20 February 2017

Fossil eggshells of Guegoolithus turolensis are also present in the Lower Cretaceous of Cameros (La Rioja, Spain)

Guegoolithus turolensis from the El Horcajo site (La Rioja). Scanning electron microscope microphotographs (a-d), petrographic microscope photograph in parallel nicols (e), and petrographic microscope photograph in cross nicols.


Moreno-Azanza et al. (2016) described the new fossil site of El Horcajo in the vicinity of Trevijano (La Rioja, Spain). It is located in the palustrine facies of the Enciso Group (Cameros Basin). This new locality has provided dozens of eggshell fragments, together with other vertebrate remains and charophyte fructifications, which allow dating of the locality as Valanginian-Hauterivian. Five ootaxa have being recognized: 1) the Spheroolithidae Guegoolithus turolensis; 2) a surprisingly thick Prismatoolithidae indet., with certain affinities to the oogenus Sankofa, that may represent a new oogenus and oospecies for this oofamily; 3) the Krokolithidae Krokolithes sp.; 4) recrystallized Testudoolithidae? eggshells; and 5) ?Geckoolithidae eggshells of uncertain affinity. 

This oodiversity is similar to that of other eggshell microsites. The ootaxonomic list differs from the other Iberian locality of the same age, Pochancalo 1 (Villanueva de Huerva Formation, Zaragoza) in lacking sauropod and megalosauroid theropod eggshells, but shares the presence the ornithopod and coelurosaurian theropod eggshells with other younger microsites found in similar facies. The age of the new locality has immediate consequences for the tectono-sedimentary framework of the Cameros Basin, and the new data will need to be considered in future stratigraphical works. Furthermore, the reliability of eggshells as biostratigraphic markers is questioned, and the viability of Guegoolithus as a guide fossil for the lower Barremian is rejected.

Eggshells of Guegoolithus have been recovered in many localities of the neighboring Iberian Basin, but its presence was restricted to the lower Barremian. If the Hauterivian-Valanginian age of El Horcajo is confirmed, it would imply that these eggs where laid in the Iberian Peninsula up to seven million years before than previously thought. Guegoolithus has been tentatively related to iguanodontoid dinosaurs on the basis of their resemblance to eggshells assigned to derived ornithopods from the Upper Cretaceous of North America and, more recently, from the Lower Cretaceous of Asia.

Reference:

Moreno-Azanza, M., Gasca, J.M., Díaz-Martínez, I., Bauluz Lázaro, B., Canudo Sanagustín, J.I., Fernández, A. Pérez-Lorente, F. 2016. A multi-ootaxic assemblage from the Lower Cretaceous of the Cameros Basin (La Rioja; Northern Spain). Spanish Journal of Palaeontology, 31 (2), 305-320. DOWNLOAD HERE

04 July 2016

Dinosaurs from the heart of Maestrazgo reach Argentina

A complete overview of the dinosaur record from the Barremian of Ladruñán, in the heart of Maestrazgo (Teruel province), was showed in the last annual meeting of vertebrate paleontology of Argentina, which took place in Buenos Aires (Museo Argentino de Ciencias Naturales "Bernardino Rivadavia").

This is the reference:
Gasca, J.M., Moreno-Azanza, M., Díaz-Martínez, I. Castanera, D., Canudo, J.I.- La Formación Mirambel: evidencia de un sistema aluvial-lacustre barremiano en el sur de Europa frecuentado por los dinosaurios. XXX JORNADAS ARGENTINAS DE PALEONTOLOGíA DE VERTEBRADOS. Buenos Aires (Argentina), 17-20 de Mayo del 2016, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” 

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

14 March 2016

Last gasps of winter

Last gasps of winter are seen this days and Lower Cretaceous outcrops from Maestrazgo are being cleared of snow: foreshadowing of many paleontological novelties ahead with good weather. The picture is a high-angle shot of the village of Allepuz (Teruel province, Spain) above Sollavientos river; opposite, the terraced hillside is formed by Barremian marine and transitional units, whereas the valley of the Alfambra river appears behind, with Wealden facies outcropping at bottom. On the background, Mesozoic materials (from Triassic to basal Cretaceous) are covered by pine forests.

30 October 2015

Vertebrate microfossils from the Camarillas Formation

Vertebrate microfossils from the locality of El Espeltar, Camarillas Formation, Teruel province, Spain: isolated teeth of crocodylomorphs (a-f: goniopholidids, atoposaurids and bernissartids); g-h- osteichthyes (g-h) and chondrichtyes (i).Vertebrate microfossil accumulations are frequent in some layers from the Wealden facies of the Galve subbasin such as those from the lacustrine El Castellar Formation. However they are not as abundant in the overlaying Camarillas Formation, with dominantly fluvial character and Barremian in age.

Reference:
Gasca, J.M., Moreno-Azanza, M. y Canudo, J.I. 2011. Dientes de dinosaurios en el Barremiense de Allepuz, Teruel. Viajando a mundos pretéritos (eds. Pérez-García, A., Gascó, F., Gasulla, J.M. y Escaso, F.), Ayuntamiento de Morella, 145-155.DOWNLOAD

25 August 2015

European iguanodont dinosaurs: the Spanish Delapparentia turolensis vs the English Barilium dawsoni

Delapparentia turolensis Ruiz-Omeñaca, 2011 was the first ornithopod erected in the Lower Cretaceous of Spain. It is described on the basis of a partial postcranial skeleton discovered in the 1950s near the village of Galve (Teruel Province), within the Camarillas Formation (Barremian). Recently, new remains have been recovered and described. Delapparentia turolensis is a large-sized, basal iguanodont which presents an autapomorphic, unusually high axial neural spine and a unique combination of postcranial characters. The ilium morphology differs from that of other basal iguanodonts and relates Delapparentia to the Valanginian Barilium dawsoni from England, with whom it shares two synapomorphies.

Reference;
Gasca, J.M., Moreno-Azanza, M., Ruiz-Omeñaca, J.I., Canudo, J.I. 2015. New material and phylogenetic position of the basal iguanodont dinosaur Delapparentia turolensis from the Barremian (Early Cretaceous) of Spain. Journal of Iberian Geology, 41 (1), 57-70. DOWNLOAD HERE

16 June 2015

New dinosaur fossils from the Mirambel Formation

New dinosaur fossils (ornithopods and sauropods) have been described in the Lower Cretaceous of Spain. In the picture an overview of the Lower Cretaceous badlands (Wealden facies) where one of the fossil sites is placed, in the Ladruñán anticline. The relief on the background consist of Upper Cretaceous marine limestones. This is the "Barrancada del Convento" site which has provided an isolated ornithopod phalanx. The short papers are available here:
Gasca, J.M., Canudo, J.I. 2015. Sobre la presencia de Sauropoda (Dinosauria) en la Formación Mirambel (Barremiense inferior, Teruel, España). Geogaceta, 57, 59-62. DOWNLOAD
Gasca, J.M., Ramón del Río, D., Moreno-Azanza, M., Canudo, J.I. 2015. Fósiles aislados de dinosaurios ornitópodos (Iguanodontia) de la Formación Mirambel (Cretácico Inferior, Teruel, España). Geogaceta, 57, 63-66. DOWNLOAD