Pararhabdodon

Taxobox
name = "Pararhabdodon"
status = fossil
fossil_range = Late Cretaceous
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Ornithischia
subordo = Ornithopoda
infraordo = Iguanodontia
superfamilia = Hadrosauroidea
familia = Hadrosauridae depending on definition
genus = "Pararhabdodon"
species = "P. isonensis"
binomial = "Pararhabdodon isonensis"
binomial_authority = Casanovas-Cladellas, Santafé-Llopis, and Isidoro-Llorens, 1993

"Pararhabdodon" (meaning "similar to "Rhabdodon" ["bar-tooth"] ) was a genus of derived hadrosauroid or basal hadrosaurid dinosaur, from the Maastrichtian-age Upper Cretaceous Tremp Formation of Spain. It is based on assorted postcranial remains, mostly vertebrae, and is notable for the reassignments it has undergone in regards to classification.

History

In 1987, Casanovas "et al". described remains of an ornithopod from northeastern Spain, including a cervical vertebra, some partial dorsals, a humerus, and a fragmentary scapula, as "Rhabdodon" sp.Casanovas, M.L, Santafé, J.S., Sanz, J.L., and Buscalioni, A.D. (1987). [Archosaurs (Crocodilia, Dinosauria) from the Upper Cretaceous of the Tremp Basin (Lleida, Spain)] . "Estudios Geológicos". Volumen extraordinario Galve-Tremp:95-110. [Spanish] ] New remains from this site (Tremp Formation, near Isona, Lleida, Spain) brought about a reconsideration of the material, and Casanovas-Cladellas "et al". named "Pararhabdodon isonense" in 1993 from a middle caudal vertebra (IPS-SRA-15), referring additional material to their new genus.Casanovas-Cladellas, M.L., Santafé-Llopis, J.V., and Isidoro-Llorens, A. (1993). ["Pararhabdodon isonense" n. gen. n. sp. (Dinosauria). Morphology, radio-tomographic study, and biomechanic considerations] . "Paleontologia i Evolució" 26-27:121-131. [Spanish] ] At the time, it was considered to be a rhabdodont-like basal iguanodont, hence the name.

Additional material from the type locality was collected in 1994, and the species name was corrected to "isonensis" in 1997 by Casanovas-Cladellas "et al". and Laurent "et al".Casanovas, M.L, Pereda-Suberbiola, X., Santafé, J.V., and Weishampel, D.B. (1999). First lambeosaurine hadrosaurid from Europe: palaeobiogeographical implications. "Geological Magazine" 136(2):205-211.] Laurent, Y., LeLoeuff, J., and Buffetaut, E. (1997). [The Hadrosauridae (Dinosauria, Ornithopoda) from the Upper Maastrichtian of the eastern Corbières (Aude, France)] . "Revue de Paléobiologie" 16:411-423. [French] ] A dentary (IPS SRA 27) from a second quarry in the Tremp Formation was also referred to the genus, now considered to be a basal lambeosaurine hadrosaurid. Laurent "et al" referred additional remains (jaw material, vertebrae, and limb bones of multiple individuals of different ages) from the uppermost Cretaceous of Aude, France, to the genus, but this was not discussed in the most recent review.Prieto-Marquez, A., Gaete, R., Rivas, G., Galobart, Á., and Boada, M. (2006). Hadrosauroid dinosaurs from the Late Cretaceous of Spain: "Pararhabdodon isonensis" revisited and "Koutalisaurus kohlerorum", gen. et sp. nov. "Journal of Vertebrate Paleontology" 26(4): 929-943.] (Oddly, the second edition of "The Dinosauria" omitted this genus altogether)

Head (2001) disputed the assignment to the Lambeosaurinae, considering it more likely to be basal to the two hadrosaurid subfamilies.Head, J.J. (2001). A reanalysis of the phylogenetic position of "Eolambia caroljonesa" (Dinosauria, Iguanodontia). "Journal of Vertebrate Paleontology" 21(2):392-396.] This is the same conclusion that Prieto-Marquez "et al." (2006) came to, finding it to be the sister group to Hadrosaurinae+Lambeosaurinae ( = Hadrosauridae in their analysis, although the definition of Hadrosauridae varies). Prieto-Marquez assigned IPS SRA 27 to its own genus, "Koutalisaurus", a more derived hadrosaurid.

Paleobiology

"Pararhabdodon" most likely was a bipedal-quadrupedal herbivore, in the neighborhood of 6 m (19.7 ft) long, fully grown. The dorsal and sacral neural spines were elongate, so the animal would have had a tall back, like other hadrosaurids. Because the material is sparse, more specific conclusions cannot be reached. Spanish material includes: a maxilla; four cervical, four dorsal, and a caudal vertebra; a sacrum; the end of an ischium; and a humerus.

References