Australia: The Land Where Time Began
WLH 50 Cranial Bone – Thickness
The marked thickening of the cranial wall of WLH 50, which was discussed above as a possible pathological condition, is one of the most notable features of WLH 50. It is notably thicker than the next thickest Willandra specimen (Webb, 1989: Table 7), based on a measure of thickness averages throughout the vault, not including the supraorbital and nuchal tori, and WLH 50 is on average 1.8 times thicker than the other partially complete Willandra male, WLH 3 (Curnoe & Green, 2013). The thickness of the WLH 50 cranium is well above the means for recent Aboriginals recovered from Kow Swamp, Coobool Creek, and the collection recovered from the Murray Valley (Brown 1987). The thickness of the WLH 50 cranium is, however, well within the range for recent Aboriginal crania, if barely. It is actually less thick than the thickest specimens from Coobool Creek that were reported by Brown (Brown, 1987). Where comparisons are possible, the WLH 50 is thicker than any specimens from Ngandong, for most thickness measures on the cranial squama.
The thickness is accomplished, to a large extent, by a greater relative and absolute thickening of the diplöe in WLH 50, and WLH 50 resembles, in this regard, other recent and modern human crania (Curnoe & Green, 2013; Kennedy, 1991; and see below). It has been reported, in contrast, that generally the concept of outer and inner tables contributing more to total bone thickness than is normal in recent crania. In the thickness of the cranial vault of Ngandong, and in the earlier remains from Sangiran and Zhoukoudian, all of the 3 constituents of the cranial vault bone take equal part of the thickening, the 2 tables slightly more than the diplöe (Weidenreich, 1943, p. 164). This pattern is typical of the construction of the vault in other crania from the Upper Pleistocene, as well as those individuals from the Ngandong series. This is the reverse of the pattern in WLH 50 (Webb, 1995: 64). Issues have been raised about whether the cranial bone thickness comparisons of WLH 50 and Ngandong crania are between homologous characteristics, more than with any other comparison, and therefore whether the thickness of the cranium can be validly compared. The internal characteristics of cranial bone can differ considerably between different positions (Marsh18, 2013), though the internal anatomy of the cranial bone of WLH 50 is well described and known at many positions (Curnoe & Green, 2013). General observations have been reported (Balzeau, 2006) of the contribution of inner and outer tables and diplöe to the thickness of cranial bone in Homo erectus, Ngandong and fossil and recent humans. It was found by Balzeau that diplöe contributes to more than 50 % of the thickness of the bone in virtually all specimens that have been studied. It was observed by Wolpoff et al. that in WLH 50 the diplöe is not exceptional in its relative thickness relative to other fossils recovered from Australia. When combined, these observations challenge previous assertions that Asian H. erectus and Ngandong were different in these regards, and support the assessment of homology of cranial bone structure, which provides validity for the comparison of the thickness of cranial bone by Wolpoff et al.
The angled forehead is long, flattened, and thick. The gentle curvature is also present along the midline from the position of the glabellar to the metopion position (the metopion is the highest point along the nasion-bregma line), about 3 cm anterior to the posterior border of the bregma, where what is basically the front of the cranium is separated from its top by a strong angulation. Metopion is not always delineated as a distinct angulation in the sagittal plane on Ngandong crania, as in Ng 1 and Ng 5. There is an angulation in the metopion position in Ng 10, though unlike WLH 50, it is more anterior, at about the centre of the frontal squama. There appears to be something like a prebregmatic eminence on WLH 50, and it has been described as such (Curnoe, 2011: 10). According to Wolpoff et al. this is not an eminence in the sense of bulging outwards from the surface of the cranium, rather it is the point of angulation described above, between the cranium top and its front defined by the slope of the forehead.
The frontal length of WLH 50 is substantially greater than in the Ngandong crania, whether described as a chord or an arc. Relative to the cranial length the frontal length of WLH 50 is 60.6 %; this exceeds greatly frontal length of the Ngandong sample (50.4-56.8, n=6). Though most of the human frontals, however, frontals that are relatively long are found through the fossil record of the Late Pleistocene everywhere – Cro Magnon 3 and 8 (61.1, 62.9), Předmostí 22 (60.5), Pavlov 1 (60.3), and Liujiang (61.8). In the Late Pleistocene an elongated frontal is unusual but not unknown.
