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Where are the egg shells



Bakker (1990) described tightly-packed pods of 6 to 35 individuals which he interpreted as representing groups of Drinker in burrows, perhaps drowned by flooding or killed by disease. If Drinker was indeed a burrower, it would be among the first known for dinosaurs; the only well-supported published case of a fossorial nonavian dinosaur is the more recently discovered, distantly related Oryctodromeus. One problem with Bakker's interpretation was the lack of fossilized egg shell fragments amongst the individuals which he stated (1992) was a family group of many juvenile/hatchlings with adults within a nesting burrow found in Como Bluff, Wyoming.

Supporting the nesting burrow idea, is it possible that a behavior amongst Drinker, and possibly other small ornithopods, were for the adults to consume the egg shell fragments after the the babies hatched as a means to replenish their loss of calicum, and thus no egg shell fragments to be found in the nest? Egg and egg shell eating is common amongst the birds ("Dinosaurs") today.

References:

-- Bakker, R.T., Galton, P.M., Siegwarth, J., and Filla, J. (1990). A new latest Jurassic vertebrate fauna, from the highest levels of the Morrison Formation at Como Bluff, Wyoming. Part IV. The dinosaurs: A new Othnielia-like hypsilophodontoid. Hunteria 2(6): 8-14. -- Bakker, R.T. (1990). A new latest Jurassic vertebrate fauna, from the highest levels of the Morrison Formation at Como Bluff, Wyoming, with comments on Morrison biochronology. Part I. Biochronology. Hunteria 2(6):1-3. -- Bakker, R. T. (1997). "Dinosaur mid-life crisis: the Jurassic-Cretaceous transition in Wyoming and Colorado". In Lucas, S.G., Kirkland, J.I., and Estep, J.W. (eds.). Lower and Middle Cretaceous Terrestrial Ecosystems. New Mexico Museum of Natural History and Science Bulletin 14. New Mexico Museum of Natural History and Science. pp. 67–77. -- Varricchio, David J.; Martin, Anthony J.; and Katsura, Yoshihiro (2007). "First trace and body fossil evidence of a burrowing, denning dinosaur". Proceedings of the Royal Society B: Biological Sciences 274 (1616): 1361–1368. -- Dinosaur Parents, Dinosaur Young: Uncovering the Mystery of Dinosaur Families By Kathleen Weidner Zoehfeld; HMH Books for Young Readers (January 22, 2007) ISBN-10: 0618752447 pgs: 31-32.