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OH 9 is significant because the features it carries in correlation to the species classification. OH 9 allows anthropologist to explore the cranium of H. erectus and the debate as to whether it should be classified as H. erectus or not.

Species Classification
Cranial bone thickness has been widely qualified for H. erectus but rarely quantified. It’s quite often that throughout craniums found, throughout different individual hominids are different cranium thicknesses. Yet in OH 9, compared to other H. Erectus, it has the biggest cranial capacity standing at 1,067 cc and one of the largest mid supra-orbital torus thickness of 18.5 mm also known as the brow ridge. OH 9 has a robust brow ridge that allows it to stand out among other H. erectus. The brow ridge made it difficult to determine whether this cranium should be classified as H. erectus or a different species. However it has been determined that this skull is that of an h. erectus. Cranial bone thickness is key when determining whether a specimen found is H. erectus. The pattern of bone thickness distribution observed in Asian H. erectus, P. paniscus, and possibly in the australopiths, early Homo or African H. ergaster/erectus analyzed appears to be a pleomorphic trait among hominids. Since cranium thickness and the OH 9 cranium capacity is larger than any found, it explored the idea of different forms of H. erectus from different areas due to migration. By the 1980's, the growing numbers of H. erectus specimens, particularly in Africa, led to the realization that Asian H. erectus (H. erectus sensu stricto), once thought so primitive, was in fact more derived than its African counter-parts, which leads into the Out of Africa Hypothesis that many homo species were believed to be a part of.

Cranial Features
The significant features of the OH 9 also consist of the structure of the skull. O.H. 9 has a flatter frontal squama curving not as steep from a broader supratoral shelf. Also, O.H. 9 shows no sign of keeling in the midline which is often found in H. erectus especially with a protruding brow ridge. The occipital torus thickness also known as the occipital bun which is the back of the head was also fairly thick compared to most H. erectus with a thickness of 18.5 mm. OH 9 being the largest cranium capacity, helped us learn the increase of brain growth in H. erectus. Which implies that major differences in the development of cognitive capabilities existed between H. erectus and anatomically modern humans. These new traits like the robust brow ridge and skull thickness confirmed that H. erectus in different areas kept evolving. In the same site, the oldowan tools found can be assumed to have been used by this exact H. erectus. It allows us to understand how advanced this unique H. erectus cognitive behavior truly was.