Wednesday, February 19, 2014

Quirks in the cladistic analysis of Lourinhasaurus

It's been barely a year since the second of the three Jurassic Portuguese sauropods, the brachiosaurid titanosauriform Lusotitan ataialensis, was put in a cladistic context by Mannion et. al. (2013). Now, Mocho et. al. (2014) have published a paper re-assessing the cladistic position of the third described Portuguese sauropod, Lourinhasaurus alenquerensis, following in the footsteps of Mannion et. al. (2012, 2013) in putting all of Portugal's sauropod taxa in a phylogenetic context.

As we all know, Lourinhasaurus was originally assigned to Apatosaurus by Lapparent and Zbyszewski (1957) and later referred to Camarasaurus by McIntosh (1990). However, Dantas et. al. (1998) removed alenquerensis from Camarasaurus and assigned it to a new genus Lourinhasaurus. Because the original description of this taxon had a rather inadequate diagnosis, Upchurch et. al. (2004) found it to be in an unstable position in Eusauropoda.

When browsing through the supplementary material for Mocho et. al. (2014), it's interesting that while the cladistic analyses both recover a monophyletic Camarasauridae formed by Camarasaurus, Lourinhasaurus, and Tehuelchesaurus, they treat nemegtosaurids as diplodocoids rather than titanosaurs and Haplocanthosaurus as a macronarian rather than a diplodocoid, while failing to support a monophyletic Euhelopodidae sensu D'Emic (2012). However, this is likely due to the failure of Mocho et. al. (2014) to incorporate characters from the cladistic analyses of D'Emic (2012) and Whitlock (2011).

If Camarasauridae sensu Mocho et. al. (2014) holds up in future cladistic analyses concerning the interrelationships of non-titanosauriform macronarians, then Lourinhasaurus would be closely related to Camarasaurus as stated by McIntosh (1990). However, putative camarasaurids like Dashanpusaurus were not included by Mocho et. al. (2014), so it's unclear whether Camarasauridae had a cosmopolitan distribution in the Jurassic.

D'Emic, M.D., 2012. The early evolution of titanosauriform sauropod dinosaurs. Zoological Journal of the Linnean Society 166 (3): 624–671.

Dantas, P., Sanz, J. L., Marques da Silva, C., Ortega, F., dos Santos V.F., & Cachão, M. 1998. Lourinhasaurus n. gen. Novo dinossáurio saurópode do Jurássico superior (Kimmeridgiano superior-Tithoniano inferior) de Portugal. Comunicações do Instituto Geológico e Mineiro 84 (1A) : 91-94.

Lapparent, A.F. de; & Zbyszewski, G. 1957. Les dinosauriens de Portugal. Mém. Serv. géol. Port. 2: 1-63.

Mannion, P. D., Upchurch P., Mateus O., Barnes R. N., & Jones M. E. H., 2012. New information on the anatomy and systematic position of Dinheirosaurus lourinhanensis (Sauropoda: Diplodocoidea) from the Late Jurassic of Portugal, with a review of European diplodocoids. Journal of Systematic Palaeontology. 10(3), 521–551.

Mannion, P. D., Upchurch P., Barnes R. N., & Mateus O., 2013. Osteology of the Late Jurassic Portuguese sauropod dinosaur Lusotitan atalaiensis (Macronaria) and the evolutionary history of basal titanosauriforms. Zoological Journal of the Linnean Society 168: 98206.

McIntosh, J.S. 1990. Sauropoda. pp. 345-501. In: Weishampel, D.B.; Dodson, P.; & Osmólska, H. (eds.): The Dinosauria. Berkeley (University of California Press).

Mocho, P., Royo-Torres, R., and Ortega, F., 2014. Phylogenetic reassessment of Lourinhasaurus alenquerensis, a basal Macronaria (Sauropoda) from the Upper Jurassic of Portugal. Zoological Journal of the Linnean Society (advance online publication) DOI: 10.1111/zoj.12113http://onlinelibrary.wiley.com/doi/10.1111/zoj.12113/abstract

Upchurch, P., Barrett, P.M. and Dodson, P. 2004. Sauropoda. In: The Dinosauria, 2nd edition. D. Weishampel, P. Dodson, and H. Osmólska (eds.). University of California Press, Berkeley. pp. 259–322.

Whitlock, J.A., 2011. A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda). Zoological Journal of the Linnean Society 161: 872–915.