Recovering Missing Morphological Data in Vertebrate Animals

An interesting new paper that proposes a method using regression equations to determine the position of preserved vertebrae in the caudal region (tail) of the herrerasaurid Staurikosaurus pricei and also provides estimates for the number and dimensions of missing vertebral elements.

Grillo, O. N., and S. A.K. Azevedo. in press.Recovering missing data: estimating position and size of caudal vertebrae in Staurikosaurus pricei Colbert, 1970. Anais da Academia Brasileira de Ciências ahead of print Epub Feb 04, 2011. doi: 10.1590/S0001-37652011005000003  



Abstract - Missing data is a common problem in paleontology. It makes it difficult to reconstruct extinct taxa accurately and restrains the inclusion of some taxa on comparative and biomechanical studies. Particularly, estimating the position of vertebrae on incomplete series is often non-empirical and does not allow precise estimation of missing parts. In this work we present a method for calculating the position of preserved middle sequences of caudal vertebrae in the saurischian dinosaur Staurikosaurus pricei, based on the length and height of preserved anterior and posterior caudal vertebral centra. Regression equations were used to estimate these dimensions for middle vertebrae and, consequently, to assess the position of the preserved middle sequences. It also allowed estimating these dimensions for non-preserved vertebrae. Results indicate that the preserved caudal vertebrae of Staurikosaurus may correspond to positions 1-3, 5, 7, 14-19/15-20, 24-25/25-26, and 29-47, and that at least 25 vertebrae had transverse processes. Total length of the tail was estimated in 134 cm and total body length was 220-225 cm.