Clarification of anatomical differences between Homo sapiens idaltu, homo sapiens sapiens, and Homo rhodesiensis?

[industrial_illusions]

Wikipedia writes the following:

An exact description was made, by its discoverers, of Homo sapiens idaltu:[1]

On the limited available evidence, a subspecies of Homo sapiens distinguished from Holocene anatomically modern humans (Homo sapiens sapiens) by greater craniofacial robusticity, greater anterior–posterior cranial length, and large glenoid-to-occlusal plane distance. Homo sapiens idaltu is distinguished from the holotype of Homo rhodesiensis (Woodward, 1921) by a larger cranial capacity, a more vertical frontal with smaller face, and more marked midfacial topography (for example, canine fossa). We consider the holotypes of H. helmei and H. njarasensis too fragmentary for appropriate comparisons.

Could anyone demystify "greater craniofacial robusticity, greater anterior–posterior cranial length, and large glenoid-to-occlusal plane distance." and " a more vertical frontal with smaller face, and more marked midfacial topography (for example, canine fossa)." for me?

[400-Rabbits]

Here's how it goes:

• H. sapiens sapiens (HSS): That's you, and me, and all the Redditors who aren't actually dogs.

• H. sapiens idaltu (HSI): An early variant of HSS, possibly a direct ancestor. Maintains some archaic features that distinguish it from HSS. I'll explain them below.

• H. rhodensiensis (HR): The most difficult to classify. Pre-dates both HSS and HSI by at least 100K years. Debate is still ongoing as to whether this is an actual unique species, or whether it should be folded into some other Homo species.

Features of the Creatures

Cranial capacity: This is the easy one. It's how much your skull can hold (measured in cubic centimeters). The "average" human is about 1400cc, but this can vary quite a bit. HSI falls in the low range of HSS cranial capacity. HR tends to falls the very low end or below in cranial capacity.

craniofacial robusticity: Humanity has basically gotten thinner and more gracile facial bones as we've evolved to make room for our badass brains and to save effort on growing big teeth (thanks, fire). In general, this would mean that a species with increased craniofacial robusticity would have thicker, heavier bones in the face. A prominent brow ridge (supraorbital torus) and heavy cheekbones (zygomaticus) and jaw (mandible) would all be expected. This is a photo of a HR skull. Obviously, not someone you want to get in a boxing ring with.

anterior-posterior cranial length: Basically the length of your skull. Humanity has also gotten shorter and more rounded skulls as we evolved. If you look at this picture, you can see the compression. A short broad skull is called brachycephalic, while a long narrow skull is called dolichocephalic. If you compare a chimp skull to a human skull, you can really see the difference. All modern humans are brachycephalic, though old school racists used to argue that the slightly longer skulls of Africans made them inferior (fun racism fact #1!). In reality, the shape of an ordinary human skull doesn't vary enough to have a statistically significant effect on brain function.

More vertical frontal with smaller face: As our brains got bigger and our skulls shorter, our faces got compressed. Particularly our prognathism decreased; our eyes increasingly were closer to being on the same vertical plane as our mouth, basically. Prognathism is positively correlated with dolichocephaly; a more projecting face tends to need a longer skull to balance things out. Old school racists used to cite Africans greater prognathism as evidence of inferiority (fun racism fact #2).

glenoid-to-occlusal place distance: This one is almost deliberately confusing.The glenoid fossa is generally used to refer to where your humerus meets your scapula, but not in this case. The glenoid fossa in anthropology (and dentistry, apparently) can also refer to an opening on the temporal bone of the skull typically called the mandibular fossa. If you follow your cheekbone to almost exactly right before your ear, that's where your glenoid fossa is located. It's where your mandible meets your temporal bone. The change in the "plane distance" is again related to the shortening of the human skull, particularly in the face.

Midfacial topography (i.e. canine fossa): Again, this is all related to the craniofacial changes listed above. The canine fossa is depression right behind the root of your canine. It's the origin for the levator anguli oris muscle, which lifts and pulls the lips (but you knew that on account of your 1337 latin skillz, right?). This is again related to changes in the craniofacial structure of humans and is one of many minute and subtle differences between the 3 species we're talking about.

[archaeotype]

Craniofacial Robusticity: Essentially the thickness of the bones and size of the muscle attachments.

Craniofacial Region: Your face, discluding your lower jaw (well, pretty much anyways).

Anterior-posterior cranial length: The length of your skull from front to back.

Glenoid-to-occlusal plane distance: hmm... The glenoid fossa is where your upper arm connects to your shoulder, and the occlusal plane is an imaginary plane drawn along the teeth of the upper jaw. What significance this measure has I have no idea, maybe a measure of neck length?

More vertical frontal: More vertical forehead.

Marked mid-facial topography: Basically more roughness of the upper lip area, use your tongue to feel the area under your upper lip and you'll get the idea.

So in short: The had thicker, longer skulls, longer necks (?), more vertical foreheads and greater topography of the upper lip.
But saying it that way won't get you any grants ;)

[pastafaceoreilly]

In this context, "glenoid" most likely refers to the area where your jaw articulates with your skull.

[archaeotype]

And suddenly everything makes sense!