View source for Orrorin

{{short description|Postulated early hominin discovered in Kenya}}
{{Automatic taxobox
| fossil_range = [[Late Miocene]]-[[Pliocene]], {{fossil range|6.1|4.5}}
| image = Orrorin NMNH.jpg
| image_caption = Cast of ''O. tugenensis'' femur (BAR 1002'00), [[National Museum of Natural History]]
| image2 = Video rendering of Orrorin tugenensis pollical distal phalanx - pone.0011727.s003.ogv
| image2_caption = The [[distal phalanx]] of the thumb of ''O. tugenensis''
| taxon = Orrorin
| authority = {{harvnb|Senut|Pickford|Gommery|Mein|2001}}
| display_parents = 2
| type_species = †'''''Orrorin tugenensis'''''
| type_species_authority = [[Brigitte Senut|Senut]] ''et al.'', 2001
| subdivision_ranks = Other species
| subdivision = * †'''''O. praegens''''' <br/><small>(Ferguson, 1989)</small>
| synonyms = *''[[Homo]] [[Neanderthal|antiquus]] praegens'' <small>Ferguson, 1989</small>
}}

'''''Orrorin''''' is an [[Extinction|extinct]] [[genus]] of [[Hominidae|great ape]] within the tribe of [[Hominini]] from the [[Miocene]] [[Lukeino Formation]] and [[Pliocene]] [[Mabaget Formation]], both of [[Kenya]].

The type species is '''''O.&nbsp;tugenenesis''''', named in 2001,<ref name="Senut-2001">{{harvnb|Senut|Pickford|Gommery|Mein|2001}}</ref> and a second species, ''O.&nbsp;praegens'',<ref name=":1" /> was assigned to the genus in 2022.<ref name=":0">{{Cite journal |last1=Pickford |first1=Martin |last2=Senut |first2=Brigitte |last3=Gommery |first3=Dominique |last4=Kipkech |first4=Joseph |date=2022 |title=New Pliocene hominid fossils from Baringo County, Kenya |url=http://fi.nm.cz/en/clanek/new-pliocene-hominid-fossils-from-baringo-county-kenya-2/ |journal=Fossil Imprint |language=en |volume=78 |issue=2 |pages=451–488 |doi=10.37520/fi.2022.020 |s2cid=255055545 |issn=2533-4069|doi-access=free }}</ref>

==Discovery and naming==

=== ''Orrorin tugenensis'' ===
[[File:Orrorin tugenensis.jpg|left|thumb|The [[holotype]] of ''O. tugenensis'']]
The first part of the [[holotype]], a lower molar, was discovered by [[Martin Pickford]] in 1974 and described by Pickford (1975).<ref>{{Cite journal |last=Pickford |first=M. |date=1975 |title=Late Miocene sediments and fossils from the Northern Kenya Rift Valley |url=http://dx.doi.org/10.1038/256279a0 |journal=Nature |volume=256 |issue=5515 |pages=279–284 |doi=10.1038/256279a0 |bibcode=1975Natur.256..279P |s2cid=4149259 |issn=0028-0836|url-access=subscription }}</ref> 

The team that found the rest of the holotype of ''O. tugenensis'' was led by [[Brigitte Senut]] and [[Martin Pickford]] from the French [[National Museum of Natural History, France|National Museum of Natural History]].<ref name="Senut-2001" /> Starting from 17 October 2000, 20 fossils were found at four sites in the [[Lukeino Formation]], Kenya: of these, the fossils at [[Cheboit]] and [[Aragai]] are the oldest ({{mya|6.1|Ma}}), while those in [[Kapsomin]] and [[Kapcheberek]] are found in the upper levels of the formation ({{mya|5.7|Ma}}).<ref name="Senut-2007">{{harvnb|Senut|2007|pp=1527–9}}</ref> 

''Orrorin tugenensis'' was named and described by Senut ''et al.'' (2001).<ref name="Senut-2001" />

