open access

bioRxiv preprint doi: https://doi.org/10.1101/2023.02.02.526656;
this version posted February 4, 2023.

https://www.biorxiv.org/content/10.1101/2023.02.02.526656v2.full.pdf

Objectives: Here, we describe the morphology and geologic
context of OH 89, a ~1.8-million-year-old partial hominid
clavicle from Olduvai Gorge, Tanzania. We compare the
morphology and clavicular curvature of OH 89 to modern
humans, extant apes, and a sample of other hominid fossil
clavicles.
....
Discussion: The OH 89 clavicle derives from an individual
of unknown hominid species with a shoulder breadth similar
to that of a large human male. The curvature of OH 89 is
relatively human-like relative to its length. Our new
methodology for measuring clavicular curvature, combined
with the utilization of t-SNE analyses, provides greater
separation of genera than previously used methods, and
wider use of t-SNE may be useful in paleoanthropological
work.
....
The discovery of the clavicle from partial skeleton of
Australopithecus afarensis KSD-VP-1/1 brought renewed
attention to the clavicle and interpreting its role in the
evolution of the hominid shoulder girdle (e.g., Melillo,
2016; Melillo et al., 2019). Applying new methodological
approaches, Melillo (2016) concluded that all
Australopithecus clavicular remains are indistinguishable
from each other and that the clavicle of A. afarensis has
morphological affinities to both chimpanzees and humans.
....
OH 89, a 1.8 Ma hominid clavicle, falls within the range
of modern humans in absolute size and clavicular curvature.
This finding indicates that there has been little
morphological change in the hominid clavicle in the last
~2 million years. It also suggests that shoulder breadth
(though not necessarily body size) may have been similar
to modern humans as far back as 1.8 Ma.
....

OH 89: a newly described ~1.8-million-year-old hominid clavicle from Olduvai Gorge
Catherine Taylor cs 2023 doi org/10.1101/2023.02.02.526656

Here, we describe the morphology & geologic context of OH-89 (~1.8 Ma Tanzania).
We compare its morphology & clavicular curvature to 50 Hs, 30 Gorilla, 31 Pan, 7 Papio & 5 hominid clavicles.
Length regression on mid-shaft size, using the extant comparative samples, is used to estimate its total length.
9 linear measurements are taken from each individual.
We also describe a new methodology for measuring clavicular curvature:
measurements of sternal & acromial curvature, from which an overall curvature measurement is calculated.
A PCA & a t-distributed stochastic neighbor embedding (t-SNE) analysis are used to compare its morphology with the extant & fossil comparative samples.
Results:
Our new method of measuring clavicular curvature successfully separates the different genera of the extant clavicles.
The length estimate + sternal & acromial curve measurements for OH-89 falls within the larger male Hs.
The PCA shows: OH-89 & most of the fossil hominids fall between the Hs & Pan groups,
the t-SNE suggests: OH-89, KSD-VP-1/1, KNM-ER-1808 & OH-48 are more similar to each other than to any of the other groups.
This analysis also plots KNM-WT-15000 with the Hs, and Krapina-158 with the Pan individuals.
Discussion:
The OH-89 clavicle derives from an unknown hominid species, with a shoulder breadth similar to that of a large Hs male.
Its curvature is rel.human-like relative to its length.
Our new methodology for measuring clavicular curvature, combined with the utilization of t-SNE analyses, provides greater separation of genera than previously used methods, and wider use of t-SNE may be useful in PA work.

> bioRxiv preprint doi: https://doi.org/10.1101/2023.02.02.526656;
> this version posted February 4, 2023.
>
> https://www.biorxiv.org/content/10.1101/2023.02.02.526656v2.full.pdf
>
> Objectives: Here, we describe the morphology and geologic
> context of OH 89, a ~1.8-million-year-old partial hominid
> clavicle from Olduvai Gorge, Tanzania. We compare the
> morphology and clavicular curvature of OH 89 to modern
> humans, extant apes, and a sample of other hominid fossil
> clavicles.
> ...
> Discussion: The OH 89 clavicle derives from an individual
> of unknown hominid species with a shoulder breadth similar
> to that of a large human male. The curvature of OH 89 is
> relatively human-like relative to its length. Our new
> methodology for measuring clavicular curvature, combined
> with the utilization of t-SNE analyses, provides greater
> separation of genera than previously used methods, and
> wider use of t-SNE may be useful in paleoanthropological
> work.
> ...
> The discovery of the clavicle from partial skeleton of
> Australopithecus afarensis KSD-VP-1/1 brought renewed
> attention to the clavicle and interpreting its role in the
> evolution of the hominid shoulder girdle (e.g., Melillo,
> 2016; Melillo et al., 2019). Applying new methodological
> approaches, Melillo (2016) concluded that all
> Australopithecus clavicular remains are indistinguishable
> from each other and that the clavicle of A. afarensis has
> morphological affinities to both chimpanzees and humans.
> ...
> OH 89, a 1.8 Ma hominid clavicle, falls within the range
> of modern humans in absolute size and clavicular curvature.
> This finding indicates that there has been little
> morphological change in the hominid clavicle in the last
> ~2 million years. It also suggests that shoulder breadth
> (though not necessarily body size) may have been similar
> to modern humans as far back as 1.8 Ma.
> ...