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ar22648-sup-0001-suppfig1.tif1705KSupplemental Fig. 1: A) Newborn skull of a human, showing a precocious and complete postorbital septum, produced by sheets of the zygomatic and alisphenoid (a) that form extensive sutural contacts with one another, as well as zygomatic contact with the frontal (fr). The zygomatic of humans and other anthropoids forms a large postorbital lamina that virtually completes separation of the orbit and temporal fossa. B) In adult tarsiers (based on AMNH # 106649), tilted in this view to help visualize the orbital fossa, the extent of postorbital closure is far less and restricted to the upper part of the framework. The small postorbital lamina of the zygomatic develops late, as the eyeball becomes ectopic, but it still leaves a relatively wide open confluence between the orbit and the temporal fossa behind it.
ar22648-sup-0002-suppfig2.tif6016KSupplemental Figure 2: Lateral views of the skull of A) late fetal Propithecus verrauxi; B) newborn Microcebus murinus; C) 0-day-old Tarsius syrichta; D) newborn Cebuella pygmaea.
ar22648-sup-0003-suppfig3.tif10705KSupplemental Figure 3: High magnification view of the postorbital membrane in Tarsius syrichta at late fetal (A), 0-day-old (B) and 6-day-old (C, D) ages. Gomori trichrome is used in Figs. A-D, and stains collagen green. At all ages, the collagen is organized in one direction, following the long axis of POM. Note the collagen is more dense, arranged in bundles, in the 6-day-old (C, D). Many of the cell nuclei are narrow, a fibroblast-like appearance. However, some cells have a chondrocyte-like appearance (D, small arrow). The Verhoeff's hematoxylin prodedure was employed to detect elastic fibers in the POM (E, 6-day-old). In a positive control section of the same specimen that included auricular cartilage (AC, F), dense black elastic matrix is clear. In the POM (E), little or no elastic fiber content is indicated. Stains: A-D, Gomori trichrome; E,F, Verhoeff's hematoxylin. Scale bars: A-C, E, 30 μm; D, 20 μm; F, 100 μm.
ar22648-sup-0004-suppfig4.tif9841KSupplemental Figure 4: Zygomaticofrontal suture (black arrow) in perinatal squirrel monkeys. A) A lateral view of the ZFS in a perinatal Saimiri boliviensis, showing the fully articulated zygomatic (z) and frontal (fr) bones. Also note the gap at anterolateral fontanelle (alf) posterior to the ZFS. B) Posterior view of the skull, which is coronally cut to show the anterior poart of the ZFS. C) A coronal section of the ZFS at a similar levels as shown in S4B. D) Magnified view of the boxed region of S4C, showing a magnified view of the suture stained with Gomori trichrome (green fibers = collagen). Note the middle zone of the suture is a mix of loose fibers and blood vessels (bv). On either side of the vascular middle zone is the capsular (caps) layer of connective tissue that surrounds each sutural front. E) A high magnification of the middle zone, showing loose connective tissue (co, collagen fibers) and blood vessels (bv). The ZF suture is structurally typical for the age. It resembles the “early growing stage” of sutures described by Pritchard et al. (1956). In particular, the “loose cellular middle zone” defines this stage of developmental, although the vascularity bears some indications of later growth stages described by Pritchard et al. (1956). Stains: C-E, Gomori trichrome. Scale bars: A,B, 1 mm; C, 0.5 mm; D, 100 μm; E, 30 μm.
ar22648-sup-0005-suppfig5.tif13448KSupplemental Figure 5: Zygomaticofrontal articulation in fetal Saguinus geoffroyi (A, B) and Alouatta seniculus (C-E). In the fetal tamarin, no suture is established. The periorbita is highly cellular, and the Verhoeff preparation indicates the presence of some elastic fibers (B). In the 81.49 CRL Alouatta fetus, the suture is at an early stage of development. The capsular layers (periostea of the bone fronts) are visible but not heavily fibrous (D). This suture resembles the “Stage of meeting of the bone territories” for facial sutures described by Pritchard et al. (1956).The middle zone is densely cellular with a sparse and random array of collagen (co) fibers (E). Anterior (F) and posterior (G) to the region indicated in S5C, the zygomatic (z) and frontal (fr) bones are slightly more separated, and the region between is similarly a loose connective tissue (H, enlargement of boxed area of S5F; I, enlargement of boxed area of S5G). ob, osteoblasts; z, zygomatic. Stains: A,B, Verhoeff's hematoxylin; C, D, hematoxylin and eosin; E-I, Gomori trichrome. Scale bars: A,C, 0.5 mm; B, E, H, I, 20 μm; D, 50 μm; F 250 μm, ; G, 300 μm.

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