. The Deseado formation of Patagonia . outer face, making this genus morespecialized in this respect than any of the other tyi^ upper molars have the deep inner inflexion bifurcated,which makes the tooth three-lobed, a character whichgrows more marked the older the individual is. The pre-maxillae are high and bring the snout well forward. Thenasals are lacking, but the bounding bones show them to EUTRACHYTHERUS 11 have been unusually broad and flat. The maxilla extendsup to the nasals, and bounds the lower border of the orbit,and projects backward in a heavy overhanging zygomaticpro
. The Deseado formation of Patagonia . outer face, making this genus morespecialized in this respect than any of the other tyi^ upper molars have the deep inner inflexion bifurcated,which makes the tooth three-lobed, a character whichgrows more marked the older the individual is. The pre-maxillae are high and bring the snout well forward. Thenasals are lacking, but the bounding bones show them to EUTRACHYTHERUS 11 have been unusually broad and flat. The maxilla extendsup to the nasals, and bounds the lower border of the orbit,and projects backward in a heavy overhanging zygomaticprocess. The lachrymal bone is large externally, with alarge but low lachrymal tubercle just below which isfound the lachrymal duct, opening just in front of themargin of the orbit. The frontals are short and wide,extending outward over the orl)it in a strong postorbitalprocess which bounds half of the rear of the orbit. Theparietals, meeting medianly, rise in a strong sagittal the back part of the cranium is Fig. 46. E. spegazziiiiauus—i/j natural size. From another specimen, which contained the brain cast,it is clear that the bulla was much inflated and hollow, andthat there was an inflation in the upper part of the squa-mosum, as in Prosothermm, etc. One specimen with the facial portion badly weathered,but retaining enough to identify the species as E. spegaz-zinianus, preserved the brain case, so that it could beprepared out. The most striking feature of this brain is its relati\elylarge size, E. spegazzinianiis being an animal about thesize of a sheep, and the brain is as large as that of thesheep, which is in strong contrast to what would be ex-pected of an Oligocene form. Compared with the hcrbiv- 78 THE DESEADO FORMATION OF PATAGONIA orous Oligocene oreodont, Eucrotaphus, an animal ofapproximately the same size, this brain is half again aslarge in every way. A second striking feature is the shortcompact character of the brain, the forebrain
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Keywords: ., bookcentury1900, bookdecade1910, bookpub, booksubjectpaleontology
