Name: Nqwebasaurus thwazi
Etymology: From the Xhosa 'Nqweba' (the name of the Kirkwood region in which it was discovered), and the Greek 'sauros' (lizard); and from the Xhosa 'thwazi' (fast running)
Distribution: Early Cretaceous (Berriasian-Valanginian) of South Africa
Type Specimen: Fragmentary skull and nearly complete skeleton
Estimated size: 0.9 m in length (juvenile)
First described by: de Klerk et al., 2000
Image from de Klerk et al., (2000)
Modern day herbivorous avian dinosaurs (birds) use gastroliths to help in the digestion of plant matter, and aquatic carnivorous animals such as crocodiles, alligators, seals, and sea lions use them for ballast or stability. However, some doubt still surrounds these theories for gastrolith use, especially as to the true function of gastroliths in non-avian dinosaurs (see the UCMP Berkeley page on gastroliths for an overall summary). Wings (2007, pp 1) provides an even more detailed review of gastrolith use, and lists the following possible reasons for swallowing rocks:
... mineral supply and storage, stomach cleaning, maintenance of a beneficial microbial gut flora, destruction of parasites and alleviation of hunger. Accidental ingestion of sediment, either by being mistaken for prey, by being attached to it, during playing or due to pathological behaviour, is considered to be common...
Charig, A. J., Milner, A. C. 1986. Baryonyx, a remarkable new theropod dinosaur. Nature 324: 359-361.
de Klerk, W. J., Forster, C. A., Sampson, S. D., Chinsamy, A., Ross, C. F. 2000. A new coelurosaurian dinosaur from the Early Cretaceous of South Africa. Journal of Vertebrate Paleontology 20 (2): 324-332
Ji, Q., Currie, P.J., Norell, M.A., Ji, S. (1998). Two feathered dinosaurs from northeastern China. Nature 393 (6687): 753–761
Wings, O. 2007. A review of gastrolith function with implications for fossil vertebrates and a revised classification. Acta Palaeontologica Polonica 52 (1): 1–16