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Aragosaurus fossils redated



From: Ben Creisler
bh480@scn.org


A new online paper:

J. I. CANUDO, J. M. GASCA, M. MORENO-AZANZA and M. AURELL 
(2011)
New information about the stratigraphic position and age 
of the sauropod Aragosaurus ischiaticus from the Early 
Cretaceous of the Iberian Peninsula.
Geological MagazineGeological Magazine (advance online 
publication)
DOI: 10.1017/S0016756811000732
http://128.232.233.5/action/displayAbstract?
fromPage=online&aid=8365749&fulltextType=RA&fileId=S001675
6811000732

The sauropod Aragosaurus ischiaticus Sanz, Buscalioni, 
Casanovas & Santafé, 1987 was the first dinosaur to be 
described in Spain. The holotype was recovered from the 
site of Las Zabacheras (Galve, Teruel province). This 
site has traditionally been situated in the El Castellar 
Formation (in the lower part of the Wealden facies). 
Recently, it has been proposed that the remains of 
Aragosaurus stem from the Villar del Arzobispo Formation 
(late Tithonian?upper part of the early Berriasian), 
which would mean that the sauropod was almost 15 million 
years older than previously thought. Detailed field work 
has been carried out, making it possible to pinpoint the 
position of the low-angle unconformity between the Villar 
del Arzobispo Formation and the El Castellar Formation. 
This unconformity originated as a result of block tilting 
that occurred during the early stages of the Early 
Cretaceous rifting episode. The upper levels of the 
Jurassic sequence (i.e. the Villar del Arzobispo 
Formation) were exposed to erosion and karstification, 
leading to the formation of a discontinuous conglomeratic 
level. This level has been locally preserved at the 
bottom of the Wealden syn-rift sequence (i.e. the El 
Castellar Formation). The results of our detailed mapping 
demonstrate that the Aragosaurus holotype was found in 
the lower part of the El Castellar Formation. Moreover, 
our revision of the existing datings suggests that the El 
Castellar Formation as a whole is Valanginian??early 
Barremian in age. Given that Aragosaurus was located in 
its lower part, it is probably Valanginian??Hauterivian 
in
age.