Paleontologists have announced the discovery of a new genus and species of troodontid theropod dinosaur based on fossils discovered in Japan.
Hypnovenator Pinus variegatus They roamed the Earth during the Early Cretaceous Period, between 112 million and 106 million years ago.
The new dinosaur TroodontidaeA group of bird-like theropods including species ranging in size from kiwi to rhea.
“The Troodontidae are a family of small, slender theropod dinosaurs,” Dr. Katsuhiro KubotaPaleontologists and colleagues from the University of Hyogo, the Museum of Nature and Human Sciences, and the Hokkaido University Museum.
“The phylogenetic position of Troodontidae has traditionally been considered to be a clade together with Dromaeosauridae that forms the Deinonychosauridae, but Troodontidae has also been considered as a sister clade to Avialidae.”
“Anchiornis from the Late Jurassic of China has questionable phylogeny and is classified as either a troodontid or aves.”
“These lively discussions will greatly improve our understanding of the phylogeny and osteology of non-avian theropods, with major implications for our understanding of early bird evolution.”
“Since the discovery of the first troodontids Troodon Troodontid fossils have been found in the Late Cretaceous of Canada, and in the Middle Jurassic and Late Cretaceous of Asia, Europe, and North America.
“However, articulated troodontid specimens are extremely rare.”
Articulated skull Hypnovenator Pinus variegatus It was discovered in deposits in the lower Mt. Oyama layer in Tanba Sasayama City, Hyogo Prefecture.
“In September 2010, during construction work on a park in Nishikosa, Tanba Sasayama City, rocks in the Lower Oyama Formation were crushed and a partial theropod skeleton, including forelimbs and knees, was discovered,” the paleontologists explained.
“The discovery was made by Kaoru Matsubara and Ryuji Oe of the amateur group 'Sasayama Group Research Association.'”
“In July 2011, an articulated theropod heel was discovered at the same site during an excavation carried out by the Hyogo Prefectural Museum of Nature and Human Sciences.”
These specimens are the only troodontid dinosaurs identified in Japan.
“Our position on phylogenetic analysis is Hypnovenator Pinus variegatus It is one of the oldest and most basal troodontids. Gobivenator mongoliensis” the researchers said.
“This discovery suggests that small maniraptorid dinosaurs in sleeping positions were common in fluvial systems as well as volcanic, aeolian and alluvial environments.”
“The geometric morphometric analysis of the claw phalanges shows that claw phalanges I and III are Hypnovenator Pinus variegatus They show considerable morphological variation but are functionally similar, reflecting a shift in manual action within troodontids that differs from that seen in non-troodontid troodontids.”
“Hypnovenator Pinus variegatus “The foot also displays a mosaic of running-related features,” the researchers added.
“This study reveals that asymmetric arc metatarsals appeared by the Albian, and morphological changes such as a shorter digit IV than digit III, a non-clawed phalange of digit III with a roller joint, and a weak gingival joint of digit IV occurred in the Early Late Cretaceous.”
This discovery paper In the journal Scientific Reports.
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Kenichi Kubota others2024. An Early Cretaceous troodontid (Dinosauria: Theropoda) from the Oyamashita Formation in Japan sheds light on the early evolution of Troodontidae. Scientific Reports 14, 16392; doi: 10.1038/s41598-024-66815-2
Source: www.sci.news