=== ''Orrorin praegens'' ===
The second species, ''O. praegens'', was first described by Ward (1985)<ref>{{Cite journal |last=Hill |first=Andrew |date=1985 |title=Early hominid from Baringo, Kenya |url=https://www.nature.com/articles/315222a0 |journal=Nature |language=en |volume=315 |issue=6016 |pages=222–224 |doi=10.1038/315222a0 |bibcode=1985Natur.315..222H |s2cid=4353464 |issn=0028-0836|url-access=subscription }}</ref> and Ward & Hill (1988),<ref>{{Cite journal |last1=Hill |first1=Andrew |last2=Ward |first2=Steven |date=1988 |title=Origin of the hominidae: The record of african large hominoid evolution between 14 my and 4 my |url=https://onlinelibrary.wiley.com/doi/10.1002/ajpa.1330310505 |journal=American Journal of Physical Anthropology |language=en |volume=31 |issue=S9 |pages=49–83 |doi=10.1002/ajpa.1330310505 |issn=0002-9483|url-access=subscription }}</ref> and was initially described as ''[[Homo]] [[Neanderthal|antiquus]] praegens'' by Ferguson (1989)<ref name=":1">{{Cite journal |last=Ferguson |first=Walter W. |date=1989 |title=Taxonomic status of the hominid mandible KNM-ER TI 13150 from the middle pliocene of tabarin, in Kenya |url=http://link.springer.com/10.1007/BF02381261 |journal=Primates |language=en |volume=30 |issue=3 |pages=383–387 |doi=10.1007/BF02381261 |s2cid=38147495 |issn=0032-8332|url-access=subscription }}</ref> based on specimen KNM-TH 13150, a mandible discovered in the [[Pliocene]] [[Mabaget Formation]] of [[Kenya]] during the early 1980s.<ref>{{Cite web |last=Hawks |first=John |date=10 October 2023 |title=Guide to ''Sahelanthropus'', ''Orrorin'' and ''Ardipithecus'' |url=https://johnhawks.net/weblog/guide-to-sahelanthropus-orrorin-and-ardipithecus/#:~:text=Orrorin%20praegens&text=Named%20by%3A%20Walter%20Ferguson%20in,he%20named%20Homo%20antiquus%20praegens. |access-date=1 February 2024 |website=John Hawks}}</ref> The mandible is known as the Tabarin mandible, which was previously classified within ''[[Ardipithecus ramidus]]'' (or cf. ''A.'' cf. ''ramidus''), ''"Ardipithecus" praegens'' or ''"[[Australopithecus|Praeanthropus]]" praegens''.

Several referred remains of ''O. praegens'' were collected between 2005 and 2011 by the Franco-Kenyan Kenya Palaeontology Expedition and they, alongside the Tabarin mandible, were classified by [[Martin Pickford|Pickford]] ''et al.'' (2022) as being separate from ''[[Homo]]'', so they were classified within ''Orrorin'' as ''O. praegens''.<ref name=":0" />

== Etymology ==
The name of genus ''Orrorin'' (plural ''Orroriek'') means "original man" in [[Tugen language|Tugen]],<ref name="Senut-2001" /><ref name="Haviland-2007-p122">{{harvnb|Haviland|Prins|Walrath|McBride|2007|p=122}}</ref> and the [[epithet]] of ''O. tugenensis'' derives from [[Tugen Hills]] in [[Kenya]], where the first [[fossil]] was found in 2000.<ref name="Haviland-2007-p122" />

The epithet of ''O. praegens'' means roughly “group of people who came before.”<ref name=":0" />

==Fossils==
{{multiple image
| align = left
| direction = horizontal
| image1 = Kenia.PNG
| width1 = 150
| caption1 = <div align="center">Location of discovery</div>
| image2 = Orrorin localities.jpg
| width2 = 140
| caption2 = <div align="center">Map detail</div>
}}
The 20 specimens belonging to ''O. tugenensis'' are believed to be from at least five individuals.<ref>{{Cite web |title=Orrorin tugenensis essay {{!}} Becoming Human |url=http://www.becominghuman.org/node/orrorin-tugenensis-essay |access-date=2022-06-10 |website=www.becominghuman.org}}</ref> They include: the posterior part of a [[mandible]] in two pieces; a [[symphysis]]<!-- according to ref, not sure what was found --> and several isolated teeth; three fragments of [[femur|femora]]; a partial [[humerus]]; a proximal [[Phalanx bones|phalanx]]; and a distal thumb phalanx.<ref name="Senut-2007" />