Flattening of the frontal squama in WLH 50 is similar to the condition in Ngandong specimens. The chord/arc index for the frontal length (107.6) for WLH 50 is close to, though very slightly above the range for the 4 Ngandong males of 103.2-106.2). The frontal of WLH 50 is thicker at bregma than Ngandong crania. The only frontal comparison that is reported in this monograph is the bregma thickness; though there are problems of identifying the same position on different crania (Marsh, 2013), those that are taken at defined points are most likely to be comparable. Transversely, the squama are evenly curved, the sagittal keel of the parietals does not extend on to the frontal as it does in Ng 5, and there is no frontal boss that is similar to that of Ng 11. WLH 50 is most similar to Ng 1 and Ng 10 in these respects.
There is a very broad bulging surface posteriorly on the frontal squama of WLH 50 which involves approximately the middle half of the frontal at the coronal suture, which narrows as it passes anteriorly to the supraorbital region. The frontal squama is shallowly concave to the temporal ridges to its sides, and in Ngandong this development varies; in this WLH 50 closely resembles Ng 10. The lateral torus on WLH 50 has a frontal trigone that is poorly developed at its lateral edge on the left, a structure that is smaller but otherwise similar to that in Ngandong crania; very similar to that in Ng 9 in particular (the trigone in Ng 9 is larger). Just medial to the trigone on the left side the supraorbital torus is 9.6 mm thick (height); the thickness is 12.6 at the trigone, a relationship of greater thickness at the corner that is similar to Ngandong. The superior surface of the lateral torus in indistinguishable from the frontal squama; and according to Wolpoff et al. this part of the torus could be described as a thickening at the end of the long, flat squama.
The postorbital constriction is pronounced in WLH 50, though to a lesser extent than in the Ngandong mean. The postorbital constriction is most like that of Ng 10, both absolutely and relative to maximum frontal breadth, whether measured across the temporal fossae or across the temporal ridges. The latter is very similar to Ngandong 10. The minimum frontal breadth is only 1 mm greater the Ngandong maximum, which is not unexpected given the similarities in the shape of the cranium and how much larger WLH 50 is. Relative to the maximum frontal breadth WLH 50 is relatively less narrow than any Ngandong cranium; but also with this measure the difference is slight as WLH 50 is 92.7 % and the maximum for Ngandong, that of Ng 10 cranium, is 92.6 %. In all, WLH 50 is very similar to Ng 10 in these absolute and relative breadths, in general above the Ngandong mean.
At the temporal fossa of WLH 50 the distance between the temporal lines, where they are actually temporal ridges, is 112 mm, which significantly exceeds the condition in Ngandong where the lines (ridges) are higher up on the cranium at this position, and thereby closer together, a range of 100 mm to 104 mm. The anterior portion of these ridges projects from the frontal and there is a distinct angulation of the bone inferior to them, where the surface of the bone along the inferior border of the ridge is more sculpted out and concave than is the case in any of the Ngandong crania (the ridge is less distinct in Ngandong and the inferior border along it is convex in all cases). The ridge becomes less prominent posteriorly on the frontal of WLH 50, as does the angulation defined by it, and the temporal ridges gradually soften to lines that are indistinct as they cross the coronal suture posteriorly. Their vertical position on the cranium changes as well, the lines rising to a higher position on WLH 50 more posteriorly, which reverse the relationship in Ngandong even the Willandra cranium is the largest by far. The distance of 98.2 mm between the temporal lines where they cross the coronal suture is below the range of Ngandong of 101.3-113.5 mm, in spite of the fact that the maximum of the breadth of the frontal is just barely above than the range in Ngandong.
The supraorbital region of WLH 50 is mostly preserved externally but not internally: “the flat frontal squama is associated with a large and anteriorly projecting supraorbital torus, and this feature results from anterior placement (growth) of the orbit relative to the frontal squama. The anterior point of the superior orbital plate is located well anterior to the angulated plane of the frontal squama” (Curnoe, 2009: 984). It has been described (Webb, 1989) the WLH 50 torus as comprised of superciliary ridges and a middle section that is “as large or larger that implies a partial torus.” According Wolpoff & Lee the issue of whether the condition of WLH 50 can be described as supraorbital torus or as superciliary ridges (or arches) is complex, not the least of which is because of differences between the left and right sides, as described below.
