2024-07-09 ノースカロライナ州立大学(NCState)
<関連情報>
- https://news.ncsu.edu/2024/07/life-underground-suited-new-dinosaur-fine/
- https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25505
- https://www.nature.com/articles/s41598-023-45658-3
ユタ州シーダーマウンテン層ムセンチュチット層から発見された半化石型の新種恐竜 A new semi-fossorial thescelosaurine dinosaur from the Cenomanian-age Mussentuchit Member of the Cedar Mountain Formation, Utah
Haviv M. Avrahami, Peter J. Makovicky, Ryan T. Tucker, Lindsay E. Zanno
The Anatomical Record Published: 09 July 2024
DOI:https://doi.org/10.1002/ar.25505
Abstract
Thescelosaurines are a group of early diverging, ornithischian dinosaurs notable for their conservative bauplans and mosaic of primitive features. Although abundant within the latest Cretaceous ecosystems of North America, their record is poor to absent in earlier assemblages, leaving a large gap in our understanding of their evolution, origins, and ecological roles. Here we report a new small bodied thescelosaurine—Fona herzogae gen. et sp. nov.—from the Mussentuchit Member of the Cedar Mountain Formation, Utah, USA. Fona herzogae is represented by multiple individuals, representing one of the most comprehensive skeletal assemblages of a small bodied, early diverging ornithischian described from North America to date. Phylogenetic analysis recovers Fona as the earliest member of Thescelosaurinae, minimally containing Oryctodromeus, and all three species of Thescelosaurus, revealing the clade was well-established in North America by as early as the Cenomanian, and distinct from, yet continental cohabitants with, their sister clade, Orodrominae. To date, orodromines and thescelosaurines have not been found together within a single North American ecosystem, suggesting different habitat preferences or competitive exclusion. Osteological observations reveal extensive intraspecific variation across cranial and postcranial elements, and a number of anatomical similarities with Oryctodromeus, suggesting a shared semi-fossorial lifestyle.
白亜紀後期のテスケロサウルス・ネグレクトス(新石器時代:テスケロサウルス科)の神経解剖学的特徴から、恐竜界における新たな生態学的特殊性が明らかになった Neuroanatomy of the late Cretaceous Thescelosaurus neglectus (Neornithischia: Thescelosauridae) reveals novel ecological specialisations within Dinosauria
David J. Button & Lindsay E. Zanno
Scientific Reports Published:06 November 2023
DOI:https://doi.org/10.1038/s41598-023-45658-3
Abstract
Ornithischian dinosaurs exhibited a diversity of ecologies, locomotory modes, and social structures, making them an ideal clade in which to study the evolution of neuroanatomy and behaviour. Here, we present a 3D digital reconstruction of the endocranial spaces of the latest Cretaceous neornithischian Thescelosaurus neglectus, in order to interpret the neuroanatomy and paleobiology of one of the last surviving non-avian dinosaurs. Results demonstrate that the brain of Thescelosaurus was relatively small compared to most other neornithischians, instead suggesting cognitive capabilities within the range of extant reptiles. Other traits include a narrow hearing range, with limited ability to distinguish high frequencies, paired with unusually well-developed olfactory lobes and anterior semicircular canals, indicating acute olfaction and vestibular sensitivity. This character combination, in conjunction with features of the postcranial anatomy, is consistent with specializations for burrowing behaviours in the clade, as evidenced by trace and skeletal fossil evidence in earlier-diverging thescelosaurids, although whether they reflect ecological adaptations or phylogenetic inheritance in T. neglectus itself is unclear. Nonetheless, our results provide the first evidence of neurological specializations to burrowing identified within Ornithischia, and non-avian dinosaurs more generally, expanding the range of ecological adaptations recognized within this major clade.