''Orrorin'' had small teeth relative to its body size. Its dentition differs from that found in ''[[Australopithecus]]'' in that its [[cheek teeth]] are smaller and less elongated [[mesial|mesio]][[Anatomical terms of location#Proximal and distal|distal]]ly and from ''[[Ardipithecus]]'' in that its [[Tooth enamel|enamel]] is thicker. The dentition differs from both these species in the presence of a mesial groove on the upper canines. The [[Canine tooth|canines]] are ape-like but reduced, like those found in Miocene apes and female chimpanzees. ''Orrorin'' had small post-canines and was [[Microdontia|microdont]], like modern humans, whereas australopithecines were [[Post-canine megadontia|megadont]].<ref name="Senut-2007" /> However, some researchers have denied that this is compelling evidence that ''Orrorin'' was more closely related to modern humans than australopithecines as early members of the genus ''Homo'', who were almost certainly the direct ancestors of modern humans, were also megadonts.<ref name=Balter>{{cite journal | url=https://www.science.org/doi/10.1126/science.291.5508.1460 | doi=10.1126/science.291.5508.1460 | title=Scientists Spar over Claims of Earliest Human Ancestor | year=2001 | last1=Balter | first1=Michael | journal=Science | volume=291 | issue=5508 | pages=1460–1461 | pmid=11234056 | s2cid=43010058 | url-access=subscription }}</ref>

In the femur, the [[Femur head|head]] is spherical and rotated anteriorly; the [[Femur neck|neck]] is elongated and oval in section and the [[lesser trochanter]] protrudes medially. While these suggest that ''Orrorin'' was bipedal, the rest of the [[postcranium]] indicates it climbed trees. While the proximal phalanx is curved, the distal [[Thumb|pollical]] phalanx is of human proportions and has thus been associated with toolmaking, but should probably be associated with grasping abilities useful for tree-climbing in this context.<ref name="Senut-2007" /> 

After the fossils were found in 2000, they were held at the Kipsaraman village community museum, but the museum was subsequently closed. Since then, according to the Community Museums of Kenya chairman Eustace Kitonga, the fossils are stored at a secret bank vault in Nairobi.<ref>{{cite news|last=|first=|date=May 19, 2009|title=Whereabouts of fossil treasure sparks row|newspaper=[[Daily Nation]]|url=http://www.nation.co.ke/News/-/1056/600372/-/ujn367/-/index.html|url-status=dead|archive-url=https://web.archive.org/web/20190430215951/https://www.nation.co.ke/News/-/1056/600372/-/ujn367/-/index.html|archive-date=2019-04-30}}</ref> 

In 2017, impressions resembling human-like footprints
were reported on the island of [[Crete]] in Greece. These "[[Trachilos footprints]]", found in fossilized beach sediments near the [[Crete|west Cretan]] village of [[Trachilos (islet)|Trachilos]], have been dated to a similar time period as ''Orrorin tugenensis'', being 6.05 million years old.<ref> [https://phys.org/news/2021-10-oldest-footprints-pre-humans-crete.html Oldest footprints of pre-humans identified in Crete.] OCTOBER 11, 2021 - phys.org</ref> However, there is no consensus that these impressions are distinct enough to confidently assign to a primate or even a [[vertebrate]], or that they are indeed footprints at all.<ref>{{Cite journal |last1=Meldrum |first1=Jeff |last2=Sarmiento |first2=Esteban |date=2018-08-01 |title=Comments on possible Miocene hominin footprints |url=https://www.sciencedirect.com/science/article/pii/S0016787818300713 |journal=Proceedings of the Geologists' Association |language=en |volume=129 |issue=4 |pages=577–580 |doi=10.1016/j.pgeola.2018.05.006 |bibcode=2018PrGA..129..577M |s2cid=134963777 |issn=0016-7878|url-access=subscription }}</ref>
{{Human timeline}}

==Classification==
If ''Orrorin'' proves to be a direct human ancestor, then according to some paleoanthropologists, [[australopithecine]]s such as ''[[Australopithecus afarensis]]'' ("Lucy") may be considered a side branch of the hominid family tree: ''Orrorin'' is both earlier, by almost 3 million years, and more similar to modern humans than is ''A. afarensis''. The main similarity is that the ''Orrorin'' femur is morphologically closer to that of ''[[Homo sapiens]]'' than is ''Lucy's''; there is, however, some debate over this point.<ref name="Pickford-interview-2001">{{harvnb|Pickford|2001| loc=Interview}}</ref> This debate is largely centered around the fact that Lucy was female and the ''Orrorin'' femur it has been compared to belonged to a male.<ref name=Balter/>

Another point of view cites comparisons between Orrorin and other [[Miocene]] apes, rather than extant great apes, which shows instead that the femur shows itself as an intermediate between that of Australopiths and said earlier apes.<ref name=ncomms3888/>

Other fossils (leaves and many mammals) found in the Lukeino Formation show that ''Orrorin'' lived in a dry evergreen forest environment, not the [[savanna]] assumed by many theories of [[human evolution]].<ref name="Pickford-interview-2001" />