The torus of WLH 50 is an osseous bar extending across the frontal. Projecting from the frontal squama, the direction of the projection is almost parallel to the squama with the result that only a weakly developed fossa supraglabellaris occurs, which is similar to the condition in Ngandong, and differs from earlier Indonesian crania. It is especially similar to the left side of Ng 5 in which the fossa supraglabellaris also extends in a lateral and superior direction across the entire front face of the torus. It is not clear if the osseous bar continues across the midline because the central portion across a portion of 11 mm at the top of the torus is missing, apart from its very top which is at, or almost at, the position of the midline. There is a suggestion of a glabellar notch similar to the case in Ngandong, and it is possible, though far from certain, that there was a broad groove at glabella that separates the 2 sides. WLH 50 differs from Ng 5 but is similar to Ng 11, in this notch being (weakly) expressed.
The bone surfaces are continuous from this break laterally to the laterally-most positions that have been preserved, not quite at the suture with the zygomatic but sufficiently lateral for the temporal line to parallel the top of the surface of the torus. The presence of some glabellar projection, as seen from above, is indicated by the bone surface that has been preserved. On the superior rim on both sides of the frontal, there are supraorbital notches, or incisura, a condition that can be seen on some Ngandong crania, such as Ng 11, though not all of the Ngandong crania.
According to Wolpoff & Lee there are 2 ways to interpret this osseous bar as expressed in WLH 50 and it would be fair to say that descriptions above by Webb and by Curnoe are correct. On the one hand, a continuous toral surface is preserved on both sides of WLH 50, which makes it reasonable to describe the structure as supraorbital torus, as has been suggested by Curnoe. While on the other hand, there is the appearance of superciliary arches that are well developed, broad, and vertically tall, that are weakly distinguished from lateral tori by an abrupt change from greater medial projection to weaker lateral projection that is less vertically tall, as described by Webb. This is more distinct on the left side than on the right. On the left the junction between these is easily visible and could be described as a supraorbital groove that is weakly superolaterally oriented, though it is more a junction between 2 surfaces than a furrow. And the position of the supraorbital notch does not correspond to the tallest part of the superciliary arch, as is common.
The torus extends across the front of the Ngandong crania in what is virtually a straight line for all except its lateral aspects, when seen from the superior surface. The superciliary arches project more anteriorly than the lateral tori which angle more posteriorly than the straighter lateral supraorbital aspect in Ngandong. The sides angle somewhat posterolateral, away from the centre, only in Ng 4 and Ng 10. In this regard, WLH 50 is most like Ng 10; though it is difficult to measure accurately, and the preservation of Ng 10 is incomplete, WLH 50 appears to have about the same angulation.
The anatomy of the supraorbital region of WLH 50 is not quite like any other fossil sample from the Late Pleistocene. The Neanderthal supraorbital torus was described (Smith & Ranyard, 1980: 589) as:
“… basically an osseous bar, extending continuously across the inferior margin of the frontal bone. The torus forms an arch over the superior margin of each orbit and appears depressed superiorly in the midline by the presence of a supraglabellar fossa.”
A structure that is in some ways similar is preserved by WLH 50. And it does not resemble closely the classic supraorbitals of Zhoukoudian, and also it differs somewhat from the Ngandong condition as described below. Whether or not WLH 50 has a true supraorbital torus is not a key diagnostic issue, because some recent Australian Aboriginals can have supraorbital tori. The supraorbital torus in Coobool 50.35, e.g., is thick and developed evenly and in contrast to WLH 50 there is not even the most incipient division of the structure into superciliary and lateral elements, in spite of the orbital notch. No cranium from Coobool or Kow Swamp has a frontal trigone expression that is as strong as even the weakest development in the sample from Ngandong.
The anatomy of the supraorbital region varies across the full range of possible expressions that have been seen in Pleistocene and recent times, in adult samples from Coobool Creek and Kow Swamp from the Late Pleistocene/Recent Australian Aboriginal, and the WLH 50 cranium fits within this range.:
· A classic supraorbital torus that is thick, developed continuously and evenly, such as Kow Swamp 15; Coobool 50.16, 50.75, 50.76, 50.82, and 50.35;
· A classic supraorbital torus that is thin, continuously and evenly developed (Kow Swamp 14; Coobool Creek 50.38);
· Tori with thinning at the mid-orbital position (Kow Swamp 5; Coobool Creek 50.29, 50.65);
· Tori that are continuously expressed and have lateral thinning (Kow Swamp 1, 3, 4, 7, 8; Coobool Creek 50.9, 50.28, 50.37, 50.41, 50.45, 50.46, 50.49, 50.66);
· The torus is divided into superciliary arches and lateral tori (Kow Swamp 154; Coobool Creek 50.10, 50.12, 50.13, 50.23, 50.36, 40.47 (R), 50.50, 50.51. 50.65 (L), 50.71); and
· Virtual or full lack of toral structures (Kow Swamp 2, almost adult; Coobool Creek 50.2, 50.7, 50.61).
