Name: Ruehleia bedheimensis
Etymology: In honour of the collector of the fossil, Hugo Ruhle von Lilienstern of Bedheim, South Thuringia.
Distribution: Late Triassic (Norian) of Thuringia, Germany.
Type Specimen: near complete composite skeleton lacking a skull.
Estimated size: ~6.5 m long
First described by: Galton, 2001a. Originally referred to Plateosaurus plieningeri HUENE, 1907-08 by Ruhle von Lilienstern et al. (1952).
It all comes down to identification and classification of specific bones.
Most animals with a backbone or spine (vertebral column) have sacral vertebrae: the part of the vertebral column that sits between the hips. Early dinosaurs had two sacral vertebrae, but some prosauropods had an extra sacral vertebrae, either being 'borrowed' from the tail end (caudosacrum - see below figure, bottom left) or from the head-end (dorsosacrum - see below figure, bottom right) of the vertebral column.
So, not only can you find new dinosaur species or genera by going into the field and digging up new fossils, or by scouring museum collections for unlabelled or uncategorised specimens, you can also find them as well preserved fossils already assigned to a species and hiding in plain site!
Galton, P. M., 2001a. Prosauropod dinosaurs from the Upper Triassic of Germany. In: Colectivo Arqueológico - Paleontológico De Salas (Eds.): Actas de las I Jornadas Internacionales Sobre Paleontología de dinosaurios y su entorno. Junta de Castilla y León, Salas de los Infantes (Burgos, España): 25-92.
Galton, P. M., 2001b. The prosauropod dinosaur Plateosaurus Meyer, 1837 (Saurischia: Sauropodomorpha; Upper Triassic). II. Notes on the referred species. Revue Paléobiologie, Genève 20(2): 435-50
Galton, P. M., Upchurch, P. 2004. Prosauropoda. In Weishampel, D. B., Dodson, P., and Osmolska, H. (eds.), The Dinosauria (second edition). University of California Press, Berkeley, pp 232-258
von Lilienstern, R., Lang, H. M., Huene, F. v., 1952. Die Saurier Thüringens. Fischer. Jena, 42 p.