The oviraptorosaurian theropod Caenagnathasia was first described from the Late Cretaceous (Turon... more The oviraptorosaurian theropod Caenagnathasia was first described from the Late Cretaceous (Turonian) vertebrate assemblage from the Bissekty Formation of the Kyzylkum Desert, Uzbekistan. Here we report a partial pair of oviraptorosaurian fused lower jaws, comprising the symphysial region, from the Upper Cretaceous (Campanian) Iren Dabasu Formation of Nei Mongol, China. This mandibular fragment can be referred to Caenagnathasia based on the following shared characters: dentaries fully fused, symphysial portion of dentary not downturned, anterior part of dorsal margin of dentary broadly concave in lateral view, lingual ridge present at margin of occlusal surface on each dentary, lingual ridge bears apical projection, vascular grooves and associated foramina do not extend to dorsal surface of symphysis, and anterior occlusal groove present. This new specimen extends the temporal and geographic range of Caenagnathasia to the Campanian of China.
Brain endocasts are rare in the fossil record because they are only preserved under exceptional c... more Brain endocasts are rare in the fossil record because they are only preserved under exceptional conditions. An equid brain endocast from the early Pleistocene of Wanrong County, Shanxi Province, China, is reported in this paper. Measuring approximately 140 × 95.2 × 83 mm, the new specimen represents a relatively advanced adult horse brain. Comparisons indicate that it is more derived than those of Hyracotherium and Mesohippus in having an expanded neocortex, and more than those of Pliohippus and Hipparion in having an enlarged network of branching sulci; in most characters involving these sulci, the Shanxi brain conforms to the extant species Equus caballus. The sulcus diagonalis of the Equus brain appears to have evolved conservatively during the early Pleistocene, whereas the sulcus suprasylvius seems to have evolved rapidly. The specimen demonstrates that the development of a high degree of complexity predates the enlargement of the brain in the horse, which increased in length, breadth, and especially height during the late Cenozoic.
The oviraptorosaurian theropod Caenagnathasia was first described from the Late Cretaceous (Turon... more The oviraptorosaurian theropod Caenagnathasia was first described from the Late Cretaceous (Turonian) vertebrate assemblage from the Bissekty Formation of the Kyzylkum Desert, Uzbekistan. Here we report a partial pair of oviraptorosaurian fused lower jaws, comprising the symphysial region, from the Upper Cretaceous (Campanian) Iren Dabasu Formation of Nei Mongol, China. This mandibular fragment can be referred to Caenagnathasia based on the following shared characters: dentaries fully fused, symphysial portion of dentary not downturned, anterior part of dorsal margin of dentary broadly concave in lateral view, lingual ridge present at margin of occlusal surface on each dentary, lingual ridge bears apical projection, vascular grooves and associated foramina do not extend to dorsal surface of symphysis, and anterior occlusal groove present. This new specimen extends the temporal and geographic range of Caenagnathasia to the Campanian of China.
Brain endocasts are rare in the fossil record because they are only preserved under exceptional c... more Brain endocasts are rare in the fossil record because they are only preserved under exceptional conditions. An equid brain endocast from the early Pleistocene of Wanrong County, Shanxi Province, China, is reported in this paper. Measuring approximately 140 × 95.2 × 83 mm, the new specimen represents a relatively advanced adult horse brain. Comparisons indicate that it is more derived than those of Hyracotherium and Mesohippus in having an expanded neocortex, and more than those of Pliohippus and Hipparion in having an enlarged network of branching sulci; in most characters involving these sulci, the Shanxi brain conforms to the extant species Equus caballus. The sulcus diagonalis of the Equus brain appears to have evolved conservatively during the early Pleistocene, whereas the sulcus suprasylvius seems to have evolved rapidly. The specimen demonstrates that the development of a high degree of complexity predates the enlargement of the brain in the horse, which increased in length, breadth, and especially height during the late Cenozoic.
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endocast from the early Pleistocene of Wanrong County, Shanxi Province, China, is reported in this paper. Measuring
approximately 140 × 95.2 × 83 mm, the new specimen represents a relatively advanced adult horse brain. Comparisons
indicate that it is more derived than those of Hyracotherium and Mesohippus in having an expanded neocortex, and more
than those of Pliohippus and Hipparion in having an enlarged network of branching sulci; in most characters involving
these sulci, the Shanxi brain conforms to the extant species Equus caballus. The sulcus diagonalis of the Equus brain appears
to have evolved conservatively during the early Pleistocene, whereas the sulcus suprasylvius seems to have evolved
rapidly. The specimen demonstrates that the development of a high degree of complexity predates the enlargement of the
brain in the horse, which increased in length, breadth, and especially height during the late Cenozoic.
endocast from the early Pleistocene of Wanrong County, Shanxi Province, China, is reported in this paper. Measuring
approximately 140 × 95.2 × 83 mm, the new specimen represents a relatively advanced adult horse brain. Comparisons
indicate that it is more derived than those of Hyracotherium and Mesohippus in having an expanded neocortex, and more
than those of Pliohippus and Hipparion in having an enlarged network of branching sulci; in most characters involving
these sulci, the Shanxi brain conforms to the extant species Equus caballus. The sulcus diagonalis of the Equus brain appears
to have evolved conservatively during the early Pleistocene, whereas the sulcus suprasylvius seems to have evolved
rapidly. The specimen demonstrates that the development of a high degree of complexity predates the enlargement of the
brain in the horse, which increased in length, breadth, and especially height during the late Cenozoic.