The most unusual morphology of the Ngandong supraorbital tori are arguably the knobby frontal trigones present at their most lateral extent, which makes the thickness of the torus in this position the greatest in any part of the structure (Weidenreich, 1957). The temporal line, which emerges from the temporal fossa, forms the left side of the trigone. The apex of the trigone is formed by the temporal line. As this line swings posteriorly it changes into a ridge. The distinct top of the supraorbital is the medial side of the trigone. On the right side of WLH 50 part of such a trigone has been preserved, though it is much smaller and less prominent than any of the Ngandong structures, and more like the structure as it is in the Kow Swamp sample. The lateral height as it is preserved in WLH 50, at what Weidenreich referred to as the “corner portion20” as it is positioned just above the supraorbital corner of the orbit, is the thinnest of the height measurements taken there, and the length of its lateral torus, from the temporal ridge to the orbital border on the side, is also smaller. WLH 50 is quite different from the condition in Ngandong in these observations. Though the condition as it is found in Ngandong is not completely lost in the fossil record of Australia. At Kow Swamp and Coobool Creek a number of the later adults have special thickening at the outer corner of the torus, which forms a frontal trigone that is similar to that of Ngandong, though, again, not expressed as strongly – Kow Swamp 5, 8, 14; Coobool Creek 50.10 (R) , 50.12, 50.15, 50.29, 40.41 (L), 50.49, 50.65, 50.66, 50.76).
The morphology of the anterior brow of the Willandra series (WLH 18, 19, 50, and 68) appear to be, in its general form, closer to that of the Zhoukoudian sample than to Ngandong (Webb, 1989: 31).
Wolpoff & Lee agree that the anterior brow region of some fossils from the Pleistocene is more similar to WLH 50 than to Ngandong remains, Though this is not the case for remains of Zhoukoudian, in Asians from the later Middle Pleistocene such as Dali there are significant similarities to the WLH 50 anterior brow that are significant (Wu & Athreya, 2013). The is also a continuous osseous bar of the same shape as WLH 50 on Dali, in this case as the region is preserved it is across the midline. There is significant arching that corresponds to a superciliary arch and a lateral portion that is less vertically tall and has a superior surface that is flat that is continuous with the frontal squama. Though not like WLH 50, Dali lacks supraorbital trigones and notches, and the surfaces of the 2 structures – the superciliary arches and the lateral tori – meet along a juncture of 2 different shapes that form the sides of a groove, they are continuous and of even curvature.
Additional to torus and posterior to it is considered (Weidenreich, 1951: 249) the manner in which the torus portion is connected with the squama frontalis as one of the 2 special features of the Ngandong crania, the other being the torus. The region has been described (Weidenreich, 1951: 251): The tori are not separated from the squama by a distinct sulcus supraorbitalis and glabellaris, which is contrary to the conditions in Sinanthropus, but continue into the squama itself without any demarcating impression, with the exception of the lateral halves of the supraorbital tori where they build the zygomatic process.
The condition portrayed by Weidenreich is quite similar in WLH 50, where no true sulcus can be observed behind the supraorbitals; instead the surface slopes almost evenly up to the frontal squama. There is a top to the supraorbital tori in WLH 50 and the Ngandong crania, though this cannot be described as a combined, continuous supraorbital sulcus and glabellar sulcus and glabella prominence as it does not extend across the midline of the frontal. The supraorbital sulcus alone exists, instead, which increases in extent from the middle of the frontal, where it does not exist, to the most lateral position, where there is an elongated surface between the rim of the torus and the beginning of the frontal squama that is the external manifestation of the top of the orbit.
An alternative way of describing this anatomy in WLH 50 and the Ngandong crania is that the anterior face of the frontal squama is strongly curved in the horizontal plane, such that the middle of the bone is positioned directly over the glabella position, though as it retreats laterally from the torus, it forms an increasingly longer orbital roof. Remembering that the roof is not angled strongly relatively to the frontal squama, as is the case, e.g., in the Zhoukoudian crania that were described by the Weidenreich citation above, at the lateral-most position the length of this roof, from the anterior face of the squama to the supraorbital border, can be measured in WLH 50 at about 32 mm, which is similar to 29 mm in Ng 11 where it is arguably most distinct among the Ngandong crania.
