiting a dextrous big toe (a characteristic unknown in any australopithecine) can be assigned to A. deyiremeda. A. deyiremeda lived in a mosaic environment featuring both open grasslands and lake- or riverside forests, and anthropologist Fred Spoor suggests it may have been involved in the Kenyan Lomekwi stone-tool industry typically assigned to Kenyanthropus. A. deyiremeda coexisted with A. afarensis, and they may have exhibited niche partitioning to avoid competing with each other for the same resources, such as by relying on different fallback foods during leaner times.

Taxonomy

[edit]

Australopithecus deyiremeda was first proposed in 2015 by Ethiopian palaeoanthropologist Yohannes Haile-Selassie and colleagues based on jawbone fossils from the Burtele and Waytaleyta areas of Woranso–Mille, Afar Region, Ethiopia. The holotype specimen, a young adult left maxilla with all teeth except the first incisor and third molar BRT-VP-3/1, was discovered on 4 March 2011 by local resident Mohammed Barao. The paratype specimens are a complete adult body of the mandible with all incisors BRT-VP-3/14, and an adult right toothless jawbone WYT-VP-2/10, which were discovered by Ethiopian fossil hunter Ato Alemayehu Asfaw [es]. A right maxilla fragment with the fourth premolar BRT-VP-3/37 was found 5 m (16 ft) east of BRT-VP-3/14, and it is unclear if these belonged to the same individual. The sediments were radiometrically dated to 3.5–3.3 million years ago, the Middle Pliocene.[1]

The describers believed the remains were distinct enough from the contemporary and well-known A. afarensis to warrant species distinction, and A. deyiremeda is counted among a growing diversity of Late Pliocene australopithecines alongside A. afarensis, A. bahrelghazali and Kenyanthropus platyops. The name deyiremeda derives from the Afar language meaning "close relative" because, existing so early in time, the discoverers considered A. deyiremeda to have been closely related to future australopiths.[1] However, though the proposed distinguishing characteristics are apparently statistically significant, given how few specimens of A. deyiremeda exist, it is unclear if this indeed warrants species distinction or if these specimens simply add to the normal range of variation for A. afarensis. If it is a valid species, then it could possibly indicate some A. afarensis specimens are currently classified into the wrong species.[2][3]

Haile-Selassie and colleagues noted that, though it shares many similarities with the robust Paranthropus, it may not have been closely related because it lacked enlarged molars which are characteristic of Paranthropus.[4]

African hominin timeline (in mya)
View references
H. sapiensH. nalediH. rhodesiensisH. ergasterAu. sedibaP. robustusP. boiseiH. rudolfensisH. habilisAu. garhiP. aethiopicusLD 350-1K. platyopsAu. bahrelghazaliAu. deyiremedaAu. africanusAu. afarensisAu. anamensisAr. ramidusAr. kadabba


Anatomy

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Despite being so early, the jaws of A. deyiremeda show some similarities to those of the later Homo and Paranthropus. The jaw jutted out somewhat (prognathism) at perhaps a 39-degree angle, similar to most other early hominins. The cheekbone is positioned more forward than most A. afarensis specimens. Unlike A. afarensis but like Paranthropus, the walls of the cheek teeth are inclined rather than coming straight up. The upper canines are proportionally smaller than those of other Australopithecus, but are otherwise morphologically similar to those of A. anamensis. The cheek teeth are quite small for an early hominin, and the first molar is the smallest reported for an adult Pliocene hominin. Nonetheless, the enamel was still thick as other early hominins, and the enamel on the second molar is quite high and more similar to P. robustus. The jawbone, though small, is robust and more similar to that of Paranthropus.[1]

Reconstruction of BRT-VP-2/73

In 2012, a 3.4-million-year-old partial foot, BRT-VP-2/73, was recovered from Woranso–Mille. It strongly diverges from contemporary and later hominins by having a dextrous big toe like the earlier Ardipithecus ramidus, and consequently has not been assigned to a species.[5] Though more diagnostic facial elements have since been discovered in the area, they are not clearly associated with the foot.[1]

Palaeoecology

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A. deyiremeda features a strong jawbone and thick enamel, consistent with a diet of tough sedges and similar foods which australopiths are generally thought to have primarily subsisted upon. The enamel on the upper incisor, canine and first premolar exhibits hypoplasia, probably caused by a period of malnutrition or illness during enamel growth in infancy while the teeth were still growing.[6] A. deyiremeda was likely a generalist feeder. A. deyiremeda and A. afarensis may have exhibited niche partitioning given they cohabited the same area. That is, given dental and chewing differences, they may have had different dietary and/or habitat preferences, unless these differences were simply a product of genetic drift.[2][7] Much like chimpanzees and gorillas which have more or less the same diet and inhabit the same areas, A. deyiremeda and A. afarensis may have shared typical foods when in abundance, and resorted to different fallback foods in times of food scarcity.[3]

