[D] Camarillasaurus cirugedae [sG] [T]
Sánchez-Hernández & Benton 2012
Cretaceous Early Barremian
Saurischia Theropoda Ceratosauria
Camarillas Formation, Camarillas, Teruel Province, Spain
Ceratosaurian theropods evolved in two bursts, first in the Middle and Late Jurassic and then in the Late Cretaceous, leaving a 20 Myr gap in the Early Cretaceous during which remains are rare. We describe here a new ceratosaurian theropod, Camarillasaurus cirugedae, from fluvial deposits of the Camarillas Formation (lower Barremian, Lower Cretaceous) of Camarillas, Teruel Province, NE Spain. The new theropod is represented by a collection of associated bones, including a tooth, a possible cervical vertebra, two sternal plates, the proximal part of a right tibia, a broken right scapulocoracoid, the incomplete sacrum, five caudal vertebrae, an isolated caudal neural arch, a chevron, an almost complete presacral rib and some fragments of vertebrae, ribs, and other elements. Camarillasaurus is differentiated from other theropods by the extreme depth of the tibia proximal end, and a deep longitudinal groove on the tibia.
Camarillasaurus cirugedae is a ceratosaur, phylogenetically close to the base of the clade, and perhaps more derived than the Chinese basal ceratosaur Limusaurus. The new taxon is significant in the evolution of the ceratosaurian dinosaurs, being placed temporally between its more common Jurassic and middle-Upper Cretaceous relatives, and it is one of only a few from Laurasia.
The bones of the new dinosaur were found associated with remains of other dinosaurian taxa, including a small theropod and isolated coprolites. The fossils come from a rock outcrop in a farm field, which, according to the discoverer of the dinosaur remains, is called Fuente Arnar, within the land of the Pedro Cirugeda Buj family, close to Camarillas village. The fossils are disarticulated, but they were all found at the same time and within an area of approximately five square metres during ploughing
Camarillas is the name of the locality and formation where the bones were found, and saurus is reptile. The species name cirugedae comes from the surname of the person who found the bones, Pedro Cirugeda Buj.
Specimen MPG-KPC1-46, a partial tooth, and associated isolated vertebrae, ribs, and limb elements. The close physical association of all the bones, their corresponding sizes, and independent evidence of ceratosaurian and/or abelisauroid characters in each suggest that all come from one taxon and one individual.
In detail, the holotype consists of the apical part of a lateral tooth (MPG-KPC43), two almost complete sternal plates (MPG-KPC1, 2) and isolated remains of sternal plates (MPG-KPC34-38), a broken right scapulocoracoid (MPG-KPC23, 30), an almost complete presacral rib (MPG165 KPC7), some rib fragments (MPG-KPC45 and 47-50), a posterior cervical or anterior dorsalvertebra (MPG-KPC9), an almost complete mid-dorsal vertebra (MPG-KPC21), two broken dorsal centra (MPG-KPC20 and 17), a broken sacrum (MPG-KPC3, 4), two sacral vertebral centra (MPG-KPC16, 18), an isolated neural arch (MPG-KPC39), a broken portion of a lateral side of a centrum with prezygapophysis (MPG-KPC51), three broken anterior caudal vertebral centra (MPG-KPC14, 15, 19), four mid-posterior caudal vertebrae (MPG-KPC10-13), a broken posterior caudal centra (MPG-KPC46), a broken portion of a vertebral centrum (MPG-KPC22), three possible broken tops of neural spines (MPG-KPC-31, 32 and 33), an almost complete chevron (MPG-KPC5, 6), an isolated broken blade of a chevron (MPG-KPC44), a proximal part of a right tibia (MPG-KPC8), and several isolated broken fragments of bones.
Fuente Arnar outcrop, near Camarillas village, Teruel Province, Aragón, NE Spain.
Light brown clay and limestone beds, in which fossil wood remains are common, of the Camarillas Formation, lower Barremian, Lower Cretaceous (Díaz and Yébenes 1987; Sánchez-Hernández et al. 2007).
A ceratosaur (see Discussion) with the following two autapomorphies: extremely broad tibia proximal end, with ratio of anteroposterior/mediolateral axis of 2.8 (the highest of any theropod); tibia with a central narrow deep longitudinal groove placed anterolaterally to the crista fibularis on the medial surface which gives a g-shaped cross-section to the tibial shaft. Other characters include the chevron with a deep broad longitudinal groove along the length of the shaft arising from a fossa placed below the haemal canal on the anterior and posterior side; presence of an articular surface on the distal end of the chevron blade; caudal vertebrae with articular surfaces that have well developed edges and are unusually broad.