The internal surface of the Ngandong frontals have been described (Weidenreich, 1951: 250-251):
“on the cerebral side of the frontal squama of all the skulls a broadly based frontal crest has developed … it rises from a point … at about the level of the metopion region. In all cases the ridge is very pronounced but somewhat rounded, Contrary to the condition of modern man; there is no trace of a division into two lips allowing space for a sagittal sinus.”
The frontal crest of WLH 50, as it has been preserved, is shorter than that in adult Ngandong crania, and also projects less and is not a sharp-edged. At its maximum height is at the most anterior point that has been preserved is 8.2 mm. The frontal crest extends posteriorly for about 33 mm, from which point it is followed by sagittal sulcus that develops into a torus up to the position of the coronal suture, which cannot be discerned internally. The low internal torus, which is 14 mm wide, is bordered by shallow pitted grooves on both sides, which are about 13 mm apart at the position of the coronal suture. In WLH 50 a sagittal sulcus with its division into 2 lips begins immediately posterior to the frontal crest 35 mm behind the most anterior part of the crest that remain, or about 68 mm posterior to glabella, though the Ngandong condition lacks a sagittal sulcus posterior to it. The sulcus lips continue posteriorly to the approximate position of the metopion (endometopion), diverging slightly with a plane that is barely diverging between. Posterior to the endometopion position the structure continues to the coronal suture as a low torus about 19 mm in breadth, which is bordered on either side by a pitted sulcus. Most of the pacchionian pits on the surface of the endocranium of the frontal are along these sulci. Asymmetrically expressed meningeal grooves are preserved to about 25 mm superior to the broken edges of the bone, in a very anterior position.
In WLH 50 the anterior of the frontal crest is broken at the frontal sinus so that its lower termination cannot be seen. On the midline a small 6.5 m piece of the anterior face of the sinus remains, about 8.5 mm anterior to the frontmost extent that has been preserved of the frontal crest. A much larger portion of the anterior face of a second sinus is attached to it. Addressing its estimated size, it was noted (Webb, 1989: 41): “the frontal sinus of WLH 50 is larger by any standard and makes a striking contrast to almost all other individuals in the [Willandra] series.” Exposed by the broken internal surface on the left side, the sinus extends laterally from the midline for 34.5 mm, the external wall in its most medial position preserved, about 6 mm lateral to the midline, is 4.7 mm thick.
In WLH 50 neither of the parietal bones is complete. They share a full sagittal edge, with a more or less continuous bone from the coronal to the lambdoidal sutures on the left, except for some patchwork with red wax. On the left side it is complete to the asterion and the parietal notch. Anterior to this there is about 20 mm of the bevel of the parietal for the temporal squama, though, anterior to that, the broken arc border of the remaining bone is superior to this bevel and there is no indication of the temporal border of the parietal that has been preserved. The superior 90 mm of the coronal suture to bregma has remained. The parietal description here is of the left bone unless otherwise noted.
As in the case of the Ngandong crania WLH 50 lacks distinct parietal bosses. The superior temporal line is barely discernible on the surface of the bone from the coronal suture to the area 86 mm posterior where the angular torus (described above) begins. Even where the angular torus is developed most weakly, a superior sulcus follows its superior border, with this sulcus continuous for the full extent of the torus, to the lambdoidal suture which the sulcus follows to a position about 10.5 mm above and behind asterion.
In WLH 50 parietals are notably larger than those of Ngandong, where they can be compared, and slightly more curved in the sagittal plane. A low, broad sagittal keel extends for 57 mm down the anterior half of the parietals of WLH 50; behind it, the surface of the bone angles from where the keel ends and flattens to lambda, together these factors form the slightly elevated curvature index along the superior surface of the parietals. This is much like the condition in Ng 9. For Ngandong the parietal curvature is low (mean of 105.3), which is unchanged from the index in earlier Indonesians from Sangiran (Bapang-AG) and Sambungmachan (Kaifu et al., 2008), and the WLH 50 parietal curvature index (108.9) is almost as low as the Ngandong maximum (108.1). Across the bone transversely (bregma or asterion of to parietal notch), the parietal of WLH 50 is also flattened and the curvature index is within the range for Ngandong and below the Ngandong mean. Along the posterior border curvature also does not differ from the condition in Ngandong.