== Evolution of bipedalism ==
The fossils of ''Orrorin tugenensis'' share no derived features of hominoid great-ape relatives.<ref name="Pickford et al 2002">{{cite journal |last1=Pickford |first1=Martin |last2=Senut |first2=Brigitte |last3=Gommery |first3=Dominique |last4=Treil |first4=Jacques |title=Bipedalism in Orrorin tugenensis revealed by its femora |journal=Comptes Rendus Palevol |date=September 2002 |volume=1 |issue=4 |pages=191–203 |doi=10.1016/s1631-0683(02)00028-3 |bibcode=2002CRPal...1..191P }}</ref> In contrast, "''Orrorin'' shares several apomorphic features with modern humans, as well as some with australopithecines, including the presence of an ''obturator externus'' groove, elongated femoral neck, anteriorly twisted head (posterior twist in ''Australopithecus''), [[wiktionary:anteroposteriorly|anteroposteriorly]] compressed femoral neck, asymmetric distribution of cortex in the femoral neck, shallow superior notch, and a well developed gluteal tuberosity which coalesces vertically with the crest that descends the femoral shaft posteriorly."<ref name="Pickford et al 2002" /> It does, however, also share many of such properties with several Miocene ape species, even showing some transitional elements between basal apes like the [[Aegyptopithecus]] and Australopithecus.<ref name=ncomms3888/>

According to recent studies ''Orrorin tugenensis'' is a basal hominid that adapted an early form of bipedalism.<ref name=science.1154197>{{cite journal |last1=Richmond |first1=B. G. |last2=Jungers |first2=W. L. |title=Orrorin tugenensis Femoral Morphology and the Evolution of Hominin Bipedalism |journal=Science |date=21 March 2008 |volume=319 |issue=5870 |pages=1662–1665 |doi=10.1126/science.1154197 |pmid=18356526 |bibcode=2008Sci...319.1662R |s2cid=20971393 |url=http://doc.rero.ch/record/15736/files/PAL_E3008.pdf }}</ref> Based on the structure of its femoral head it still exhibited some arboreal properties, likely to forage and build shelters.<ref name=science.1154197/> The length of the femoral neck in ''Orrorin tugenensis'' fossils is elongated and is similar in shape and length to modern humans and ''Australopithicines''.<ref name="Pickford et al 2002" /> While it was originally claimed that its femoral head is larger in comparison to ''Australopithicines'' and is much closer in shape and relative size to ''Homo sapiens'',<ref name="Pickford et al 2002" /> this claim has been challenged by some researchers who have noted that the femoral heads of male australopithicines are more akin to those of ''Orrorin'', and by extension modern humans, than those of female australopithicines. Proponents of the notion that ''Orrorin'' is more closely related to humans than Lucy is have addressed this by asserting that the male australopithicine femurs in question in fact belong to a different species than Lucy.<ref name=Balter/> ''O. tugenensis'' appears to have developed bipedalism 6 million years ago.<ref name=science.1154197/>

''O. tugenensis'' shares an early hominin feature in which their iliac blade is flared to help counter the torque of their body weight; this shows that they adapted bipedalism around 6 MYA.<ref name=science.1154197/> These features are shared with many species of ''Australopithecus''.<ref name=science.1154197/> It has been suggested by Pickford that the many features ''Orrorin'' shares with modern humans show that it is more closely related to ''Homo'' ''sapiens'' than to ''Australopithecus''.<ref name="Pickford et al 2002" /> This would mean that Australopithecus would represent a side branch in the homin evolution that does not directly lead to ''Homo''.<ref name="Pickford et al 2002" /> However the femora morphology of ''O. tugenensis'' shares many similarities with ''Australopithicine'' femora morphology, which weakens this claim.<ref name=science.1154197/> Another study conducted by Almecija suggested that ''Orrorin'' is more closely related to early hominins than to ''Homo''.<ref name=ncomms3888>{{cite journal |last1=Almécija |first1=Sergio |last2=Tallman |first2=Melissa |last3=Alba |first3=David M. |last4=Pina |first4=Marta |last5=Moyà-Solà |first5=Salvador |last6=Jungers |first6=William L. |title=The femur of Orrorin tugenensis exhibits morphometric affinities with both Miocene apes and later hominins |journal=Nature Communications |date=3 December 2013 |volume=4 |issue=1 |page=2888 |doi=10.1038/ncomms3888 |pmid=24301078 |bibcode=2013NatCo...4.2888A |doi-access=free }}</ref> An analysis of the BAR 10020' 00 femur showed that ''Orrorin'' is an intermediate between ''Pan'' and ''Australopithecus afarensis''.<ref name=ncomms3888/> The current prevailing theory is that ''Orrorin tugenensis'' is a basal hominin and that bipedalism developed early in the hominin clade and successfully evolved down the human evolutionary tree.<ref name=science.1154197/> While the phylogeny of ''Orrorin'' is uncertain, the evidence of the evolution of bipedalism is an invaluable discovery from this early fossil hominin. A recent phylogenetic analysis also recovered ''Orrorin'' as a hominin.<ref>{{Cite journal |last1=Sevim-Erol |first1=Ayla |last2=Begun |first2=D. R. |last3=Sözer |first3=Ç Sönmez |last4=Mayda |first4=S. |last5=van den Hoek Ostende |first5=L. W. |last6=Martin |first6=R. M. G. |last7=Alçiçek |first7=M. Cihat |date=2023-08-23 |title=A new ape from Türkiye and the radiation of late Miocene hominines |journal=Communications Biology |language=en |volume=6 |issue=1 |page=842 |doi=10.1038/s42003-023-05210-5 |issn=2399-3642 |pmc=10447513 |pmid=37612372}}</ref>

