Sorry that the link didnÃ¢â‚¬â„¢t work. The article is called Ã¢â‚¬Å“Systematic assessment of a maxilla of Homo from Hadar, EthiopiaÃ¢â‚¬Â, so maybe you can track it down elsewhere (I just found it on Google Scholar). They compared the maxilla to several other fossils from Australopithecus, Paranthropus and Homo. The traits they compared were very specific measurements of the jaw proportions and size of the teeth.
I looked up the page and it did'nt give much of any details. Woods and Collard have done the largest comparison of the Species. They compared all of the H. habilis fossil material to modern human and have found a difference significant enough that H. habilis should'nt be classified in the genus Homo. They also concluded that the variation was too wide for it be specimens from only a single taxon.
Others researchers (Stringer, 1986; Chamberlain &
Wood, 1987; Lieberman et al., 1988; Wood, 1991,
1992; Rightmire, 1993; Lieberman et al., 1996; Prat,
1997, 2000) do not support the retention of a single
taxon. They argue that the degree of variation within
Homo habilis sensu lato is too large relative to what can
be justified for a single taxon. Different parameters
have been studied: morphology, endocranial volume,
S@xual dimorphism, and degree and pattern of variation
of the cranio-facial measurements. This point of view
is the current consensus opinion, but it is important to
note that the specimens included in these species differ
according to the authors. A majority of the distinctive
traits are located on the face. For example, Homo
rudolfensis exhibits a greater absolute size of the brain
case, a face that is widest in its mid-part, complex roots
and large crowns, and a powerful masticatory apparatus.
(3) the species habilis and rudolfensis do not belong to
the genus Homo but to the genus Australopithecus.
For many years, the criteria used to allocate species
to Homo, and those proposed by Leakey and colleagues
to define the genus Homo (Leakey et al., 1964), have
been considered insufficient or inappropriate. In 1999,
Bernard Wood and Mark Collard proposed alternative
criteria for defining the genus Homo. Wood and
Collard (1999 a, suggested that the definition of the
genus should follow both the evolutionary systematic
method of classification and the cladistic criteria.
They tested whether or not the genus Homo (including
both Homo habilis and Homo rudolfensis) is
monophyletic and adaptively coherent. For them, all
the species within genus Homo must share a functionally
coherent adaptive strategy with H. sapiens rather
than with other genera (e.g. Australopithecus). But the
species habilis and rudolfensis present an australopithlike
pattern rather than a modern human-like pattern for
body mass (relatively low), body shape (interpreted in
terms of thermoregulation as being better suited to a
relatively closed environment), locomotion (combination
of terrestrial bipedalism with proficient climbing),
morphology of the jaws and teeth, development and
brain size (Wood & Collard, 1999b). Moreover, the
genus Homo is monophyletic, in the spirit of Wood
and Collard, only if the species habilis and rudolfensis
are excluded. Therefore, they proposed that habilis
and rudolfensis should be placed in the genus
Australopithecus as Australopithecus habilis and
Australopithecus rudolfensis, respectively (Wood & Collard, 1999 a, .
Given the fact that AL-666-1 is within human variation,it can't belong to H. habilis. And as I linked to earlier, the fossil material is aligned with orangutans and not chimps or humans.