The 3 sides of WLH 50 that have been preserved define the surface of an irregular triangle, with 3 included angles. The dimensions of the 3 sides for WLH 50 exceed all of the Ngandong crania and the area of the included triangle is 35 % larger (5.9 σ21) than mean values for Ngandong. The difference for the triangle that has been preserved is greatest for the superior surface (bregma-lambda), WLH 50 is 4 σ larger. The WLH 50 parietal is also larger transversely, but not as much so (for bregma-asterion, WLH 50 is 3.3 σ larger). A relatively elongated parietal bone is reflected by the shape difference. The angles of the irregular triangle that are included are similar, in that the values for WLH 50 can be found within the Ngandong range for the angles at bregma and lambda. The WLH 50 angle at asterion is, however, above the Ngandong range, which reflects the comparisons of the triangle sides, above, wherein the WLH 50 bregma-lambda length has the greatest difference from Ngandong specimens. Bregma-asterion is the side opposite the asterion angle in the irregular triangle.
The thickness of the vault varies greatly across the bone. The thickness of the WLH 50 parietal, where comparisons can be made, is exceptional, exceeding the maximum for Ngandong at every measurement point except asterion, where it matches the maximum. Thickness is somewhat less at some places away from the standardised points; such as reaching only 7.7 mm at the posterior lower border of the bone at the superior anterior position remaining on the bevel for the temporal, 30 mm anterior and superior to the parietal notch.
On the Endocranial surface, the sagittal sinus continues behind the coronal suture for more than half the length of the parietal, which corresponds to the external portion of the parietal that is keeled. For that length the sinus is double lipped. There are some details of the impressions of the anterior middle meningeal artery on both of the endocranial sides; where the sides can be compared, the arterial impressions differ. Though the considerable breakage internally, as well as the broken edges of the preserved bone, make discerning of the full pattern of branching and ramifications on either side. The internal position and the course of the lambdoidal suture near it can be seen, but for the most part endocranial portions of the lambdoidal and sagittal sutures are closed and obliterated.
The temporal bones of WLH 50 are preserved only posteriorly and mostly externally; neither the petrous portion nor the anterior squama remains, though on the right side there is posterior squama extending some 36 mm anterior to the parietal notch and 22 mm above it, and, on the left, a 21 mm length of the most posterior aspect of the 14.6 mm tall bevelled surface on the left parietal shows where the posterior temporal squama had been. The internal surface has been sheared away on both sides, to expose the internal pneumatised structure of the mastoid region that is described below. On the left side slightly more of the internal bone remains, the petrous pyramid has also gone here as well. Neither of the temporal bones is complete enough for the length measurements. Whether the temporal bones of WLH 50 show any of the unique temporal bone-related aspects described for Ngandong relative to earlier Indonesians (Kaifu et al, 2008) can be addressed only for the mastoid process and a small part of the region around it.
In WLH 50 the remaining portions of temporal bone are of similar size to the Ngandong specimens where comparisons are possible. Comprised of the rear-most 65 mm of the bone, the left temporal is more complete, which extend to asterion, missing all of the petrous portion, external auditory meatus, or glenoid area. An arc that is formed by the edge of the preserved bone continues from the anterior face of the mastoid, extending along the side of the temporal just below the root of the zygomatic arch to the approximate position of the auricular point which is the most anterior point which has been preserved; and Wolpoff & Lee do not believe it extends as far anteriorly as the anterior rim of the external auditory meatus. There is no evidence that has been preserved that there was a postglenoid process. The bone surface is preserved along this arc externally but not internally. On this side none of the zygomatic root has been preserved. On the right, however, to posterior 41 mm of the supramastoid crest is preserved on the temporal squama, with its most posterior 18 mm above the mastoid notch.
The outer bone surface on the temporal squama has been sheared away at the equivalent position on the left side; however, it appears that the more anterior part of the lower border of the sheared area corresponds to the position of the supramastoid crest on the right side. This reaches the lower border of the bone that has been preserved at the position that has been attributed by Wolpoff & Lee to auricular point; immediately above and actually bordering what maybe the supramastoid crest, the outer bone surface has been sheared or broken away; the surface has been preserved as described above below it. What has remained of the temporal of WLH 50, given its larger cranial capacity, is not especially large. The length of the parietomastoid suture is smaller than any Ngandong specimen. The distance from the approximate position of the auricular point to asterion of 58 mm, at the back of the bone, is only slightly larger than the 57.2 mm Ngandong mean. In another comparison the distance from the front edge of the mastoid process at its base to the most anterior point that has been preserved where Wolpoff & Lee believe the auricular point lies in WLH 50 is about 20 mm; The equivalent distance measured to the auricular point on Ng 5 is 17 mm.
