Another new ref in Geological Magazine

[jigruiz@unizar.es]

D.I. WHITESIDE and J.E.A. MARSHALL. 2007. The age, fauna and  
palaeoenvironment of the Late Triassic fissure deposits of  
Tytherington, South Gloucestershire, UK Geological Magazine, Published  
online by Cambridge University Press 17 Sep 2007

Abstract ? Important vertebrate faunas occur in fissure deposits of  
Late Triassic?Jurassic age in SW Britain. Although the faunas are well  
described, their age and palaeoenvironment remain poorly understood.  
One such fissure system was documented in detail during quarrying  
operations at Tytherington and has yielded in situ palynomorphs that  
add much information concerning its age and palaeoenvironment.  
Significantly, the Tytherington fauna is of the sauropsid type that  
has generally been dated as Norian or pre-Penarth Group transgression  
and was also regarded as representing a distinct upland fauna. The  
palynomorphs, which include a significant marine component,  
demonstrate that the Tytherington Triassic fissures are infilled with  
Late Triassic (Rhaetian) sediments that match specific levels in the  
Westbury Formation. In addition, many of the Tytherington solutional  
fissures probably formed during the Rhaetian and are consistent with a  
fluctuating saline to freshwater environment. There is no prima facie  
evidence of solutional formation and infilling of the reptilebearing  
deposits before the Rhaetian trangression. The fissure reptile fauna,  
which includes the early dinosaur Thecodontosaurus, inhabited a small  
fire-swept limestone island in the Rhaetian sea. The features of the  
herpetofauna are entirely consistent with this island model which has  
Quaternary analogues.

Keywords: palynomorphs, Rhaetian, reptiles, transgression, dinosaurs,  
fissures, islands.

-------------------------------------------
Jose Ignacio Ruiz-Omeñaca
Museo del Jurásico de Asturias (MUJA)
E-33328 Colunga, Spain
www.museojurasicoasturias.com
www.aragosaurus.com
-------------------------------------------