where is the zygomatic arch and how do you locate it
Zygomatic arch The zygomatic arch, or cheek bone, is formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygomatic bone (the side of the cheekbone), the two being united by an oblique suture (zygomaticotemporal suture);[1] the tendon of the temporalis passes medial to the arch to gain insertion into the coronoid process of the mandible. The jugal point is the point at the anterior end of the upper border of the zygomatic arch where the masseteric and maxillary edges meet at an angle. The jugal point is the anterior end of upper border of the zygomatic arch where it meets the process of the zygomatic bone.
Oldest dated rocks The oldest material of terrestrial origin that has been dated is a zircon mineral of 4.404 ±0.008 Ga enclosed in a metamorphosed sandstone conglomerate in the Jack Hills of the Narryer Gneiss Terrane of Western Australia.[4] The 4.404 ±0.008 Ga zircon is a slight outlier, with the oldest consistently-dated zircon falling closer to 4.35 Ga.[5] This zircon is part of a population of zircons within the metamorphosed conglomerate, which is believed to have been deposited about 3.060 Ga, which is the age of the youngest detrital zircon in the rock. Recent developments in atom-probe tomography have led to a further constraint on the age of the oldest continental zircon, with the most recent age quoted as 4.374 Ga ±0.006.[6]