On the left side most of the mastoid process remains; it is short and triangular. In WLH 50 the process is more narrowed anterior-posteriorly and more pointed than the mastoids on the Ngandong sample. In general, where there is considerable variation in the anatomy of the lateral mastoid face at Ngandong, The left mastoid of WLH 50 resembles most clearly the left side of Ng 10. The external of the WLH 50 structure is, however, curved and cants medially to a slight degree, though it is basically oriented vertically. The external face in all of the Ngandong mastoids the external face is more curved and cants even more strongly medially, as seen from the rear. A low mastoid crest extends down the middle of the external surface of the mastoid in WLH 50; and as described below it is formed by the superior branch of the Nuchal ridge.
There is a short portion of the posterior aspect of the digastric sulcus that remains, which defines the medial and posterior borders of the mastoid process. As it is preserved, the mastoid process projects about 5.5 mm inferior to the floor of the digastric sulcus, though this is not a true value, as it appears there is an unknown portion of the tip of the mastoid missing. Measurements to mastoidale have not been reported, as the correct position of this point is not clear. This portion is shallow and broad, definitely broader than in any of the Ngandong specimens, but the angulation of the sulcus relative to the cranial midline is close to the same as in the Ngandong specimens that preserve it. For the posterior portion that has been preserved, a low and narrow ridge, the lateral juxtamastoid, borders it medially. More medially, no cortical surface has been preserved. The pneumatisation is extensive. It has been described (Webb, 1989: 41) “it extends posteriorly to the occipitomastoid border, superiorly to the parietal notch and anteriorly above the supramastoid crest. The cells themselves are uniformly large, the largest being 13.9 mm at its greatest diameter. Medial portions of the mastoid region are missing, making any comment about their spread in this direction impossible. It is likely, however, that the extent of pneumatisation in this direction was commensurate with that observed in other robust individuals.”
The occipital bone of WLH 50 is only partially preserved. Almost the entire occipital plane has been preserved, but of the nuchal plane only small portions have been preserved, much of which is incomplete or broken, and as has been noted above, the outer bone table has been destroyed by erosion, as well as an unknown amount of diplöe across the nuchal torus. Though the bone is large it is comparatively narrow, relative to the occipitals of Ngandong the sample. Biasterionic breadth is less than all the Ngandong males, and only Ng 6 is smaller. In WLH 50 distances from lambda to inion or asterion are on average about 10 % greater that the Ngandong mean, though the distance from lambda to the lowest inion position is markedly larger, which reflects the significant downward turn of the superior nuchal lines at the midline to form a prominent tuberculum linearum. At lambda there are no extrasutural bones, but some large ossicles are incorporated in the lambdoidal suture.
The vertical face is formed by the bulge below lambda that extends through the upper portion of the occipital plane that helps form the vertical surface that is 29 mm tall which reaches the superior edge of a tall, elliptically rounded suprainiac fossa, forms the vertical face. There is a similar bulge on most Ngandong crania, but the surface below it, is outwardly angled, though straight. The suprainiac fossa in WLH 50 is 35 mm wide, and extends for 19 mm above the supreme nuchal line, and at its deepest just above its inferior border (the supreme nuchal line). The supratoral depression that extends along the supreme nuchal line is, in fact, limited to the base of the suprainiac fossa and differs from the condition in Ngandong in not extending across the entire width of the bone. It also differs from most of the Ngandong crania in that this depression dips inferiorly (with the supreme nuchal line) at the midline (22). The suprainiac fossa is larger and more distinct in WLH 50 than any Ngandong specimen, though Ng 9 is similar and smaller fossae are present in Ng 6 and Ng 11. The WLH 50 fossae are similar to the condition in Neanderthal (Caspari, 2005, and contra Trinkhaus, 2004) in that they appear as an elliptical, flattened and a surface that is somewhat concave above the superior nuchal line, transversely elongated, with a rough, pocked surface. These similarities are shared with WLH 50. Lateral to the suprainiac fossa on the left side which is better preserved, a supratoral sulcus continues to border the superior surface of the nuchal torus, continuing to the position where the supreme and superior nuchal lines converge to almost meet. This is 46 mm from the midline of the occiput, as measured along the bone surface.
As has been noted, the external surface of the nuchal torus has been eroded between the distinct superior and supreme nuchal lines, and at first glance some of the similarities with nuchal tori in the Ngandong remains are obscured. As a result it is inaccurate to determine the thickness of the torus or the length of the arc to inion that includes the distance over the torus. Though even comparisons of the WLH 50 cranium that had thickness dimensions that were incomplete that were preserved on the remaining bone to Ngandong or the Herto cranium strongly suggest the full thickness in this region would have been quite exceptional.