The Lomekwi stone-tool industry from northern Kenya is loosely associated with the Middle Pliocene Kenyanthropus based on an upper jaw fragment assigned to Kenyanthropus based on forward cheekbones, three-rooted premolars, and a small first molar. Since these features are also exhibited in A. deyiremeda, anthropologist Fred Spoor suggested that A. deyiremeda was actually present at the site.[7] Identified at 3.3 million years old, the Lomekwian is the earliest culture. These knappers flaked off pieces of cores made of basalt, phonolite and trachyphonolite.[8] They held the core with one hand and struck it vertically with a hammerstone, which is a simple process, though more complex than the tool-making behaviours of non-human primates.[9]

The Middle Pliocene of Woranso–Mille features grazing impalas, alcelaphins, and elephants, as well as browsing giraffes, tragelaphins, and forest-dwelling monkeys. The feet of the bovid species do not seem to be specialised for any particular type of ground (such as wet, pliable, or hard), and the teeth of hoofed species indicates an equal abundance of grazers, browsers and mixed feeders. These suggest a mixed environment which features both open grasslands as well as forests probably growing on a lake- or riverside. Similar mosaic landscapes were inhabited by A. anamensis and A. afarensis who seem to have had no preferred environment.[10]

See also

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References

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  1. ^ a b c d Haile-Selassie, Yohannes; Gibert, Luis; Melillo, Stephanie M.; Ryan, Timothy M.; Alene, Mulugeta; Deino, Alan; Levin, Naomi E.; Scott, Gary; Saylor, Beverly Z. (2015). "New species from Ethiopia further expands Middle Pliocene hominin diversity" (PDF). Nature. 521 (7553): 483–488. Bibcode:2015Natur.521..483H. doi:10.1038/nature14448. PMID 26017448. S2CID 4455029.
  2. ^ a b Spoor, F.; Leakey, M. G.; O'Higgins, P. (2016). "Middle Pliocene hominin diversity: Australopithecus deyiremeda and Kenyanthropus platyops". Philosophical Transactions of the Royal Society B. 371 (1698). doi:10.1098/rstb.2015.0231. PMC 4920288. PMID 27298462.
  3. ^ a b Haile-Selassie, Y.; Melillo, S. M.; Su, D. F. (2016). "The Pliocene hominin diversity conundrum: Do more fossils mean less clarity?". Proceedings of the National Academy of Sciences. 113 (23): 6364–6371. Bibcode:2016PNAS..113.6364H. doi:10.1073/pnas.1521266113. PMC 4988594. PMID 27274043.
  4. ^ Haile-Selassie, Y.; Gilbert, L.; Melillo, S. M.; et al. (2015). "New species from Ethiopia further expands Middle Pliocene hominin diversity" (PDF). Nature. 521 (14448): 483–488. Bibcode:2015Natur.521..483H. doi:10.1038/nature14448. PMID 26017448. S2CID 4455029.
  5. ^ Haile-Selassie, Y. (2012). "A new hominin foot from Ethiopia shows multiple Pliocene bipedal adaptations". Nature. 483 (7391): 565–570. Bibcode:2012Natur.483..565H. doi:10.1038/nature10922. PMID 22460901. S2CID 4425418.
  6. ^ Sperber, G. H. (2015). "Teeth, Genes, and Genealogy" (PDF). Quintessence International. 46 (9): 747–749. doi:10.3290/j.qi.a34622. PMID 26287023. Archived from the original (PDF) on October 2, 2020. Retrieved July 13, 2020.
  7. ^ a b Spoor, Fred (2015). "Palaeoanthropology: The middle Pliocene gets crowded". Nature. 521 (7553): 432–433. Bibcode:2015Natur.521..432S. doi:10.1038/521432a. ISSN 0028-0836. PMID 26017440. S2CID 4472489.
  8. ^ Harmand, S.; et al. (2015). "3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya". Nature. 521 (7552): 310–315. Bibcode:2015Natur.521..310H. doi:10.1038/nature14464. PMID 25993961. S2CID 1207285.
  9. ^ Lombard, M.; Högberg, A.; Haidle, M. N. (2018). "Cognition: From Capuchin Rock Pounding to Lomekwian Flake Production". Cambridge Archaeological Journal. 29 (2): 201–231. doi:10.1017/S0959774318000550.
  10. ^ Curran, S. C.; Haile-Selassie, Y. (2016). "Paleoecological reconstruction of hominin-bearing middle Pliocene localities at Woranso-Mille, Ethiopia". Journal of Human Evolution. 96: 97–112. doi:10.1016/j.jhevol.2016.04.002. PMID 27343774.
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