06 May 2016

Aragosaurus and Galvesaurus were not contemporary dinosaurs

Despite the noise generated previously in the scientific literature, a new study makes clear that the sauropod dinosaurs Aragosaurus (from the Cretaceous Galve Formation) and Galvesaurus (from the Jurassic Villar del Arzobispo Formation) correspond to different geological units and ages.

A review of the stratigraphy of the Galve sub-basin (western Maestrazgo Basin, eastern Spain) around the Jurassic-Cretaceous transition has been presented based on new data acquired after extensive geological mapping and logging complemented with facies analysis, new biostratigraphic data and a revision of the published information available. New information on the age and setting of numerous dinosaur fossil- and track-sites found across the Galve sub-basin and in the northern part of the nearby Penyagolosa sub-basin is provided here. Two new lithostratigraphic units are defined and characterized, the Aguilar del Alfambra and the Galve formations. The previous stratigraphic framework considered only two
lithostratigraphic units (the Villar del Arzobispo and El Castellar formations) bounded by a single regional unconformity, and this resulted in significant misinterpretations. 

The whitish limestones, red lutites and cross-bedded sandstones of the Aguilar del Alfambra Formation were deposited in transitional environments, ranging from coastal lutitic plains to restricted lagoons. Of particular interest are the laminated micritic-peloidal limestones with abundant fenestral porosity (supratidal ponds to intertidal flats), which preserve common dinosaur footprints. 

The overlying Galve Formation is of variable thickness (from 0–100 m) and is also bounded by regional unconformities described in detail here. It consists of red lutites with cross-bedded and tabular-burrowed sandstones representing channel and overflow deposits in an alluvial floodplain. The sauropod dinosaur Aragosaurus ischiaticus found in this unit has a controversial age assignment. The age of the Galve Formation is poorly constrained from late Berriasian to Hauterivian, but new biostratigraphic data presented here, combined with the correlation with the nearby Penyagolosa and Salzedella sub-basins, suggest a possible equivalence to the upper Berriasian–lower Valanginian sequence deposited during the initial stage of syn-rift sequence 2.

Reference:

Aurell, M., Bádenas, B., Gasca, J.M., Canudo, J.I., Liesa, C.L., Soria, A.R., Moreno-Azanza, M., Najes, L., Stratigraphy and evolution of the Galve sub-basin (Spain) in the middle Tithonian–early Barremian: Implications for the setting and age of some dinosaur fossil sites, Cretaceous Research (2016), doi: 10.1016/j.cretres.2016.04.020.DOWNLOAD

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