Functional Aspects of Titanosaur Osteoderms.

• Main Author: Thiago da Silva Marinho
• Format: Article
• Language: English
• Published: Universidade Federal do Rio de Janeiro 2007-07-01
• Series: Anuário do Instituto de Geociências
• Online Access: http://www.anuario.igeo.ufrj.br/anuario_2007_1/2007_1_comunic_251.pdf

Although titanosaur osteoderms are not commonfindings, these elements are recorded widely inGondwana and part of Laurasia. This assembly knownby the date offers few resources for studies on theecology of this group of dinosaurs. Recently, someeggs bearing titanosaur embryos with preserved skin,from Patagonia, Argentina, may shed some light onthe function and disposition pattern of these dermicbones. Some of the skin patches associated with thetitanosaur embryos show two distinct patterns oftuberosities: a longitudinal row and rosettes, bothcomposed of closely attached tuberosities. Thesetuberosities do not seem to be ossified, but this mightbe due to the ontogenetic stage of the titanosaurs.Here is proposed that these tuberosities might havebeen ossified in later ontogenetic stages, and thenturning into real osteoderms providing physicaldefense for the juvenile titanosaurs. Amongst theremains of large titanosaurs like Mendozasaurusneguyelap some osteoderms were recovered, but itis contrasting small to the animals when comparedto other dinosaurs and crocodyliforms. These boneswould not provide real defensive advantage to anadult titanosaur as they are small and also havea very spongy internal structure. This apparentfragility also may be the reason that few titanosaurosteoderms have been preserved. In comparison,the tuberosity of a young titanosaur is much largerthan an adult osteoderm and its body armor wouldbe much more effective against small predators likenotosuchian crocodyliforms and small theropods.And if the titanosaur osteoderms are originated fromthe embryo’s tuberosities, the disposition of theseelements in an adult animal would be very distant toeach other. Therefore, the function of osteoderms inadult titanosaurs would have been of calcium reserverather defensing.