Final answer:
A robust hominid skull is typically characterized by a prominent sagittal crest, large teeth and jaws, flared zygomatic arches, less prognathism, and a possible sagittal keel or occipital bun. The postcranial skeleton may show evidence of bipedalism with humanlike feet.
Step-by-step explanation:
If you've found a fossilized skull and have concluded that it's from a robust hominid, there are specific features that it must have. To be classified as a robust hominid, the skull would generally exhibit characteristics such as a prominent sagittal crest, which indicates the presence of large temporalis jaw muscles needed for chewing hard plant material. Additionally, robust hominids often have large teeth and jaws to accommodate their heavy chewing. Another distinguishable characteristic might include flared cheeks or zygomatic arches that flare outward. It's also typical for these skulls to show less prognathism compared to gracile hominids. Due to their diets, the teeth may also be adapted for grinding, with larger molar teeth relative to the size of the incisors and canines.
The presence of a sagittal keel or a small raised ridge on the top of the skull, similar to what is seen in Homo erectus, can be another identifying feature. It's also possible to observe features like a reduced chin or a projecting nasal spine, which are indicative of the robust group of hominids. Additionally, the occipital bun, a bulbous projection at the back of the skull, might be present, as seen in Neanderthals and Homo erectus.
When it comes to the postcranial skeleton, if available, you might find evidence of a bipedal gait and humanlike feet with arches and ankles. Since these features pertain to the locomotion of the individual, it might confirm the classification of the fossil as a robust hominid.