The nuchal torus on WLH 50 does not extend the full width of the occiput, though it is quite large. The torus covers the middle 70 mm of the bone and at the midline it is at its significantly tallest because of the tuberculum linearum that is vertically prominent. It is not known what its full extension away from the bone was as a result of the erosion, as noted, but the large downwards pointing triangle of the tuberculum linearum almost doubles vertical height of the torus at the midline, and the torus is vertically taller than any of the Ngandong crania, to a considerable degree. The remaining parts of the WLH 50 nuchal torus appears much like Ng 5, though markedly larger. The torus and the tuberculum are vertically taller in WLH 50 than in any Ngandong specimen.
Part of the posterior aspect of the nuchal plane is all that is preserved including its lateral border up to the mastoid on the left side. Lateral to the nuchal torus, the supreme and superior nuchal lines converge though don’t quite meet. They delineate what is described by Wolpoff & Lee as a nuchal ridge (or much smaller torus) just below 6 mm in height, i.e. the lines are about 6 mm apart, those arcs laterally from the nuchal torus across the occipitomastoid suture on the temporal 14.7 mm inferior to asterion on the left. The retromastoid process that is described and illustrated by Weidenreich for the Ngandong crania is not present on WLH 50. Wolpoff & Lee suggest that if there had been one on WLH 50 it would have been on the nuchal ridge they described here, most probably at or close to the bifurcation point.
The elements combine to obscure some details in this region or make them difficult to define:
1) The condition of the surface of the bone,
2) A significant break that has repaired, and
3) The loss of most of the nuchal surface.
Nuchal ridge on the occipital is the attachment area for a large splenius capitis and more laterally, a sternocleidomastoid. The nuchal ridge appears to bifurcate on the occipital, 4.6 mm posterior to the occipitomastoid suture. Almost at this point the 12 mm segment of the linea obliquus that remains extends anteromedially as the lateral border of the semispinalis capitis insertion.
The superior branch of the nuchal ridge on the lateral occipital continues onto the mastoid process and, turning inferiorly, becomes the mastoid crest, as has been described above. The inferior branch travels 24 mm in a parasagittal direction to the broken edge of the nuchal plane. Wolpoff & Lee believe, though key portions of the region are missing, that its anatomy would have resembled most closely the anatomy of Ng 11 (23, and that is the inferior branch had been preserved, it would have extended to form a medial juxtamastoid process. None of the medial juxtamastoid process was preserved with the exception of the 9 most anterior millimetres preserved of the inferior branch that becomes markedly taller and more crest-like.
Medial to the mastoid process, a small portion of the lateral juxtamastoid appears to remain, again assuming an anatomy that is similar to Ng 11, separated from the mastoid by a shallow digastric groove. Therefore, as reconstructed by Wolpoff & Lee the region, including its missing portions, there were both medial and lateral juxtamastoid processes divided by an occipital groove on the left side of the cranial base of WLH 50 .
A part of an assorted cheek bone was recovered, most of a large zygomatic bone fragment with a bone thickness of 14 mm at the base of the zygomaxillary suture, and a maximum thickness of the masseter attachment on the lower border of the bone of 12 mm. This is an exceptional thickness, greater than other Australian fossils generally (24) – only robust australopithecines have bones that are thicker in this region. A linear dimension comparative data is known for is the breadth of frontal pillar, the minimum distance from the orbital rim to the posterior of the zygomatic column, just above the jugale position. This dimension is larger than in any recent human that has been observed and in the Late Pleistocene it is matched only by the large Klasies 16651 partial zygomatic. Among earlier remains, WLH 50 is matched by the KNM-ER 3733 zygomatic dimension, and exceeded by archaic specimens such as Kabwe and Sangiran 10 and 17, and greatly so by OH 5. Sangiran 17, a specimen with an exceptionally broad face and large cheeks, has the largest earlier zygomatic bone from the region. The Sangiran male has a broader frontal pillar, but the thicknesses are slightly less than WLH 50.
In an unusual anatomy, there are 2 ridges paralleling the zygomaxillary suture, one above it and the other below.
Wolpoff & Lee describe as foolhardy the idea of reconstructing from this information about part of a zygomatic bone, though WLH 50 clearly had a large cheek, one of the largest known from the Late Pleistocene, with masseter muscles providing significant masticatory strength. As previously noted, powerful mastication might contribute to the cranial vault thickness of the specimens.
|Author: M.H.Monroe Email: email@example.com Sources & Further reading|