Species status of Kenyanthropus platyops and Australopithecus deyiremeda

https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/comptes-rendus-palevol2024v23a29.pdf
Mid-Pliocene hominin diversity revisited
Abstract
Geometric morphometric analyses are used to
examine the maxillary shape of the
Kenyanthropus platyops Leakey, Spoor, Brown,
Gathogo, Kiarie, Leakey & McDougall, 2001
holotype KNM-WT 40000 and the Australopithecus
deyiremeda Haile-Selassie, Gilbert, Melillo,
Ryan, Alene, Deino, Levin, Scott & Saylor,
2015 holotype BRT-VP-3/1, expanding on the
work of Spoor et al. (2010, 2016) by using
more accurate data and a larger comparative
sample. The main objective is to assess
whether these two specimens differ from the
contemporary taxon Australopithecus afarensis
Johanson, White & Coppens, 1978 and more
broadly from species of Australopithecus
Dart, 1925 and Paranthropus Broom, 1938,
as well as from each other. Five
two-dimensional landmarks recorded on
virtual models obtained from computed
tomography scans quantify key features of
the maxilla used in the differential
diagnoses of K. platyops and A. deyiremeda.
Principal component analyses were performed
to describe shape differences, and the
magnitudes of these differences and their
statistical significance were assessed using
Procrustes and Mahalanobis distances,
respectively. The maxillary shapes of both
KNM-WT 40000 and BRT-VP-3/1 are significantly
different from A. afarensis, the former more
so than the latter, and they differ from A.
afarensis in dissimilar ways. Where
KNM-WT 40000 has a more anterosuperiorly
positioned zygomatic process with a longer,
more orthognathic, and transversely flat
subnasal clivus than A. afarensis, the shape
difference of BRT-VP-3/1 is best described
as a posterior shift (retraction) of the
entire dental arcade. The findings of this
study quantitatively support the species
status of K. platyops and A. deyiremeda, and
corroborate the notion that hominin diversity
extended well into the mid-Pliocene of
eastern Africa.