Pithecanthropus rudolfensis Alexeev, 1986
Year: 1986
Taxonomic Rank: Species
Lectotype: KNM-ER 1470
Status: Potentially valid

Richard Leakey et al. (1973) first described KNM-ER 1470, and attributed it to Homo sp. indet. based on the large endocranial volume (> 800 cc) and difference from known Australopithecus specimens. Also the associated post cranial bones, KNM-ER 1472, 1473 and 1481 did not claerly differ from modern humans. Subsequent analyses of the Homo habilis hypodigm (sensu lato) led Wood (1992) to conclude multiple species were present and he deployed the name Homo rudolfensis (Alekseev, 1986).

Alexeev (1986), in his book length treatment of the fossil record, suggested KNM-ER 1470 resembled later Homo and assigned the fossil to a new species, Pithecanthropus rudolfensis. Wood recognized the Alexeev publication as a valid nomencaltural act and considered the nomen 'rudolfensis' as available and valid, though this was contested at the time (Kennedy 1999).

Because of its status as a debated species H. rudolfensis is often referred to as a subspecies of Homo habilis though arguments have been made that it may also be subsumed into Australopithecus, as Australopithecus rudolfensis (Wood and Collard 1999). This discourse comes from the australopithecine features H. rudolfensis retained in contrast with the early Homo characteristics presented in its body plan (McHenry and Coffing, 2000). 

Aiello and Collard (2001) invoked the nomen as Kenyanthropus rudolfensis.

The name 'rudolfensis' is widely established and actively used with ca 60 citations in the past 50 years by at least 10 authors, including Lieberman et al. (1996), Karl (2012), Argue et al. (2009), Wood and Baker (2011), Ungar et al (2006), Anton (2007), Prat (2007), Will and Stock (2015), Agusti (2018), Smith and Grine (2008) etc.  The name is established and actively used.

Authorship Reference
V. P. Alexeev
The Origin of the Human Race
The Origin of the Human Race, Moscow: Progress Publishers, Moscow, 1986
Additional References
R. E. F. Leakey
Evidence for an Advanced Plio-Pleistocene Hominid from East Rudolf, Kenya
Nature, 242(5398), 447-450, 1973

V. P. Alexeev
The origin of the human race
The origin of the human race (First definition of Pithecanthropus rudolfensis), Progress Publishers, Moscow, 1986

B. Wood
Early hominid species and speciation
J. Hum. Evol., 22(4), 351-365, 1992
G. E. Kennedy
Is ``Homo rudolfensis'' a valid species?
Journal of Human Evolution, 36(1), 119-121, 1999
B. Wood and M. Collard
The changing face of genus Homo
Evol. Anthropol., 8(6), 195-207, 1999

B. Wood
'Homo rudolfensis' Alexeev, 1986-fact or phantom?
J. Hum. Evol. (Defines lectotype of Homo rudolfensis), 36(1), 115-118, 1999

H. M. McHenry and K. Coffing
Australopithecus to Homo: Transformations in body and mind
Annu. Rev. Anthropol., 29, 125-146, 2000

M. Collard and B. Wood
Homoplasy and the early hominid masticatory system: inferences from analyses of extant hominoids and papionins
J. Hum. Evol., 41(3), 167-194, 2001

L. C. Aiello and M. Collard
Palaeoanthropology Our newest oldest ancestor?
Nature, 410(6828), 526-527, 2001