==See also==
* [[List of human evolution fossils]] ''(with images)''

==References==
{{Reflist}}

==Sources==
{{refbegin|colwidth=30em}}
* {{cite web | author = CogWeb
 | title = Orrorin Tugenensis: Pushing back the hominin line
 | publisher = UCLA
 | url = http://cogweb.ucla.edu/ep/Orrorin.html
 | access-date = December 1, 2010
}}<!-- previously used as a reference -->
* {{cite book | last1 = Haviland | first1 = William A.
 | last2 = Prins | first2 = Harald E. L.
 | last3 = Walrath | first3 = Dana
 | last4 = McBride | first4 = Bunny
 | title = Evolution and prehistory: the human challenge
 | publisher = Cengage Learning | year = 2007
 | isbn = 978-0-495-38190-7
 | url = https://books.google.com/books?id=LfYirloa_rUC&q=Orrorin&pg=PA122
}}
* {{cite book | doi = 10.1007/978-3-540-33761-4_49 | title = Handbook of Paleoanthropology | year = 2007 |last1 = Senut | first1 = Brigitte | chapter = 6 the Earliest Putative Hominids | pages=1519–1538 | editor1-last = Henke | editor1-first = Winfried | editor2-last = Hardt | editor2-first = Thorolf | editor3-last = Tattersall | editor3-first = Ian | isbn=978-3-540-32474-4 }}
* {{cite web
 | last1 = Pickford
 | first1 = Martin
 | title = Martin Pickford answers a few questions about this month's fast breaking paper in field of Geosciences
 | publisher = Essential Science Indicators
 | date = December 2001
 | url = http://www.esi-topics.com/fbp/comments/december-01-Martin-Pickford.html
 | access-date = 2002-04-07
 | archive-url = https://web.archive.org/web/20020602053619/http://esi-topics.com/fbp/comments/december-01-Martin-Pickford.html
 | archive-date = 2002-06-02
 | url-status = dead
 }}
* {{cite journal |last1=Senut |first1=Brigitte |last2=Pickford |first2=Martin |last3=Gommery |first3=Dominique |last4=Mein |first4=Pierre |last5=Cheboi |first5=Kiptalam |last6=Coppens |first6=Yves |title=First hominid from the Miocene (Lukeino Formation, Kenya) |journal=Comptes Rendus de l'Académie des Sciences, Série IIA |date=January 2001 |volume=332 |issue=2 |pages=137–144 |doi=10.1016/S1251-8050(01)01529-4 |bibcode=2001CRASE.332..137S |s2cid=14235881 }}
{{refend}}

==External links==
{{Commons category}}
* [http://humanorigins.si.edu/evidence/human-fossils/species/orrorin-tugenensis Orrorin tugenensis] - The Smithsonian Institution's Human Origins Program
* [http://humanorigins.si.edu/evidence/human-evolution-timeline-interactive Human Timeline (Interactive)] – [[Smithsonian Institution|Smithsonian]], [[National Museum of Natural History]] (August 2016).

{{Human Evolution}}
{{Haplorhini|Ho.}}
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[[Category:Hominini]]
[[Category:Neogene mammals of Africa]]
[[Category:Miocene primates]]
[[Category:Pliocene primates]]
[[Category:Fossil taxa described in 2001]]
[[Category:Prehistoric Kenya]]
[[Category:Baringo County]]
[[Category:Articles containing video clips]]
[[Category:Taxa named by Martin Pickford]]