LATE CRETACEOUS NON-MARINE GASTROPODA FROM THE DINOSAUR EGG-BEARING STRATA OF XIXIA BASIN,HENAN
Notice bibliographique
Résumé
The Xixia Basin of Henan Province is covered with a set of deep brown and maroon continental clastic sediments,containing plenty of dinosaur eggs.Upwards the thick covering strata is divided into Gaogou Formation,Majiacun Formation and Sigou Formation.In 2006 the authors collected some gastropod specimens in the neighborhood of Fanying Village and Ligou Village.Here we describe five among them.Gastropod fossils of Bithynia cf.elongata Martinson,Pyrgulifera sp.,Physa sp.and Gyraulus sp.preserved in green lenticular mudstone and red silstone(Bed 9) were found in the lower part of the Gaogou Formation near Fayying,while Mesolanistes efremovi(Martinson) and Gyraulus sp.were from the Majiacun Formation near Ligou,which were also preserved in green lenticular mudstone(Bed 24).Mesolanistes was established by Yen Teng-Chien in 1945 based on a specimen from Upper Cretaceous(Upper Kaiparowits Formation) of Southwestern Utah,United States,type species:Mesolanistes cretaceus Yen,it is considered as Maastrichtian stage(Yen,1945).Mesolanistes is also widely distributed in Upper Milk River Formation of Western Alberta,Canada(Ressell,1929),Nemeget Formation(Maastrichtian stage) of Nemeget Basin of Mongolia(Martinson,1961) and Late Cretaceous strata of China except a few species of this genus found from the Low Cretaceous in China(Pan,1980).In geological distribution,as we known so far,there are two Mesolanistes-bearing beds:one is in lower Late Cretaceous;the other is in upper Late Cretaceous.The former includes the Nenjiang Formation in Songliao Basin,Northeastern China and the Upper Milk River Formation in West Alberta,Canada(Ressell,1929),while the latter includes the Upper Kaiparowits Formation in Utah of U.S.A.,the Nemeget Formation in Nemeget Basin,Mongolia,the Honglishan Formation in Junggar Basin,Xinjiang,the Sifangtai Formation in the Songliao Basin,the Taizhou Formation in North Jiangsu;the Mankuanhe Formation in Yunnan and the Zhenshui Member of Nanxiong Formation in Nanxiong Basin,Guangdong.A specimen from the Majiacun Formation is identified as conspecific with Mesolanistes efrempvi(Martinson) from the Nemeget Formation and the Honglishan Formation because of their similar size,shell and some other features.Also,Bithy-nia cf.elongata Martinson from the Gaogou Formation is very similar to Bithynia elongata Martinson in size and shell shape,which was also found in the Nemeget Formation.Therefore,the gastropod fauna from Xixia Basin is closely comparable to those from the Nemeget Formation and the Honglishan Formation,which is generally considered to be of Santonian—Maastrichitian stage.The gastropod fauna is associated with bivalves,ostracoda and charophyta.Modern ecologists suggest that,in addition to the depth and turbidity of water,the types of sediments,and the stability of substrata,the stability of environment are the key factors in establishing a diverse population.Sandstone,conglomerate,gravel,and torrent occurring in Xixia Basin are all disadvantages for gastropod faunas to live.But in fact,we did discover plenty of dinosaur eggs in Xixia Basin.That is why it is so important to us in studying palaeogeography,palaeoenviroment and palaeoclimate of China and North Asia.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».