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Wyszukujesz frazę "Chamberlain, K." wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
A U/Pb age for the Mygatt-Moore Quarry, Upper Jurassic Morrison Formation, Mesa County, Colorado
Autorzy:
Trujillo, K.
Foster, J.
Hunt-Foster, R.
Chamberlain, K.
Powiązania:
https://bibliotekanauki.pl/articles/2077340.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Morrison Formation
U-Pb dating
CA-TIMS
dinosaurs
North American Jurassic
Formacja Morrisona
dinozaury
Opis:
Mygatt-Moore Quarry in the Brushy Basin Member of the Upper Jurassic Morrison Formation is one of the more important large dinosaur quarries in the formation, yielding fossils of sauropod dinosaurs including Apatosaurus, Camarasaurus, and an indeterminate diplodocine (cf. Diplodocus or Barosaurus), the theropod dinosaurs Allosaurus and Ceratosaurus, and the ornithischians Othnielosaurus and Mymoorapelta. Fossil wood and carbonized plants are known from the deposit, and carbonized dinosaur skin has also been discovered. We report here on a new U/Pb radiometric age for the Mygatt-Moore Quarry, from a smectitic mudstone collected at the quarry horizon. We isolated zircons using an ultrasonic separation technique and standard heavy liquid and magnetic methods, analyzed single zircons using a chemical abrasion method (CA-TIMS). The age determined for this dinosaur quarry, 152.18 ±0.29 Ma, places the quarry at the boundary between the Kimmeridgian and Tithonian stages of the Late Jurassic Period. This age can now be used to place the quarry into stratigraphic position with respect to other dated horizons in the Morrison Formation and other rock units worldwide. We will also use this age along with other ages to create a radiometrically based stratigraphic framework for the Morrison Formation.
Źródło:
Volumina Jurassica; 2014, 12, 2; 107--114
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A morganucodontan mammalia form from the Upper Jurassic Morrison Formation, Utah, USA
Autorzy:
Davis, Brian M.
Jäger, Kai R.K.
Rougier, Guillermo W.
Trujillo, Kelli
Chamberlain, Kevin
Powiązania:
https://bibliotekanauki.pl/articles/2216314.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Mammalia
Morganucodonta
dentition
Jurassic
Morrison Formation
Opis:
We describe two skull fragments of a new morganucodontan from the Cisco Mammal Quarry (Upper Jurassic Morrison Formation), preserving portions of the palate and snout in excellent 3D detail as well as the complete upper postcanine dentition. Morganucodontans are best known by isolated elements and relatively complete skulls of several species of Morganucodon from the Lower Jurassic of Wales and China; this group is fundamental to our understanding of the early evolution of mammals. Cifellilestes ciscoensis gen. et sp. nov. possesses derived features of the snout paired with plesiomorphic construction of the molars; the distal premolars are complex and there is an unusually low count (two) of strongly imbricated molars. This character combination expands craniodental variation for the group. We sampled mudstone from the Cisco Mammal Quarry for ash-fall zircon analysis and obtained a date of 151.50 ± 0.28 Ma. This dates the locality to the earliest Tithonian and slightly younger than other major dated mammalbearing localities in the Morrison Formation. Cifellilestes represents one of the youngest members of this group and extends the record of morganucodontans in North America by more than 30 Ma. Morganucodontans are a rare component of Late Jurassic faunas but display surprising dental diversity through variations in a tooth count and cusp morphology of a deeply conserved, generalized mammalian tooth pattern, which was fully established in brasilodontid (non-mammalian) ancestors at least 80 my prior.
Źródło:
Acta Palaeontologica Polonica; 2022, 67, 1; 77-93
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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