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A new genus and a new species of hadrosaurid dinosaur (duckbill) were identified from bone discovered six years ago in Japan.
Reconstruction of the life of Kamuysaurus japonicus with a mosasaur carcass (Phosphorosaurus ponpetelegans), a sea turtle (Mesodermochelys waves) and ammonoid shells (Compressed patagiosites and Gaudryceras hobetsense) and bivalves (Nannonavis elongatus) on the beach. Image credit: Kobayashi et al, doi: 10.1038 / s41598-019-48607-1.
The newly identified dinosaur named Kamuysaurus japonicus, lived about 72 million years ago (Cretaceous period).
It belongs to the family Hadrosauridae, one of the most successful herbivorous dinosaur groups of the Late Cretaceous era.
The fossil remains of these dinosaurs are common in the highest Cretaceous deposits of the supercontinent Laurasia (North America, Asia and Europe) and in some areas of the Gondwana Supercontinent (South America and Antarctica).
The almost complete skeleton of Kamuysaurus japonicus was found in the outer deposits of the Late Cretaceous Hakobuchi Formation in the Hobetsu region of Mukawa City, Hokkaido, in 2013.
This is the first medium to large dinosaur skeleton almost complete from Japan.
An almost complete skeleton of Kamuysaurus japonicus. Image credit: Hobetsu Musem / Hokkaido University Museum.
The specimen was analyzed by paleontologists from Japan, the United States and Mongolia who concluded that the dinosaur belonged to the Hadrosaurid clade Edmontosaurini and was closely related to other hadrosaurids of the Far East, such as Laiyangosaurus from China and Kerberosaurus Siberian.
"It was an adult aged 9 years or older, 8 meters long and weighing 4 or 5.3 tons – depending on whether it was walking on two or four feet respectively – when 39; he was alive, "said the main author, Professor Yoshitsugu. Kobayashi from the Museum of Hokkaido University and his colleagues.
The researchers also identified a number of unique features, including a small crest on the skull and a short row of neural spines pointing to the front.
"We found that Kamuysaurus japonicus presents three unique characteristics that do not share the other dinosaurs of the Edmontosaurini clade: the low position of the cranial notch, the short ascending process of the jaw bone and the anterior inclination of the neural spines of the dorsal vertebrae from the sixth to the twelfth, "they explained.
Carcass of Kamuysaurus japonicus, floating in the sea, with two mosasaurs (Mosasaurus hobetsuensis), two sea turtles (Mesodermochelys waves) and four ammonoids (Pachydiscus japonicus). Image credit: Kobayashi et al, doi: 10.1038 / s41598-019-48607-1.
According to the team, the discovery of Kamuysaurus japonicus in an environment of marine influence is rare for hadrosaurids and contributes to the understanding of their diversity in these environments.
"It is possible that the ancestors of the Hadrosauridae family and its subfamilies, Hadrosaurinae and Lambeosaurinae, preferred to live in areas close to the ocean, suggesting that the coastal environment was an important factor. the diversification of hadrosaurids during its early evolution, particularly in the north. America, "said the scientists.
The discovery is reported in a newspaper article Scientific reports.
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Yoshitsugu Kobayashi et al. 2019. A new Hadrosaurine (Dinosauria: Hadrosauridae) from the marine deposits of the Upper Cretaceous Hakobuchi Formation, Yezo Group, Japan. Scientific reports 9, article number: 12389; doi: 10.1038 / s41598-019-48607-1
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